Inhibitors of platelet aggregation
Cilostazol is an inhibitor of PDE-3 with antithrombotic activity. Its use in healthy individuals at a dose of 150 mg for 5 days did not lead to an extension of bleeding time.
Acetylsalicylic acid
Short-term (for ≤ 4 days) concurrent use of cilostazol and acetylsalicylic acid leads to an increase in blocking by 23-25% of ADP-induced platelet aggregation under conditions ex vivo compared with monotherapy with acetylsalicylic acid. There was no obvious tendency to increase hemorrhagic side effects in patients who received cilostazol and aspirin compared with patients taking placebo and an equivalent dose of acetylsalicylic acid.
Clopidogrel and other antiplatelet drugs
In a study in healthy volunteers, concurrent use of cilostazol with clopidogrel had no effect on platelet count, prothrombin time (PT), and activated partial thromboplastin time (APTT). When using clopidogrel in both monotherapy and in combination with cilostazol, the time of bleeding increased in healthy volunteers.The administration of cilostazol did not lead to an additional significant lengthening of bleeding time. Nevertheless, caution should be exercised when using concurrent use of cilostazol with any agent that inhibits aggregation thrombocytes. It is recommended to regularly monitor bleeding time. The use of cilostazol is contraindicated in patients receiving simultaneously two or more antiplatelet agents and / or anticoagulant medications.
Oral anticoagulants
In a clinical study, a single administration of cilostazol did not inhibit warfarin metabolism and did not affect blood clotting parameters (PT, APTT, bleeding time). Nevertheless, caution is advised when using concurrent use of cilostazol with any anticoagulant drug. The use of cilostazol is contraindicated in patients receiving simultaneously two or more antiplatelet agents and / or anticoagulant medications.
Inhibitors of cytochrome P-450 isoenzymes
In the liver cilostazol is mainly metabolized by the action of cytochrome P-450 enzymes, mainly CYP3A4 and CYP2C19 and, to a lesser extent, CYP1A2. It is believed that dehydrocylostazole, 4-7 times greater than cilostazol on the ability to inhibit platelet aggregation, is formed mainly with the participation of CYP3A4. 4'-trans-hydroxycilostazol, having a five-fold less pronounced ability to inhibit platelet aggregation, is formed mainly by the action of CYP2C19. Accordingly, drugs that inhibit CYP3A4 (for example, some macrolides [erythromycin, clarithromycin], azole antifungals [ketoconazole, itraconazole], protease inhibitors) and CYP2C19 (eg, proton pump inhibitors [omeprazole, esomeprazole]) increase the overall pharmacological activity of cilostazol and can enhance its undesirable effects. Accordingly, patients receiving powerful inhibitors CYP3A4 or CYP2C19, it is recommended to appoint cilostazol in a dose of 50 mg 2 times a day.
With the simultaneous administration of cilostazol with erythromycin (a potent inhibitor CYP3A4) indicators AUC cilostazol, dehydrocystolostazol and 4'-trans-hydroxycylostazole increased by 72%, 6% and 119%, respectively. Based on changes in indicators AUC It was established that the total pharmacological activity of cilostazol, when applied simultaneously with erythromycin, is increased by 34%.Based on these data, it is recommended that cilostazol in a dose of 50 mg twice daily with erythromycin or similar drugs (eg clarithromycin).
With concurrent administration of cilostazol with ketoconazole (a potent inhibitor CYP3A4) index AUC Cystic acid is increased by 117%, the index AUC dehydrocystostiazol decreases by 15%, the index AUC 4'-trans-hydroxycylostasol increases by 87%. Based on changes in indicators AUC It was found that the total pharmacological activity of cilostazol, when used concomitantly with ketoconazole, is increased by 35%. Based on these data, it is recommended to apply cilostazol in a dose of 50 mg twice a day with simultaneous administration with ketoconazole or similar medications (eg, itraconazole).
With concomitant administration of cilostazol with diltiazem (a weak inhibitor CYP3A4) indicators AUC Cilostazolum, dehydrocystolostazol and 4'-trans-hydroxycylostazol increased by 44%, 4% and 43%, respectively. Based on changes in indicators AUC It was established that the total pharmacological activity of cilostazol, when used simultaneously with diltiazem, is increased by 19%.Correction of the dose of cilostazol with simultaneous application with diltiazem is not required.
With a single admission of 100 mg of cilostazol concurrently with 240 ml of grapefruit juice (an inhibitor of the intestinal CYP3A4) there was no significant change in pharmacokinetic indices of cilostazol. Correction of the dose of cilostazol is not required. Nevertheless, the intake of grapefruit juice in a larger amount may affect the pharmacokinetics of cilostazol.
With concurrent administration of cilostazol with omeprazole (a potent inhibitor CYP2C19) indicators AUC Cilostazol and dehydrocylostazole increased by 22% and 68%, respectively, while AUC 4'-trans-hydroxycilostazole decreases by 36%. Based on changes in indicators AUC It has been established that the total pharmacological activity of cilostazol when applied simultaneously with omeprazole is increased by 47%. It is recommended to reduce the dose of cilostazol to 50 mg 2 times a day with simultaneous application with omeprazole.
Substrates of cytochrome P-450 isoenzymes
Cilostazol increases the indices AUC lovastatin (substrate CYP3A4) and its beta-hydroxyl metabolite by 70%, caution should be exercised when using cilostazol with substrates at the same time CYP3A4, having a narrow therapeutic range (such as cisapride, halofantrine, pimozide, ergot alkaloids). It is also advisable to use caution while using cilostazol with HMG-CoA reductase inhibitors (statins), metabolizing with the participation of CYP3A4 (simvastatin, atorvastatin and lovastatin).
Inductors of cytochrome P-450 isoenzymes
The effects of drugs that increase activity CYP3A4 and CYP2C19 (such as carbamazepine, phenytoin, rifampicin, preparations of St. John's wort perfumed), on the pharmacokinetics of cilostazol has not been studied. With simultaneous admission, it is theoretically possible to reduce the antiplatelet effect of cilostazol, therefore, it is necessary to regularly monitor bleeding time. In clinical studies, it has been established that smoking (an activity enhancing factor CYP1A2) reduces the concentration of cilostazol in the blood plasma by 18%.
Other medicines
Caution should be exercised when combined use of cilostazol with antihypertensive drugs, as well as any other drugs that potentially reduce blood pressure (including nitrates and phosphodiesterase-5 inhibitors), since an additive hypotensive effect is possible with the development of reflex tachycardia.An increase in heart rate and peripheral edema was noted with simultaneous use of cilostazol and other vasodilating agents, for example, dihydropyridine calcium channel blockers.