Tuberculosis is not an easy disease to treat. The duration of treatment is months. Multiple antibiotics are needed to prevent drug resistance, and side-effects are common. Some drugs are expensive. We need treatment that is shorter, simpler, less toxic, and affordable.
Why has there been no new drug in over 40 years? Lack of industry interest is one reason. TB mainly affects poor people in the developing countries, and for pharmaceutical companies this is not a profitable market. Also, unlike HIV and AIDS, where activists, patients and civil society have demanded better and more affordable drugs, there has been little activism for TB patients.
But breakthroughs are coming, thanks to partnerships such as the Global Alliance for TB Drug Development (TB Alliance), pharma companies, academics, the Stop TB Partnership, and donors such as the Bill & Melinda Gates Foundation.
New drugs are likely in the next two years. There are promising drugs in development and in clinical trials. A large trial called REMox TB is on to evaluate a four-month moxifloxacin-based regimen versus the six-month standard of care in drug-sensitive patients. Moxifloxacin has the potential to be the first new drug to treat drug-sensitive TB in 50 years, and a moxifloxacin-containing regimen could shorten treatment duration by a third. If trial results succeed, this regimen is expected to get initial market approvals in 2014.
The future lies in rapidly evaluating combinations of novel drugs, rather than testing one drug at a time. Such trials are under way, and some have the potential to further reduce treatment duration. The TB Alliance published a trial this year that showed that a novel drug combination treatment (called PaMZ) containing PA-824, moxifloxacin and pyrazinamide, was highly effective. It has the potential to treat patients with drug-sensitive and drug-resistant TB.
Shortening treatment to two or even four months should increase cure rates, improve patient adherence, and reduce the likelihood of drug resistance. This is very relevant for India.
TB management practices in the Indian private sector vary widely, often deviating from established standards. Inaccurate, blood-based, antibody tests are widely used despite a government ban, along with irrational drug regimens. Since all antibiotics are available over-the-counter, antibiotic-resistance is the single biggest threat in the introduction of drugs into the unregulated Indian market.
So, the excitement about the impending introduction of drugs must be tempered with reality. Before drugs enter India, mechanisms must be put in place to ensure that they are not abused. TB drugs must not be dispensed without prescriptions, which must come from qualified allopathic practitioners. Doctors must follow national and international guidelines, and not create their own regimens.
Patients must take medication as prescribed. Fixed-dose combinations can help improve adherence and minimise the risk of resistance. When new drugs become available, it will be critical to ensure that doctors do not use them as single drugs, or add a new drug to a drug regimen that is ineffective. That will make bacteria resistant to drugs.
(Dr. Madhukar Pai is Professor at McGill University in Montreal. madhukar.pai@mcgill.ca)
