India: Dosage of key drug for HIV+ too low to counter TB, reveals study
CHENNAI: Experts may fret about overprescription of drugs for tuberculosis, but it has emerged that central health authorities' mandatory dosage of a key drug for HIV-infected patients with the disease is too low for it to be effective.
A study by National Institute for Research in Tuberculosis found that dosage of rifabutin — a second-line drug for HIV-infected TB patients — prescribed by Revised National TB Control Programme (RNTCP) is insufficient to tackle mycobacterium tuberculosis, the causative agent of the disease, one of the leading causes of death among AIDS/HIV+ patients.
"The programme recommends 150mg of the drug thrice a week. But based on our studies of blood samples collected from 17 patients, we found that for 150mg of rifabutin to work, patients would have to take the drug every day," said Dr Geetha Ramachandran, who led the study.
The subjects of the study were all patients at Government Hospital of Thoracic Medicine, Tambaram. All of them had failed to respond to first-line treatment.
Researchers found that the RNTCP stipulated dosage administered to seven patients was too low to counter the disease. Four of the subjects died during the course of the study.
"Ten of the patients, who received a dosage of around 30mg/ml higher than that prescribed by the RNTCP, showed favourable response to the treatment," Dr Ramachandran said.
Experts say the dosage of the drug has always been a matter of debate, with doctors exercising extra caution due to possible chemical interaction of medicines for HIV and TB.
"While in some countries like the US, the dosage of rifabutin has been increased from 150mg three days a week to the same amount daily, in India insufficient data and studies resulted in health authorities failing to increase the dosage," NIRT director Soumya Swaminathan said.
The researchers have presented the results of the study to the National AIDS Control Organisation. "A multi-centric study will be undertaken in different parts of the country to assess the effect of rifabutin. This could change the drug regimen for HIV-positive patients with TB," Dr Swaminathan said.
Experts say 60%-70% of HIV-infected patients are likely to develop TB, mostly those on second-line therapy.
"There are several factors that may lead to poor treatment outcome, including malnutrition and other infections. The dosage of rifabutin, which kills the bacteria, is also a contributing factor which can't be taken lightly. Although we recommend daily dosage, more studies will be required to determine the optimal level," Dr Ramachandran said.
Source: The Times of India
