What is the standard initial regimen for drug-susceptible TB?

• A. 2 months of RIPE (Rifampin, Isoniazid, Pyrazinamide, Ethambutol)
• B. 6 months of INH only
• C. 9 months of Ethambutol and Pyrazinamide
• D. 4 months of Streptomycin, Rifampin, and Ethambutol

Answer: (A)

The standard approach for drug-susceptible TB begins with a short, intensive phase that uses four first-line drugs together. This four-drug combo rapidly kills actively growing bacilli and prevents the bacteria from developing resistance, which is why this initial phase is essential. After those two months, treatment continues with a four-month continuation phase using rifampin and isoniazid (often keeping ethambutol and pyrazinamide only until susceptibility is confirmed). This combination approach targets the bacteria effectively while minimizing the risk of relapse.

Other regimens that rely on fewer drugs, or omit rifampin and pyrazinamide, are not effective enough and carry a higher risk of treatment failure and relapse.