CLINICAL PHARMACOLOGY
Mechanism Of Action
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 JANUVIA, 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, JANUVIA 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.
Pharmacodynamics
General
In patients with type 2
diabetes, administration of JANUVIA 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, JANUVIA 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 JANUVIA 100 mg, JANUVIA 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 JANUVIA 100
mg (N=81) or JANUVIA 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.
Pharmacokinetics
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.
Absorption
The absolute bioavailability of sitagliptin is
approximately 87%. Because coadministration of a high-fat meal with JANUVIA had
no effect on the pharmacokinetics, JANUVIA may be administered with or without
food.
Distribution
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%).
Metabolism
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. Excretion
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.
Special Populations
Renal Insufficiency
A single-dose, open-label study was conducted to evaluate
the pharmacokinetics of JANUVIA (50 mg dose) in patients with varying degrees
of chronic renal insufficiency compared to normal healthy control subjects. The
study included patients with renal insufficiency 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 insufficiency on sitagliptin
pharmacokinetics in patients with type 2 diabetes and mild or moderate renal
insufficiency 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:
CrCl = [140 -age (years)] x weight (kg) {x 0.85 for
female patients} / [72 x serum creatinine (mg/dL)]
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 insufficiency. Because increases of this magnitude
are not clinically relevant, dosage adjustment in patients with mild renal insufficiency
is not necessary. Plasma AUC levels of sitagliptin were increased approximately
2-fold and 4-fold in patients with moderate renal insufficiency and in patients
with severe renal insufficiency, including patients with ESRD on hemodialysis,
respectively. Sitagliptin was modestly removed by hemodialysis (13.5% over a
3to 4-hour hemodialysis session starting 4 hours postdose). To achieve plasma
concentrations of sitagliptin similar to those in patients with normal renal
function, lower dosages are recommended in patients with moderate and severe
renal insufficiency, as well as in ESRD patients requiring dialysis. [See DOSAGE
AND ADMINISTRATION]
Hepatic Insufficiency
In patients with moderate hepatic insufficiency
(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 JANUVIA. These differences
are not considered to be clinically meaningful. No dosage adjustment for
JANUVIA is necessary for patients with mild or moderate hepatic insufficiency.
There is no clinical experience in patients with severe
hepatic insufficiency (Child-Pugh score >9).
Body Mass Index (BMI)
No dosage adjustment is necessary based on BMI. 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
No dosage adjustment is necessary based on gender. 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
No dosage adjustment is required based solely on age.
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.
Pediatric
Studies characterizing the pharmacokinetics of
sitagliptin in pediatric patients have not been performed.
Race
No dosage adjustment is necessary based on race. 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
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 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).
Digoxin
Sitagliptin had a minimal effect on the pharmacokinetics
of digoxin. Following administration of 0.25 mg digoxin concomitantly with 100
mg of JANUVIA daily for 10 days, the plasma AUC of digoxin was increased by
11%, and the plasma Cmax by 18%.
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.
Simvastatin
Single-dose pharmacokinetics of simvastatin, a CYP3A4
substrate, was not meaningfully altered in subjects receiving multiple daily
doses of sitagliptin. Therefore, sitagliptin is not an inhibitor of
CYP3A4-mediated metabolism.
Thiazolidinediones
Single-dose pharmacokinetics of rosiglitazone was not meaningfully
altered in subjects receiving multiple daily doses of sitagliptin, indicating
that JANUVIA 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 JANUVIA 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.
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)controlled 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 JANUVIA
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 JANUVIA
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, JANUVIA 100 mg, or JANUVIA 200 mg, and in the 24-week
study 741 patients were randomized to placebo, JANUVIA 100 mg, or JANUVIA 200
mg. Patients who failed to meet specific glycemic goals during the studies were
treated with metformin rescue, added on to placebo or JANUVIA.
Treatment with JANUVIA at 100 mg daily provided
significant improvements in A1C, FPG, and 2-hour PPG compared to placebo (Table
4). In the 18-week study, 9% of patients receiving JANUVIA 100 mg and 17% who
received placebo required rescue therapy. In the 24-week study, 9% of patients
receiving JANUVIA 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
JANUVIA appears to be related to the degree of A1C elevation at baseline. In
these 18-and 24week 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 JANUVIA, 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. The
effect of JANUVIA on lipid endpoints was similar to placebo. Body weight did
not increase from baseline with JANUVIA therapy in either study, compared to a
small reduction in patients given placebo.
Table 4: Glycemic Parameters in 18-and 24-Week
Placebo-Controlled Studies of JANUVIA in Patients with Type 2 Diabetes*
|
18-Week Study |
24-Week Study |
JANUVIA 100 mg |
Placebo |
JANUVIA 100 mg |
Placebo |
A1C (%) |
N = 193 |
N = 103 |
N = 229 |
N = 244 |
Baseline (mean) |
8.0 |
8.1 |
8.0 |
8.0 |
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. |
Additional Monotherapy Study
A multinational, randomized,
double-blind, placebo-controlled study was also conducted to assess the safety
and tolerability of JANUVIA in 91 patients with type 2 diabetes and chronic
renal insufficiency (creatinine clearance <50 mL/min). Patients with
moderate renal insufficiency received 50 mg daily of JANUVIA and those with
severe renal insufficiency or with ESRD on hemodialysis or peritoneal dialysis
received 25 mg daily. In this study, the safety and tolerability of JANUVIA
were generally similar to placebo. A small increase in serum creatinine was
reported in patients with moderate renal insufficiency treated with JANUVIA
relative to those on placebo. In addition, the reductions in A1C and FPG with
JANUVIA compared to placebo were generally similar to those observed in other
monotherapy studies. [See CLINICAL PHARMACOLOGY]
Combination Therapy
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 JANUVIA 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 JANUVIA 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,
JANUVIA provided significant improvements in A1C, FPG, and 2-hour PPG compared
to placebo with metformin (Table 5). Rescue glycemic therapy was used in 5% of
patients treated with JANUVIA 100 mg and 14% of patients treated with placebo.
