Gemfibrozil

3. Drug Interactions ( A) HMG-CoA Reductase Inhibitors: The concomitant administration of gemfibrozil with simvastatin is contraindicated (see CONTRAINDICATIONS and WARNINGS ). Avoid concomitant use of gemfibrozil with rosuvastatin. If concomitant use cannot be avoided, initiate rosuvastatin at 5 mg once daily. The dose of rosuvastatin should not exceed 10 mg once daily. The risk of myopathy and rhabdomyolysis is increased with combined gemfibrozil and HMG-CoA reductase inhibitor therapy. Myopathy or rhabdomyolysis with or without acute renal failure have been reported as early as three weeks after initiation of combined therapy or after several months (see WARNINGS ). There is no assurance that periodic monitoring of creatine kinase will prevent the occurrence of severe myopathy and kidney damage. (B) Anticoagulants: CAUTION SHOULD BE EXERCISED WHEN WARFARIN IS GIVEN IN CONJUNCTION WITH GEMFIBROZIL. THE DOSAGE OF 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. (C) CYP2C8 Substrates: Gemfibrozil is a strong inhibitor of CYP2C8 and may increase exposure of drugs mainly metabolized by CYP2C8 (e.g., dabrafenib, enzalutamide, loperamide, montelukast, paclitaxel, pioglitazone, rosiglitazone). Therefore, dosing reduction of drugs that are mainly metabolized by CYP2C8 enzyme may be required when gemfibrozil is used concomitantly (see WARNINGS ). Repaglinide: In healthy volunteers, co-administration with gemfibrozil (600 mg twice daily for 3 days) resulted in an 8.1-fold (range 5.5-to 15.0­fold) higher repaglinide AUC and a 28.6-fold (range 18.5- to 80.1- fold) higher repaglinide plasma concentration 7 hours after the dose. In the same study, gemfibrozil (600 mg twice daily for 3 days) + itraconazole (200 mg in the morning and 100 mg in the evening at Day 1, then 100 mg twice daily at Day 2–3) resulted in a 19.4-(range 12.9- to 24.7-fold) higher repaglinide AUC and a 70.4­ fold (range 42.9-to 119.2-fold) higher repaglinide plasma concentration 7 hours after the dose. In addition, gemfibrozil alone or gemfibrozil + itraconazole prolonged the hypoglycemic effects of repaglinide. Co-administration of gemfibrozil and repaglinide increases the risk of severe hypoglycemia and is contraindicated (see CONTRAINDICATIONS ). Dasabuvir: Co-administration of gemfibrozil with dasabuvir increased dasabuvir AUC and C max (ratios: 11.3 and 2.01, respectively) due to CYP2C8 inhibition. Increased dasabuvir exposure may increase the risk of QT prolongation, therefore, co-administration of gemfibrozil with dasabuvir is contraindicated (see CONTRAINDICATIONS ). Selexipag: Co-administration of gemfibrozil with selexipag doubled exposure to selexipag and increased exposure to the active metabolite by approximately 11-fold. Concomitant administration of gemfibrozil with selexipag is contraindicated (see CONTRAINDICATIONS ). Enzalutamide: In healthy volunteers given a single 160 mg dose of enzalutamide after gemfibrozil 600 mg twice daily, the AUC of enzalutamide plus active metabolite (N-desmethyl enzalutamide) was increased by 2.2 fold and corresponding C max was decreased by 16%. Increased enzalutamide exposure may increase the risk of seizures. If co-administration is considered necessary, the dose of enzalutamide should be reduced (see WARNINGS ). (D) OATP1B1 substrates: Gemfibrozil is an inhibitor of OATP1B1 transporter and may increase exposure of drugs that are substrates of OATP1B1 (e.g., atrasentan, atorvastatin, bosentan, ezetimibe, fluvastatin, glyburide, SN-38 [active metabolite of irinotecan], rosuvastatin, pitavastatin, pravastatin, rifampin, valsartan, olmesartan). Therefore, dosing reductions of drugs that are substrates of OATP1B1 may be required when gemfibrozil is used concomitantly (see WARNINGS ). Combination therapy of gemfibrozil with simvastatin or with repaglinide, which are OATP1B1 substrates, is contraindicated (see CONTRAINDICATIONS ). (E) In vitro studies of CYP enzymes, UGTA enzymes and OATP1B1 transporter: In vitro studies have shown that gemfibrozil is an inhibitor of CYP1A2, CYP2C8, CYP2C9, CYP2C19, OATP1B1, and UDP-glucuronosyltransferase (UGT) 1A1 and 1A3 (see WARNINGS ). (F) Bile Acid-Binding Resins: Gemfibrozil AUC was reduced by 30% when gemfibrozil was given (600 mg) simultaneously with resin-granule drugs such as colestipol (5 g). Administration of the drugs two hours or more apart is recommended because gemfibrozil exposure was not significantly affected when it was administered two hours apart from colestipol. (G) Colchicine: Myopathy, including rhabdomyolysis, has been reported with chronic administration of colchicine at therapeutic doses. Concomitant use of gemfibrozil may potentiate the development of myopathy. Patients with renal dysfunction and elderly patients are at increased risk. Caution should be exercised when prescribing gemfibrozil with colchicine, especially in elderly patients or patients with renal dysfunction.

Indicated as adjunctive therapy to diet for "treatment of adult patients with very high elevations of serum triglyceride levels (Types IV and V hyperlipidemia) who present a risk of pancreatitis," and for "reducing the risk of developing coronary heart disease only in Type IIb patients without history or symptoms of existing coronary heart disease" who have low HDL-cholesterol plus elevated LDL-cholesterol and triglycerides and have not responded to diet.

DOSAGE AND ADMINISTRATION The recommended dose for adults is 1,200 mg administered in two divided doses 30 minutes before the morning and evening meals (see CLINICAL PHARMACOLOGY ).

Most common adverse reactions are gastrointestinal, occurring in "34.2%" of patients, including dyspepsia ("19.6%") and abdominal pain ("9.8%"). Serious reactions include rhabdomyolysis and myopathy (particularly with statin co-administration), acute appendicitis, cholestatic jaundice, and hematologic effects such as anemia, leukopenia, and thrombocytopenia.