Why is rifampicin given only once a month?
Rifampicin is an exceptionally potent bactericidal agent against M. leprae. A single dose of 600 mg is capable of killing 99.9% or more of viable organisms. However, the rate of killing is not proportionately enhanced by subsequent doses. It is also possible that rifampicin exerts a delayed antibiotic effect for several days, during which the organism is incapable of multiplying. The high bactericidal activity of rifampicin makes a once a month application of the drug feasible and cost-effective for leprosy control programmes.
