CLINICAL PHARMACOLOGY
Mechanism Of Action
Rosiglitazone, a member of the thiazolidinedione class of
antidiabetic agents, improves glycemic control by improving insulin
sensitivity. Rosiglitazone is a highly selective and potent agonist for the
peroxisome proliferator-activated receptor-gamma (PPARγ). In humans, PPAR
receptors are found in key target tissues for insulin action such as adipose
tissue, skeletal muscle, and liver. Activation of PPARy nuclear receptors
regulates the transcription of insulin-responsive genes involved in the control
of glucose production, transport, and utilization. In addition,
PPARγ-responsive genes also participate in the regulation of fatty acid
metabolism.
Insulin resistance is a common feature characterizing the
pathogenesis of type 2 diabetes. The antidiabetic activity of rosiglitazone has
been demonstrated in animal models of type 2 diabetes in which hyperglycemia
and/or impaired glucose tolerance is a consequence of insulin resistance in
target tissues. Rosiglitazone reduces blood glucose concentrations and reduces
hyperinsulinemia in the ob/ob obese mouse, db/db diabetic mouse, and fa/fa
fatty Zucker rat.
In animal models, the antidiabetic activity of
rosiglitazone was shown to be mediated by increased sensitivity to insulin's
action in the liver, muscle, and adipose tissues. Pharmacological studies in
animal models indicate that rosiglitazone inhibits hepatic gluconeogenesis. The
expression of the insulin-regulated glucose transporter GLUT-4 was increased in
adipose tissue. Rosiglitazone did not induce hypoglycemia in animal models of
type 2 diabetes and/or impaired glucose tolerance.
Pharmacodynamics
Patients with lipid abnormalities were not excluded from
clinical trials of AVANDIA. In all 26-week controlled trials, across the
recommended dose range, AVANDIA as monotherapy was associated with increases in
total cholesterol, LDL, and HDL and decreases in free fatty acids. These
changes were statistically significantly different from placebo or glyburide
controls (Table 7).
Increases in LDL occurred primarily during the first 1 to
2 months of therapy with AVANDIA and LDL levels remained elevated above
baseline throughout the trials. In contrast, HDL continued to rise over time.
As a result, the LDL/HDL ratio peaked after 2 months of therapy and then
appeared to decrease over time. Because of the temporal nature of lipid
changes, the 52-week, glyburide-controlled trial is most pertinent to assess
long-term effects on lipids. At baseline, Week 26, and Week 52, mean LDL/HDL
ratios were 3.1, 3.2, and 3.0, respectively, for AVANDIA 4 mg twice daily. The
corresponding values for glyburide were 3.2, 3.1, and 2.9. The differences in
change from baseline between AVANDIA and glyburide at Week 52 were
statistically significant.
The pattern of LDL and HDL changes following therapy with
AVANDIA in combination with other hypoglycemic agents were generally similar to
those seen with AVANDIA in monotherapy.
The changes in triglycerides during therapy with AVANDIA
were variable and were generally not statistically different from placebo or
glyburide controls.
