Prescription Drug Information: Pioglitazone Hydrochloride and Metformin Hydrochloride (Page 2 of 8)

5.3 Edema

In controlled clinical trials with pioglitazone, edema was reported more frequently in patients treated with pioglitazone than in placebo-treated patients and is dose related [see Adverse Reactions (6.1)]. In postmarketing experience, reports of new onset or worsening of edema have been received.Pioglitazone and metformin hydrochloride should be used with caution in patients with edema. Because thiazolidinediones, including pioglitazone, can cause fluid retention, which can exacerbate or lead to congestive heart failure, pioglitazone and metformin hydrochloride should be used with caution in patients at risk for congestive heart failure. Patients treated with pioglitazone and metformin hydrochloride should be monitored for signs and symptoms of congestive heart failure [see Boxed Warning , Warnings and Precautions (5.1), and Patient Counseling Information (17)].

5.4 Hypoglycemia

Patients receiving pioglitazone and metformin hydrochloride in combination with insulin or other antidiabetic medications (particularly insulin secretagogues such as sulfonylureas) may be at risk for hypoglycemia. A reduction in the dose of the concomitant antidiabetic medication may be necessary to reduce the risk of hypoglycemia [see Drug Interactions (7.7)]. Hypoglycemia can also occur when caloric intake is deficient or when strenuous exercise is not compensated by caloric supplement. Elderly, debilitated, or malnourished patients, and those with adrenal or pituitary insufficiency or alcohol intoxication are particularly susceptible to hypoglycemic effects. Hypoglycemia may be difficult to recognize in the elderly, and in people who are taking beta-adrenergic blocking drugs.

5.5 Hepatic Effects

There have been postmarketing reports of fatal and nonfatal hepatic failure in patients taking pioglitazone, although the reports contain insufficient information necessary to establish the probable cause. There has been no evidence of drug-induced hepatotoxicity in the pioglitazone controlled clinical trial database to date [see Adverse Reactions (6.1)].
Patients with type 2 diabetes may have fatty liver disease or cardiac disease with episodic congestive heart failure, both of which may cause liver test abnormalities, and they may also have other forms of liver disease, many of which can be treated or managed. Therefore, obtaining a liver test panel (serum alanine aminotransferase [ALT], aspartate aminotransferase [AST], alkaline phosphatase, and total bilirubin) and assessing the patient is recommended before initiating pioglitazone and metformin hydrochloride therapy.
In patients with abnormal liver tests, pioglitazone and metformin hydrochloride should be initiated with caution.
Measure liver tests promptly in patients who report symptoms that may indicate liver injury, including fatigue, anorexia, right upper abdominal discomfort, dark urine or jaundice. In this clinical context, if the patient is found to have abnormal liver tests (ALT greater than three times the upper limit of the reference range), pioglitazone and metformin hydrochloride treatment should be interrupted and investigation done to establish the probable cause. Pioglitazone and metformin hydrochloride should not be restarted in these patients without another explanation for the liver test abnormalities.
Patients who have serum ALT greater than three times the reference range with serum total bilirubin greater than two times the reference range without alternative etiologies are at risk for severe drug-induced liver injury, and should not be restarted on pioglitazone and metformin hydrochloride. For patients with lesser elevations of serum ALT or bilirubin and with an alternate probable cause, treatment with pioglitazone and metformin hydrochloride can be used with caution.

