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warnings
WARNINGS Because of chemical, pharmacological, and clinical similarities between gemfibrozil and clofibrate, the adverse findings with clofibrate in two large clinical studies may also apply to gemfibrozil. In the first of those studies, the Coronary Drug Project, 1000 subjects with previous myocardial infarction were treated for five years with clofibrate. There was no difference in mortality between the clofibrate-treated subjects and 3000 placebo-treated subjects, but twice as many clofibrate-treated subjects developed cholelithiasis and cholecystitis requiring surgery. In the other study, conducted by the World Health Organization (WHO), 5000 subjects without known coronary heart disease were treated with clofibrate for five years and followed one year beyond. There was a statistically significant, 44%, higher age-adjusted total mortality in the clofibrate-treated than in a comparable placebo-treated control group during the trial period. The excess mortality was due to a 33% increase in non-cardiovascular causes, including malignancy, post-cholecystectomy complications, and pancreatitis. The higher risk of clofibrate treated subjects for gallbladder disease was confirmed. Because of the more limited size of the Helsinki Heart Study, the observed difference in mortality from any cause between the gemfibrozil and placebo group is not statistically significantly different from the 29% excess mortality reported in the clofibrate group in the separate WHO study at the nine year follow-up (see CLINICAL PHARMACOLOGY ). Noncoronary heart disease related mortality showed an excess in the group originally randomized to gemfibrozil primarily due to cancer deaths observed during the open-label extension. During the five year primary prevention component of the Helsinki Heart Study, mortality from any cause was 44 (2.2%) in the gemfibrozil group and 43 (2.1 %) in the placebo group; including the 3.5 year follow-up period since the trial was completed, cumulative mortality from any cause was 101 (4.9%) in the gemfibrozil group and 83 (4.1 %) in the group originally randomized to placebo (hazard ratio 1:20 in favor of placebo). Because of the more limited size of the Helsinki Heart Study, the observed difference in mortality from any cause between the gemfibrozil and placebo groups at Year-5 or at Year 8.5 is not statistically significantly different from the 29% excess mortality reported in the clofibrate group in the separate WHO study at the nine year follow-up. Noncoronary heart disease related mortality showed an excess in the group originally randomized to gemfibrozil at the 8.5 year follow-up (65 gemfibrozil versus 45 placebo noncoronary deaths). The incidence of cancer (excluding basal cell carcinoma) discovered during the trial and in the 3.5 years after the trial was completed was 51 (2.5%) in both originally randomized groups. In addition, there were 16 basal cell carcinomas in the group originally randomized to gemfibrozil and 9 in the group randomized to placebo (p=0.22). There were 30 (1.5%) deaths attributed to cancer in the group originally randomized to gemfibrozil and 18 (0.9%) in the group originally randomized to placebo (p=0.11). Adverse outcomes, including coronary events, were higher in gemfibrozil patients in a corresponding study in men with a history of known or suspected coronary heart disease in the secondary prevention component of the Helsinki Heart Study. (See CLINICAL PHARMACOLOGY .) A comparative carcinogenicity study was also done in rats comparing three drugs in this class: fenofibrate (10 and 60 mg/kg; 0.3 and 1.6 times the human dose), clofibrate (400 mg/kg; 1.6 times the human dose), and gemfibrozil (250 mg/kg; 1.7 times the human dose). Pancreatic acinar adenomas were increased in males and females on fenofibrate; hepatocellular carcinoma and pancreatic acinar adenomas were increased in males and hepatic neoplastic nodules in females treated with clofibrate; hepatic neoplastic nodules were increased in males and females treated with clofibrate; hepatic neoplastic nodules were increased in males and females treated with gemfibrozil while testicular interstitial cell (Leydig cell) tumors were increased in males on all three drugs. A gallstone prevalence substudy of 450 Helsinki Heart Study participants showed a trend toward a greater prevalence of gallstones during the study within the gemfibrozil treatment group (7.5% vs 4.9% for the placebo group, a 55% excess for the gemfibrozil group). A trend toward a greater incidence of gallbladder surgery was observed for the gemfibrozil group (17 vs 11 subjects, a 54% excess). This result did not differ statistically from the increased incidence of cholecystectomy observed in the WHO study in the group treated with clofibrate. Both clofibrate and gemfibrozil may increase cholesterol excretion into the bile leading to cholelithiasis. If cholelithiasis is suspected, gallbladder studies are indicated. Gemfibrozil therapy should be discontinued if gallstones are found. Cases of cholelithiasis have been reported with gemfibrozil therapy. Since a reduction of mortality from coronary heart disease has not been demonstrated and because liver and interstitial cell testicular tumors were increased in rats, gemfibrozil should be administered only to those patients described in the INDICATIONS AND USAGE section. If a significant serum lipid response is not obtained, gemfibrozil should be discontinued. Concomitant Anticoagulants-Caution should be exercised when warfarin is given in conjunction with gemfibrozil. The dosage of the warfarin should be reduced to maintain the prothrombin time at the desired level to prevent bleeding complications. Frequent prothrombin determinations are advisable until it has been definitely determined that the prothrombin level has stabilized. The concomitant administration of gemfibrozil with simvastatin is contraindicated (see CONTRAINDICATIONS and PRECAUTIONS). Concomitant therapy with gemfibrozil and an HMG-CoA reductase inhibitor is associated with an increased risk of skeletal muscle toxicity manifested as rhabdomyolysis, markedly elevated creatine kinase (CPK) levels, and myoglobinuria, leading in a high proportion of cases to acute renal failure and death. IN PATIENTS WHO HAVE HAD AN UNSATISFACTORY LIPID RESPONSE TO EITHER DRUG ALONE, THE BENEFIT OF COMBINED THERAPY WITH GEMFIBROZIL AND an HMG-CoA REDUCTASE INHIBITOR DOES NOT OUTWEIGH THE RISKS OF SEVERE MYOPATHY, RHABDOMYOLYSIS, AND ACUTE RENAL FAILURE (see PRECAUTIONS, Drug Interactions). The use of fibrates alone, including gemfibrozil, may occasionally be associated with myositis. Patients receiving gemfibrozil and complaining of muscle pain, tenderness, or weakness should have prompt medical evaluation for myositis, including serum creatine-kinase level determination. If myositis is suspected or diagnosed, gemfibrozil therapy should be withdrawn. Cataracts-Subcapsular bilateral cataracts occurred in 10%, and unilateral in 6.3%, of male rats treated with gemfibrozil at 10 times the human dose.
