Study: Four-month regimen of anti-TB drugs works just as well as standard regimen

A new four-month regimen of anti-TB drugs that includes rifapentine and moxifloxacin works just as well as the standard six-month regimen, according to a study.

A shorter course of treatment can reduce costs and drug side effects while also ensuring greater compliance of patients, says the study published this month (May) in the New England Journal of Medicine.

TB affects an estimated 10 million people each year, and about 1.5 million of those die from the disease, according to the World Health Organization (WHO).

The shorter term regimen which comprises rifapentine, isoniazid, pyrazinamide, and moxifloxacin yields very similar results to the standard six-month course consisting of rifampin, isoniazid, pyrazinamide, and ethambutol.

The study was carried out by researchers from several institutes including the University of California San Francisco (UCSF) Center for Tuberculosis and the University of Texas Health Science Center San Antonio, both in the US, the National Lung Hospital in Vietnam, and the College of Health Sciences at the University of Zimbabwe. It looked at 2,516 patients with newly diagnosed pulmonary TB from 13 countries including China (Hong Kong), India, Malawi, Thailand, Vietnam and the US.

"Four months of multi-drug therapy that included rifapentine and moxifloxacin treated active TB as effectively as the standard six-month regimen in a multinational study, cutting treatment time by a third," says a news release on the study.

Marc Weiner, co-author of the study, at the University of Texas Health Science Center at San Antonio's Joe R. and Teresa Lozano Long School of Medicine, tells SciDev.Net that shorter treatment would be easier for people to complete treatment without missing doses, and ultimately may be cost-effective.

"These drugs have been around for more than 20 years and are widely available," Weiner adds.

While nearly 95 per cent of patients on the standard six-month TB regimen are cured, the new rifapentine-moxifloxacin-based regimen was "well tolerated" and yielded a "meaningfully shorter" duration of therapy, according to the news release.

Payam Nahid, corresponding author of the study and director of the UCSF Center for Tuberculosis, tells SciDev.Net:

Safely reducing the duration of treatment for adolescents and adults with active pulmonary TB by one third, without compromising overall cure rates, is a remarkable achievement for the TB therapeutics field.

Myriad challenges exist to successfully bringing better treatments forward for TB, and whereas a two-month reduction in duration may seem incremental to some, in reality this new, shorter regimen, with comparable efficacy, safety and tolerability to the current standard six- month duration regimen, is a first in over 40 years of advancement in the field."

This is an important trial that shows promise for shortening the duration of treatment for drug-sensitive tuberculosis, comments Madhukar Pai, associate director at the McGill International TB Centre, McGill University, Montreal, Canada.

"But [its] relevance for high TB burden settings is unclear because of the widespread use of fluoroquinolones [a class of antibiotics that includes moxifloxacin] in many low and middle-income countries," he tells SciDev.Net.

According to Pai, given the expected high rate of resistance to fluoroquinolones, the applicability of a regimen containing moxifloxacin needs further investigation.

Sushmita Roychowdhury, director of pulmonology, Fortis Hospital in Kolkata, India, says the study has implications for the developing world in terms of cost effectiveness and higher chances of compliance in both supervised and unsupervised patients, although the substantial overuse of moxifloxacin may compromise its effectiveness due to increased chances of resistance.

"Checking for moxifloxacin sensitivity before commencing the new regimen would be imperative in India," Chowdhury tells SciDev.Net. Apart from that, she adds, the "chances of long-term recurrence of [the disease] at five years still need to be assessed."​​​​​