Table 7: Summary of Mean Lipid Changes in 26-Week,
Placebo-controlled and 52-Week, Glyburide-controlled Monotherapy Trials
Parameter |
Placebo-controlled Trials Week 26 |
Glyburide-controlled Trial Week 26 and Week 52 |
Placebo |
AVANDIA |
Glyburide Titration |
AVANDIA 8 mg |
|
4 mg Dailya |
8 mg Dailya |
Week 26 |
Week 52 |
Week 26 |
Week 52 |
Free fatty acids |
N |
207 |
428 |
436 |
181 |
168 |
166 |
145 |
Baseline (mean) % |
18.1 |
17.5 |
17.9 |
26.4 |
26.4 |
26.9 |
26.6 |
Change from baseline(mean) |
+0.2% |
-7.8% |
-14.7% |
-2.4% |
-4.7% |
-20.8% |
-21.5% |
LDL |
N |
190 |
400 |
374 |
175 |
160 |
161 |
133 |
Baseline (mean) % |
123.7 |
126.8 |
125.3 |
142.7 |
141.9 |
142.1 |
142.1 |
Change from baseline(mean) |
+4.8% |
+14.1% |
+18.6% |
-0.9% |
-0.5% |
+11.9% |
+12.1% |
HDL |
N |
208 |
429 |
436 |
184 |
170 |
170 |
145 |
Baseline (mean) % |
44.1 |
44.4 |
43.0 |
47.2 |
47.7 |
48.4 |
48.3 |
Change from baseline(mean) |
+8.0% |
+11.4% |
+14.2% |
+4.3% |
+8.7% |
+14.0% |
+18.5% |
a Once-daily and twice-daily dosing groups
were combined. |
Pharmacokinetics
Maximum plasma concentration (Cmax) and the area under
the curve (AUC) of rosiglitazone increase in a dose-proportional manner over
the therapeutic dose range (Table 8). The elimination half-life is 3 to 4 hours
and is independent of dose.
Table 8: Mean (SD) Pharmacokinetic Parameters for
Rosiglitazone Following Single Oral Doses (N = 32)
Parameter |
1 mg Fasting |
2 mg Fasting |
8 mg Fasting |
8 mg Fed |
AUC0-inf (ng.h/mL) |
358 (112) |
733 (184) |
2,971 (730) |
2,890 (795) |
Cmax (ng/mL) |
76 (13) |
156 (42) |
598 (117) |
432 (92) |
T½ (h) |
3.16 (0.72) |
3.15 (0.39) |
3.37 (0.63) |
3.59 (0.70) |
CL/F (L/h) |
3.03 (0.87) |
2.89 (0.71) |
2.85 (0.69) |
2.97 (0.81) |
AUC = area under the curve; Cmax = maximum concentration;
T½ = terminal half-life; CL/F = Oral clearance. |
Absorption
The absolute bioavailability of rosiglitazone is 99%.
Peak plasma concentrations are observed about 1 hour after dosing. Administration
of rosiglitazone with food resulted in no change in overall exposure (AUC), but
there was an approximately 28% decrease in Cmax and a delay in Tmax (1.75
hours). These changes are not likely to be clinically significant; therefore,
AVANDIA may be administered with or without food.
Distribution
The mean (CV%) oral volume of distribution (Vss/F) of
rosiglitazone is approximately 17.6 (30%) liters, based on a population
pharmacokinetic analysis. Rosiglitazone is approximately 99.8% bound to plasma
proteins, primarily albumin.
Metabolism
Rosiglitazone is extensively metabolized with no
unchanged drug excreted in the urine. The major routes of metabolism were
N-demethylation and hydroxylation, followed by conjugation with sulfate and
glucuronic acid. All the circulating metabolites are considerably less potent
than parent and, therefore, are not expected to contribute to the
insulin-sensitizing activity of rosiglitazone.
In vitro data demonstrate that rosiglitazone is
predominantly metabolized by Cytochrome P450 (CYP) isoenzyme 2C8, with CYP2C9
contributing as a minor pathway.
Excretion
Following oral or intravenous administration of [14C]rosiglitazone
maleate, approximately 64% and 23% of the dose was eliminated in the urine and
in the feces, respectively. The plasma half-life of [14C]related
material ranged from 103 to 158 hours.
Population Pharmacokinetics in Patients With Type 2
Diabetes
Population pharmacokinetic analyses from 3 large clinical
trials including 642 men and 405 women with type 2 diabetes (aged 35 to 80
years) showed that the pharmacokinetics of rosiglitazone are not influenced by
age, race, smoking, or alcohol consumption. Both oral clearance (CL/F) and oral
steady-state volume of distribution (Vss/F) were shown to increase with increases
in body weight. Over the weight range observed in these analyses (50 to 150
kg), the range of predicted CL/F and Vss/F values varied by < 1.7-fold and
< 2.3-fold, respectively. Additionally, rosiglitazone CL/F was shown to be
influenced by both weight and gender, being lower (about 15%) in female
patients.
