Pharmacokinetics of rifapentine and rifampin in a rabbit model of tuberculosis and correlation with clinical trial data

Citation: Rifat D, Prideaux B, Savic RM, Urbanowski ME, Parsons TL, Luna B, Marzinke MA, Ordonez AA, DeMarco VP, Jain SK, Dartois V, Bishai WR, Dooley KE. Pharmacokinetics of rifapentine and rifampin in a rabbit model of tuberculosis and correlation with clinical trial data. Sci Transl Med. 2018 Apr 4;10(435). pii: eaai7786. doi: 10.1126/scitranslmed.aai7786. PMID: 29618565. PMCID: PMC5969904.

Access full article:

https://www.ncbi.nlm.nih.gov/pubmed/29618565

In clinical trials of two rifamycin antibiotics (rifampin and rifapentine) for treating tuberculosis (TB), patients with cavitary lung lesions did not appear to derive benefit from rifapentine. Rifapentine was found not to outperform rifampin, despite a lower minimum inhibitory concentration against Mycobacterium tuberculosis in mouse models of TB. To understand these findings, we have developed a rabbit model of TB that reliably develops lung cavities with features similar to those of patients with pulmonary cavitary TB. After single or multiple doses of rifampin or rifapentine that produced human-equivalent plasma exposures, rabbits were sacrificed at different time points after dosing. We measured site-of-disease drug pharmacokinetics and tissue drug distribution. We used pharmacokinetic-pharmacodynamic (PK/PD) modeling to estimate drug penetration into different types of tubercular lesions. Both drugs penetrated rabbit lung cellular lesions, as well as the fibrotic cavity wall of cavitary lesions (penetration coefficients ≥1 compared to plasma). For the necrotic liquefied material inside cavitary lesions known as caseum (which contains high numbers of bacteria), the penetration coefficient was 1.0 for rifampin but only 0.25 for rifapentine. When estimates of site-of-disease drug PK were substituted into clinical PK/PD models, the relationship between site-of-action exposure and sputum culture conversion was significant (P < 10-7). We propose that poor penetration of rifapentine into lung cavitary lesions explains, in part, why rifapentine doses required to improve treatment outcomes in two phase 2 clinical trials were four times higher in TB patients with large cavities compared to TB patients without cavitary lung disease.

Categories

CRS
Topics

Clinical Trials

P1108: A Phase I/II, Open-Label, Single Arm Study to...

This purpose of this study is to evaluate the pharmacokinetics (PK), safety, and tolerability of bedaquiline (BDQ) in...

Read More

NWCS 408: Examining Longitudinal Cytokine Profiles in HIV-TB...

Using existing data from A5274 and data obtained from retrospectively testing available biospecimens, we propose the following...

Read More

A5274: REMEMBER, Reducing Early Mortality and Early...

This study is being done in people who are starting HIV treatment and who live in areas where the TB infection rate is high. The...

Read More

A5290, A Randomized, Phase 2b Study of a Double-Dose...

Rifampin (RIF), the cornerstone of TB treatment, has very problematic drug-drug interactions with PIs. The use of relatively...

Read More

NWCS 445: Novel Biomarkers to Shorten TB Treatment

Objectives: Primary: To develop a highly predictive algorithm that identifies TB patients who will be cured by treatment...

Read More