Clinical Significance of the Plasma Protein Binding of Rifampicin in the Treatment of Tuberculosis Patients

Excerpt

The standard dose regimen for active pulmonary tuberculosis (TB) consists of an initial 2-month intensive treatment phase with rifampicin, isoniazid, pyrazinamide, and ethambutol, followed by a 4-month continuation phase with rifampicin, isoniazid, and ethambutol [1]. Despite the use of standard dose regimens, weight-banding, and directly observed treatment, the pharmacokinetics (PK) of rifampicin show very high interindividual variability, which may be explained by various factors, including variable oral absorption, pharmacogenetic differences in drug-metabolizing/transporter activities, nutritional status, sex differences, drug–drug interactions, comorbidities such as diabetes, and HIV co-infection [2‐4]. The high interindividual variability in the PK of rifampicin leads to highly variable systemic exposure, with supratherapeutic plasma concentrations potentially leading to adverse reactions such as liver toxicity, and subtherapeutic plasma concentrations resulting in slow response to treatment and development of drug resistance [5, 6]. Consequently, therapeutic drug monitoring of first-line anti-TB drugs has been proposed to improve treatment outcomes in certain patient groups, such as slow responders, patients with diabetes, and those with HIV co-infection [7, 8]. This commentary focuses on the potential consequences of interpatient variability in plasma binding of rifampicin on its PK and pharmacodynamics (PD). …