In a large, CDC-sponsored trial, combination therapy weekly for 3 months was as effective as single-drug therapy daily for 9 months.
On May 16, the results of one of the largest U.S. government clinical trials on tuberculosis (TB) preventive therapy were reported in an oral presentation at the 2011 meeting of the American Thoracic Society. In this randomized study, 3 months of directly observed combination therapy (rifapentine 900 mg plus isoniazid 900 mg once weekly) was compared with the current standard regimen — 9 months of nonobserved monotherapy (isoniazid 300 mg daily) — in 8053 individuals with latent TB infection, predominantly in the U.S. and Canada. Participants were evaluated 33 months after enrollment. Because of concern about drug interactions, HIV-infected individuals taking antiretrovirals were excluded.
TB disease developed in 7 participants in the 3-month combination-treatment group, compared with 15 in the 9-month isoniazid-monotherapy group. The proportion of participants who completed the regimen was substantially higher in the 3-month treatment group (82% vs. 69%). The new regimen was found to be safe.
Comment: These findings suggest that weekly combination therapy for 3 months is as effective as the current standard therapy in areas with low to medium TB incidence. Revised guidelines for treatment of latent TB in the U.S. will likely feature this new regimen. However, additional research is needed before the regimen can be recommended in countries with a high TB incidence — especially those with high rates of HIV infection.
Published in Journal Watch Infectious Diseases May 25, 2011