Special Populations
Geriatric: Results of the population
pharmacokinetic analysis (n = 716 < 65 years; n = 331 ≥65 years) showed
that age does not significantly affect the pharmacokinetics of rosiglitazone.
Gender: Results of the population pharmacokinetics
analysis showed that the mean oral clearance of rosiglitazone in female
patients (n = 405) was approximately 6% lower compared with male patients of
the same body weight (n = 642).
As monotherapy and in combination with metformin, AVANDIA
improved glycemic control in both males and females. In metformin combination
trials, efficacy was demonstrated with no gender differences in glycemic
response.
In monotherapy trials, a greater therapeutic response was
observed in females; however, in more obese patients, gender differences were
less evident. For a given body mass index (BMI), females tend to have a greater
fat mass than males. Since the molecular target PPARy is expressed in adipose
tissues, this differentiating characteristic may account, at least in part, for
the greater response to AVANDIA in females. Since therapy should be
individualized, no dose adjustments are necessary based on gender alone.
Hepatic Impairment: Unbound oral clearance of
rosiglitazone was significantly lower in patients with moderate to severe liver
disease (Child-Pugh Class B/C) compared with healthy subjects. As a result,
unbound Cmax and AUC0-inf were increased 2- and 3-fold, respectively.
Elimination half-life for rosiglitazone was about 2 hours longer in patients
with liver disease, compared with healthy subjects.
Therapy with AVANDIA should not be initiated if the
patient exhibits clinical evidence of active liver disease or increased serum
transaminase levels (ALT >2.5X upper limit of normal) at baseline [see WARNINGS AND PRECAUTIONS].
Pediatric: Pharmacokinetic parameters of
rosiglitazone in pediatric patients were established using a population
pharmacokinetic analysis with sparse data from 96 pediatric patients in a
single pediatric clinical trial including 33 males and 63 females with ages
ranging from 10 to 17 years (weights ranging from 35 to 178.3 kg). Population
mean CL/F and V/F of rosiglitazone were 3.15 L/h and 13.5 L, respectively.
These estimates of CL/F and V/F were consistent with the typical parameter
estimates from a prior adult population analysis.
Renal Impairment: There are no clinically relevant
differences in the pharmacokinetics of rosiglitazone in patients with mild to
severe renal impairment or in hemodialysis-dependent patients compared with
subjects with normal renal function. No dosage adjustment is therefore required
in such patients receiving AVANDIA. Since metformin is contraindicated in
patients with renal impairment, coadministration of metformin with AVANDIA is
contraindicated in these patients.
Race: Results of a population pharmacokinetic
analysis including subjects of Caucasian, black, and other ethnic origins
indicate that race has no influence on the pharmacokinetics of rosiglitazone.
Drug-drug Interactions
Drugs That Inhibit, Induce, or are Metabolized by
Cytochrome P450
In vitro drug metabolism studies suggest that
rosiglitazone does not inhibit any of the major P450 enzymes at clinically
relevant concentrations. In vitro data demonstrate that rosiglitazone is
predominantly metabolized by CYP2C8, and to a lesser extent, 2C9. AVANDIA (4 mg
twice daily) was shown to have no clinically relevant effect on the
pharmacokinetics of nifedipine and oral contraceptives (ethinyl estradiol and norethindrone),
which are predominantly metabolized by CYP3A4.
Gemfibrozil: Concomitant administration of
gemfibrozil (600 mg twice daily), an inhibitor of CYP2C8, and rosiglitazone (4
mg once daily) for 7 days increased rosiglitazone AUC by 127%, compared with
the administration of rosiglitazone (4 mg once daily) alone. Given the
potential for dose-related adverse events with rosiglitazone, a decrease in the
dose of rosiglitazone may be needed when gemfibrozil is introduced [see DRUG INTERACTIONS].
