CLINICAL PHARMACOLOGY
Mechanism Of Action
Sitagliptin
Sitagliptin is a DPP-4 inhibitor, which is believed to
exert its actions in patients with type 2 diabetes by slowing the inactivation
of incretin hormones. Concentrations of the active intact hormones are
increased by JUVISYNC, thereby increasing and prolonging the action of these
hormones. Incretin hormones, including glucagon-like peptide-1 (GLP-1) and
glucose-dependent insulinotropic polypeptide (GIP), are released by the
intestine throughout the day, and levels are increased in response to a meal.
These hormones are rapidly inactivated by the enzyme, DPP-4. The incretins are
part of an endogenous system involved in the physiologic regulation of glucose
homeostasis. When blood glucose concentrations are normal or elevated, GLP-1
and GIP increase insulin synthesis and release from pancreatic beta cells by
intracellular signaling pathways involving cyclic AMP. GLP-1 also lowers
glucagon secretion from pancreatic alpha cells, leading to reduced hepatic
glucose production. By increasing and prolonging active incretin levels,
JUVISYNC increases insulin release and decreases glucagon levels in the
circulation in a glucose-dependent manner. Sitagliptin demonstrates selectivity
for DPP-4 and does not inhibit DPP-8 or DPP-9 activity in vitro at
concentrations approximating those from therapeutic doses.
Simvastatin
Simvastatin is a prodrug and is hydrolyzed to its active β-hydroxyacid
form, simvastatin acid, after administration. Simvastatin is a specific inhibitor
of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, the enzyme that
catalyzes the conversion of HMG-CoA to mevalonate, an early and rate limiting
step in the biosynthetic pathway for cholesterol. In addition, simvastatin
reduces VLDL and TG and increases HDL-C.
Pharmacodynamics
Sitagliptin
General
In patients with type 2 diabetes, administration of
sitagliptin led to inhibition of DPP-4 enzyme activity for a 24-hour period.
After an oral glucose load or a meal, this DPP-4 inhibition resulted in a 2-to
3-fold increase in circulating levels of active GLP-1 and GIP, decreased
glucagon concentrations, and increased responsiveness of insulin release to glucose,
resulting in higher C-peptide and insulin concentrations. The rise in insulin
with the decrease in glucagon was associated with lower fasting glucose
concentrations and reduced glucose excursion following an oral glucose load or
a meal.
In a two-day study in healthy subjects, sitagliptin alone
increased active GLP-1 concentrations, whereas metformin alone increased active
and total GLP-1 concentrations to similar extents. Coadministration of
sitagliptin and metformin had an additive effect on active GLP-1
concentrations. Sitagliptin, but not metformin, increased active GIP
concentrations. It is unclear how these findings relate to changes in glycemic
control in patients with type 2 diabetes.
In studies with healthy subjects, sitagliptin did not
lower blood glucose or cause hypoglycemia.
Cardiac Electrophysiology
In a randomized, placebo-controlled crossover study, 79
healthy subjects were administered a single oral dose of sitagliptin 100 mg,
sitagliptin 800 mg (8 times the recommended dose), and placebo. At the
recommended dose of 100 mg, there was no effect on the QTc interval obtained at
the peak plasma concentration, or at any other time during the study. Following
the 800 mg dose, the maximum increase in the placebo-corrected mean change in QTc
from baseline was observed at 3 hours postdose and was 8.0 msec. This increase
is not considered to be clinically significant. At the 800 mg dose, peak
sitagliptin plasma concentrations were approximately 11 times higher than the
peak concentrations following a 100 mg dose.
In patients with type 2 diabetes administered sitagliptin
100 mg (N=81) or sitagliptin 200 mg (N=63) daily, there were no meaningful
changes in QTc interval based on ECG data obtained at the time of expected peak
plasma concentration.
Simvastatin
Epidemiological studies have demonstrated that elevated
levels of total-C, LDL-C, as well as decreased levels of HDL-C are associated
with the development of atherosclerosis and increased cardiovascular risk.
Lowering LDL-C decreases this risk. However, the independent effect of raising
HDL-C or lowering TG on the risk of coronary and cardiovascular morbidity and
mortality has not been determined.
Pharmacokinetics
General
JUVISYNC
The results of bioequivalence studies in healthy subjects
demonstrated that JUVISYNC (sitagliptin and simvastatin) is bioequivalent to
coadministration of sitagliptin and simvastatin as individual tablets.
Sitagliptin and simvastatin do not have a clinically
meaningful pharmacokinetic interaction.
Absorption
JUVISYNC
A high-fat breakfast did not affect sitagliptin exposure
following administration of JUVISYNC, while simvastatin AUC decreased by 24%,
simvastatin Cmax increased by 20%, and simvastatin acid AUC and Cmax increased
by 37% and 116%, respectively. The clinical significance of the above exposure
changes in simvastatin and simvastatin acid is not known. JUVISYNC is
recommended to be taken in the evening as indicated in simvastatin labeling.
Sitagliptin
The pharmacokinetics of sitagliptin has been extensively
characterized in healthy subjects and patients with type 2 diabetes. After oral
administration of a 100 mg dose to healthy subjects, sitagliptin was rapidly
absorbed, with peak plasma concentrations (median Tmax) occurring 1 to 4 hours
postdose. Plasma AUC of sitagliptin increased in a dose-proportional manner.
Following a single oral 100 mg dose to healthy volunteers, mean plasma AUC of
sitagliptin was 8.52 μM•hr, Cmax was 950 nM, and apparent terminal
half-life (t½) was 12.4 hours. Plasma AUC of sitagliptin increased
approximately 14% following 100 mg doses at steady-state compared to the first
dose. The intra-subject and inter-subject coefficients of variation for
sitagliptin AUC were small (5.8% and 15.1%). The pharmacokinetics of
sitagliptin was generally similar in healthy subjects and in patients with type
2 diabetes.
The absolute bioavailability of sitagliptin is
approximately 87%.
Simvastatin
Simvastatin is a lactone that is readily hydrolyzed in
vivo to the corresponding β-hydroxyacid (simvastatin acid), a potent
inhibitor of HMG-CoA reductase.
Peak plasma concentrations of simvastatin lactone and
simvastatin acid were attained within 1.5 and 4-6 hours postdose, respectively.
For simvastatin no substantial deviation from linearity of AUC of inhibitors in
the general circulation was observed at doses up to 120 mg.
Distribution
Sitagliptin
The mean volume of distribution at steady state following
a single 100 mg intravenous dose of sitagliptin to healthy subjects is approximately
198 liters. The fraction of sitagliptin reversibly bound to plasma proteins is
low (38%).
Simvastatin
Both simvastatin and its β-hydroxyacid metabolite
are highly bound (approximately 95%) to human plasma proteins. Rat studies
indicate that when radiolabeled simvastatin was administered, simvastatinÂderived
radioactivity crossed the blood-brain barrier.
Metabolism
Sitagliptin
Approximately 79% of sitagliptin is excreted unchanged in
the urine with metabolism being a minor pathway of elimination.
Following a [14C]sitagliptin oral dose,
approximately 16% of the radioactivity was excreted as metabolites of
sitagliptin. Six metabolites were detected at trace levels and are not expected
to contribute to the plasma DPP-4 inhibitory activity of sitagliptin. In vitro studies
indicated that the primary enzyme responsible for the limited metabolism of
sitagliptin was CYP3A4, with contribution from CYP2C8.
Simvastatin
The major active metabolites of simvastatin present in
human plasma are the β-hydroxyacid of simvastatin and its
6'-hydroxy, 6'-hydroxymethyl, and 6'-exomethylene
derivatives. Since simvastatin undergoes extensive first-pass extraction in the
liver, the availability of the drug to the general circulation is low ( < 5%).
Excretion
Sitagliptin
Following administration of an oral [14C]sitagliptin
dose to healthy subjects, approximately 100% of the administered radioactivity
was eliminated in feces (13%) or urine (87%) within one week of dosing. The
apparent terminal t½ following a 100 mg oral dose of sitagliptin was
approximately 12.4 hours and renal clearance was approximately 350 mL/min.
Elimination of sitagliptin occurs primarily via renal
excretion and involves active tubular secretion. Sitagliptin is a substrate for
human organic anion transporter-3 (hOAT-3), which may be involved in the renal
elimination of sitagliptin. The clinical relevance of hOAT-3 in sitagliptin transport
has not been established. Sitagliptin is also a substrate of p-glycoprotein,
which may also be involved in mediating the renal elimination of sitagliptin.