5.6 Urinary Bladder Tumors

Tumors were observed in the urinary bladder of male rats in the two-year carcinogenicity study [see Nonclinical Toxicology (13.1)]. In addition, during the three year PROactive clinical trial, 14 patients out of 2605 (0.54%) randomized to pioglitazone and 5 out of 2633 (0.19%) randomized to placebo were diagnosed with bladder cancer. After excluding patients in whom exposure to study drug was less than one year at the time of diagnosis of bladder cancer, there were 6 (0.23%) cases on pioglitazone and two (0.08%) cases on placebo. After completion of the trial, a large subset of patients was observed for up to 10 additional years, with little additional exposure to pioglitazone. During the 13 years of both PROactive and observational follow-up, the occurrence of bladder cancer did not differ between patients randomized to pioglitazone or placebo (HR =1; [95% CI: 0.59 to 1.72]).
Findings regarding the risk of bladder cancer in patients exposed to pioglitazone vary among observational studies; some did not find an increased risk of bladder cancer associated with pioglitazone, while others did.
A large prospective10-year observational cohort study conducted in the United States found no statistically significant increase in the risk of bladder cancer in diabetic patients ever exposed to pioglitazone, compared to those never exposed to pioglitazone (HR =1.06 [95% CI 0.89 to 1.26]).
A retrospective cohort study conducted with data from the United Kingdom found a statistically significant association between ever exposure to pioglitazone and bladder cancer (HR: 1.63; [95% CI: 1.22 to 2.19]).
Associations between cumulative dose or cumulative duration of exposure to pioglitazone and bladder cancer were not detected in some studies including the 10-year observational study in the U.S., but were in others. Inconsistent findings and limitations inherent in these and other studies preclude conclusive interpretations of the observational data.
Pioglitazone may be associated with an increase in the risk of urinary bladder tumors. There are insufficient data to determine whether pioglitazone is a tumor promoter for urinary bladder tumors. Consequently, pioglitazone and metformin hydrochloride should not be used in patients with active bladder cancer and the benefits of glycemic control versus unknown risks for cancer recurrence with pioglitazone and metformin hydrochloride should be considered in patients with a prior history of bladder cancer.

5.7 Fractures

In PROactive (the Prospective Pioglitazone Clinical Trial in Macrovascular Events), 5238 patients with type 2 diabetes and a history of macrovascular disease were randomized to pioglitazone (N=2605), force-titrated up to 45 mg daily or placebo (N=2633) in addition to standard of care. During a mean follow-up of 34.5 months, the incidence of bone fracture in females was 5.1% (44/870) for pioglitazone versus 2.5% (23/905) for placebo. This difference was noted after the first year of treatment and persisted during the course of the study. The majority of fractures observed in female patients were nonvertebral fractures including lower limb and distal upper limb. No increase in the incidence of fracture was observed in men treated with pioglitazone (1.7%) versus placebo (2.1%). The risk of fracture should be considered in the care of patients, especially female patients, treated with pioglitazone and metformin hydrochloride and attention should be given to assessing and maintaining bone health according to current standards of care.

5.8 Macular Edema

Macular edema has been reported in postmarketing experience in diabetic patients who were taking pioglitazone or another thiazolidinedione. Some patients presented with blurred vision or decreased visual acuity, but others were diagnosed on routine ophthalmologic examination.
Most patients had peripheral edema at the time macular edema was diagnosed. Some patients had improvement in their macular edema after discontinuation of the thiazolidinedione.Patients with diabetes should have regular eye exams by an ophthalmologist according to current standards of care. Patients with diabetes who report any visual symptoms should be promptly referred to an ophthalmologist, regardless of the patient’s underlying medications or other physical findings [see Adverse Reactions (6.1)].

5.9 Vitamin B12 Levels

In controlled clinical trials of metformin of 29 weeks’ duration, a decrease to subnormal levels of previously normal serum vitamin B12 levels, without clinical manifestations, was observed in approximately 7% of patients. Such decrease, possibly due to interference with B12 absorption from the B12 -intrinsic factor complex, is, however, very rarely associated with anemia and appears to be rapidly reversible with discontinuation of metformin or vitamin B12 supplementation. Measurement of hematologic parameters on an annual basis is advised in patients on pioglitazone and metformin hydrochloride and any apparent abnormalities should be appropriately investigated and managed. Certain individuals (those with inadequate vitamin B12 or calcium intake or absorption) appear to be predisposed to developing subnormal vitamin B12 levels. In these patients, routine serum vitamin B12 measurements at two- to three-year intervals may be useful.

5.10 Macrovascular Outcomes

There have been no clinical studies establishing conclusive evidence of macrovascular risk reduction with pioglitazone and metformin hydrochloride.

6 ADVERSE REACTIONS

The following serious adverse reactions are discussed elsewhere in the labeling:

6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Pioglitazone

Over 8500 patients with type 2 diabetes have been treated with pioglitazone in randomized, double-blind, controlled clinical trials, including 2605 patients with type 2 diabetes and macrovascular disease treated with pioglitazone from the PROactive clinical trial. In these trials, over 6000 patients have been treated with pioglitazone for six months or longer, over 4500 patients have been treated with pioglitazone for one year or longer, and over 3000 patients have been treated with pioglitazone for at least two years.

