Pentobarbital Miconazole

Clinically important, potentially hazardous interactions with allopurinol, amiodarone, amobarbital, anabolic steroids, anti-thyroid agents, aprobarbital, aspirin, barbiturates, bivalirudin, butabarbital, butalbital, cimetidine, clofibrate, clopidogrel, cyclosporine, delavirdine, disulfiram, fenofibrate, fluconazole, gemfibrozil, glutethimide, imatinib, itraconazole, ketoconazole, levothyroxine, liothyronine, mephobarbital, methimazole, metronidazole, miconazole, penicillins, pentobarbital, phenobarbital, phenylbutazones, piperacillin, prednisone, primidone, propylthiouracil, quinidine, quinine, rifabutin, rifampin, rifapentine, rofecoxib, salicylates, secobarbital, sulfinpyrazone, sulfonamides, testosterone, thyroid, zileuton... 

Miconazole increases serum pentobarbital levels. The hypnotic effects of pentobarbital are reduced or abolished by the concurrent use of caffeine. 

High-dose intravenous pentobarbital was given to 5 patients in intensive care to decrease intracranial pressure. When miconazole was also given, all patients had marked rises in plasma pentobarbital levels, and a 50 to 90% reduction in total plasma clearance. This is thought to occur because miconazole inhibits the liver enzymes concerned with the metabolism of the barbiturate, thereby reducing its clearance from the body. It would be prudent to monitor the effects of concurrent use to ensure that plasma barbiturate levels do not rise too high. Note that miconazole oral gel can be absorbed in sufficient amounts to potentially interact. There seems to be no information about other barbiturates. 

Heinemeyer G, Roots I, Schulz H, DennhardtR Hemmung der Pentobarbital-Elimination du-rch Miconazol bei Intesivdierapie des erhohten intracraniellen Druckes. Intensivmed (1985) 22,164-7. 

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