Rifampin: Rifampin administration (600 mg once a
day), an inducer of CYP2C8, for 6 days is reported to decrease rosiglitazone
AUC by 66%, compared with the administration of rosiglitazone (8 mg) alone [see
DRUG INTERACTIONS].1
Glyburide
AVANDIA (2 mg twice daily) taken concomitantly with
glyburide (3.75 to 10 mg/day) for 7 days did not alter the mean steady-state
24-hour plasma glucose concentrations in diabetic patients stabilized on
glyburide therapy. Repeat doses of AVANDIA (8 mg once daily) for 8 days in
healthy adult Caucasian subjects caused a decrease in glyburide AUC and Cmax of
approximately 30%. In Japanese subjects, glyburide AUC and Cmax slightly
increased following coadministration of AVANDIA.
Glimepiride
Single oral doses of glimepiride in 14 healthy adult
subjects had no clinically significant effect on the steady-state
pharmacokinetics of AVANDIA. No clinically significant reductions in
glimepiride AUC and Cmax were observed after repeat doses of AVANDIA (8 mg once
daily) for 8 days in healthy adult subjects.
Metformin
Concurrent administration of AVANDIA (2 mg twice daily)
and metformin (500 mg twice daily) in healthy volunteers for 4 days had no
effect on the steady-state pharmacokinetics of either metformin or rosiglitazone.
Acarbose
Coadministration of acarbose (100 mg three times daily)
for 7 days in healthy volunteers had no clinically relevant effect on the
pharmacokinetics of a single oral dose of AVANDIA.
Digoxin
Repeat oral dosing of AVANDIA (8 mg once daily) for 14
days did not alter the steady-state pharmacokinetics of digoxin (0.375 mg once
daily) in healthy volunteers.
Warfarin
Repeat dosing with AVANDIA had no clinically relevant
effect on the steadystate pharmacokinetics of warfarin enantiomers.
Ethanol
A single administration of a moderate amount of alcohol
did not increase the risk of acute hypoglycemia in type 2 diabetes mellitus
patients treated with AVANDIA.
Ranitidine
Pre-treatment with ranitidine (150 mg twice daily for 4
days) did not alter the pharmacokinetics of either single oral or intravenous
doses of rosiglitazone in healthy volunteers. These results suggest that the
absorption of oral rosiglitazone is not altered in conditions accompanied by
increases in gastrointestinal pH.
Animal Toxicology
Heart weights were increased in mice (3 mg/kg/day), rats
(5 mg/kg/day), and dogs (2 mg/kg/day) with rosiglitazone treatments
(approximately 5, 22, and 2 times human AUC at the maximum recommended human
daily dose, respectively). Effects in juvenile rats were consistent with those
seen in adults. Morphometric measurement indicated that there was hypertrophy
in cardiac ventricular tissues, which may be due to increased heart work as a
result of plasma volume expansion.
Clinical Studies
Monotherapy
In clinical trials, treatment with AVANDIA resulted in an
improvement in glycemic control, as measured by FPG and HbA1c, with a
concurrent reduction in insulin and C-peptide. Postprandial glucose and insulin
were also reduced. This is consistent with the mechanism of action of AVANDIA
as an insulin sensitizer.
The maximum recommended daily dose is 8 mg. Dose-ranging
trials suggested that no additional benefit was obtained with a total daily
dose of 12 mg.
Short-term Clinical Trials
A total of 2,315 patients with type 2 diabetes,
previously treated with diet alone or antidiabetic medication(s), were treated
with AVANDIA as monotherapy in 6 double-blind trials, which included two
26-week, placebo-controlled trials; one 52-week, glyburide-controlled trial;
and 3 placebo-controlled, dose-ranging trials of 8 to 12 weeks' duration.
