Rifampicin Amiodarone

AMIODARONE RIFAMPICIN 1 levels of amiodarone Uncertain, but rifampicin is a known enzyme inducer and therefore may T metabolism of amiodarone Watch for a poor response to amiodarone... 

Association to allopurinol, amiodarone, fluoroquinolones, carbamazepine, pheno-barbital, rifampicin, and others Inhibition of CYP activity by the drugs... 

In a 33-year-old woman taking amiodarone 400 mg/day the addition of rifampicin 600 mg/day resulted in paroxysms of atrial fibrillation and atrial flutter, with a very low serum amiodarone concentration and an undetectable concentration of desethylamiodarone (262). This was attributed to induction of the metabolism of amiodarone and desethylamiodarone, and after withdrawal of rifampicin the concentrations of the two compounds rose to within the target ranges. 

Rifampicin has been reported to reduce the effects of amiodarone (96). 

The authors discussed the possible reasons for this interaction, including a reduction in systemic availability of amiodarone or induction of metabolism by rifampicin. 

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 case report suggests that rifampicin may decrease the serum levels of amiodarone and its metabolite Al-desethylamlo-darone. 

A woman with congenital heart disease and atrial and ventricular arrhythmias managed by an implanted cardioverter defibrillator, epicardial pacing and amiodarone 400 mg daily, experienced deterioration in the control of her condition. She developed palpitations and experienced a shock from the defibrillator. Her amiodarone serum levels were 40% lower than 2 months previously, and her A-desethylamiodarone levels were undetectable. It was noted that 5 weeks earlier rifampicin 600 mg daily had been started to treat an infection of the pacing system. The amiodarone dose was doubled, but the palpitations continued. Amiodarone and A-desethy-lamiodarone levels increased after rifampicin was discontinued. Rifampicin is a potent enzyme inducer and it may have increased the metabolism and clearance of amiodarone. This case suggests that combined use of amiodarone and rifampicin should be well monitored. 

---