Phase I safety, pharmacokinetics, and pharmacogenetics study of the antituberculosis drug PA-824 with concomitant lopinavir-ritonavir, efavirenz, or rifampin.

Dooley KE, Luetkemeyer AF, Park JG, Allen R, Cramer Y, Murray S, Sutherland D, Aweeka F, Koletar SL, Marzan F, Bao J, Savic R, Haas DW, AIDS Clinical Trials Group A5306 Study Team
Antimicrob Agents Chemother. 2014 58 (9): 5245-52

PMID: 24957823 · PMCID: PMC4135849 · DOI:10.1128/AAC.03332-14

There is an urgent need for new antituberculosis (anti-TB) drugs, including agents that are safe and effective with concomitant antiretrovirals (ARV) and first-line TB drugs. PA-824 is a novel antituberculosis nitroimidazole in late-phase clinical development. Cytochrome P450 (CYP) 3A, which can be induced or inhibited by ARV and antituberculosis drugs, is a minor (∼20%) metabolic pathway for PA-824. In a phase I clinical trial, we characterized interactions between PA-824 and efavirenz (arm 1), lopinavir/ritonavir (arm 2), and rifampin (arm 3) in healthy, HIV-uninfected volunteers without TB disease. Participants in arms 1 and 2 were randomized to receive drugs via sequence 1 (PA-824 alone, washout, ARV, and ARV plus PA-824) or sequence 2 (ARV, ARV with PA-824, washout, and PA-824 alone). In arm 3, participants received PA-824 and then rifampin and then both. Pharmacokinetic sampling occurred at the end of each dosing period. Fifty-two individuals participated. Compared to PA-824 alone, plasma PA-824 values (based on geometric mean ratios) for maximum concentration (Cmax), area under the concentration-time curve from 0 to 24 h (AUC0-24), and trough concentration (Cmin) were reduced 28%, 35%, and 46% with efavirenz, 13%, 17%, and 21% with lopinavir-ritonavir (lopinavir/r) and 53%, 66%, and 85% with rifampin, respectively. Medications were well tolerated. In conclusion, lopinavir/r had minimal effect on PA-824 exposures, supporting PA-824 use with lopinavir/r without dose adjustment. PA-824 exposures, though, were reduced more than expected when given with efavirenz or rifampin. The clinical implications of these reductions will depend upon data from current clinical trials defining PA-824 concentration-effect relationships. (This study has been registered at ClinicalTrials.gov under registration no. NCT01571414.).

Copyright © 2014, American Society for Microbiology. All Rights Reserved.

MeSH Terms (16)

Adult Antitubercular Agents Antiviral Agents Benzoxazines Drug Combinations Drug Therapy, Combination Female Humans Lopinavir Male Middle Aged Nitroimidazoles Pharmacogenetics Rifampin Ritonavir Young Adult

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