Phenobarbital with quinidine

Clinically important, potentially hazardous interactions with adefovir, alprazolam, amprenavir, anisindione, anticoagulants, buprenorphine, carbamazepine, dicumarol, dihydroergotamine, ergot, fosamprenavir, indinavir, ixabepilone, lovastatin, methadone, methysergide, midazolam, phenobarbital, phenytoin, quinidine, rifabutin, rifampin, sildenafil, simvastatin, triazolam, warfarin... 

Similar results were found with phenytoin in another study in 3 healthy subjeets. Other eases have also been reported with phenytoin, primidone, pentobarbital and phenobarbital. In one ease, quinidine levels fell by 44% when phenytoin was given with quinidine to a patient with reeurrent ventrieular taehyeardia. In another report quinidine levels increased from a mean of 0.8 to 2.2 mierograms/mL 15 days after pentobarbital was discontinued. Interestingly, in this case the patient was also on digoxin, and stopping phenobarbital precipitated digoxin toxicity by causing an increase in quinidine levels. 

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... 

Clinically important, potentially hazardous interactions with amiodarone, astemizole, bepridil, carbamazepine, chloroquine, cisapride, clarithromycin, dihydroergotamine, disopyramide, ergotamine, grapefruit juice, halofantrine, haloperidol, itraconazole, ketoconazole, methadone, moxifloxacin, phenobarbital, phenytoin, pimozide, procainamide, quinidine, rifampicin, ritonavir, sotalol, St John s wort, telithromycin, terfenadine, voriconazole... 

An isolated report describes cardiac failure in a patient given aj-maiine with Udocaine. Quinidine causes a very considerable increase in the plasma levels of ajmaline, and phenobarbital appears to cause a marked reduction. 

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