Which of the following anti-tuberculosis drugs can damage the 8th cranial nerve?

Appeared in: KPSC Staff Nurse - 2016

Explanation

Streptomycin is an aminoglycoside antibiotic, a class of drugs known for causing ototoxicity.
Ototoxicity refers to damage to the inner ear, specifically affecting the 8th cranial nerve, also known as the vestibulocochlear nerve.
Damage to the cochlear branch of the 8th nerve results in hearing loss and tinnitus (ringing in the ears).
Damage to the vestibular branch of the 8th nerve results in vertigo (dizziness), nystagmus (involuntary eye movements), and ataxia (loss of balance).

Option A: Isoniazid's primary neurotoxicity is peripheral neuropathy, not damage to the 8th cranial nerve. This side effect is managed by co-administering Vitamin B6 (pyridoxine).
Option B: Para-amino Salicylic Acid (PAS) is primarily associated with severe gastrointestinal side effects like nausea and vomiting. It does not have a known toxicity to the 8th cranial nerve.
Option C: Ethambutol causes optic neuritis, which is damage to the 2nd cranial nerve (optic nerve), leading to visual disturbances like red-green color blindness and reduced visual acuity.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Adverse effects of anti-tuberculosis medications, specifically ototoxicity as background academic context rather than a clinical decision trigger.
Nurses must perform baseline and periodic audiometry tests for patients on long-term Streptomycin therapy to detect early signs of hearing loss.
It is a critical nursing responsibility to educate patients to immediately report any symptoms of ototoxicity, such as ringing in the ears (tinnitus), dizziness, or hearing difficulties.
Streptomycin is also nephrotoxic (damages the kidneys). Renal function (BUN, creatinine) must be monitored closely, as impaired kidney function increases the risk of drug accumulation and toxicity.

How to Approach the Question

First, identify the key part of the question: 'damage the 8th cranial nerve'.
Recall or deduce the function of the 8th cranial nerve (vestibulocochlear nerve), which is related to hearing and balance. Damage to this nerve is termed 'ototoxicity'.
Review the four options, which are all anti-tuberculosis drugs.
Systematically recall the most prominent and unique side effect associated with each drug:
Isoniazid is linked to peripheral neuropathy.
PAS is known for gastrointestinal issues.

Concept Tested & Keywords

Concept Tested: Adverse effects of anti-tuberculosis medications, specifically ototoxicity.
Stem keywords: anti-tuberculosis drugs, damage, 8th cranial nerve
Lead-in keywords: Which
Negative lead-in flag: false

Q2Q6NuanIfWz1aRWboQRjy

E6 Pharmacology Katzung 16e p. 1320-1322

E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart B (pp 202-403 of 604) p. 27-29

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

Practise the full KPSC Staff Nurse - 2016

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