A patient complaining visual disturbance, nurse knows that this side effect occurs due to?

AIIMS Rishikesh & Jodhpur NO - 2017

Pharmacology

Easy

Appeared in: AIIMS Rishikesh & Jodhpur NO - 2017

Explanation

Ethambutol is an antitubercular medication known to cause optic neuritis as a primary and serious adverse effect.
Optic neuritis is the inflammation of the optic nerve, which leads to symptoms like reduced visual acuity, blurred vision, and a specific inability to distinguish between red and green colors.
This side effect is dose-dependent and usually reversible if the drug is discontinued promptly upon the appearance of symptoms.
Due to this risk, baseline and periodic visual examinations are a standard part of care for patients receiving Ethambutol.

Option A: Lithium is a mood stabilizer. Its primary side effects are neurological (like tremors), endocrine (hypothyroidism), and renal (nephrogenic diabetes insipidus). While it can cause blurred vision, it is not its most characteristic or common side effect in the way optic neuritis is for Ethambutol.
Option B: Pyrazinamide is another antitubercular drug. Its main adverse effects are hepatotoxicity (liver damage) and hyperuricemia, which can precipitate a gout attack. It is not associated with visual disturbances.
Option C: Rifampicin is a core antitubercular drug. Its most famous and benign side effect is causing a harmless orange-red discoloration of body fluids like urine, sweat, and tears. It can also cause hepatotoxicity but is not known for causing visual disturbances.

Clinical Relevance

Nursing practice connection: Use the key finding related to Adverse effects of antitubercular drugs to guide bedside assessment, documentation, and the next nursing action.
A crucial nursing responsibility is to perform a baseline visual acuity and color discrimination test before a patient starts Ethambutol and to repeat it monthly.
Patient education is vital. The nurse must instruct the patient to immediately report any changes in vision, such as blurriness, difficulty reading, or changes in color perception.
What if? If a patient on a multi-drug TB regimen (including Ethambutol) reports blurred vision, the nurse's priority is to withhold the Ethambutol dose and notify the physician immediately for further evaluation to prevent permanent damage.

How to Approach the Question

First, identify the key symptom in the question stem, which is 'visual disturbance'.
Next, review the options provided, which are all pharmacological agents.
Recall or deduce the primary side effect profile for each drug.
For Lithium, think of mood stabilization and its effects on the kidneys and thyroid.
For the antitubercular drugs (Pyrazinamide, Rifampicin, Ethambutol), recall their specific toxicities.
Match the key symptom 'visual disturbance' to the drug most famously associated with it. Ethambutol's link to optic neuritis is a classic and frequently tested fact in nursing pharmacology.

Concept Tested & Keywords

QgpvqtdhhhK4WIxpCO-51M

E6 Medicine Harrison 22e Part 1 pp. 1461-1463, 1464-1466

E6 Medicine Davidson Principles Practice 24e p. 613-615