Which anti tuberculosis drug is contraindicated during pregnancy?

Appeared in: TMC Staff Nurse - 2019

Explanation

Streptomycin belongs to the aminoglycoside class of antibiotics.
This drug is known to cross the placenta and can accumulate in fetal tissues.
The primary toxicity is to the developing auditory system, specifically causing damage to the 8th cranial nerve (vestibulocochlear nerve).
This ototoxicity can result in permanent, irreversible bilateral hearing loss or deafness in the newborn.

Option A: Ethambutol is a first-line anti-TB drug that is considered safe for use during pregnancy.
Option B: Isoniazid (INH) is a primary drug for treating TB and is safe to use during pregnancy.
Option D: Rifampicin is another essential first-line anti-TB drug that is considered safe for use throughout pregnancy.

Clinical Relevance

Nursing practice connection: Knowing Pharmacology and contraindications of anti-tuberculosis drugs in pregnancy helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses must perform a thorough medication reconciliation for all pregnant patients to ensure no teratogenic drugs, like streptomycin, are prescribed.
Patient education is a key nursing responsibility. It's crucial to explain the importance of adherence to the prescribed safe regimen (e.g., INH, Rifampicin) to treat TB effectively and protect both mother and baby.
Untreated tuberculosis poses a greater risk to the pregnant woman and fetus than the treatment itself (using safe drugs).

How to Approach the Question

First, identify the keywords in the question: 'anti-tuberculosis drug', 'contraindicated', and 'pregnancy'. This is a direct recall question about pharmacology.
Recall the standard first-line drugs for treating tuberculosis. The common acronym is RIPE: Rifampicin, Isoniazid (INH), Pyrazinamide, and Ethambutol.
Review the options provided: Ethambutol, INH, and Rifampicin are all standard first-line drugs.
Consider the remaining option, Streptomycin. Recall that it belongs to the aminoglycoside class of antibiotics.
Access your knowledge about drug classes and their major side effects. Aminoglycosides are well-known for causing ototoxicity (hearing damage) and nephrotoxicity (kidney damage).
Connect this toxicity to the context of pregnancy. Drugs that are toxic to an adult's organs are often highly dangerous to a developing fetus. Therefore, Streptomycin's ototoxicity makes it contraindicated in pregnancy.

Concept Tested & Keywords

Concept Tested: Pharmacology and contraindications of anti-tuberculosis drugs in pregnancy.
Stem keywords: anti tuberculosis drug, contraindicated, pregnancy
Lead-in keywords: Which
Negative lead-in flag: false

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart B (pp 202-403 of 604) p. 41-43

E6 Medicine Harrison 22e Part 1 p. 1467-1469

Practise the full TMC Staff Nurse - 2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.