In six pooled 16- to 26-week placebo-controlled monotherapy and 16- to 24-week add-on combination therapy trials, the incidence of withdrawals due to adverse events was 4.5% for patients treated with pioglitazone and 5.8% for comparator-treated patients. The most common adverse events leading to withdrawal were related to inadequate glycemic control, although the incidence of these events was lower (1.5%) with pioglitazone than with placebo (3%).

In the PROactive trial, the incidence of withdrawals due to adverse events was 9% for patients treated with pioglitazone and 7.7% for placebo-treated patients. Congestive heart failure was the most common serious adverse event leading to withdrawal occurring in 1.3% of patients treated with pioglitazone and 0.6% of patients treated with placebo.

Common Adverse Events: 16- to 26-Week Monotherapy Trials

A summary of the incidence and type of common adverse events reported in three pooled 16- to 26-week placebo-controlled monotherapy trials of pioglitazone is provided in Table 1. Terms that are reported represent those that occurred at an incidence of >5% and more commonly in patients treated with pioglitazone than in patients who received placebo. None of these adverse events were related to the pioglitazone dose.

Table 1. Three Pooled 16- to 26-Week Placebo-Controlled Clinical Trials of Pioglitazone Monotherapy: Adverse Events Reported at an Incidence >5% and More Commonly in Patients Treated with Pioglitazone than in Patients Treated with Placebo
% of Patients
Placebo N=259 Pioglitazone N=606
Upper Respiratory Tract Infection 8.5 13.2
Headache 6.9 9.1
Sinusitis 4.6 6.3
Myalgia 2.7 5.4
Pharyngitis 0.8 5.1

Common Adverse Events: 16- to 24-Week Add-on Combination Therapy Trials

A summary of the overall incidence and types of common adverse events reported in trials of pioglitazone add-on to metformin is provided in Table 2. Terms that are reported represent those that occurred at an incidence of >5% and more commonly with the highest tested dose of pioglitazone.

Table 2. 16- to 24-Week Clinical Trials of Pioglitazone Add-on to Metformin
16-Week Placebo-Controlled Trial Adverse Events Reported in >5% of Patients and More Commonly in Patients Treated with Pioglitazone + Metformin than in Patients Treated with Placebo + Metformin
% of Patients
Placebo + Metformin N=160 Pioglitazone 30 mg + Metformin N=168
Edema 2.5 6
Headache 1.9 6
24-Week Non-Controlled Double-Blind Trial Adverse Events Reported in >5% of Patients and More Commonly in Patients Treated with Pioglitazone 45 mg + Metformin than in Patients Treated with Pioglitazone 30 mg + Metformin
% of Patients
Pioglitazone 30 mg + Metformin N=411 Pioglitazone 45 mg + Metformin N=416
Upper Respiratory Tract Infection 12.4 13.5
Edema 5.8 13.9
Headache 5.4 5.8
Weight Increased 2.9 6.7

Note: The preferred terms of edema peripheral, generalized edema, pitting edema, and fluid retention were combined to form the aggregate term of “edema.”

Common Adverse Events: 24-Week Pioglitazone and metformin hydrochloride Clinical Trial

Table 3 summarizes the incidence and types of adverse reactions reported in a controlled, 24-week double-blind clinical trial of pioglitazone and metformin hydrochloride dosed twice daily in patients with inadequate glycemic control on diet and exercise (N=600).

Table 3. Adverse Events (≥5% for Pioglitazone and metformin hydrochloride) Reported by Patients with Inadequate Glycemic Control on Diet and Exercise in a 24-Week Double-Blind Clinical Trial of Pioglitazone and metformin hydrochloride Administered Twice Daily
% of Patients
Pioglitazone and metformin hydrochloride 15/850 mg Twice Daily N=201 Pioglitazone 15 mg Twice Daily N=190 Metformin 850 mg Twice Daily N=209
Diarrhea 9 2.6 15.3
Headache 5.5 2.6 4.8

In this 24-week trial, abdominal pain was reported in 2% of patients in the pioglitazone and metformin hydrochloride group, 1.6% in the pioglitazone monotherapy group and 3.3% in the metformin monotherapy group.

