A dose‐finding study to guide use of verapamil as an adjunctive therapy in tuberculosis

Published version
Repository DOI

Change log
Authors
Padmapriyadarsini,, Chandrasekaran 
Szumowski,, John D 
Akbar,, Nabila 
Shanmugasundaram,, Prema 
Jain,, Anilkumar 
Abstract

jats:pInduction of mycobacterial efflux pumps is a cause of jats:italicMycobacterium tuberculosis</jats:italic> (Mtb) drug tolerance, a barrier to shortening antitubercular treatment. Verapamil inhibits Mtb efflux pumps that mediate tolerance to rifampin, a cornerstone of tuberculosis treatment. Verapamil's mycobacterial efflux pump inhibition also limits Mtb growth in macrophages in the absence of antibiotic treatment. These findings suggest that verapamil could be used as an adjunctive therapy for TB treatment shortening. However, verapamil is rapidly and substantially metabolized when co‐administered with rifampin. We determined in a dose‐escalation clinical trial of persons with pulmonary tuberculosis that rifampin‐induced clearance of verapamil can be countered without toxicity by the administration of larger than usual doses of verapamil. An oral dosage of 360 mg sustained‐release (SR) verapamil given every 12 hours concomitantly with rifampin achieved median verapamil exposures of 903.1 ng.h/ml (AUC 0‐12h) in the 18 participants receiving this highest studied verapamil dose; these AUC findings are similar to those in persons receiving daily doses of 240 mg verapamil SR but not rifampin. Moreover, norverapamil:verapamil, R:S verapamil and R:S norverapamil AUC ratios were all significantly greater than those of historical controls receiving SR verapamil in the absence of rifampin. Thus, rifampin administration favors the less‐cardioactive verapamil metabolites and enantiomers that retain similar Mtb efflux inhibitory activity to verapamil, increasing overall benefit. Finally, rifampin exposures were 50% greater after verapamil administration, which may also be advantageous. Our findings suggest that a higher dosage of verapamil can be safely used as adjunctive treatment in rifampin‐containing treatment regimens.</jats:p>

Description

Publication status: Published

Keywords
Humans, Antitubercular Agents, Mycobacterium tuberculosis, Rifampin, Tuberculosis, Verapamil
Journal Title
Clinical Pharmacology and Therapeutics
Conference Name
Journal ISSN
0009-9236
1532-6535
Volume Title
Publisher
American Society for Clinical Pharmacology and Therapeutics
Sponsorship
Wellcome Trust (223103/Z/21/Z)
National Institutes of Health (NIH) (2R01AI054504-20A1)