How are antitubercular drugs classified?

• A. First and second generation
• B. Primary and secondary
• C. Major and minor
• D. Active and passive

Answer: (B)

Drugs are classified by their role in treatment: primary versus secondary. Primary drugs are the first-choice agents used in the initial, standard TB regimen because they have strong bactericidal activity, good tolerability, and work well together to prevent resistance. Secondary drugs come into play when the initial regimen fails or when the strain is resistant or the patient cannot tolerate the primary drugs; these options are used for retreatment or drug-resistant TB and often have more toxicity and a narrower evidence base. This framework keeps therapy effective and helps prevent the emergence of resistance by reserving the more potent or specialized drugs for when they’re really needed.