For which of the following medications would genetic testing be necessary before prescription?

Genetic testing is necessary before prescribing carbamazepine due to the risk of severe skin reactions, such as Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN), which are associated with specific human leukocyte antigen (HLA) alleles. For example, individuals of Asian descent who carry the HLA-B1502 allele are at a significantly increased risk for these adverse reactions when treated with carbamazepine. As a result, genetic testing for the HLA-B1502 allele is recommended in certain populations before initiating treatment with carbamazepine to prevent these potentially life-threatening side effects.

In contrast, while other medications listed like lithium, valproic acid, and aripiprazole may have important clinical considerations, they do not have established genetic testing guidelines that are as critical as those for carbamazepine. Thus, the need for genetic testing before prescribing carbamazepine is both predictive of adverse reactions and essential for ensuring patient safety.