Modelling the long-acting administration of anti-tuberculosis agents using PBPK: a proof of concept study

SETTING: Anti-tuberculosis formulations necessitate uninterrupted treatment to cure tuberculosis (TB), but are characterised by suboptimal adherence, which jeopardises therapeutic efficacy. Long-acting injectable (LAI) formulations or implants could address these associated issues.

OBJECTIVE: niazid, rifapentine, bedaquiline and delamanid—in adults for treatment for latent tuberculous infection (LTBI).

DESIGN: PBPK models were developed and qualified against available clinical data by integrating drug physicochemical properties and in vitro and population pharmacokinetic data into a mechanistic description of drug distribution. Combinations of optimal dose and release rates were simulated such that plasma concentrations were maintained over the epidemiological cut-off or minimum inhibitory concentration for the dosing interval.

RESULTS: The PBPK model identified 1500 mg of delamanid and 250 mg of rifapentine as sufficient doses for monthly intramuscular administration, if a formulation or device can deliver the required release kinetics of 0.001–0.0025 h⁻¹ and 0.0015–0.0025 h⁻¹, respectively. Bedaquiline and isoniazid would require weekly to biweekly intramuscular dosing.

CONCLUSION: We identified the theoretical doses and release rates of LAI anti-tuberculosis formulations. Such a strategy could ease the problem of suboptimal adherence provided the associated technological complexities for LTBI treatment are addressed.