However, cyclosporine, a p-glycoprotein inhibitor, did not reduce the renal
clearance of sitagliptin.
Simvastatin
Following an oral dose of 14C-labeled
simvastatin in man, 13% of the dose was excreted in urine and 60% in feces.
Plasma concentrations of total radioactivity (simvastatin plus 14C-metabolites)
peaked at 4 hours and declined rapidly to about 10% of peak by 12 hours
postdose.
Special Populations
Renal Impairment
Sitagliptin
A single-dose, open-label study was conducted to evaluate
the pharmacokinetics of sitagliptin (50 mg dose) in patients with varying
degrees of chronic renal impairment compared to normal healthy control
subjects. The study included patients with renal impairment classified on the
basis of creatinine clearance as mild (50 to < 80 mL/min), moderate (30 to
< 50 mL/min), and severe ( < 30 mL/min), as well as patients with ESRD on
hemodialysis. In addition, the effects of renal impairment on sitagliptin
pharmacokinetics in patients with type 2 diabetes and mild or moderate renal
impairment were assessed using population pharmacokinetic analyses. Creatinine
clearance was measured by 24-hour urinary creatinine clearance measurements or
estimated from serum creatinine based on the Cockcroft-Gault formula:
Males: |
(weight in kg) x (140 – age) |
(72) x serum creatinine (mg/100 mL) |
Females |
(0.85) x (above value) |
Compared to normal healthy control subjects, an
approximate 1.1-to 1.6-fold increase in plasma AUC of sitagliptin was observed
in patients with mild renal impairment. Because increases of this magnitude are
not clinically relevant, dosage adjustment in patients with mild renal
impairment is not necessary. Plasma AUC levels of sitagliptin were increased
approximately 2-fold and 4-fold in patients with moderate renal impairment and
in patients with severe renal impairment, including patients with ESRD on
hemodialysis, respectively. To achieve plasma concentrations of sitagliptin
similar to those in patients with normal renal function, a lower dosage is
recommended in patients with moderate renal impairment. JUVISYNC should not be
used in patients with severe renal impairment. [See DOSAGE AND
ADMINISTRATION; WARNINGS AND PRECAUTIONS]
Hepatic Impairment
Sitagliptin
In patients with moderate hepatic impairment (Child-Pugh
score 7 to 9), mean AUC and Cmax of sitagliptin increased approximately 21% and
13%, respectively, compared to healthy matched controls following
administration of a single 100 mg dose of sitagliptin. These differences are
not considered to be clinically meaningful.
There is no clinical experience in patients with severe
hepatic impairment (Child-Pugh score > 9). Body Mass Index (BMI)
Sitagliptin
Body mass index had no clinically meaningful effect on
the pharmacokinetics of sitagliptin based on a composite analysis of Phase I
pharmacokinetic data and on a population pharmacokinetic analysis of Phase I and
Phase II data.
Gender
Sitagliptin
Gender had no clinically meaningful effect on the
pharmacokinetics of sitagliptin based on a composite analysis of Phase I
pharmacokinetic data and on a population pharmacokinetic analysis of Phase I
and Phase II data.
Geriatric
Sitagliptin
When the effects of age on renal function are taken into
account, age alone did not have a clinically meaningful impact on the
pharmacokinetics of sitagliptin based on a population pharmacokinetic analysis.
Elderly subjects (65 to 80 years) had approximately 19% higher plasma
concentrations of sitagliptin compared to younger subjects.
Simvastatin
In a study including 16 elderly patients between 70 and
78 years of age who received simvastatin 40 mg/day, the mean plasma level of
HMG-CoA reductase inhibitory activity was increased approximately 45% compared
with 18 patients between 18-30 years of age [see WARNINGS AND PRECAUTIONS;
Use In Specific Populations].
Pediatric
Sitagliptin
Studies characterizing the pharmacokinetics of
sitagliptin in pediatric patients have not been performed.
Race
Sitagliptin
Race had no clinically meaningful effect on the
pharmacokinetics of sitagliptin based on a composite analysis of available
pharmacokinetic data, including subjects of white, Hispanic, black, Asian, and
other racial groups.
Drug Interactions
Sitagliptin
In Vitro Assessment of Drug Interactions
Sitagliptin is not an inhibitor of CYP isozymes CYP3A4,
2C8, 2C9, 2D6, 1A2, 2C19 or 2B6, and is not an inducer of CYP3A4. Sitagliptin is
a p-glycoprotein substrate, but does not inhibit p-glycoprotein mediated
transport of digoxin. Based on these results, sitagliptin is considered
unlikely to cause interactions with other drugs that utilize these pathways.
Sitagliptin is not extensively bound to plasma proteins.
Therefore, the propensity of sitagliptin to be involved in clinically
meaningful drug-drug interactions mediated by plasma protein binding
displacement is very low.
In Vivo Assessment of Drug Interactions
Effects of Coadministered Sitagliptin and Simvastatin
on Other Drugs
Digoxin: There was an increase in the area under
the curve (AUC, 26%) and mean peak drug concentration (Cmax, 41%) of digoxin
with the coadministration of 100 mg sitagliptin and 80 mg simvastatin for 5
days. Patients receiving digoxin and JUVISYNC should be monitored.
Effects of Sitagliptin on Other Drugs
In clinical studies, as described below, sitagliptin did
not meaningfully alter the pharmacokinetics of metformin, glyburide, simvastatin,
rosiglitazone, warfarin, or oral contraceptives, providing in vivo evidence of
a low propensity for causing drug interactions with substrates of CYP3A4,
CYP2C8, CYP2C9, and organic cationic transporter (OCT).
Metformin: Coadministration of multiple twice-daily
doses of sitagliptin with metformin, an OCT substrate, did not meaningfully
alter the pharmacokinetics of metformin in patients with type 2 diabetes.
Therefore, sitagliptin is not an inhibitor of OCT-mediated transport.
Sulfonylureas: Single-dose pharmacokinetics of
glyburide, a CYP2C9 substrate, was not meaningfully altered in subjects
receiving multiple doses of sitagliptin. Clinically meaningful interactions
would not be expected with other sulfonylureas (e.g., glipizide, tolbutamide,
and glimepiride) which, like glyburide, are primarily eliminated by CYP2C9.
Thiazolidinediones: Single-dose pharmacokinetics
of rosiglitazone was not meaningfully altered in subjects receiving multiple
daily doses of sitagliptin, indicating that sitagliptin is not an inhibitor of
CYP2C8-mediated metabolism.
Warfarin: Multiple daily doses of sitagliptin did
not meaningfully alter the pharmacokinetics, as assessed by measurement of S(-)
or R(+) warfarin enantiomers, or pharmacodynamics (as assessed by measurement
of prothrombin INR) of a single dose of warfarin. Because S(-) warfarin is
primarily metabolized by CYP2C9, these data also support the conclusion that
sitagliptin is not a CYP2C9 inhibitor.
Oral Contraceptives: Coadministration with
sitagliptin did not meaningfully alter the steady-state pharmacokinetics of
norethindrone or ethinyl estradiol.
Effects of Other Drugs on Sitagliptin
Clinical data described below suggest that sitagliptin is
not susceptible to clinically meaningful interactions by coadministered
medications.
Metformin: Coadministration of multiple
twice-daily doses of metformin with sitagliptin did not meaningfully alter the
pharmacokinetics of sitagliptin in patients with type 2 diabetes.
Cyclosporine: A study was conducted to assess the
effect of cyclosporine, a potent inhibitor of p-glycoprotein, on the
pharmacokinetics of sitagliptin. Coadministration of a single 100 mg oral dose
of sitagliptin and a single 600 mg oral dose of cyclosporine increased the AUC
and Cmax of sitagliptin by approximately 29% and 68%, respectively. These
modest changes in sitagliptin pharmacokinetics were not considered to be
clinically meaningful. The renal clearance of sitagliptin was also not
meaningfully altered. Therefore, meaningful interactions would not be expected
with other p-glycoprotein inhibitors.
Effects of Simvastatin on Other Drugs
CYP3A4 Inhibitors: In a study of 12 healthy
volunteers, simvastatin at the 80 mg dose had no effect on the metabolism of
the probe cytochrome P450 isoform 3A4 (CYP3A4) substrates midazolam and
erythromycin. This indicates that simvastatin is not an inhibitor of CYP3A4,
and, therefore, is not expected to affect the plasma levels of other drugs
metabolized by CYP3A4. Effects of Other Drugs on Simvastatin
Cyclosporine: Although the mechanism is not fully
understood, cyclosporine has been shown to increase the AUC of statins. The
increase in AUC for simvastatin acid is presumably due, in part, to inhibition
of CYP3A4.
