Medications That Increase Acyclovir Levels
Acyclovir levels rise with drugs that reduce kidney clearance, raising toxicity risk like kidney damage or neurotoxicity. Probenecid cuts tubular secretion by 50% [1]. Tenofovir and cidofovir compete for renal elimination [2]. Mycophenolate and valganciclovir add similar strain [3].
Drugs That Raise Acyclovir Toxicity Risk
Nephrotoxic agents worsen acyclovir's kidney effects. Aminoglycosides (gentamicin), amphotericin B, vancomycin, and NSAIDs (ibuprofen) damage tubules alongside acyclovir [1][2]. Foscarnet and cyclosporine amplify neurotoxicity and renal failure odds [3].
Acyclovir's Impact on Other Drugs
Acyclovir has few direct effects but competes with other antivirals like ganciclovir for renal handling, potentially prolonging their exposure [2]. No major CYP450 interactions occur, so it spares most oral meds [1].
How Interactions Happen
Most stem from acyclovir's 70-90% renal excretion. Dose adjustments needed for kidney impairment or with blockers. Monitor creatinine clearance; cut acyclovir dose 50% if under 50 mL/min [1][3].
Common Patient Scenarios
HIV patients on tenofovir or transplant recipients with cyclosporine face highest risks—hospital data shows doubled acute kidney injury rates [2]. No food or OTC interactions stand out beyond NSAIDs [1].
Management Tips
Space doses, hydrate (2-3L/day), check kidney function weekly during combo therapy. No interactions with vaccines, PPIs, or statins [3].
[1]: FDA Acyclovir Label
[2]: Lexicomp: Acyclovir Interactions
[3]: UpToDate: Acyclovir Overview