Clinical Medicine Insights: Therapeutics

Published analyses have noted elevated alanine aminotransferase (ALT) activity in patients taking up to 4000 mg/day of acetaminophen. Data from 3 osteoarthritis trials of acetaminophen 3900–4000 mg/day in which ALT and aspartate aminotransferase (AST) were recorded within approximately 2 weeks of therapy initiation were retrospectively analyzed. Patients with baseline ALT or AST above the upper limit of the reference range (ULRR) were excluded. Among 466 patients, 376 (80.7%) had no ALT elevations within approximately 2 weeks of treatment initiation. Elevations >1.5 and >3.0 times ULRR occurred in 4.5% and 0.9% of patients, respectively. Elevations were transient as most resolved (72.9%) or declined (22.4%) with continued treatment beyond 2 weeks. Within approximately 2 weeks of therapy initiation, no patient had ALT > 5 times ULRR or ALT > 3 times ULRR combined with bilirubin >2 times ULRR. ALT elevations were transient and asymptomatic; almost all resolved or declined while on continued therapy and appear not to be clinically important.

Clinical trials.gov ID numbers: NCT00240799, NCT00240786