FPGEE for National Association of Boards of Pharmacy (NABP) Practice Exam 2025 - Free NABP Practice Questions and Study Guide

Fast acetylators are particularly susceptible to hepatotoxicity from isoniazid due to their metabolic processing of the drug. Isoniazid is primarily metabolized in the liver, and its byproducts can be harmful to liver cells. In individuals who are fast acetylators, the drug is metabolized rapidly, leading to the production of more reactive metabolites in a shorter time frame. This increased exposure to these toxic metabolites can overwhelm the liver's capacity to detoxify them, resulting in liver damage and potential hepatotoxicity.

The mechanism aligns with the pharmacogenetics of isoniazid, where the rate of acetylation can significantly impact the risk of liver injury. Slow acetylators tend to have a lower risk of hepatotoxicity since they metabolize the drug more slowly, reducing the concentration of reactive metabolites at any given time. Understanding this distinction is crucial, especially in a clinical setting, as it guides monitoring and potential dose adjustments based on the patient's acetylation status.

As for the other adverse effects listed, while isoniazid can cause peripheral neuropathy, gastrointestinal toxicity, and cardiovascular complications, these are not specifically linked to the acetylator phenotype in the same way hepatotoxicity is. Peripheral neuropathy is primarily