Previous antidiabetic medication(s) were withdrawn and patients entered a 2- to
4-week placebo run-in period prior to randomization.
Two 26-week, double-blind, placebo-controlled trials, in
patients with type 2 diabetes (n = 1,401) with inadequate glycemic control
[mean baseline FPG approximately 228 mg/dL (101 to 425 mg/dL) and mean baseline
HbA1c 8.9% (5.2% to 16.2%)], were conducted. Treatment with AVANDIA produced
statistically significant improvements in FPG and HbA1c compared with baseline
and relative to placebo. Data from one of these trials are summarized in Table
9.
Table 9: Glycemic Parameters in a 26-Week,
Placebo-controlled Trial
Parameter |
Placebo |
AVANDIA |
AVANDIA |
N = 173 |
4 mg Once Daily
N = 180 |
2 mg Twice Daily
N = 186 |
8 mg Once Daily
N = 181 |
4 mg Twice Daily
N = 187 |
FPG (mg/dL) |
Baseline (mean) |
225 |
229 |
225 |
228 |
228 |
Change from baseline (mean) |
8 |
-25 |
-35 |
-42 |
-55 |
Difference from placebo (adjusted mean) |
- |
-31a |
-43a |
-49a |
-62a |
% of patients with ≥30 mg/dL decrease from baseline |
19% |
45% |
54% |
58% |
70% |
HbA1c (%) |
Baseline (mean) |
8.9 |
8.9 |
8.9 |
8.9 |
9.0 |
Change from baseline (mean) |
0.8 |
0.0 |
-0.1 |
-0.3 |
-0.7 |
Difference from placebo (adjusted mean) |
- |
-0.8a |
-0.9a |
-1.1a |
-1.5a |
% of patients with ≥0.7% decrease from baseline |
9% |
28% |
29% |
39% |
54% |
a P < 0.0001 compared with placebo. |
When administered at the same total daily dose, AVANDIA
was generally more effective in reducing FPG and HbA1c when administered in
divided doses twice daily compared with once-daily doses. However, for HbA1c,
the difference between the 4 mg once-daily and 2 mg twice-daily doses was not
statistically significant.
Long-term Clinical Trials
Long-term maintenance of effect was evaluated in a 52-
week, double-blind, glyburide-controlled trial in patients with type 2
diabetes. Patients were randomized to treatment with AVANDIA 2 mg twice daily
(N = 195) or AVANDIA 4 mg twice daily (N = 189) or glyburide (N = 202) for 52
weeks. Patients receiving glyburide were given an initial dosage of either 2.5
mg/day or 5.0 mg/day. The dosage was then titrated in 2.5-mg/day increments
over the next 12 weeks, to a maximum dosage of 15.0 mg/day in order to optimize
glycemic control. Thereafter, the glyburide dose was kept constant.
The median titrated dose of glyburide was 7.5 mg. All
treatments resulted in a statistically significant improvement in glycemic
control from baseline (Figure 3 and Figure 4). At the end of Week 52, the
reduction from baseline in FPG and HbA1c was -40.8 mg/dL and-0.53% with AVANDIA
4 mg twice daily; -25.4 mg/dL and -0.27% with AVANDIA 2 mg twice daily; and
-30.0 mg/dL and -0.72% with glyburide. For HbA1c, the difference between
AVANDIA 4 mg twice daily and glyburide was not statistically significant at
Week 52. The initial fall in FPG with glyburide was greater than with AVANDIA;
however, this effect was less durable over time. The improvement in glycemic
control seen with AVANDIA 4 mg twice daily at Week 26 was maintained through
Week 52 of the trial.
