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.

Over 8500 patients with type 2 diabetes have been treated with pioglitazone hydrochloride in randomized, double-blind, controlled clinical trials, including 2605 patients with type 2 diabetes and macrovascular disease treated with pioglitazone hydrochloride in the PROactive clinical trial. In these trials, over 6000 patients have been treated with pioglitazone hydrochloride for 6 months or longer, over 4500 patients have been treated with pioglitazone hydrochloride for one year or longer, and over 3000 patients have been treated with pioglitazone hydrochloride for at least 2 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 hydrochloride 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 hydrochloride than with placebo (3.0%).

In the PROactive trial, the incidence of withdrawals due to adverse events was 9.0% for patients treated with pioglitazone hydrochloride 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 hydrochloride 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 hydrochloride 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 hydrochloride than in patients who received placebo. None of these adverse events were related to pioglitazone hydrochloride dose.

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 hydrochloride add-on to sulfonylurea 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 hydrochloride.

A summary of the overall incidence and types of common adverse events reported in trials of pioglitazone hydrochloride add-on to metformin is provided in Table 3. Terms that are reported represent those that occurred at an incidence of >5% and more commonly with the highest tested dose of pioglitazone hydrochloride.

Table 4 summarizes the incidence and types of common adverse events reported in trials of pioglitazone hydrochloride add-on to insulin. Terms that are reported represent those that occurred at an incidence of > 5% and more commonly with the highest tested dose of pioglitazone hydrochloride.

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

Congestive Heart Failure: A summary of the incidence of adverse events related to congestive heart failure is provided in Table 6 for the 16 to 24-week add-on to sulfonylurea trials, for the 16 to 24-week add-on to insulin trials, and for the 16 to 24-week add-on to metformin trials. None of the events were fatal.

Patients with type 2 diabetes and NYHA class II or early class III congestive heart failure were randomized to receive 24 weeks of double-blind treatment with either pioglitazone hydrochloride at daily doses of 30 mg to 45 mg (n=262) or glyburide at daily doses of 10 mg to 15 mg (n=256). A summary of the incidence of adverse events related to congestive heart failure reported in this study is provided in Table 7.

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

Cardiovascular Safety: In the PROactive trial, 5238 patients with type 2 diabetes and a history of macrovascular disease were randomized to pioglitazone hydrochloride (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 hydrochloride 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, non-fatal 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 hydrochloride and 572 (21.7%) placebo-treated patients experienced at least one event from the primary composite endpoint (hazard ratio 0.90; 95% Confidence Interval: 0.80, 1.02; p=0.10).

Although there was no statistically significant difference between pioglitazone hydrochloride and placebo for the 3-year incidence of a first event within this composite, there was no increase in mortality or in total macrovascular events with pioglitazone hydrochloride. The number of first occurrences and total individual events contributing to the primary composite endpoint is shown in Table 9.

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

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

Edema: Edema induced from taking pioglitazone hydrochloride is reversible when pioglitazone hydrochloride is discontinued. The edema usually does not require hospitalization unless there is coexisting congestive heart failure. A summary of the frequency and types of edema adverse events occurring in clinical investigations of pioglitazone hydrochloride is provided in Table 12.

Hepatic Effects: There has been no evidence of pioglitazone hydrochloride-induced hepatotoxicity in the pioglitazone hydrochloride controlled clinical trial database to date. One randomized, double-blind, 3-year trial comparing pioglitazone hydrochloride to glyburide as add-on to metformin and insulin therapy was specifically designed to evaluate the incidence of serum ALT elevation to greater than 3 times the upper limit of the reference range, measured every 8 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 hydrochloride and 9/1046 (0.9%) patients treated with glyburide developed ALT values >3 times the upper limit of the reference range. None of the patients treated with pioglitazone hydrochloride in the pioglitazone hydrochloride clinical trial database to date have had a serum ALT > 3 times the upper limit of the reference range and a corresponding total bilirubin >2 times the upper limit of the reference range, a combination predictive of the potential for severe drug-induced liver injury.

Hypoglycemia: In the pioglitazone hydrochloride 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 hydrochloride 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 hydrochloride 15 mg, 15.4% with pioglitazone hydrochloride 30 mg, and 4.8% with placebo.

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

Three patients in these four trials were hospitalized due to hypoglycemia. All three patients were receiving pioglitazone hydrochloride 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 hydrochloride 45 mg in combination with sulfonylurea (n=2) or pioglitazone hydrochloride 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)]. In two 3-year trials in which pioglitazone hydrochloride was compared to placebo or glyburide, there were 16/3656 (0.44%) reports of bladder cancer in patients taking pioglitazone hydrochloride compared to 5/3679 (0.14%) in patients not taking pioglitazone hydrochloride. After excluding patients in whom exposure to study drug was less than one year at the time of diagnosis of bladder cancer, there were six (0.16%) cases on pioglitazone hydrochloride and two (0.05%) cases on placebo. There are too few events of bladder cancer to establish causality.