CYP3A4 Inhibitors: The risk of myopathy is
increased by high levels of HMG-CoA reductase inhibitory activity in plasma.
Inhibitors of CYP3A4 can raise the plasma levels of HMG-CoA reductase
inhibitory activity and increase the risk of myopathy [see WARNINGS AND
PRECAUTIONS; DRUG INTERACTIONS].
Table 6: Effect of Coadministered Drugs or Grapefruit
Juice on Simvastatin Systemic Exposure
Coadministered Drug or Grapefruit Juice |
Dosing of Coadministered Drug or Grapefruit Juice |
Dosing of Simvastatin |
Geometric Mean Ratio (Ratio* with / without coadministered drug) No Effect = 1.00 |
|
AUC |
Cmax |
Contraindicated with JUVISYNC [see CONTRAINDICATIONS; WARNINGS AND PRECAUTIONS] |
Telithromycin† |
200 mg QD for 4 days |
80 mg |
simvastatin acid‡ |
12 |
15 |
simvastatin |
8.9 |
5.3 |
Nelfinavir† |
1250 mg BID for 14 days |
20 mg QD for 28 days |
simvastatin acid‡ |
|
|
simvastatin |
6 |
6.2 |
Itraconazole† |
200 mg QD for 4 days |
80 mg |
simvastatin acid‡ |
13.1 |
|
simvastatin |
13.1 |
|
Posaconazole |
100 mg (oral suspension) QD for 13 days 200 mg (oral suspension) QD for 13 days |
40 mg |
simvastatin acid |
7.3 |
9.2 |
simvastatin |
10.3 |
9.4 |
40 mg |
simvastatin acid |
8.5 |
9.5 |
simvastatin |
10.6 |
11.4 |
Gemfibrozil |
600 mg BID for 3 days |
40 mg |
simvastatin acid |
2.85 |
2.18 |
simvastatin |
1.35 |
0.91 |
Avoid grapefruit juice [see WARNINGS AND PRECAUTIONS] |
Grapefruit Juice§ (high dose) |
200 mL of double-strength TID¶ |
60 mg single dose |
simvastatin acid |
7 |
|
simvastatin |
16 |
|
Grapefruit Juice§ (low dose) |
8 oz (about 237 mL) of single-strength# |
20 mg single dose |
simvastatin acid |
1.3 |
|
simvastatin |
1.9 |
|
Avoid taking with > 10 mg simvastatin (100 mg/10 mg or 50 mg/10 mg JUVISYNC), based on clinical and/or postmarketing experience [see WARNINGS AND PRECAUTIONS] |
Verapamil SR |
240 mg QD Days 1-7 then 240 mg BID on Days 8-10 |
80 mg on Day 10 |
simvastatin acid |
2.3 |
2.4 |
simvastatin |
2.5 |
2.1 |
Diltiazem |
120 mg BID for 10 days |
80 mg on Day 10 |
simvastatin acid |
2.69 |
2.69 |
simvastatin |
3.10 |
2.88 |
Diltiazem |
120 mg BID for 14 days |
20 mg on Day 14 |
simvastatin |
4.6 |
3.6 |
Dronedarone |
400 mg BID for 14 days |
40 mg QD for 14 days |
simvastatin acid |
1.96 |
2.14 |
simvastatin |
3.90 |
3.75 |
Avoid taking with > 20 mg simvastatin (100 mg/20 mg or 50 mg/20 mg JUVISYNC), based on clinical and/or postmarketing experience [see WARNINGS AND PRECAUTIONS] |
Amlodipine |
10 mg QD for 10 days |
80 mg on Day 10 |
simvastatin acid |
1.58 |
1.56 |
simvastatin |
1.77 |
1.47 |
Ranolazine SR |
1000 mg BID for 7 days |
80 mg on Day 1 and Days 6-9 |
simvastatin acid |
2.26 |
2.28 |
simvastatin |
1.86 |
1.75 |
Amiodarone |
400 mg QD for 3 days |
40 mg on Day 3 |
simvastatin acid |
1.75 |
1.72 |
simvastatin |
1.76 |
1.79 |
Avoid taking with >20 mg simvastatin (or 40 mg for patients who have previously taken 80 mg simvastatin chronically, e.g., for 12 months or more, without evidence of muscle toxicity), based on clinical experience |
Lomitapide |
60 mg QD for 7 days |
40 mg single dose |
simvastatin acid |
1.7 |
1.6 |
simvastatin |
2 |
2 |
Lomitapide |
10 mg QD for 7 days |
20 mg single dose |
simvastatin acid |
1.4 |
1.4 |
simvastatin |
1.6 |
1.7 |
No dosing adjustmments required for the following: |
Fenofibrate |
160 mg QD for 14 days |
80 mg QD on Days 8-14 |
simvastatin acid |
0.64 |
0.89 |
simvastatin |
0.89 |
0.83 |
Niacin extended-release Þ |
2 g single dose |
20 mg single dose |
simvastatin acid |
1.6 |
1.84 |
simvastatin |
1.4 |
1.08 |
Propranolol |
80 mg single dose |
80 mg single dose |
total inhibitor |
0.79 |
↓from 33.6 to 21.1 ng•eq/mL |
active inhibitor |
0.79 |
↓from 7.0 to 4.7 ng•eq/mL |
* Results based on a chemical assay except results with
propranolol as indicated.
† Results could be representative of the following CYP3A4 inhibitors:
ketoconazole, erythromycin, clarithromycin, HIV protease inhibitors, and
nefazodone.
‡ Simvastatin acid refers to the β-hydroxyacid of simvastatin.
§ The effect of amounts of grapefruit juice between those used in these two
studies on simvastatin pharmacokinetics has not been studied.
¶ Double-strength: one can of frozen concentrate diluted with one can of water.
Grapefruit juice was administered TID for 2 days, and 200 mL together with
single dose simvastatin and 30 and 90 minutes following single dose simvastatin
on Day 3.
# Single-strength: one can of frozen concentrate diluted with 3 cans of water.
Grapefruit juice was administered with breakfast for 3 days, and simvastatin
was administered in the evening on Day 3.
Þ Chinese patients have an increased risk for myopathy with simvastatin
coadministered with lipid-modifying doses ( ≥ 1 gram/day niacin) of
niacin-containing products, and the risk is dose-related [see WARNINGS AND
PRECAUTIONS; DRUG INTERACTIONS]. |
Animal Toxicology And/Or Pharmacology
Simvastatin
Optic nerve degeneration was seen in clinically normal
dogs treated with simvastatin for 14 weeks at 180 mg/kg/day, a dose that
produced mean plasma drug levels about 24 times higher than the mean plasma
drug level in humans taking 40 mg/day.
A chemically similar drug in this class also produced
optic nerve degeneration (Wallerian degeneration of retinogeniculate fibers) in
clinically normal dogs in a dose-dependent fashion starting at 60 mg/kg/day, a
dose that produced mean plasma drug levels about 30 times higher than the mean
plasma drug level in humans taking the highest recommended dose (as measured by
total enzyme inhibitory activity). This same drug also produced
vestibulocochlear Wallerian-like degeneration and retinal ganglion cell
chromatolysis in dogs treated for 14 weeks at 180 mg/kg/day, a dose that
resulted in a mean plasma drug level similar to that seen with the 60 mg/kg/day
dose.
CNS vascular lesions, characterized by perivascular
hemorrhage and edema, mononuclear cell infiltration of perivascular spaces,
perivascular fibrin deposits and necrosis of small vessels were seen in dogs
treated with simvastatin at a dose of 360 mg/kg/day, a dose that produced mean
plasma drug levels that were about 28 times higher than the mean plasma drug
levels in humans taking 40 mg/day. Similar CNS vascular lesions have been
observed with several other drugs of this class.
There were cataracts in female rats after two years of
treatment with 50 and 100 mg/kg/day (44 and 50 times the human AUC at 40
mg/day, respectively) and in dogs after three months at 90 mg/kg/day (38 times)
and at two years at 50 mg/kg/day (10 times).
Clinical Studies
Sitagliptin Clinical Studies
There were approximately 5200 patients with type 2
diabetes randomized in nine double-blind, placebo-controlled clinical safety
and efficacy studies conducted to evaluate the effects of sitagliptin on
glycemic control. In a pooled analysis of seven of these studies, the
ethnic/racial distribution was approximately 59% white, 20% Hispanic, 10%
Asian, 6% black, and 6% other groups. Patients had an overall mean age of approximately
55 years (range 18 to 87 years). In addition, an active (glipizide)Âcontrolled
study of 52 weeks duration was conducted in 1172 patients with type 2 diabetes
who had inadequate glycemic control on metformin.
