Rifampicin-Amlodipine Interaction: A Case Report of Hypertension Exacerbation

Abstract

Introduction: Rifampicin, a first-line anti-tubercular therapy drug, is a strong inducer of hepatic cytochrome P450 (CYP). Amlodipine and metoprolol, two anti-hypertensives that are CYP substrates, have the potential to interact pharmacologically with rifampicin. Therefore, individuals with hypertension receiving rifampicin-based anti-tubercular therapy are at risk for worsening hypertension.

Case Details: We report a case of a 63-year-old female patient, who developed accelerated hypertension after initiating rifampicin. Later, up to four antihypertensive drugs were administered as part of a gradual increase in dosage but did not successfully lower blood pressure to a desirable level. After clinical pharmacist intervention, Tab. Amlodipine+Metoprolol 5 mg+50 mg was discontinued and the blood pressure measurements gradually improved.

Conclusion: We postulate that rifampicin diminished the therapeutic effect of amlodipine and metoprolol and hence recommend that prudent monitoring for worsening hypertension should be carried out in hypertensive patients with chronic kidney disease receiving anti-tubercular therapy.