Which set lists the four drugs used in the first-line RIPE regimen for drug-susceptible pulmonary TB?

• A. Rifampin, Isoniazid, Pyrazinamide, Streptomycin.
• B. Rifampin, Isoniazid, Pyrazinamide, Amikacin.
• C. Rifampin, Isoniazid, Ethambutol, Levofloxacin.
• D. Rifampin, Isoniazid, Pyrazinamide, Ethambutol.

Answer: (D)

RIPE stands for Rifampin, Isoniazid, Pyrazinamide, and Ethambutol—the four drugs used in the initial intensive phase of treatment for drug-susceptible pulmonary TB. Each drug contributes to rapid bacterial kill and helps prevent resistance: Rifampin and Isoniazid are highly bactericidal, Pyrazinamide adds activity in the acidic environment of TB lesions and helps shorten the total treatment time, and Ethambutol provides additional activity and helps prevent resistance while susceptibility is being confirmed. This four-drug combination is given for about two months, then therapy continues with isoniazid and rifampin. The other drugs listed aren’t part of the standard first-line regimen for drug-susceptible TB—aminoglycosides like streptomycin or amikacin are used in different contexts, and levofloxacin is typically reserved for drug-resistant TB or specific situations.