In patients with type 2 diabetes, treatment with
sitagliptin produced clinically significant improvements in hemoglobin A1C,
fasting plasma glucose (FPG) and 2-hour post-prandial glucose (PPG) compared to
placebo.
Monotherapy
A total of 1262 patients with type 2 diabetes
participated in two double-blind, placebo-controlled studies, one of 18-week
and another of 24-week duration, to evaluate the efficacy and safety of
sitagliptin monotherapy. In both monotherapy studies, patients currently on an
antihyperglycemic agent discontinued the agent, and underwent a diet, exercise,
and drug washout period of about 7 weeks. Patients with inadequate glycemic
control (A1C 7% to 10%) after the washout period were randomized after
completing a 2-week single-blind placebo run-in period; patients not currently
on antihyperglycemic agents (off therapy for at least 8 weeks) with inadequate
glycemic control (A1C 7% to 10%) were randomized after completing the 2-week
single-blind placebo run-in period. In the 18-week study, 521 patients were
randomized to placebo, sitagliptin 100 mg, or sitagliptin 200 mg, and in the
24-week study 741 patients were randomized to placebo, sitagliptin 100 mg, or
sitagliptin 200 mg. Patients who failed to meet specific glycemic goals during
the studies were treated with metformin rescue, added on to placebo or
sitagliptin.
Treatment with sitagliptin at 100 mg daily provided
significant improvements in A1C, FPG, and 2-hour PPG compared to placebo (Table
7). In the 18-week study, 9% of patients receiving sitagliptin 100 mg and 17%
who received placebo required rescue therapy. In the 24-week study, 9% of
patients receiving sitagliptin 100 mg and 21% of patients receiving placebo
required rescue therapy. The improvement in A1C compared to placebo was not
affected by gender, age, race, prior antihyperglycemic therapy, or baseline
BMI. As is typical for trials of agents to treat type 2 diabetes, the mean
reduction in A1C with sitagliptin appears to be related to the degree of A1C
elevation at baseline. In these 18-and 24-week studies, among patients who were
not on an antihyperglycemic agent at study entry, the reductions from baseline
in A1C were -0.7% and -0.8%, respectively, for those given sitagliptin, and
-0.1% and -0.2%, respectively, for those given placebo. Overall, the 200 mg
daily dose did not provide greater glycemic efficacy than the 100 mg daily
dose. Body weight did not increase from baseline with sitagliptin therapy in
either study, compared to a small reduction in patients given placebo.
Table 7: Glycemic Parameters in 18-and 24-Week
Placebo-Controlled Studies of Sitagliptin in Patients with Type 2 Diabetes*
|
18-Week Study |
24-Week Study |
Sitagliptin 100 mg |
Placebo |
Sitagliptin 100 mg |
Placebo |
A1C (%) |
N = 193 |
N = 103 |
N = 229 |
N = 244 |
Baseline (mean) |
8 |
8.1 |
8 |
8 |
Change from baseline (adjusted mean†) |
-0.5 |
0.1 |
-0.6 |
0.2 |
Difference from placebo (adjusted mean†) (95% CI) |
-0.6‡ (-0.8, -0.4) |
|
-0.8‡ (-1.0, -0.6) |
|
Patients (%) achieving A1C < 7% |
69 (36%) |
16 (16%) |
93 (41%) |
41 (17%) |
FPG (mg/dL) |
N = 201 |
N = 107 |
N = 234 |
N = 247 |
Baseline (mean) |
180 |
184 |
170 |
176 |
Change from baseline (adjusted mean†) |
-13 |
7 |
-12 |
5 |
Difference from placebo (adjusted mean†) (95% CI) |
-20‡ (-31, -9) |
|
-17‡ (-24, -10) |
|
2-hour PPG (mg/dL) |
§ |
§ |
N = 201 |
N = 204 |
Baseline (mean) |
|
|
257 |
271 |
Change from baseline (adjusted mean†) |
|
|
-49 |
-2 |
Difference from placebo (adjusted mean†) (95% CI) |
|
|
-47‡ (-59, -34) |
|
* Intent-to-treat population using last observation on
study prior to metformin rescue therapy.
† Least squares means adjusted for prior antihyperglycemic therapy status and
baseline value.
‡ p < 0.001 compared to placebo.
§ Data not available. |
Add-on Combination Therapy with Metformin
A total of 701 patients with type 2 diabetes participated
in a 24-week, randomized, double-blind, placebo-controlled study designed to
assess the efficacy of sitagliptin in combination with metformin. Patients
already on metformin (N=431) at a dose of at least 1500 mg per day were
randomized after completing a 2-week single-blind placebo run-in period.
Patients on metformin and another antihyperglycemic agent (N=229) and patients
not on any antihyperglycemic agents (off therapy for at least 8 weeks, N=41)
were randomized after a run-in period of approximately 10 weeks on metformin
(at a dose of at least 1500 mg per day) in monotherapy. Patients with
inadequate glycemic control (A1C 7% to 10%) were randomized to the addition of
either 100 mg of sitagliptin or placebo, administered once daily. Patients who
failed to meet specific glycemic goals during the studies were treated with
pioglitazone rescue.
In combination with metformin, sitagliptin provided
significant improvements in A1C, FPG, and 2-hour PPG compared to placebo with
metformin (Table 8). Rescue glycemic therapy was used in 5% of patients treated
with sitagliptin 100 mg and 14% of patients treated with placebo. A similar
decrease in body weight was observed for both treatment groups.
Table 8: Glycemic Parameters at Final Visit (24-Week
Study) for Sitagliptin in Add-on Combination Therapy with Metformin*
|
Sitagliptin 100 mg + Metformin |
Placebo + Metformin |
A1C (%) |
N = 453 |
N = 224 |
Baseline (mean) |
8 |
8 |
Change from baseline (adjusted mean†) |
-0.7 |
0 |
Difference from placebo + metformin (adjusted mean†) (95% CI) |
-0.7‡ (-0.8, -0.5) |
|
Patients (%) achieving A1C < 7% |
213 (47%) |
41 (18%) |
FPG (mg/dL) |
N = 454 |
N = 226 |
Baseline (mean) |
170 |
174 |
Change from baseline (adjusted mean†) |
-17 |
9 |
Difference from placebo + metformin (adjusted mean†) (95% CI) |
-25‡ (-31, -20) |
|
2-hour PPG (mg/dL) |
N = 387 |
N = 182 |
Baseline (mean) |
275 |
272 |
Change from baseline (adjusted mean†) |
-62 |
-11 |
Difference from placebo + metformin (adjusted mean†) (95% CI) |
-51‡ (-61, -41) |
|
* Intent-to-treat population using last observation on
study prior to pioglitazone rescue therapy.
† Least squares means adjusted for prior antihyperglycemic therapy and baseline
value.
‡ p < 0.001 compared to placebo + metformin. |
Initial Combination Therapy with Metformin
A total of 1091 patients with type 2 diabetes and
inadequate glycemic control on diet and exercise participated in a 24-week,
randomized, double-blind, placebo-controlled factorial study designed to assess
the efficacy of sitagliptin as initial therapy in combination with metformin.
Patients on an antihyperglycemic agent (N=541) discontinued the agent, and
underwent a diet, exercise, and drug washout period of up to 12 weeks duration.
After the washout period, patients with inadequate glycemic control (A1C 7.5%
to 11%) were randomized after completing a 2-week single-blind placebo run-in
period. Patients not on antihyperglycemic agents at study entry (N=550) with
inadequate glycemic control (A1C 7.5% to 11%) immediately entered the 2-week
single-blind placebo run-in period and then were randomized. Approximately
equal numbers of patients were randomized to receive initial therapy with
placebo, 100 mg of sitagliptin once daily, 500 mg or 1000 mg of metformin twice
daily, or 50 mg of sitagliptin twice daily in combination with 500 mg or 1000
mg of metformin twice daily. Patients who failed to meet specific glycemic
goals during the study were treated with glyburide (glibenclamide) rescue.