Common Adverse Events: PROactive Trial

A summary of the overall incidence and types of common adverse events reported in the PROactive trial is provided in Table 4. Terms that are reported represent those that occurred at an incidence of >5% and more commonly in patients treated with pioglitazone than in patients who received placebo.

Table 4. PROactive Trial: Incidence and Types of Adverse Events Reported in >5% of Patients Treated with Pioglitazone and More Commonly than Placebo
% of Patients
Placebo N=2633 Pioglitazone N=2605
Hypoglycemia 18.8 27.3
Edema 15.3 26.7
Cardiac Failure 6.1 8.1
Pain in Extremity 5.7 6.4
Back Pain 5.1 5.5
Chest Pain 5 5.1

Mean duration of patient follow-up was 34.5 months.
Congestive Heart Failure
A summary of the incidence of adverse events related to congestive heart failure is provided in Table 5 for the 16- to 24-week add-on to metformin trials. None of the events were fatal.

Table 5. Treatment-Emergent Adverse Events of Congestive Heart Failure (CHF) Patients Treated with Pioglitazone or Placebo Added on to Metformin
Number (%) of Patients
Placebo-Controlled Trial (16 weeks) Non-Controlled Double-Blind Trial (24 weeks)
Placebo + Metformin N=160 Pioglitazone 30 mg + Metformin N=168 Pioglitazone 30 mg + Metformin N=411 Pioglitazone 45 mg + Metformin N=416
At least one congestive heart failure event 0 1 (0.6%) 0 1 (0.2%)
Hospitalized 0 1 (0.6%) 0 1 (0.2%)
Table 6. Treatment-Emergent Adverse Events of Congestive Heart Failure (CHF)
Patients Treated with Pioglitazone or Placebo Added on to a Sulfonylurea
Number (%) of Patients
Placebo-Controlled Trial (16 weeks) Non-Controlled Double-Blind Trial (24 weeks)
Placebo + Sulfonylurea N=187 Pioglitazone 15 mg + Sulfonylurea N=184 Pioglitazone 30 mg + Sulfonylurea N=189 Pioglitazone 30 mg + Sulfonylurea N=351 Pioglitazone 45 mg + Sulfonylurea N=351
At least one congestive heart failure event 2 (1.1%) 0 0 1 (0.3%) 6 (1.7%)
Hospitalized 2 (1.1%) 0 0 0 2 (0.6%)
Patients Treated with Pioglitazone or Placebo Added on to Insulin
Number (%) of Patients
Placebo-Controlled Trial (16 weeks) Non-Controlled Double-Blind Trial (24 weeks)
Placebo + Insulin N=187 Pioglitazone 15 mg + Insulin N=191 Pioglitazone 30 mg + Insulin N=188 Pioglitazone 30 mg + Insulin N=345 Pioglitazone 45 mg + Insulin N=345
At least one congestive heart failure event 0 2 (1%) 2 (1.1%) 3 (0.9%) 5 (1.4%)
Hospitalized 0 2 (1%) 1 (0.5%) 1 (0.3%) 3 (0.9%)
Patients Treated with Pioglitazone or Placebo Added on to Metformin
Number (%) of Patients
Placebo-Controlled Trial (16 weeks) Non-Controlled Double-Blind Trial (24 weeks)
Placebo + Metformin N=160 Pioglitazone 30 mg + Metformin N=168 Pioglitazone 30 mg + Metformin N=411 Pioglitazone 45 mg + Metformin N=416
At least one congestive heart failure event 0 1 (0.6%) 0 1 (0.2%)
Hospitalized 0 1 (0.6%) 0 1 (0.2%)
Table 7. Treatment–Emergent Adverse Events of Congestive Heart Failure (CHF) in Patients with NYHA Class II or III Congestive Heart Failure Treated with Pioglitazone or Glyburide
Number (%) of Subjects
Pioglitazone N=262 Glyburide N=256
Death due to cardiovascular causes (adjudicated) 5 (1.9%) 6 (2.3%)
Overnight hospitalization for worsening CHF (adjudicated) 26 (9.9%) 12 (4.7%)
Emergency room visit for CHF (adjudicated) 4 (1.5%) 3 (1.2%)
Patients experiencing CHF progression during study 35 (13.4%) 21 (8.2%)

Congestive heart failure events leading to hospitalization that occurred during the PROactive trial are summarized in Table 8.

