What is the rationale to use such a combination of drugs? (2 marks)

The standard combinat­ion of the RIPE regimen has arisen due to:

• their diverse mechanisms of action
• their complementary activities
• Combined this way reduce the risk of resistance and the duration of treatment 

The most important point to make is that a combination of antibiotics is required to prevent resistance developing to the few antibiotics which are effective against MTB.