Initial therapy with the combination of sitagliptin and
metformin provided significant improvements in A1C, FPG, and 2-hour PPG
compared to placebo, to metformin alone, and to sitagliptin alone (Table 9,
Figure 1). Mean reductions from baseline in A1C were generally greater for
patients with higher baseline A1C values. For patients not on an
antihyperglycemic agent at study entry, mean reductions from baseline in A1C
were: sitagliptin 100 mg once daily, -1.1%; metformin 500 mg bid, -1.1%;
metformin 1000 mg bid, -1.2%; sitagliptin 50 mg bid with metformin 500 mg bid,
-1.6%; sitagliptin 50 mg bid with metformin 1000 mg bid, -1.9%; and for
patients receiving placebo, -0.2%. The decrease in body weight in the groups
given sitagliptin in combination with metformin was similar to that in the
groups given metformin alone or placebo.
Table 9: Glycemic Parameters at Final Visit (24-Week
Study) for Sitagliptin and Metformin, Alone and in Combination as Initial
Therapy*
|
Placebo |
Sitagliptin 100 mg QD |
Metformin 500 mg bid |
Metformin 1000 mg bid |
Sitagliptin 50 mg bid + Metformin 500 mg bid |
Sitagliptin 50 mg bid + Metformin 1000 mg bid |
A1C (%) |
N = 165 |
N = 175 |
N = 178 |
N = 177 |
N = 183 |
N = 178 |
Baseline (mean) |
8.7 |
8.9 |
8.9 |
8.7 |
8.8 |
8.8 |
Change from baseline (adjusted mean†) |
0.2 |
-0.7 |
-0.8 |
-1.1 |
-1.4 |
-1.9 |
Difference from placebo (adjusted mean†) (95% CI) |
|
-0.8‡ (-1.1, -0.6) |
-1.0‡ (-1.2, -0.8) |
-1.3‡ (-1.5, -1.1) |
-1.6‡ (-1.8, -1.3) |
-2.1‡ (-2.3, -1.8) |
Patients (%) achieving A1C < 7% |
15 (9%) |
35 (20%) |
41 (23%) |
68 (38%) |
79 (43%) |
118 (66%) |
% Patients receiving rescue medication |
32 |
21 |
17 |
12 |
8 |
2 |
FPG (mg/dL) |
N = 169 |
N = 178 |
N = 179 |
N = 179 |
N = 183 |
N = 180 |
Baseline (mean) |
196 |
201 |
205 |
197 |
204 |
197 |
Change from baseline (adjusted mean†) |
6 |
-17 |
-27 |
-29 |
-47 |
-64 |
Difference from placebo (adjusted mean†) (95% CI) |
|
-23‡ (-33, -14) |
-33‡ (-43, -24) |
-35‡ (-45, -26) |
-53‡ (-62, -43) |
-70‡ (-79, -60) |
2-hour PPG (mg/dL) |
N = 129 |
N = 136 |
N = 141 |
N = 138 |
N = 147 |
N = 152 |
Baseline (mean) |
277 |
285 |
293 |
283 |
292 |
287 |
Change from baseline (adjusted mean†) |
0 |
-52 |
-53 |
-78 |
-93 |
-117 |
Difference from placebo (adjusted mean†) (95% CI) |
|
-52‡ (-67, -37) |
-54‡ (-69, -39) |
-78‡ (-93, -63) |
-93‡ (-107, -78) |
-117‡ (-131, -102) |
* Intent-to-treat population using last observation on
study prior to glyburide (glibenclamide) rescue therapy.
† Least squares means adjusted for prior antihyperglycemic therapy status and
baseline value.
‡ p < 0.001 compared to placebo. |
Figure 1: Mean Change from Baseline for A1C (%) over
24 Weeks with Sitagliptin and Metformin, Alone and in Combination as Initial
Therapy in Patients with Type 2 Diabetes*
* All Patients Treated Population; least squares means
adjusted for prior antihyperglycemic therapy and baseline value.
Initial combination therapy or maintenance of combination
therapy may not be appropriate for all patients. These management options are
left to the discretion of the health care provider.
Active-Controlled Study vs Glipizide in Combination with
Metformin
The efficacy of sitagliptin was evaluated in a 52-week,
double-blind, glipizide-controlled noninferiority trial in patients with type 2
diabetes. Patients not on treatment or on other antihyperglycemic agents
entered a run-in treatment period of up to 12 weeks duration with metformin
monotherapy (dose of ≥ 1500 mg per day) which included washout of
medications other than metformin, if applicable. After the run-in period, those
with inadequate glycemic control (A1C 6.5% to 10%) were randomized 1:1 to the
addition of sitagliptin 100 mg once daily or glipizide for 52 weeks. Patients
receiving glipizide were given an initial dosage of 5 mg/day and then
electively titrated over the next 18 weeks to a maximum dosage of 20 mg/day as
needed to optimize glycemic control. Thereafter, the glipizide dose was to be
kept constant, except for down-titration to prevent hypoglycemia. The mean dose
of glipizide after the titration period was 10 mg.
After 52 weeks, sitagliptin and glipizide had similar
mean reductions from baseline in A1C in the intent-to-treat analysis (Table
10). These results were consistent with the per protocol analysis (Figure 2). A
conclusion in favor of the non-inferiority of sitagliptin to glipizide may be
limited to patients with baseline A1C comparable to those included in the study
(over 70% of patients had baseline A1C < 8% and over 90% had A1C < 9%).
Table 10: Glycemic Parameters in a 52-Week Study
Comparing Sitagliptin to Glipizide as Add-On Therapy in Patients Inadequately
Controlled on Metformin (Intent-to-Treat Population)*
|
Sitagliptin 100 mg |
Glipizide |
A1C (%) |
N = 576 |
N = 559 |
Baseline (mean) |
7.7 |
7.6 |
Change from baseline (adjusted mean†) |
-0.5 |
-0.6 |
FPG (mg/dL) |
N = 583 |
N = 568 |
Baseline (mean) |
166 |
164 |
Change from baseline (adjusted mean†) |
-8 |
-8 |
* The intent-to-treat analysis used the patients' last
observation in the study prior to discontinuation.
† Least squares means adjusted for prior antihyperglycemic therapy status and
baseline A1C value. |
Figure 2: Mean Change from Baseline for A1C (%) Over
52 Weeks in a Study Comparing Sitagliptin to Glipizide as Add-On Therapy in
Patients Inadequately Controlled on Metformin (Per Protocol Population)*
* The per protocol population (mean baseline A1C of 7.5%)
included patients without major protocol violations who had observations at
baseline and at Week 52.
The incidence of hypoglycemia in the sitagliptin group
(4.9%) was significantly (p < 0.001) lower than that in the glipizide group
(32.0%). Patients treated with sitagliptin exhibited a significant mean
decrease from baseline in body weight compared to a significant weight gain in
patients administered glipizide (-1.5 kg vs +1.1 kg).
Add-on Combination Therapy with Pioglitazone
A total of 353 patients with type 2 diabetes participated
in a 24-week, randomized, double-blind, placebo-controlled study designed to
assess the efficacy of sitagliptin in combination with pioglitazone. Patients
on any oral antihyperglycemic agent in monotherapy (N=212) or on a PPARγ
agent in combination therapy (N=106) or not on an antihyperglycemic agent (off
therapy for at least 8 weeks, N=34) were switched to monotherapy with
pioglitazone (at a dose of 30-45 mg per day), and completed a run-in period of
approximately 12 weeks in duration. After the run-in period on pioglitazone
monotherapy, patients with inadequate glycemic control (A1C 7% to 10%) were
randomized to the addition of either 100 mg of sitagliptin or placebo,
administered once daily. Patients who failed to meet specific glycemic goals
during the studies were treated with metformin rescue. Glycemic endpoints
measured were A1C and fasting glucose.
In combination with pioglitazone, sitagliptin provided
significant improvements in A1C and FPG compared to placebo with pioglitazone
(Table 11). Rescue therapy was used in 7% of patients treated with sitagliptin
100 mg and 14% of patients treated with placebo. There was no significant
difference between sitagliptin and placebo in body weight change.
Table 11: Glycemic Parameters at Final Visit (24-Week
Study) for Sitagliptin in Add-on Combination Therapy with Pioglitazone*
|
Sitagliptin 100 mg + Pioglitazone |
Placebo + Pioglitazone |
A1C (%) |
N = 163 |
N = 174 |
Baseline (mean) |
8.1 |
8 |
Change from baseline (adjusted mean†) |
-0.9 |
-0.2 |
Difference from placebo + pioglitazone (adjusted mean†) (95% CI) |
-0.7‡ (-0.9, -0.5) |
|
Patients (%) achieving A1C < 7% |
74 (45%) |
40 (23%) |
FPG (mg/dL) |
N = 163 |
N = 174 |
Baseline (mean) |
168 |
166 |
Change from baseline (adjusted mean†) |
-17 |
1 |
Difference from placebo + pioglitazone (adjusted mean†) (95% CI) |
-18‡ (-24, -11) |
|
* Intent-to-treat population using last observation on
study prior to metformin rescue therapy.