Table 8. Treatment–Emergent Adverse Events of Congestive Heart Failure (CHF) in PROactive Trial
Number (%) of Patients
Placebo N=2633 Pioglitazone N=2605
At least one hospitalized congestive heart failure event 108 (4.1%) 149 (5.7%)
Fatal 22 (0.8%) 25 (1%)
Hospitalized, nonfatal 86 (3.3%) 124 (4.7%)

Cardiovascular Safety In the PROactive trial, 5238 patients with type 2 diabetes and a history of macrovascular disease were randomized to pioglitazone (N=2605), force-titrated up to 45 mg daily or placebo (N=2633) in addition to standard of care. Almost all patients (95%) were receiving cardiovascular medications (beta blockers, ACE inhibitors, angiotensin II receptor blockers, calcium channel blockers, nitrates, diuretics, aspirin, statins, and fibrates). At baseline, patients had a mean age of 62 years, mean duration of diabetes of 9.5 years, and mean HbA1c of 8.1%. Mean duration of follow-up was 34.5 months.

The primary objective of this trial was to examine the effect of pioglitazone on mortality and macrovascular morbidity in patients with type 2 diabetes mellitus who were at high risk for macrovascular events. The primary efficacy variable was the time to the first occurrence of any event in a cardiovascular composite endpoint that included all-cause mortality, nonfatal myocardial infarction (MI) including silent MI, stroke, acute coronary syndrome, cardiac intervention including coronary artery bypass grafting or percutaneous intervention, major leg amputation above the ankle, and bypass surgery or revascularization in the leg. A total of 514 (19.7%) patients treated with pioglitazone and 572 (21.7%) placebo-treated patients experienced at least one event from the primary composite endpoint (HR 0.9; 95% CI: 0.8, 1.02; p=0.1).

Although there was no statistically significant difference between pioglitazone and placebo for the three-year incidence of a first event within this composite, there was no increase in mortality or in total macrovascular events with pioglitazone. The number of first occurrences and total individual events contributing to the primary composite endpoint is shown in Table 9.

Table 9. PROactive Trial: Number of First and Total Events for Each Component Within the Cardiovascular Composite Endpoint
Cardiovascular Events Placebo N=2633 Pioglitazone N=2605
First Events n (%) Total Events n First Events n (%) Total Events n
Any event 572 (21.7) 900 514 (19.7) 803
All-cause mortality 122 (4.6) 186 110 (4.2) 177
Nonfatal myocardial infarction (MI) 118 (4.5) 157 105 (4) 131
Stroke 96 (3.6) 119 76 (2.9) 92
Acute coronary syndrome 63 (2.4) 78 42 (1.6) 65
Cardiac intervention (CABG/PCI) 101 (3.8) 240 101 (3.9) 195
Major leg amputation 15 (0.6) 28 9 (0.3) 28
Leg revascularization 57 (2.2) 92 71 (2.7) 115

CABG = coronary artery bypass grafting; PCI = percutaneous intervention

Weight Gain Dose-related weight gain occurs when pioglitazone is used alone or in combination with other antidiabetic medications. The mechanism of weight gain is unclear but probably involves a combination of fluid retention and fat accumulation.

Tables 10, 11, and 12 summarize the changes in body weight with pioglitazone and placebo in the 16- to 26-week randomized, double-blind monotherapy and 16- to 24-week combination add-on therapy trials, the PROactive trial, and the 24-week pioglitazone and metformin hydrochloride trial.

Table 10. Weight Changes (kg) from Baseline During Randomized, Double-Blind Clinical Trials
Control Group (Placebo) Pioglitazone 15 mg Pioglitazone 30 mg Pioglitazone 45 mg
Median(25th , 75th percentile) Median(25th , 75th percentile) Median(25th , 75th percentile) Median(25th , 75th percentile)
Monotherapy (16 to 26 weeks) -1.4(-2.7, 0)N=256 0.9(-0.5, 3.4)N=79 1(-0.9, 3.4)N=188 2.6(0.2, 5.4)N=79
Combination Therapy (16 to 24 weeks) Sulfonylurea -0.5(-1.8, 0.7)N=187 2(0.2, 3.2)N=183 3.1(1.1, 5.4)N=528 4.1(1.8, 7.3)N=333
Metformin -1.4(-3.2, 0.3)N=160 N/A 0.9(-1.3, 3.2)N=567 1.8(-0.9, 5)N=407
Insulin 0.2(-1.4, 1.4)N=182 2.3(0.5, 4.3)N=190 3.3(0.9, 6.3)N=522 4.1(1.4, 6.8)N=338
Table 11. Median Change in Body Weight in Patients Treated with Pioglitazone Versus Patients Treated with Placebo During the Double-Blind Treatment Period in the PROactive Trial
Placebo Pioglitazone
Median(25th , 75th percentile) Median(25th , 75th percentile)
Change from baseline to final visit (kg) -0.5(-3.3, 2)N=2581 +3.6(0, 7.5)N=2560

