Comprehensive Nursing Pharmacology Q 127

Correct Answer: C. ETH (ethambutol)

Ethambutol will cause changes in visual acuity and color perception. Remember “E” for ethambutol and eyes. However, there are reports of cases of irreversible blindness. Due to the adverse effect of ethambutol associated optic neuropathy, visual acuity testings such as a baseline visual acuity, color vision, and a Humphrey visual field (HVF), should be performed when administering EMB treatment and periodically during the regimen.

Option A: Peripheral neuropathy is a side effect associated with INH. Peripheral neuropathy is also a commonly-associated adverse event of isoniazid therapy, although its incidence is less than 0.2%. In all adults preparing to begin isoniazid treatment, the clinician should order baseline measurements of aspartate aminotransferase (AST), alanine aminotransferase (ALT), bilirubin, alkaline phosphatase, serum creatinine, and platelet count.

Option B: Gout is a side effect associated with pyrazinamide. Pyrazinamide can increase uric acid concentrations and precipitate acute gout flare-ups in predisposed individuals. The recommendation is to monitor uric acid concentrations routinely for patients managed with pyrazinamide.

Option D: Ototoxicity may occur with streptomycin. Monitoring is based on the limited therapeutic index of aminoglycosides and known toxicities, particularly nephrotoxicity and ototoxicity. In general, clinicians should avoid concomitant use of additional medications with possible ototoxic or nephrotoxic effects. Ototoxicity and vestibular impairment are often thought to be the hallmark of streptomycin toxicity. In extreme cases, deafness may occur due to ototoxicity, thus caution must be exercised when combining streptomycin with other potentially ototoxic drugs. Vestibular impairment usually manifests during the course of treatment and is typically permanent.