Figure 3: Mean FPG Over Time in a 52-Week,
Glyburide-controlled Trial
Figure 4: Mean HbAlc Over Time in a 52-Week,
Glyburide-controlled Trial
Hypoglycemia was reported in 12.1% of glyburide-treated
patients versus 0.5% (2 mg twice daily) and 1.6% (4 mg twice daily) of patients
treated with AVANDIA. The improvements in glycemic control were associated with
a mean weight gain of 1.75 kg and 2.95 kg for patients treated with 2 mg and 4
mg twice daily of AVANDIA, respectively, versus 1.9 kg in glyburidetreated
patients. In patients treated with AVANDIA, C-peptide, insulin, pro-insulin,
and proinsulin split products were significantly reduced in a dose-ordered
fashion, compared with an increase in the glyburide-treated patients.
A Diabetes Outcome Progression Trial (ADOPT) was a
multicenter, double-blind, controlled trial (N = 4,351) conducted over 4 to 6
years to compare the safety and efficacy of AVANDIA, metformin, and glyburide
monotherapy in patients recently diagnosed with type 2 diabetes mellitus ( ≤ 3
years) inadequately controlled with diet and exercise. The mean age of patients
in this trial was 57 years and the majority of patients (83%) had no known
history of cardiovascular disease. The mean baseline FPG and HbA1c were 152
mg/dL and 7.4%, respectively. Patients were randomized to receive either
AVANDIA 4 mg once daily, glyburide 2.5 mg once daily, or metformin 500 mg once
daily, and doses were titrated to optimal glycemic control up to a maximum of 4
mg twice daily for AVANDIA, 7.5 mg twice daily for glyburide, and 1,000 mg
twice daily for metformin. The primary efficacy outcome was time to consecutive
FPG >180 mg/dL after at least 6 weeks of treatment at the maximum tolerated
dose of study medication or time to inadequate glycemic control, as determined
by an independent adjudication committee.
The cumulative incidence of the primary efficacy outcome
at 5 years was 15% with AVANDIA, 21% with metformin, and 34% with glyburide (HR
0.68 [95% CI: 0.55, 0.85] versus metformin, HR 0.37 [95% CI: 0.30, 0.45] versus
glyburide).
Cardiovascular and adverse event data (including effects
on body weight and bone fracture) from ADOPT for AVANDIA, metformin, and
glyburide are described in WARNINGS AND PRECAUTIONS (5.2, 5.4, and 5.7) and
Adverse Reactions (6.1), respectively. As with all medications, efficacy
results must be considered together with safety information to assess the
potential benefit and risk for an individual patient.
Combination With Metformin Or Sulfonylurea
The addition of AVANDIA to either metformin or
sulfonylurea resulted in significant reductions in hyperglycemia compared with
either of these agents alone. These results are consistent with an additive
effect on glycemic control when AVANDIA is used as combination therapy.
Combination With Metformin
A total of 670 patients with type 2 diabetes participated
in two 26-week, randomized, double-blind, placebo/active-controlled trials
designed to assess the efficacy of AVANDIA in combination with metformin.
AVANDIA, administered in either oncedaily or twice-daily dosing regimens, was
added to the therapy of patients who were inadequately controlled on a maximum
dose (2.5 grams/day) of metformin.
In one trial, patients inadequately controlled on 2.5
grams/day of metformin (mean baseline FPG 216 mg/dL and mean baseline HbA1c
8.8%) were randomized to receive 4 mg of AVANDIA once daily, 8 mg of AVANDIA
once daily, or placebo in addition to metformin. A statistically significant
improvement in FPG and HbA1c was observed in patients treated with the
combinations of metformin and 4 mg of AVANDIA once daily and 8 mg of AVANDIA
once daily, versus patients continued on metformin alone (Table 10).
