Drug resistance to the TB is a challenging problem. According to WHO 8 million new cases of multi-drug resistant TB (MDR TB) are reported worldwide. Most of these cases occur in developing world where lack of resources and education leads to improper treatment. It is unfortunate that despite this growing resistance to existing drugs; discovery of new anti TB drugs is slow.
However after waiting for 40 years, a new anti TB drug bedaquiline is now available with trade name of “Sirturo”. It was approved by FDA for treatment of MDR TB, in December 2012. In June 2013, WHO also approved this drug and published interim guidance for use of bedaquiline as part of combination therapy for MDR TB.
Bedaquiline belongs to a new class of drug known as diarylquinolines. It is a bactericidal which means it kills mycobacterium bacillus by inhibiting adenosine triphosphate (ATP) synthase enzyme. It has good oral absorption and is given as one tablet a day.
Common side effects of bedaquiline include nausea, arthralgia, headache, anorexia, rash and raised liver function tests. Besides this a less common but potentially fatal adverse effect is prolongation of QT interval. This also led to black box warning that the drug can affect the heart’s electrical activity.
According to WHO interim guidelines it is approved only for treatment of MDR TB. It is recommended that informed consent should be taken before adding it to treatment regimen. It should be added along with 3 other drugs. It is not meant to replace any drug in existing regimen and should only be added when a regimen fails.
Also patient should be closely monitored for development of any side effect or resistance to the drug. WHO has limited the use of bedaquiline up to 6 month due to lack of studies on its safety during long term treatment. For the same reason, it is not approved for use in HIV patients, especially those on antiretroviral therapy.
WHO guidelines have also determined several research gaps. So far limited data is available regarding the safety and efficacy of this drug in infants, children and pregnant women. Also this drug has not been tested in developing world where most of cases of MDR TB occur. Moreover it has not been tested for treating extensively drug resistant TB (XDR TB).
It is needed that more trials of this drug should occur to determine its safety, efficacy and optimal combination with other drugs. Also cost-effectiveness studies should be carried out in developing world. Besides this more funds and resources should be allocated for discovery of more anti-tuberculosis drugs.