Professional and Linguistic Assessments Board (PLAB) Practice Exam

Which tuberculosis medication is associated with peripheral neuropathy?

1. Isoniazid

2. Ethambutol

3. Rifampin

4. Pyrazinamide

The correct answer is: Isoniazid

Isoniazid is associated with peripheral neuropathy primarily because it inhibits the synthesis of vitamin B6 (pyridoxine), which is essential for the proper functioning of certain neurotransmitters. The depletion of vitamin B6 can lead to symptoms of peripheral neuropathy, including numbness, tingling, and pain in the extremities. This side effect is especially significant in individuals at higher risk, such as those with diabetes or malnutrition, who may already have lower levels of vitamin B6. In clinical practice, healthcare providers often prescribe pyridoxine alongside isoniazid to prevent this adverse effect, recognizing the medication's association with nerve damage when used without supplementation. Other medications for tuberculosis, such as ethambutol, rifampin, and pyrazinamide, are not commonly linked to peripheral neuropathy and have different side effect profiles. Ethambutol can cause visual disturbances, rifampin is known for its liver toxicity and staining bodily fluids, while pyrazinamide is associated with hepatotoxicity as well but not with peripheral neuropathy.