Which of the following anti-tubercular drug causes red-orange discoloration of urine?

GMCH Chandigarh - 2022

Pharmacology

Easy

Appeared in: GMCH Chandigarh - 2022

Explanation

Rifampicin is a first-line anti-tubercular drug that is well-known for causing a harmless red-orange discoloration of body fluids.
This discoloration affects urine, sweat, tears, saliva, and sputum.
While the color change is not harmful, it can permanently stain soft contact lenses, so patients should be advised to wear glasses instead during treatment.
This side effect is a hallmark characteristic used to identify Rifampicin in clinical scenarios and examinations.

Option A: Isoniazid's primary toxicities are peripheral neuropathy and hepatotoxicity. It does not cause red-orange urine.
Option B: Streptomycin, an aminoglycoside, is known for causing ototoxicity (hearing/balance issues) and nephrotoxicity (kidney damage). It does not discolor urine.
Option C: Ethambutol's signature adverse effect is optic neuritis, leading to decreased visual acuity and difficulty distinguishing between red and green colors. It does not affect urine color.

Visual 1: Infographic: A chart summarizing the first-line anti-tubercular drugs (Rifampicin, Isoniazid, Pyrazinamide, Ethambutol) with their primary mechanisms of action and key adverse effects. This provides a high-yield visual summary for memorization.
Visual 2: Illustration: A simple diagram showing a patient with a bottle of Rifampicin, with arrows pointing to icons representing urine, tears, and sweat, all colored red-orange to reinforce the key side effect.

Clinical Relevance

Nursing practice connection: Knowing Adverse effects of anti-tubercular medications helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Patient education is a critical nursing responsibility. Nurses must inform patients taking Rifampicin about the expected red-orange discoloration of body fluids to prevent alarm and ensure treatment adherence.
Nurses should advise patients to avoid wearing soft contact lenses as they can be permanently stained. Using eyeglasses during the treatment period is recommended.
Rifampicin is a potent inducer of cytochrome P450 enzymes, which accelerates the metabolism of many other drugs, including oral contraceptives and warfarin. Nurses must assess for interacting medications and educate patients on the need for alternative contraceptive methods.

How to Approach the Question

First, identify the core question: It asks for a specific, hallmark side effect of an anti-tubercular drug.
Scan the keywords in the question: "red-orange discoloration of urine". This is a very distinct and well-known adverse effect.
Mentally review the side effect profiles of the common first-line anti-TB drugs provided in the options.
Match the keyword "red-orange discoloration" to the correct drug. Recall that Isoniazid causes neuropathy, Ethambutol causes optic neuritis, and Streptomycin causes oto/nephrotoxicity.
Conclude that Rifampicin is the drug responsible for the red-orange discoloration of body fluids.
Select the option corresponding to Rifampicin.

Concept Tested & Keywords

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