Note: Median exposure for both pioglitazone and placebo was 2.7 years.

Table 12. Weight Changes (kg) from Baseline During Double-Blind Clinical Trial with Pioglitazone and metformin hydrochloride in Patients with Inadequate Glycemic Control on Diet and Exercise
Pioglitazone and Metformin Hydrochloride 15/850 mg Twice Daily Pioglitazone 15 mg Twice Daily Metformin 850 mg Twice Daily
Median (25th , 75th percentile) Median (25th , 75th percentile) Median (25th , 75th percentile)
Change from baseline to final visit (kg) 1 (-1, 3)N=198 1.35 (-0.7, 4.1)N=178 -1 (-2.6, 0.4)N=203

Note: Trial duration of 24 weeks.

Edema Edema induced from taking pioglitazone is reversible when pioglitazone is discontinued. The edema usually does not require hospitalization unless there is coexisting congestive heart failure.

In the 24-week pioglitazone and metformin hydrochloride trial, edema was reported in 3% of patients in the pioglitazone and metformin hydrochloride group, 4.2% in the pioglitazone monotherapy group, and 1.4% in the metformin monotherapy group.

A summary of the frequency and types of edema adverse events occurring in clinical investigations of pioglitazone is provided in Table 13.

Table 13. Adverse Events of Edema in Patients Treated with Pioglitazone
Number (%) of Patients
Placebo Pioglitazone 15 mg Pioglitazone 30 mg Pioglitazone 45 mg
Monotherapy (16 to 26 weeks) 3 (1.2%)N=259 2 (2.5%)N=81 13 (4.7%)N=275 11 (6.5%)N=169
Combined Therapy (16 to 24 weeks) Sulfonylurea 4 (2.1%)N=187 3 (1.6%)N=184 61 (11.3%)N=540 81 (23.1%)N=351
Metformin 4 (2.5%)N=160 N/A 34 (5.9%)N=579 58 (13.9%)N=416
Insulin 13 (7%)N=187 24 (12.6%)N=191 109 (20.5%)N=533 90 (26.1%)N=345

Note: The preferred terms of edema peripheral, generalized edema, pitting edema, and fluid retention were combined to form the aggregate term of “edema.”

Table 14. Adverse Events of Edema in Patients in the PROactive Trial
Number (%) of Patients
Placebo N=2633 Pioglitazone N=2605
419 (15.9%) 712 (27.3%)

Note: The preferred terms of edema peripheral, generalized edema, pitting edema, and fluid retention were combined to form the aggregate term of “edema.”

Hepatic Effects
There has been no evidence of pioglitazone-induced hepatotoxicity in the pioglitazone controlled clinical trial database to date. One randomized, double-blind, three-year trial comparing pioglitazone to glyburide as add-on to metformin and insulin therapy was specifically designed to evaluate the incidence of serum ALT elevation to greater than three times the upper limit of the reference range, measured every eight weeks for the first 48 weeks of the trial then every 12 weeks thereafter. A total of 3/1051 (0.3%) patients treated with pioglitazone and 9/1046 (0.9%) patients treated with glyburide developed ALT values greater than three times the upper limit of the reference range. None of the patients treated with pioglitazone in the pioglitazone controlled clinical trial database to date have had a serum ALT greater than three times the upper limit of the reference range and a corresponding total bilirubin greater than two times the upper limit of the reference range, a combination predictive of the potential for severe drug-induced liver injury.
Hypoglycemia
In the pioglitazone clinical trials, adverse events of hypoglycemia were reported based on clinical judgment of the investigators and did not require confirmation with fingerstick glucose testing.