ADVERSE REACTIONS In the double-blind controlled phase of the primary prevention component of the Helsinki Heart Study, 2046 patients received gemfibrozil for up to five years. In that study, the following adverse reactions were statistically more frequent in subjects in the gemfibrozil group: GEMFIBROZIL(N = 2046) PLACEBO(N = 2035) Frequency in percent of subjects Gastrointestinal reactions 34.2 23.8 Dyspepsia 19.6 11.9 Abdominal pain 9.8 5.6 Acute appendicitis (histologically confirmed in most cases where data were available) 1.2 0.6 Atrial fibrillation 0.7 0.1 Adverse events reported by more than 1% of subjects, but without a significant difference between groups: Diarrhea 7.2 6.5 Fatigue 3.8 3.5 Nausea/Vomiting 2.5 2.1 Eczema 1.9 1.2 Rash 1.7 1.3 Vertigo 1.5 1.3 Constipation 1.4 1.3 Headache 1.2 1.1 Gallbladder surgery was performed in 0.9% of gemfibrozil and 0.5% of placebo subjects in the primary prevention component, a 64% excess, which is not statistically different from the excess of gallbladder surgery observed in the clofibrate compared to the placebo group of the WHO study. Gallbladder surgery was also performed more frequently in the gemfibrozil group compared to placebo (1.9% vs 0.3%, p=0.07) in the secondary prevention component. A statistically significant increase in appendectomy in the gemfibrozil group was seen also in the secondary prevention component (6 on gemfibrozil vs 0 on placebo, p=0.014). Nervous system and special senses adverse reactions were more common in the gemfibrozil group. These included hypesthesia, paresthesias, and taste perversion. Other adverse reactions that were more common among gemfibrozil treatment group subjects but where a causal relationship was not established include cataracts, peripheral vascular disease, and intracerebral hemorrhage. From other studies it seems probable that gemfibrozil is causally related to the occurrence of MUSCULOSKELETAL SYMPTOMS (see WARNINGS ), and to ABNORMAL LIVER FUNCTION TESTS and HEMATOLOGIC CHANGES (see PRECAUTIONS ). Reports of viral and bacterial infections (common cold, cough, urinary tract infections) were more common in gemfibrozil treated patients in other controlled clinical trials of 805 patients. Additional adverse reactions that have been reported for gemfibrozil are listed below by system. These are categorized according to whether a causal relationship to treatment with gemfibrozil is probable or not established: CAUSAL RELATIONSHIP PROBALE CAUSAL RELATIONSHIP NOT ESTABLISHED General: weight loss Cardiac: extrasystoles Gastrointestinal: cholestatic jaundice pancreatitis hepatoma colitis Central Nervous System: dizziness somnolence paresthesia peripheral neuritis decreased libido depression headache confusion convulsions syncope Eye: blurred vision retinal edema Genitourinary: impotence decreased male fertility renal dysfunction Musculoskeletal: myopathy myasthenia myalgia painful extremities arthralgia synovitis rhabdomyolysis (see WARNINGS and Drug Interactions under PRECUATIONS ) Clinical Laboratory: increased creatine phosphokinase increased bilirubin increased liver transaminases (AST,ALT) increased alkaline phosphatase positive antinuclear antibody Hematopoietic: anemia leukopenia bone marrow hypoplasia eosinophilia thrombocytopenia Immunologic: angicedema laryngeal edema urticaria anaphylaxis Lupus like syndrome vasculitis Integumentary: exfoliative dermatitis rash dermatitis pruritus alopecia photosensitivity Additional adverse reactions that have been reported include cholecystitis and cholelithiasis (see WARNINGS ).