A similar decrease in body weight was observed for both treatment groups.
Table 5: Glycemic Parameters at Final Visit (24-Week
Study) for JANUVIA in Add-on Combination Therapy with Metformin*
|
JANUVIA 100 mg + Metformin |
Placebo + Metformin |
A1C (%) |
N = 453 |
N = 224 |
Baseline (mean) |
8.0 |
8.0 |
Change from baseline (adjusted mean†) |
-0.7 |
-0.0 |
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 JANUVIA 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 JANUVIA and metformin provided significant improvements in A1C,
FPG, and 2-hour PPG compared to placebo, to metformin alone, and to JANUVIA
alone (Table 6, 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: JANUVIA 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%. Lipid effects were generally neutral. 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 6: Glycemic Parameters at Final Visit (24-Week
Study) for Sitagliptin and Metformin, Alone and in Combination as Initial
Therapy*
|
Placebo |
Sitagliptin (JANUVIA) 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*
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 JANUVIA 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 JANUVIA 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, JANUVIA and
glipizide had similar mean reductions from baseline in A1C in the
intent-to-treat analysis (Table 7). These results were consistent with the per
protocol analysis (Figure 2). A conclusion in favor of the non-inferiority of
JANUVIA 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 7: Glycemic Parameters in a 52-Week Study
Comparing JANUVIA to Glipizide as Add-On Therapy in Patients Inadequately Controlled
on Metformin (Intent-to-Treat Population)*
|
JANUVIA 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 JANUVIA to Glipizide as
Add-On Therapy in Patients Inadequately Controlled on Metformin (Per Protocol
Population)*
The incidence of hypoglycemia
in the JANUVIA group (4.9%) was significantly (p<0.001) lower than that in
the glipizide group (32.0%). Patients treated with JANUVIA 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 JANUVIA 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 JANUVIA 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, JANUVIA provided
significant improvements in A1C and FPG compared to placebo with pioglitazone
(Table 8). Rescue therapy was used in 7% of patients treated with JANUVIA 100
mg and 14% of patients treated with placebo. There was no significant
difference between JANUVIA and placebo in body weight change.
Table 8: Glycemic Parameters at Final Visit (24-Week
Study) for JANUVIA in Add-on Combination Therapy with Pioglitazone*
|
JANUVIA 100 mg + Pioglitazone |
Placebo + Pioglitazone |
A1C (%) |
N = 163 |
N = 174 |
Baseline (mean) |
8.1 |
8.0 |
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 JANUVIA 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 JANUVIA 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 JANUVIA and pioglitazone provided significant improvements in
A1C, FPG, and 2-hour PPG compared to pioglitazone monotherapy (Table 9). 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 JANUVIA 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). Lipid effects were generally neutral.
Table 9: Glycemic Parameters
at Final Visit (24-Week Study) for JANUVIA in Combination with Pioglitazone as
Initial Therapy*
|
JANUVIA 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 JANUVIA 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 JANUVIA 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 Week 18.
In combination with metformin
and rosiglitazone, JANUVIA provided significant improvements in A1C, FPG, and
2-hour PPG compared to placebo with metformin and rosiglitazone (Table 10) at
Week 18. At Week 54, mean reduction in A1C was -1.0% for patients treated with
JANUVIA 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 JANUVIA 100 mg and 40% of patients treated with placebo. There was no
significant difference between JANUVIA and placebo in body weight change.
Table 10: Glycemic
Parameters at Week 18 for JANUVIA in Add-on Combination Therapy with Metformin
and Rosiglitazone*
|
JANUVIA 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 |
-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 JANUVIA 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 JANUVIA 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, JANUVIA provided significant
improvements in A1C and FPG compared to placebo (Table 11). In the entire study
population (patients on JANUVIA in combination with glimepiride and patients on
JANUVIA 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 JANUVIA 100 mg and 27%
of patients treated with placebo. In this study, patients treated with JANUVIA
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 11: Glycemic
Parameters at Final Visit (24-Week Study) for JANUVIA as Add-On Combination
Therapy with Glimepiride, with or without Metformin*
|
JANUVIA 100 mg + Glimepiride |
Placebo + Glimepiride |
JANUVIA 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 JANUVIA 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 JANUVIA 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 JANUVIA 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), JANUVIA provided significant improvements
in A1C, FPG, and 2-hour PPG compared to placebo (Table 12). 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
JANUVIA. [See WARNINGS AND PRECAUTIONS; ADVERSE REACTIONS]
Table 12: Glycemic Parameters at Final Visit (24-Week
Study) for JANUVIA as Add-on Combination Therapy with Insulin*
|
JANUVIA 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. |