Table 10: Glycemic Parameters in a 26-Week Combination
Trial of AVANDIA Plus Metformin
Parameter |
Metformin
N = 113 |
AVANDIA 4 mg Once Daily + Metformin
N = 116 |
AVANDIA 8 mg Once Daily +Metformin
N = 110 |
FPG (mg/dL) |
Baseline (mean) |
214 |
215 |
220 |
Change from baseline (mean) |
6 |
-33 |
-48 |
Difference from metformin alone (adjusted mean) |
- |
-40a |
-53a |
% of patients with ≥30 mg/dL decrease from baseline |
20% |
45% |
61% |
HbAlc (%) |
Baseline (mean) |
8.6 |
8.9 |
8.9 |
Change from baseline (mean) |
0.5 |
-0.6 |
-0.8 |
Difference from metformin alone (adjusted mean) |
- |
-1.0a |
-1.2a |
% of patients with ≥0.7% decrease from baseline |
11% |
45% |
52% |
a P < 0.0001 compared with metformin. |
In a second 26-week trial, patients with type 2 diabetes inadequately
controlled on 2.5 grams/day of metformin who were randomized to receive the
combination of AVANDIA 4 mg twice daily and metformin (N = 105) showed a
statistically significant improvement in glycemic control with a mean treatment
effect for FPG of -56 mg/dL and a mean treatment effect for HbA1c of -0.8% over
metformin alone. The combination of metformin and AVANDIA resulted in lower
levels of FPG and HbA1c than either agent alone.
Patients who were inadequately controlled on a maximum
dose (2.5 grams/day) of metformin and who were switched to monotherapy with
AVANDIA demonstrated loss of glycemic control, as evidenced by increases in FPG
and HbA1c. In this group, increases in LDL and VLDL were also seen.
Combination With a Sulfonylurea
A total of 3,457 patients with type 2 diabetes
participated in ten 24- to 26-week randomized, double-blind,
placebo/active-controlled trials and one 2-year double-blind, active-controlled
trial in elderly patients designed to assess the efficacy and safety of AVANDIA
in combination with a sulfonylurea. AVANDIA 2 mg, 4 mg, or 8 mg daily was
administered, either once daily (3 trials) or in divided doses twice daily (7
trials), to patients inadequately controlled on a submaximal or maximal dose of
sulfonylurea.
In these trials, the combination of AVANDIA 4 mg or 8 mg
daily (administered as single-or twice-daily divided doses) and a sulfonylurea
significantly reduced FPG and HbA1c compared with placebo plus sulfonylurea or
further up-titration of the sulfonylurea. Table 11 shows pooled data for 8
trials in which AVANDIA added to sulfonylurea was compared with placebo plus
sulfonylurea.
Table 11: Glycemic Parameters in 24- to 26-Week
Combination Trials of AVANDIA Plus Sulfonylurea
Twice-Daily Divided Dosing (5 Trials) |
Sulfonylurea
N = 397 |
AVANDIA 2 mg Twice Daily + Sulfonylurea
N = 497 |
Sulfonylurea
N = 248 |
AVANDIA 4 mg Twice Daily + Sulfonylurea
N = 346 |
FPG (mg/dL) |
Baseline (mean) |
204 |
198 |
188 |
187 |
Change from baseline (mean) |
11 |
-29 |
8 |
-43 |
Difference from sulfonylurea alone(adjusted mean) |
- |
-42a |
- |
-53a |
% of patients with ≥30 mg/dL decrease from baseline |
17% |
49% |
15% |
61% |
HbA1c (%) |
Baseline (mean) |
9.4 |
9.5 |
9.3 |
9.6 |
Change from baseline (mean) |
0.2 |
-1.0 |
0.0 |
-1.6 |
Difference from sulfonylurea alone(adjusted mean) |
- |
-1.1a |
- |
-1.4a |
% of patients with ≥0.7% decrease from baseline |
21% |
60% |
23% |
75% |
Once-Daily Dosing (3 Trials) |
Sulfonylurea
N = 172 |
AVANDIA 4 mg Once Daily +Sulfonylurea
N = 172 |
Sulfonylurea
N = 173 |
AVANDIA 8 mg Once Daily + Sulfonylurea
N = 176 |
FPG (mg/dL) |
Baseline (mean) |
198 |
206 |
188 |
192 |
Change from baseline (mean) |
17 |
-25 |
17 |
-43 |
Difference from sulfonylurea alone(adjusted mean) |
- |
-47a |
- |
-66a |
% of patients with ≥ 30 mg/dL decrease from baseline |
17% |
48% |
19% |
55% |
HbA1c (%) |
Baseline (mean) |
8.6 |
8.8 |
8.9 |
8.9 |
Change from baseline (mean) |
0.4 |
-0.5 |
0.1 |
-1.2 |
Difference from sulfonylurea alone(adjusted mean) |
- |
-0.9a |
- |
-1.4a |
% of patients with ≥ 0.7% decrease from baseline |
11% |
36% |
20% |
68% |
a P < 0.0001 compared with sulfonylurea
alone. |
One of the 24- to 26-week trials included patients who
were inadequately controlled on maximal doses of glyburide and switched to 4 mg
of AVANDIA daily as monotherapy; in this group, loss of glycemic control was
demonstrated, as evidenced by increases in FPG and HbA1c.