† Least squares means adjusted for prior antihyperglycemic therapy status and
baseline value.
‡ p < 0.001 compared to placebo + pioglitazone. |
Initial Combination Therapy with Pioglitazone
A total of 520 patients with type 2 diabetes and
inadequate glycemic control on diet and exercise participated in a 24-week,
randomized, double-blind study designed to assess the efficacy of sitagliptin
as initial therapy in combination with pioglitazone. Patients not on
antihyperglycemic agents at study entry ( < 4 weeks cumulative therapy over
the past 2 years, and with no treatment over the prior 4 months) with
inadequate glycemic control (A1C 8% to 12%) immediately entered the 2-week
single-blind placebo run-in period and then were randomized. Approximately
equal numbers of patients were randomized to receive initial therapy with 100
mg of sitagliptin in combination with 30 mg of pioglitazone once daily or 30 mg
of pioglitazone once daily as monotherapy. There was no glycemic rescue therapy
in this study.
Initial therapy with the combination of sitagliptin and
pioglitazone provided significant improvements in A1C, FPG, and 2-hour PPG
compared to pioglitazone monotherapy (Table 12). The improvement in A1C was
generally consistent across subgroups defined by gender, age, race, baseline
BMI, baseline A1C, or duration of disease. In this study, patients treated with
sitagliptin in combination with pioglitazone had a mean increase in body weight
of 1.1 kg compared to pioglitazone alone (3.0 kg vs. 1.9 kg).
Table 12: Glycemic Parameters at Final Visit (24-Week
Study) for Sitagliptin in Combination with Pioglitazone as Initial Therapy*
|
Sitagliptin 100 mg + Pioglitazone |
Pioglitazone |
A1C (%) |
N = 251 |
N = 246 |
Baseline (mean) |
9.5 |
9.4 |
Change from baseline (adjusted mean†) |
-2.4 |
-1.5 |
Difference from pioglitazone (adjusted mean†) (95% CI) |
-0.9‡ (-1.1, -0.7) |
|
Patients (%) achieving A1C < 7% |
151 (60%) |
68 (28%) |
FPG (mg/dL) |
N = 256 |
N = 253 |
Baseline (mean) |
203 |
201 |
Change from baseline (adjusted mean†) |
-63 |
-40 |
Difference from pioglitazone (adjusted mean†) (95% CI) |
-23‡ (-30, -15) |
|
2-hour PPG (mg/dL) |
N = 216 |
N = 211 |
Baseline (mean) |
283 |
284 |
Change from baseline (adjusted mean†) |
-114 |
-69 |
Difference from pioglitazone (adjusted mean†) (95% CI) |
-45‡ (-57, -32) |
|
* Intent-to-treat population using last observation on
study.
† Least squares means adjusted for baseline value.
‡ p < 0.001 compared to placebo + pioglitazone. |
Add-on Combination Therapy with Metformin and
Rosiglitazone
A total of 278 patients with type 2 diabetes participated
in a 54-week, randomized, double-blind, placebo-controlled study designed to
assess the efficacy of sitagliptin in combination with metformin and
rosiglitazone. Patients on dual therapy with metformin ≥ 1500 mg/day and
rosiglitazone ≥ 4 mg/day or with metformin ≥ 1500 mg/day and
pioglitazone ≥ 30 mg/day (switched to rosiglitazone ≥ 4 mg/day)
entered a dose-stable run-in period of 6 weeks. Patients on other dual therapy
were switched to metformin ≥ 1500 mg/day and rosiglitazone ≥ 4 mg/day
in a dose titration/stabilization run-in period of up to 20 weeks in duration.
After the run-in period, patients with inadequate glycemic control (A1C 7.5% to
11%) were randomized 2:1 to the addition of either 100 mg of sitagliptin or
placebo, administered once daily. Patients who failed to meet specific glycemic
goals during the study were treated with glipizide (or other sulfonylurea)
rescue. The primary time point for evaluation of glycemic parameters was W eek
18.
In combination with metformin and rosiglitazone,
sitagliptin provided significant improvements in A1C, FPG, and 2-hour PPG
compared to placebo with metformin and rosiglitazone (Table 13) at W eek 18. At
Week 54, mean reduction in A1C was -1.0% for patients treated with sitagliptin
and -0.3% for patients treated with placebo in an analysis based on the
intent-to-treat population. Rescue therapy was used in 18% of patients treated
with sitagliptin 100 mg and 40% of patients treated with placebo. There was no
significant difference between sitagliptin and placebo in body weight change.
Table 13: Glycemic Parameters at Week 18 for
Sitagliptin in Add-on Combination Therapy with Metformin and Rosiglitazone*
|
Sitagliptin 100 mg + Metformin + Rosiglitazone |
Placebo + Metformin + Rosiglitazone |
A1C (%) |
N = 176 |
N = 93 |
Baseline (mean) |
8.8 |
8.7 |
Change from baseline (adjusted mean†) |
-1 |
-0.4 |
Difference from placebo + rosiglitazone + metformin (adjusted mean†) (95% CI) |
-0.7‡ (-0.9, -0.4) |
|
Patients (%) achieving A1C < 7% |
39 (22%) |
9 (10%) |
FPG (mg/dL) |
N = 179 |
N = 94 |
Baseline (mean) |
181 |
182 |
Change from baseline (adjusted mean†) |
-30 |
-11 |
Difference from placebo + rosiglitazone + metformin (adjusted mean†) (95% CI) |
-18‡ (-26, -10) |
|
2-hour PPG (mg/dL) |
N = 152 |
N = 80 |
Baseline (mean) |
256 |
248 |
Change from baseline (adjusted mean†) |
-59 |
-21 |
Difference from placebo + rosiglitazone + metformin (adjusted mean†) (95% CI) |
-39‡ (-51, -26) |
|
* Intent-to-treat population using last observation on
study prior to glipizide (or other sulfonylurea) rescue therapy.
† Least squares means adjusted for prior antihyperglycemic therapy status and
baseline value.
‡ p < 0.001 compared to placebo + metformin + rosiglitazone. |
Add-on Combination Therapy with Glimepiride, with or
without Metformin
A total of 441 patients with type 2 diabetes participated
in a 24-week, randomized, double-blind, placebo-controlled study designed to
assess the efficacy of sitagliptin in combination with glimepiride, with or
without metformin. Patients entered a run-in treatment period on glimepiride
( ≥ 4 mg per day) alone or glimepiride in combination with metformin
( ≥ 1500 mg per day). After a dose-titration and dose-stable run-in period
of up to 16 weeks and a 2-week placebo run-in period, patients with inadequate
glycemic control (A1C 7.5% to 10.5%) were randomized to the addition of either
100 mg of sitagliptin or placebo, administered once daily. Patients who failed
to meet specific glycemic goals during the studies were treated with
pioglitazone rescue.
In combination with glimepiride, with or without
metformin, sitagliptin provided significant improvements in A1C and FPG
compared to placebo (Table 14). In the entire study population (patients on
sitagliptin in combination with glimepiride and patients on sitagliptin in
combination with glimepiride and metformin), a mean reduction from baseline
relative to placebo in A1C of -0.7% and in FPG of -20 mg/dL was seen. Rescue
therapy was used in 12% of patients treated with sitagliptin 100 mg and 27% of
patients treated with placebo. In this study, patients treated with sitagliptin
had a mean increase in body weight of 1.1 kg vs. placebo (+0.8 kg vs. -0.4 kg).
In addition, there was an increased rate of hypoglycemia. [See WARNINGS AND
PRECAUTIONS; ADVERSE REACTIONS]
Table 14: Glycemic Parameters at Final Visit (24-Week
Study) for Sitagliptin as Add-On Combination Therapy with Glimepiride, with or
without Metformin*
|
Sitagliptin 100 mg + Glimepiride |
Placebo + Glimepiride |
Sitagliptin 100 mg + Glimepiride + Metformin |
Placebo + Glimepiride + Metformin |
A1C (%) |
N = 102 |
N = 103 |
N = 115 |
N = 105 |
Baseline (mean) |
8.4 |
8.5 |
8.3 |
8.3 |
Change from baseline (adjusted mean†) |
-0.3 |
0.3 |
-0.6 |
0.3 |
Difference from placebo (adjusted mean†) (95% CI) |
-0.6‡ (-0.8, -0.3) |
|
-0.9‡ (-1.1, -0.7) |
|
Patients (%) achieving A1C < 7% |
11 (11%) |
9 (9%) |
26 (23%) |
1 (1%) |
FPG (mg/dL) |
N = 104 |
N = 104 |
N = 115 |
N = 109 |
Baseline (mean) |
183 |
185 |
179 |
179 |
Change from baseline (adjusted mean†) |
-1 |
18 |
-8 |
13 |
Difference from placebo (adjusted mean†) (95% CI) |
-19§ (-32, -7) |
|
-21‡ (-32, -10) |
|
* Intent-to-treat population using last observation on
study prior to pioglitazone rescue therapy.
