Which of the following is a second-line antituberculosis drug:

HP CHO -9 October 2022

Pharmacology

Easy

Appeared in: HP CHO -9 October 2022

Explanation

Levofloxacin is a fluoroquinolone antibiotic, which is classified as a second-line drug for treating tuberculosis (TB).
Second-line drugs are reserved for cases where first-line drugs are ineffective due to resistance (like in Multidrug-Resistant TB, MDR-TB) or cannot be used due to patient intolerance.
The other options provided—Rifampicin, Ethambutol, and Isoniazid—are all primary, first-line drugs that form the core of standard TB treatment regimens (HRZE).

Option A: Rifampicin is a core first-line anti-TB drug, not a second-line agent. It is the 'R' in the standard HRZE regimen and is known for its potent bactericidal activity.
Option B: Ethambutol is a first-line anti-TB drug, the 'E' in the HRZE regimen. It is primarily bacteriostatic and is used to prevent the emergence of drug resistance.
Option D: Isoniazid (INH) is the most potent first-line anti-TB drug and a cornerstone of treatment. It is the 'H' in the HRZE regimen.

Clinical Relevance

Nursing practice connection: Knowing Classification of antituberculosis drugs (first-line vs. second-line) helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses must be able to differentiate between first-line and second-line anti-TB drugs to ensure correct administration, anticipate and monitor for specific side effects, and provide appropriate patient education, especially regarding the importance of adherence in complex MDR-TB regimens.
Understanding this classification is critical for patient safety. Administering a second-line drug like Levofloxacin for a simple, drug-susceptible TB case would be inappropriate and could contribute to the development of fluoroquinolone resistance.
What if? If a patient with TB develops resistance to Rifampicin and Isoniazid (MDR-TB), the treatment regimen must be changed to include second-line drugs like Levofloxacin, and the nurse's monitoring priorities would shift to include side effects specific to these agents (e.g., tendonitis, QT prolongation).

How to Approach the Question

First, identify the key term in the question: "second-line antituberculosis drug". This requires you to classify the given options.
Recall the standard first-line TB treatment regimen, commonly known by the acronym HRZE or RIPE.
List the drugs in the HRZE regimen: H = Isoniazid, R = Rifampicin, Z = Pyrazinamide, E = Ethambutol.
Systematically check each option against your list of first-line drugs.
Option A (Rifampicin), Option B (Ethambutol), and Option D (Isoniazid) are all part of the first-line HRZE regimen.
By elimination, the only remaining option, Levofloxacin (Option C), is not a first-line drug and must therefore be the correct answer.

Concept Tested & Keywords

Concept Tested: Classification of antituberculosis drugs (first-line vs. second-line).
Stem keywords: second-line, antituberculosis drug
Lead-in keywords: Which
Negative lead-in flag: false

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