In a 2-year, double-blind trial, elderly patients (aged
59 to 89 years) on half-maximal sulfonylurea (glipizide 10 mg twice daily) were
randomized to the addition of AVANDIA (n = 115, 4 mg once daily to 8 mg as
needed) or to continued up-titration of glipizide (n = 110), to a maximum of 20
mg twice daily. Mean baseline FPG and HbA1c were 157 mg/dL and 7.72%,
respectively, for the arm receiving AVANDIA plus glipizide and 159 mg/dL and
7.65%, respectively, for the glipizide up-titration arm. Loss of glycemic
control (FPG >180 mg/dL) occurred in a significantly lower proportion of
patients (2%) on AVANDIA plus glipizide compared with patients in the glipizide
up-titration arm (28.7%). About 78% of the patients on combination therapy completed
the 2 years of therapy while only 51% completed on glipizide monotherapy. The
effect of combination therapy on FPG and HbA1c was durable over the 2-year
trial period, with patients achieving a mean of 132 mg/dL for FPG and a mean of
6.98% for HbA1c compared with no change on the glipizide arm.
Combination With Sulfonylurea Plus Metformin
In two 24- to 26-week, double-blind, placebo-controlled
trials designed to assess the efficacy and safety of AVANDIA in combination
with sulfonylurea plus metformin, AVANDIA 4 mg or 8 mg daily, was administered
in divided doses twice daily, to patients inadequately controlled on submaximal
(10 mg) and maximal (20 mg) doses of glyburide and maximal dose of metformin (2
g/day). A statistically significant improvement in FPG and HbA1c was observed
in patients treated with the combinations of sulfonylurea plus metformin and 4
mg of AVANDIA and 8 mg of AVANDIA versus patients continued on sulfonylurea
plus metformin, as shown in Table 12.
Table 12: Glycemic Parameters in a 26-Week Combination
Trial of AVANDIA Plus Sulfonylurea and Metformin
Parameter |
Sulfonylurea + Metformin
N = 273 |
AVANDIA 2 mg Twice Daily + Sulfonylurea + Metformin
N = 276 |
AVANDIA 4 mg Twice Daily + Sulfonylurea + Metformin
N = 277 |
FPG (mg/dL) |
Baseline (mean) |
189 |
190 |
192 |
Change from baseline (mean) |
14 |
-19 |
-40 |
Difference from sulfonylurea plus metformin (adjusted mean) |
- |
-30a |
-52a |
% of patients with ≥30 mg/dL decrease from baseline |
16% |
46% |
62% |
HbA1c (%) |
Baseline (mean) |
8.7 |
8.6 |
8.7 |
Change from baseline (mean) |
0.2 |
-0.4 |
-0.9 |
Difference from sulfonylurea plus metformin (adjusted mean) |
- |
-0.6a |
-1.1a |
% of patients with ≥ 0.7% decrease from baseline |
16% |
39% |
63% |
a P < 0.0001 compared with placebo. |
REFERENCES
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