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warnings and cautions
5 WARNINGS AND PRECAUTIONS • Congestive heart failure: Fluid retention may occur and can exacerbate or lead to congestive heart failure. Combination use with insulin and use in congestive heart failure NYHA Class I and II may increase risk. Monitor patients for signs and symptoms. ( 5.1 ) • Edema: Dose-related edema may occur. ( 5.3 ) • Hypoglycemia: Consider a lower dose of insulin or insulin secretagogue to reduce risk of hypoglycemia when used in combination with pioglitazone and metformin hydrochloride. ( 5.4 ) • Hepatic effects: Postmarketing reports of hepatic failure, sometimes fatal. Causality cannot be excluded. If liver injury is detected, promptly interrupt pioglitazone and metformin hydrochloride and assess patient for probable cause, then treat cause if possible, to resolution or stabilization. Do not restart pioglitazone and metformin hydrochloride if liver injury is confirmed and no alternate etiology can be found. ( 5.5 ) • Urinary Bladder Tumors: May increase the risk of bladder cancer. Do not use in patients with active bladder cancer. Use caution when using in patients with a prior history of bladder cancer. ( 5.6 ) • Fractures: Increased incidence in female patients. Apply current standards of care for assessing and maintaining bone health. ( 5.7 ) • Macular edema: Postmarketing reports. Recommend regular eye exams in all patients with diabetes according to current standards of care with prompt evaluation for acute visual changes. ( 5.8 ) • Vitamin B 12 deficiency: Metformin may lower vitamin B 12 levels. Monitor hematologic parameters annually and vitamin B 12 at 2 to 3 year intervals and manage any abnormalities. ( 5.9 )) 5.1 Congestive Heart Failure Pioglitazone, like other thiazolidinediones, can cause dose-related fluid retention when used alone or in combination with other antidiabetic medications and is most common when pioglitazone is used in combination with insulin. Fluid retention may lead to or exacerbate congestive heart failure. Observe patients for signs and symptoms of congestive heart failure. If congestive heart failure develops while taking pioglitazone and metformin hydrochloride tablets, consider discontinuation of pioglitazone and metformin hydrochloride tablets,or dosage reduction of pioglitazone in pioglitazone and metformin hydrochloride tablets, [see Boxed Warning, Contraindications ( 4 ), Adverse Reactions ( 6.1 )]. 5.2 Lactic Acidosis Lactic Acidosis There have been postmarketing cases of metformin-associated lactic acidosis, including fatal cases. These cases had a subtle onset and were accompanied by nonspecific symptoms such as malaise, myalgias, abdominal pain, respiratory distress, or increased somnolence; however, hypothermia, hypotension and resistant bradyarrhythmias have occurred with severe acidosis. Metformin-associated lactic acidosis was characterized by elevated blood lactate concentrations (greater than 5 mmol/L), anion gap acidosis (without evidence of ketonuria or ketonemia), an increased lactate: pyruvate ratio, and metformin plasma levels generally greater than 5 mcg/mL. Metformin decreases liver uptake of lactate increasing lactate blood levels which may increase the risk of lactic acidosis, especially in patients at risk. If metformin-associated lactic acidosis is suspected, general supportive measures should be instituted promptly in a hospital setting, along with immediate discontinuation of pioglitazone and metformin hydrochloride tablets. In pioglitazone and metformin hydrochloride-treated patients with a diagnosis or strong suspicion of lactic acidosis, prompt hemodialysis is recommended to correct the acidosis and remove accumulated metformin (metformin hydrochloride is dialyzable, with a clearance of up to 170 mL/min under good hemodynamic conditions). Hemodialysis has often resulted in reversal of symptoms and recovery. Educate patients and their families about the symptoms of lactic acidosis and if these symptoms occur instruct them to discontinue pioglitazone and metformin hydrochloride and report these symptoms to their healthcare provider. For each of the known and possible risk factors for metformin-associated lactic acidosis, recommendations to reduce the risk of and manage metformin-associated lactic acidosis are provided below: Renal Impairment The postmarketing metformin-associated lactic acidosis cases primarily occurred in patients with significant renal impairment. The risk of metformin accumulation and metformin associated lactic acidosis increases with the severity of renal impairment because metformin is substantially excreted by the kidney. Clinical recommendations based upon the patient's renal function include [see Dosage and Administration ( 2.2 ), Clinical Pharmacology ( 12.3 )]. • Before initiating pioglitazone and metformin hydrochloride tablets, obtain an eGFR. • P ioglitazone and metformin hydrochloride tablets are contraindicated in patients with an eGFR less than 30mL/min /1.73 m2. Initiation of pioglitazone and metformin hydrochloride tablets is not recommended in patients with eGFR between 30 to 45 mL/min [see contraindications ( 4 )]. • Obtain an eGFR at least annually in all patients taking pioglitazone and metformin hydrochloride tablets. In patients at increased risk for the development of renal impairment (e.g., the elderly), renal function should be assessed more frequently. • In patients taking pioglitazone and metformin hydrochloride tablets whose eGFR later falls below 45 mL/min/1.73 m 2 , assess the benefit and risk of continuing therapy. Drug Interactions The concomitant use of pioglitazone and metformin hydrochloride tablets with specific drugs may increase the risk of metformin-associated lactic acidosis: those that impair renal function, result in significant