In the 16-week add-on to sulfonylurea trial, the incidence of reported hypoglycemia was 3.7% with pioglitazone 30 mg and 0.5% with placebo. In the 16-week add-on to insulin trial, the incidence of reported hypoglycemia was 7.9% with pioglitazone 15 mg, 15.4% with pioglitazone 30 mg, and 4.8% with placebo.

The incidence of reported hypoglycemia was higher with pioglitazone 45 mg compared to pioglitazone 30 mg in both the 24-week add-on to sulfonylurea trial (15.7% versus 13.4%) and in the 24-week add-on to insulin trial (47.8% versus 43.5%).

Three patients in these four trials were hospitalized due to hypoglycemia. All three patients were receiving pioglitazone 30 mg (0.9%) in the 24-week add-on to insulin trial. An additional 14 patients reported severe hypoglycemia (defined as causing considerable interference with patient’s usual activities) that did not require hospitalization. These patients were receiving pioglitazone 45 mg in combination with sulfonylurea (n=2) or pioglitazone 30 mg or 45 mg in combination with insulin (n=12).
Urinary Bladder Tumors
Tumors were observed in the urinary bladder of male rats in the two-year carcinogenicity study [see Nonclinical Toxicology (13.1)]. During the three year PROactive clinical trial, 14 patients out of 2605 (0.54%) randomized to pioglitazone and 5 out of 2633 (0.19%) randomized to placebo were diagnosed with bladder cancer. After excluding patients in whom exposure to study drug was less than one year at the time of diagnosis of bladder cancer, there were 6 (0.23%) cases on pioglitazone and two (0.08%) cases on placebo. After completion of the trial, a large subset of patients was observed for up to 10 additional years, with little additional exposure to pioglitazone. During the 13 years of both PROactive and observational follow-up, the occurrence of bladder cancer did not differ between patients randomized to pioglitazone or placebo (HR =1; 95% CI: 0.59 to 1.72) [see Warnings and Precautions (5.6)].

Metformin hydrochloride

In a double-blind clinical study of metformin in patients with type 2 diabetes, a total of 141 patients received metformin therapy (up to 2550 mg per day) and 145 patients received placebo. Adverse reactions reported in greater than 5% of the metformin patients, and that were more common in metformin than placebo-treated patients, are listed in Table 15. In this trial, diarrhea led to discontinuation of study medication in 6% of patients treated with metformin.

Table 15. Most Common Adverse Reactions (>5%) in a Placebo-Controlled Clinical Study of Metformin Monotherapy*
Adverse Reaction Metformin Monotherapy (n=141) Placebo (n=145)
% of Patients
Diarrhea 53.2 11.7
Nausea/Vomiting 25.5 8.3
Flatulence 12.1 5.5
Asthenia 9.2 5.5
Indigestion 7.1 4.1
Abdominal Discomfort 6.4 4.8
Headache 5.7 4.8
*Reactions that were more common in metformin than placebo-treated patients.

Laboratory Abnormalities

Hematologic Effects

Pioglitazone may cause decreases in hemoglobin and hematocrit. In placebo-controlled monotherapy trials, mean hemoglobin values declined by 2% to 4% in patients treated with pioglitazone compared with a mean change in hemoglobin of -1% to +1% in placebo-treated patients. These changes primarily occurred within the first four to 12 weeks of therapy and remained relatively constant thereafter. These changes may be related to increased plasma volume associated with pioglitazone therapy and are not likely to be associated with any clinically significant hematologic effects.

Vitamin B12 Concentrations

Metformin may lower serum vitamin B12 concentrations. Measurement of hematologic parameters on an annual basis is advised in patients on pioglitazone and metformin hydrochloride and any apparent abnormalities should be appropriately investigated and managed [see Warnings and Precautions (5.9)].

Creatine Phosphokinase

During protocol-specified measurement of serum creatine phosphokinase (CPK) in pioglitazone clinical trials, an isolated elevation in CPK to greater than 10 times the upper limit of the reference range was noted in nine (0.2%) patients treated with pioglitazone (values of 2150 to 11400 IU/L) and in no comparator-treated patients. Six of these nine patients continued to receive pioglitazone, two patients were noted to have the CPK elevation on the last day of dosing, and one patient discontinued pioglitazone due to the elevation. These elevations resolved without any apparent clinical sequelae. The relationship of these events to pioglitazone therapy is unknown.

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