† Least squares means adjusted for prior antihyperglycemic therapy status and
baseline value.
‡ p < 0.001 compared to placebo.
§ p < 0.01 compared to
placebo. |
Add-on Combination Therapy with Insulin (with or without
Metformin)
A total of 641 patients with type 2 diabetes participated
in a 24-week, randomized, double-blind, placebo-controlled study designed to
assess the efficacy of sitagliptin as add-on to insulin therapy (with or
without metformin). The racial distribution in this study was approximately 70%
white, 18% Asian, 7% black, and 5% other groups. Approximately 14% of the
patients in this study were Hispanic. Patients entered a 2-week, single-blind
run-in treatment period on pre-mixed, long-acting, or intermediate-acting
insulin, with or without metformin ( ≥ 1500 mg per day). Patients using
short-acting insulins were excluded unless the short-acting insulin was
administered as part of a pre-mixed insulin. After the run-in period, patients
with inadequate glycemic control (A1C 7.5% to 11%) were randomized to the
addition of either 100 mg of sitagliptin or placebo, administered once daily.
Patients were on a stable dose of insulin prior to enrollment with no changes
in insulin dose permitted during the run-in period. Patients who failed to meet
specific glycemic goals during the double-blind treatment period were to have
uptitration of the background insulin dose as rescue therapy.
The median daily insulin dose at baseline was 42 units in
the patients treated with sitagliptin and 45 units in the placebo-treated
patients. The median change from baseline in daily dose of insulin was zero for
both groups at the end of the study. In combination with insulin (with or
without metformin), sitagliptin provided significant improvements in A1C, FPG,
and 2-hour PPG compared to placebo (Table 15). Both treatment groups had an
adjusted mean increase in body weight of 0.1 kg from baseline to Week 24. There
was an increased rate of hypoglycemia in patients treated with sitagliptin. [See
WARNINGS AND PRECAUTIONS; ADVERSE REACTIONS]
Table 15: Glycemic Parameters at Final Visit (24-Week
Study) for Sitagliptin as Add-on Combination Therapy with Insulin*
|
Sitagliptin 100 mg + Insulin (+/-Metformin) |
Placebo + Insulin (+/-Metformin) |
A1C (%) |
N = 305 |
N = 312 |
Baseline (mean) |
8.7 |
8.6 |
Change from baseline (adjusted mean†) |
-0.6 |
-0.1 |
Difference from placebo (adjusted mean†,‡) (95% CI) |
-0.6§ (-0.7, -0.4) |
|
Patients (%) achieving A1C < 7% |
39 (12.8%) |
16 (5.1%) |
FPG (mg/dL) |
N = 310 |
N = 313 |
Baseline (mean) |
176 |
179 |
Change from baseline (adjusted mean†) |
-18 |
-4 |
Difference from placebo (adjusted mean†) (95% CI) |
-15§ (-23, -7) |
|
2-hour PPG (mg/dL) |
N = 240 |
N = 257 |
Baseline (mean) |
291 |
292 |
Change from baseline (adjusted mean†) |
-31 |
5 |
Difference from placebo (adjusted mean†) (95% CI) |
-36§ (-47, -25) |
|
* Intent-to-treat population using last observation on
study prior to rescue therapy.
† Least squares means adjusted for metformin use at the screening visit
(yes/no), type of insulin used at the screening visit (pre-mixed vs.
non-pre-mixed [intermediate-or long-acting]), and baseline value.
‡ Treatment by stratum interaction was not significant (p > 0.10) for
metformin stratum and for insulin stratum.
§ p < 0.001 compared to
placebo. |
Simvastatin Clinical Studies
Reductions in Risk of CHD Mortality and Cardiovascular
Events
In 4S, the effect of therapy with simvastatin on total
mortality was assessed in 4444 patients with CHD and baseline total cholesterol
212-309 mg/dL (5.5-8.0 mmol/L). In this multicenter, randomized, double-blind,
placebo-controlled study, patients were treated with standard care, including
diet, and either simvastatin 20-40 mg/day (n=2221) or placebo (n=2223) for a
median duration of 5.4 years. Over the course of the study, treatment with
simvastatin led to mean reductions in total-C, LDL-C and TG of 25%, 35%, and
10%, respectively, and a mean increase in HDL-C of 8%. Simvastatin
significantly reduced the risk of mortality by 30% (p=0.0003, 182 deaths in the
simvastatin group vs 256 deaths in the placebo group). The risk of CHD
mortality was significantly reduced by 42% (p=0.00001, 111 vs 189 deaths).
There was no statistically significant difference between groups in
non-cardiovascular mortality. Simvastatin significantly decreased the risk of
having major coronary events (CHD mortality plus hospital-verified and silent
non-fatal myocardial infarction [MI]) by 34% (p < 0.00001, 431 vs 622 patients
with one or more events). The risk of having a hospital-verified non-fatal MI
was reduced by 37%. Simvastatin significantly reduced the risk for undergoing
myocardial revascularization procedures (coronary artery bypass grafting or
percutaneous transluminal coronary angioplasty) by 37% (p < 0.00001, 252 vs
383 patients). Simvastatin significantly reduced the risk of fatal plus
non-fatal cerebrovascular events (combined stroke and transient ischemic
attacks) by 28% (p=0.033, 75 vs 102 patients). Simvastatin reduced the risk of
major coronary events to a similar extent across the range of baseline total
and LDL cholesterol levels. Because there were only 53 female deaths, the
effect of simvastatin on mortality in women could not be adequately assessed.
However, simvastatin significantly lessened the risk of having major coronary
events by 34% (60 vs 91 women with one or more event). The randomization was
stratified by angina alone (21% of each treatment group) or a previous MI.
Because there were only 57 deaths among the patients with angina alone at
baseline, the effect of simvastatin on mortality in this subgroup could not be
adequately assessed. However, trends in reduced coronary mortality, major coronary
events and revascularization procedures were consistent between this group and
the total study cohort. Additionally, simvastatin resulted in similar decreases
in relative risk for total mortality, CHD mortality, and major coronary events
in elderly patients ( ≥ 65 years), compared with younger patients.
The Heart Protection Study (HPS) was a large,
multi-center, placebo-controlled, double-blind study with a mean duration of 5
years conducted in 20,536 patients (10,269 on simvastatin 40 mg and 10,267 on
placebo), including 5963 patients with diabetes mellitus (2978 on simvastatin
and 2985 on placebo). Patients were allocated to treatment using a covariate
adaptive method which took into account the distribution of 10 important
baseline characteristics of patients already enrolled and minimized the
imbalance of those characteristics across the groups. Patients had a mean age
of 64 years (range 40Â80 years), were 97% Caucasian and were at high risk of
developing a major coronary event because of existing CHD (65%), diabetes (Type
2, 26%; Type 1, 3%), history of stroke or other cerebrovascular disease (16%),
peripheral vessel disease (33%), or hypertension in males ≥ 65 years (6%).
At baseline, 3421 patients (17%) had LDL-C levels below 100 mg/dL, of whom 953
(5%) had LDL-C levels below 80 mg/dL; 7068 patients (34%) had levels between
100 and 130 mg/dL; and 10,047 patients (49%) had levels greater than 130 mg/dL.
The HPS results showed that simvastatin 40 mg/day
significantly reduced: total and CHD mortality; non-fatal MI, stroke, and
revascularization procedures (coronary and non-coronary) (see Table 16).
