CHENNAI: In a study that could change the intake schedule of tuberculosis drugs, a group of researchers have found that food reduces the effectiveness of most medicines prescribed as the first line of treatment for the infection.
A team from the National Institute for Research in Tuberculosis (NIRT) — after examining 25 TB patients in Chennai who had food just before they took their medication — found that the anti-TB drug concentrations had significantly lowered and there was delay in their absorption. They studied the concentrations of three key first-line drugs: rifampicin, isoniazid and pyrazinamide.
Dr Soumya Swaminathan, director-general of Indian Council of Medical Research who was one of the co-authors, said although most doctors were aware of the clinical impact of food on rifampicin, guidelines on when to take the other drugs were hazy. “Our study shows that at least two other first-line drugs need to be taken on fasting,” she said, adding their findings are significant as the dosage of first-line drugs is low. “And if food reduces it even further, it is a cause of concern,” she said.
However, not everyone can tolerate having these drugs on an empty stomach. “In such cases, leave a gap of at least three hours after food,” she said.
The research, which was published in the Indian Journal of Medical Research, involved studying patients who had medicines after a breakfast of four idlies with coconut chutney and sambar and a cup of coffee. The same group was examined after an overnight fast of 12 hours, followed by drug administration and breakfast after two hours of drug administration.
Drug administration with food caused the plasma concentration (time taken for any drug to start taking effect after being absorbed in blood) to decrease by 50%, 45% and 34% for rifampicin, isoniazid and pyrazinamide, respectively.
The study recommended doctors to explain to patients the beneficial effects of taking anti-TB drugs in a fasting state and advised to do so. “There is also need for more research on optimization of dosing to maximize efficacy and safety of currently used drugs,” said Dr Swaminathan.