Impact of Recent Methamphetamine Use on Vancomycin Clearance

Purpose: To determine whether recent methamphetamine use increases vancomycin clearance. Methods: This was a multi-center, retrospective, IRB-approved study at two tertiary care medical centers. Adult patients with a urine drug screen, ≥3 consecutive vancomycin doses, and an appropriately drawn vancomycin trough were assessed and classified as amphetamine positive or amphetamine negative. The primary outcome was vancomycin clearance. Results: 88 patients were included in the analysis, with 44 patients in each group. Vancomycin clearance was greater in the amphetamine positive group (94.54 vs. 86.84 mL/min, p = 0.042, 95% CI 0.29-15.09). There was no significant difference in goal vancomycin trough achievement between groups (34.1% amphetamine positive vs. 43.2% amphetamine negative; p = 0.512). Per multifactorial logistic regression analysis, older age and male gender were associated with decreased vancomycin clearance, while higher BMI and cocaine positive urine drug screen were associated with increased vancomycin clearance. Conclusion: Recent methamphetamine use may increase vancomycin clearance. Larger prospective trials with protocolized vancomycin dosing strategies are needed to further elucidate the impact of methamphetamine use on attainment of goal vancomycin troughs in addition to the potential impact on vancomycin clearance.