United States Medical Licensing Examination (USMLE) Step 3 Practice Exam 2025 - Free USMLE Step 3 Practice Questions and Study Guide

The correct answer is associated with nucleotide reverse transcriptase inhibitors (NRTIs) because these medications are known to interfere with mitochondrial DNA synthesis, leading to mitochondrial toxicity. This toxicity can result in a reduction of the cells' ability to produce energy, ultimately causing a disturbance in aerobic metabolism. When aerobic metabolism is impaired, the body may shift to anaerobic metabolism, which produces lactic acid as a byproduct. High levels of lactic acid in the bloodstream can lead to lactic acidosis—a potentially life-threatening condition.

Some specific NRTIs, such as stavudine, didanosine, and zidovudine, have a higher association with this side effect. Patients with pre-existing renal impairment, liver disease, or those taking multiple medications that also affect mitochondrial function are at an increased risk for lactic acidosis when treated with NRTIs.

In contrast, the other classes of antiretrovirals listed do not share this mechanism of action. For instance, protease inhibitors, NNRTIs, and integrase inhibitors do not typically result in mitochondrial toxicity leading to lactic acidosis. Each of these drug classes has its own profiles of side effects, but lactic acidosis is particularly associated with NRTIs, making them