Table 16: Summary of Heart Protection Study Results
Endpoint |
Simvastatin
(N=10,269)
n (%)* |
Placebo
(N=10,267)
n (%)* |
Risk Reduction (%) (95% CI) |
p-Value |
Primary |
Mortality |
1328 (12.9) |
1507 (14.7) |
13 (6-19) |
p=0.0003 |
CHD mortality |
587 (5.7) |
707 (6.9) |
18 (8-26) |
p=0.0005 |
Secondary |
Non-fatal |
357 (3.5) |
574 (5.6) |
38 (30-46) |
p < 0.0001 |
MI Stroke |
444 (4.3) |
585 (5.7) |
25 (15-34) |
p < 0.0001 |
Tertiary |
Coronary revascularization |
513 (5) |
725 (7.1) |
30 (22-38) |
p < 0.0001 |
Peripheral and other non-coronary revascularization |
450 (4.4) |
532 (5.2) |
16 (5-26) |
p=0.006 |
* n = number of patients with indicated event |
Two composite endpoints were defined in order to have
sufficient events to assess relative risk reductions across a range of baseline
characteristics (see Figure 3). A composite of major coronary events (MCE) was
comprised of CHD mortality and non-fatal MI (analyzed by time-to-first event;
898 patients treated with simvastatin had events and 1212 patients on placebo
had events). A composite of major vascular events (MVE) was comprised of MCE,
stroke and revascularization procedures including coronary, peripheral and
other non-coronary procedures (analyzed by time-to-first event; 2033 patients
treated with simvastatin had events and 2585 patients on placebo had events).
Significant relative risk reductions were observed for both composite endpoints
(27% for MCE and 24% for MVE, p < 0.0001). Treatment with simvastatin produced
significant relative risk reductions for all components of the composite
endpoints. The risk reductions produced by simvastatin in both MCE and MVE were
evident and consistent regardless of cardiovascular disease related medical
history at study entry (i.e., CHD alone; or peripheral vascular disease,
cerebrovascular disease, diabetes or treated hypertension, with or without
CHD), gender, age, creatinine levels up to the entry limit of 2.3 mg/dL,
baseline levels of LDL-C, HDL-C, apolipoprotein B and A-1, baseline concomitant
cardiovascular medications (i.e., aspirin, beta blockers, or calcium channel
blockers), smoking status, alcohol intake, or obesity. Diabetic patients showed
risk reductions for MCE and MVE (27% and 22%, respectively; p < 0.0001) due to
simvastatin treatment regardless of baseline A1C levels or obesity with the
greatest effects seen for diabetic patients without CHD.
Figure 3: The Effects of Treatment with Simvastatin on
Major Vascular Events and Major Coronary Events in HPS
N = number of patients in each subgroup. The inverted
triangles are point estimates of the relative risk, with their 95% confidence
intervals represented as a line. The area of a triangle is proportional to the
number of patients with MVE or MCE in the subgroup relative to the number with
MVE or MCE, respectively, in the entire study population. The vertical solid
line represents a relative risk of one. The vertical dashed line represents the
point estimate of relative risk in the entire study population.
Modifications of Lipid Profiles
Primary Hyperlipidemia (Fredrickson type lla and llb)
Simvastatin has been shown to be effective in reducing
total-C and LDL-C in heterozygous familial and non-familial forms of
hyperlipidemia and in mixed hyperlipidemia. Maximal to near maximal response is
generally achieved within 4-6 weeks and maintained during chronic therapy.
Simvastatin consistently and significantly decreased total-C, LDL-C,
total-C/HDL-C ratio, and LDL-C/HDL-C ratio; simvastatin also decreased TG and
increased HDL-C (see Table 17).
Table 17: Mean Response in Patients with Primary
Hyperlipidemia and Combined (mixed) Hyperlipidemia (Mean Percent Change from
Baseline After 6 to 24 Weeks)
TREATMENT |
N |
TOTAL-C |
LDL-C |
HDL-C |
TG* |
Lower Dose Comparative Study† (Mean % Change at Week 6) |
Simvastatin 5 mg q.p.m. |
109 |
-19 |
-26 |
10 |
-12 |
Simvastatin 10 mg q.p.m. |
110 |
-23 |
-30 |
12 |
-15 |
Scandinavian Simvastatin Survival Study‡ (Mean % Change at Week 6) |
Placebo |
2223 |
-1 |
-1 |
0 |
-2 |
Simvastatin 20 mg q.p.m. |
2221 |
-28 |
-38 |
8 |
-19 |
Upper Dose Comparative Study§,¶ (Mean % Change Averaged at Weeks 18 and 24) |
Simvastatin 40 mg q.p.m. |
433 |
-31 |
-41 |
9 |
-18 |
Multi-Center Combined Hyperlipidemia Study# (Mean % Change at Week 6) |
Placebo |
125 |
1 |
2 |
3 |
-4 |
Simvastatin 40 mg q.p.m. |
123 |
-25 |
-29 |
13 |
-28 |
* median percent change
† mean baseline LDL-C 244 mg/dL and median baseline TG 168 mg/dL
‡ mean baseline LDL-C 188 mg/dL and median baseline TG 128 mg/dL
§ mean baseline LDL-C 226
mg/dL and median baseline TG 156 mg/dL
¶ Study also included another
treatment arm receiving a different dose of simvastatin; baseline mean LDL-C
and median TG values were calculated across all treatment arms in study
# mean baseline LDL-C 156
mg/dL and median baseline TG 391 mg/dL. |
Hypertriglyceridemia (Fredrickson type lV)
The results of a subgroup analysis in 74 patients with
type lV hyperlipidemia from a 130-patient, double-blind, placebo-controlled,
3-period crossover study are presented in Table 18.
Table 18: Six-Week, Lipid-Lowering Effects of
Simvastatin in Type lV Hyperlipidemia Median Percent Change (25th and 75th percentile) from Baseline*
TREATMENT |
N |
Total-C |
LDL-C |
HDL-C |
TG |
VLDL-C |
Non-HDL-C |
Placebo |
74 |
+2 (-7, +7) |
+1 (-8, +14) |
+3 (-3, +10) |
-9 (-25, +13) |
-7 (-25, +11) |
+1 (-9, +8) |
Simvastatin 40 mg/day |
74 |
-25 (-34, -19) |
-28 (-40, -17) |
+11 (+5, +23) |
-29 (-43, -16) |
-37 (-54, -23) |
-32 (-42, -23) |
* The median baseline values (mg/dL) for the patients in
this study were: total-C = 254, LDL-C = 135, HDL-C = 36, TG = 404, VLDL-C = 83,
and non-HDL-C = 215. |
Dysbetalipoproteinemia (Fredrickson type lll)
The results of a subgroup analysis in 7 patients with
type lll hyperlipidemia (dysbetalipoproteinemia) (apo E2/2) (VLDL-C/TG > 0.25)
from a 130-patient, double-blind, placebo-controlled, 3-period crossover study
are presented in Table 19.
Table 19: Six-Week, Lipid-Lowering Effects of
Simvastatin in Type lll Hyperlipidemia Median Percent Change (min, max) from
Baseline*
TREATMENT |
N |
Total-C |
LDL-C + IDL |
HDL-C |
TG |
VLDL-C +IDL |
Non-HDL-C |
Placebo |
7 |
-8(-24, +34) |
-8(-27, +23) |
-2(-21, +16) |
4(-22, +90) |
-4(-28, +78) |
-8(-26, -39) |
Simvastatin 40 mg/day |
7 |
-50(-66, -39) |
-50(-60, -31) |
7(-8, +23) |
-41(-74, -16) |
-58(-90, -37) |
-57(-72, -44) |
* The median baseline values (mg/dL) were: total-C = 324,
LDL-C = 121, HDL-C = 31, TG = 411, VLDL-C = 170, and non-HDL-C = 291. |
Homozygous Familial Hypercholesterolemia
In a controlled clinical study, 4 patients, 19-27 years
of age, with homozygous familial hypercholesterolemia received simvastatin 40
mg/day in a single dose or in 3 divided doses. Reductions in LDL-C were
observed for all patients. The mean LDL-C reduction for the 40 mg dose was 14%
(range 8% to 23%, median 12%).
Endocrine Function
In clinical studies, simvastatin did not impair adrenal
reserve or significantly reduce basal plasma cortisol concentration. Small
reductions from baseline in basal plasma testosterone in men were observed in
clinical studies with simvastatin, an effect also observed with other statins
and the bile acid sequestrant cholestyramine. There was no effect on plasma
gonadotropin levels. In a placebo-controlled, 12-week study there was no
significant effect of simvastatin 80 mg on the plasma testosterone response to
human chorionic gonadotropin. In another 24-week study, simvastatin 20-40 mg had
no detectable effect on spermatogenesis. In 4S, in which 4444 patients were
randomized to simvastatin 20-40 mg/day or placebo for a median duration of 5.4
years, the incidence of male sexual adverse events in the two treatment groups
was not significantly different. Because of these factors, the small changes in
plasma testosterone are unlikely to be clinically significant. The effects, if
any, on the pituitary-gonadal axis in pre-menopausal women are unknown.