Update on rifampin drug interactions

Baciewicz, Anne M.

doi:10.1001/archinte.147.3.565

Cited by 18 publications

(21 citation statements)

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“…Serum theophylline concentrations should be periodically checked to ensure optimal therapeutic response and avoidance of life-threatening toxic reactions, including seizures and cardiac arrhythmias that may occur suddenly (Baciewicz et al 1987).…”

Section: Theophyllinementioning

confidence: 99%

Pharmacokinetic Drug Interactions with Rifampicin

Venkatesan

1992

Clinical Pharmacokinetics

123

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Rifampicin, an antituberculosis drug, is usually administered for 4 to 12 months with other antituberculosis drugs or medications from other classes. A potential for drug interactions often exists because rifampicin is a potent inducer of hepatic drug metabolism, as evidenced by a proliferation of smooth endoplasmic reticulum and an increase in the cytochrome P450 content in the liver. The induction is a highly selective process and not every drug metabolised via oxidation is affected. Case reports and studies have demonstrated enhanced metabolism of several drugs; most of these interactions are clinically important. At the start of rifampicin treatment, and again at the end, clinicians must check the dosages of any accompanying medications with which rifampicin may potentially interact. Monitoring of clinical response and blood drug concentrations is essential to adjust the drug dosage during rifampicin therapy. Rifampicin also interacts with cholephils such as bilirubin and bromosulphthalein. Its pharmacokinetics are reported to be altered by ethambutol, p-aminosalicylic acid (through its excipient component), ketoconazole, cyclosporin, clofazimine, probenecid and phenobarbital through one or other of the following mechanisms--impaired absorption of rifampicin, competition between the drug and rifampicin for hepatic uptake and altered hepatic metabolism of rifampicin. Most interactions affecting rifampicin have been relatively minor or are not expected to alter its therapeutic efficacy.

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Section: Theophyllinementioning

confidence: 99%

Pharmacokinetic Drug Interactions with Rifampicin

Venkatesan

1992

Clinical Pharmacokinetics

123

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“…An increase in cytochrome P450 (CYP) content and rates of demethylation and hydroxylation were reported during rifampin administration. 3,4 Amiodarone is deethylated in the liver by the CYP system to the active metabolite desethylamiodarone (DEA). The CYP3A subfamily, particularly 3A4, is the primary isoenzyme believed to be responsible for the parent drug' s metabolism.…”

mentioning

confidence: 99%

Impact of Rifampin on Serum Amiodarone Concentrations in a Patient with Congenital Heart Disease

et al. 1999

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A 33-year-old woman with congenital heart disease and atrial and ventricular arrhythmias, managed over the long term with an implantable cardioverter defibrillator, epicardial pacing system, and amiodarone, experienced an increase in palpitations and a shock from her defibrillator. Evaluation revealed decreases in amiodarone and desethylamiodarone serum concentrations from previous levels. Rifampin had been added to her therapy 5 weeks earlier. Increases in amiodarone and desethylamiodarone concentrations were observed after an increase in the amiodarone dosage and discontinuation of rifampin. The time course suggested that the addition of rifampin led to reductions in serum concentrations of both the drug and metabolite.

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“…Recommendations for managing the drug interaction between phenytoin and rifampin include monitoring of serum drug concentrations for both drugs and for the clinical presence of seizure activity. [16][17][18] The patient presented in this case displayed a rapid decline in total and free phenytoin concentrations after the initiation of rifampin that outweighed any potential inhibition associated with isoniazid. Due to the short half-life of rifampin, enzyme induction of CYP2C has been apparent within 24 hours, and full induction should be reached in 1-2 weeks.…”

Section: Discussionmentioning

confidence: 87%

Phenytoin‐Rifampin Drug Interaction in a Hypoalbuminemic, Renal Failure Patient: A Complex Clinical Case

2013

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Phenytoin, a commonly used antiepileptic, is difficult to dose optimally due to its narrow therapeutic window, nonlinear pharmacokinetics, extensive protein binding, and participation in clinically significant drug interactions. Although clinicians are aware of the interaction with two widely used antituberculosis agents, rifampin and isoniazid, few reports have described the implications for managing phenytoin dosing in this situation. To our knowledge, only two reports of the clinical experience with this interaction have been published, and only one of these reports involved the addition of isoniazid. We present a case of a 60-year-old man treated with triple antiepileptic therapy, including phenytoin, who experienced seizures shortly after hospital admission. Dosing of phenytoin proved difficult in this patient due to an acute kidney injury and severe hypoalbuminemia requiring hemodialysis. A further complexity was the addition of antituberculosis therapy (rifampin, isoniazid, pyrazinamide, and ethambutol [RIPE]) for suspected tuberculosis meningitis after the patient experienced persistent encephalopathy. Phenytoin concentrations decreased steadily after rifampin and isoniazid initiation despite dose increases, and the free concentration of phenytoin reached a low of less than 0.5 µg/ml on day 8 of RIPE therapy. The patient continued on a stable dose of phenytoin and RIPE therapy for unconfirmed tuberculosis meningitis until discharge. This report is the first description of this drug interaction in 20 years and highlights the need for appropriate management of phenytoin in a patient with complicated needs for pharmacotherapy.

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Update on rifampin drug interactions

Cited by 18 publications

References 0 publications

Pharmacokinetic Drug Interactions with Rifampicin

Pharmacokinetic Drug Interactions with Rifampicin

Impact of Rifampin on Serum Amiodarone Concentrations in a Patient with Congenital Heart Disease

Phenytoin‐Rifampin Drug Interaction in a Hypoalbuminemic, Renal Failure Patient: A Complex Clinical Case

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