Rifampicin Can Be Given as Flat-Dosing Instead of Weight-Band Dosing

BACKGROUND: The weight-band dosing in tuberculosis treatment regimen has been implemented in clinical practice for decades. Patients will receive different number of fixed dose combination tablets according to their weight-band. However, some analysis has shown that weight was not the best covariate to explain variability of rifampicin exposure. Furthermore, the rationale for using weight-band dosing instead of flat-dosing becomes questionable. Therefore, this study aimed to compare the average and the variability of rifampicin exposure after weight-band dosing and flat-dosing. METHODS: Rifampicin exposure were simulated using previously published population pharmacokinetics model at dose 10–40 mg/kg for weight-band dosing and dose 600–2400 mg for flat-dosing. The median area under the curve (AUC(0–24 h)) after day 7 and 14 were compared as well as the variability of each dose group between weight-band and flat-dosing. RESULTS: The difference of median AUC(0–24 h) of all dose groups between flat-dosing and weight-band dosing were considered low (< 20%) except for the lowest dose. At the dose of 10 mg/kg (600 mg for flat-dosing), flat-dosing resulted in higher median AUC(0–24h) compared to the weight-band dosing. A marginal decrease in between-patient variability was predicted for weight-band dosing compared to flat-dosing. CONCLUSIONS: Weight-band dosing yields a small and non-clinically relevant decrease in variability of AUC(0–24h).