hemodynamic change, interfere with acid-base balance or increase metformin accumulation (e.g. cationic drugs) [see Drug Interactions ( 7 )]. Therefore, consider more frequent monitoring of patients. Age 65 or Greater The risk of metformin-associated lactic acidosis increases with the patient's age because elderly patients have a greater likelihood of having hepatic, renal, or cardiac impairment than younger patients. Assess renal function more frequently in elderly patients [see Use in Specific Populations ( 8.5 )]. Radiological Studies with Contrast Administration of intravascular iodinated contrast agents in metformin-treated patients has led to an acute decrease in renal function and the occurrence of lactic acidosis. Stop pioglitazone and metformin hydrochloride tablets at the time of, or prior to, an iodinated contrast imaging procedure in patients with an eGFR between 30 and 60 mL/min; in patients with a history of hepatic impairment, alcoholism, or heart failure; or in patients who will be administered intra-arterial iodinated contrast. Re-evaluate eGFR 48 hours after the imaging procedure, and restart pioglitazone and metformin hydrochloride tablets if renal function is stable. Surgery and Other Procedures Withholding of food and fluids during surgical or other procedures may increase the risk for volume depletion, hypotension and renal impairment. Pioglitazone and metformin hydrochloride tablets should be temporarily discontinued while patients have restricted food and fluid intake. Hypoxic States Several of the postmarketing cases of metformin-associated lactic acidosis occurred in the setting of acute congestive heart failure (particularly when accompanied by hypoperfusion and hypoxemia). Cardiovascular collapse (shock), acute myocardial infarction, sepsis, and other conditions associated with hypoxemia have been associated with lactic acidosis and may also cause prerenal azotemia. When such events occur, discontinue pioglitazone and metformin hydrochloride tablets. Excessive Alcohol Intake Alcohol potentiates the effect of metformin on lactate metabolism and this may increase the risk of metformin-associated lactic acidosis. Warn patients against excessive alcohol intake while receiving pioglitazone and metformin hydrochloride tablets. Hepatic Impairment Patients with hepatic impairment have developed with cases of metformin-associated lactic acidosis. This may be due to impaired lactate clearance resulting in higher lactate blood levels. Therefore, avoid use of pioglitazone and metformin hydrochloride tablets in patients with clinical or laboratory evidence of hepatic disease. 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 tablets 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 tablets should be used with caution in patients at risk for congestive heart failure. Patients treated with pioglitazone and metformin hydrochloride tablets should be monitored for signs and symptoms of congestive heart failure [see Boxed Warning, Warnings and Precautions ( 5.1 )]. 5.4 Hypoglycemia with Concomitant Use with Insulin or Insulin Secretagogues Insulin and insulin secretagogues, such as sulfonylureas, are known to cause hypoglycemia. Therefore, a lower dosage of insulin or insulin secretagogue may be required to minimize the risk of hypoglycemia when used in combination with pioglitazone and metformin hydrochloride tablets, [see Drug Interactions ( 7.6 , 7.7 )]. 5.5 Hepatic Effects There have been postmarketing reports of fatal and non-fatal 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 mellitus 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 tablets therapy. In patients with abnormal liver tests, pioglitazone and metformin hydrochloride tablets 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 clinically significant liver enzyme elevations (serum ALT greater than three times the ULN) and if abnormal liver tests persist or worsen, pioglitazone and metformin hydrochloride tablets should be interrupted and investigation done to establish the probable cause. Pioglitazone and metformin hydrochloride tablets should not be restarted in these patients without another explanation for the liver test abnormalities. 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 PRO active clinical trial, 14 patients out of 2,605 (0.54%) randomized to pioglitazone and 5 out of 2,633 (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 2 (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 [Hazard Ratio (HR) = 1.00; (95% Confidence Interval (CI) : 0.59, 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 prospective 10-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 0.89–1.26]). 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: 1.22–2.19]). 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 tablets 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 tablets 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 mellitus 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 tablets 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 B 12 Levels In metformin clinical trials of 29-week duration, a decrease to subnormal levels of previously normal serum vitamin B 12 levels was observed in approximately 7% of patients. Such decrease, possibly due to interference with B 12 absorption from the B 12 -intrinsic factor complex, may be associated with anemia but appears to be rapidly reversible with discontinuation of metformin or vitamin B 12 supplementation. Certain individuals (those with inadequate vitamin B 12 or calcium intake or absorption) appear to be predisposed to developing subnormal vitamin B 12 levels. Measure hematologic parameters on an annual basis and vitamin B 12 at 2 to 3 year intervals in patients on pioglitazone and metformin hydrochloride tablets and manage any abnormalities [see Adverse Reactions ( 6.1 )].