Which of the following is a first-line drug for tuberculosis?

UP NHM CHO 7 Sept 2022 (Shift-2)

Pharmacology

Easy

Appeared in: UP NHM CHO 7 Sept 2022 (Shift-2)

Explanation

Isoniazid (INH) is a primary first-line antitubercular drug, considered the most essential and widely used agent for treating all forms of tuberculosis.
It is a core component of the standard short-course chemotherapy regimen, commonly known by the acronym HRZE (Isoniazid, Rifampin, Pyrazinamide, Ethambutol).
Isoniazid is highly effective (bactericidal against actively dividing mycobacteria), orally active, and relatively inexpensive, making it a cornerstone of TB treatment worldwide.
Its mechanism involves inhibiting the synthesis of mycolic acid, a crucial component of the mycobacterial cell wall, which accounts for its high selectivity.

Option A: Para-aminosalicylic acid (PAS) is a second-line antitubercular drug. It has lower efficacy and a higher risk of adverse effects compared to first-line agents.
Option C: While historically classified as a first-line drug, Streptomycin is an injectable aminoglycoside. Current guidelines, including India's National Tuberculosis Elimination Programme, now consider it a second-line agent. It is not a routine oral drug like Isoniazid.
Option D: Amikacin is an injectable aminoglycoside antibiotic classified strictly as a second-line drug. It is reserved for treating complex cases of drug-resistant TB.

Clinical Relevance

Nursing practice connection: Knowing Classification of antitubercular drugs helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
The cornerstone of TB treatment is multi-drug therapy to prevent the emergence of drug resistance. Nurses play a vital role in educating patients about the importance of strict adherence to their regimen (e.g., DOTS - Directly Observed Treatment, Short-course).
A key nursing responsibility is monitoring for adverse effects of Isoniazid, primarily hepatotoxicity (jaundice, fatigue, elevated liver enzymes) and peripheral neuropathy (tingling, numbness in hands and feet).
To prevent peripheral neuropathy, patients on Isoniazid are routinely prescribed Pyridoxine (Vitamin B6) supplementation (10 mg/day).

How to Approach the Question

This is a factual recall question that tests your knowledge of pharmacology.
First, read the question carefully to identify the key concept: 'first-line drug for tuberculosis'.
Mentally review the classification of antitubercular drugs into first-line and second-line categories.
Recall the primary, most common drugs used in the standard TB regimen (HRZE: Isoniazid, Rifampin, Pyrazinamide, Ethambutol).
Evaluate each option against this classification. Isoniazid is a core first-line drug. PAS and Amikacin are clearly second-line. Streptomycin is an older, injectable drug now reclassified as second-line in many modern protocols.
Select the option that is unequivocally a primary, routinely used first-line drug, which is Isoniazid.

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