Acyclovir Disease Interactions

Acyclovir is primarily eliminated by the kidney. Patients with renal impairment may be at greater risk for neuro- and nephrotoxicity (including further deterioration in renal function, tubular damage and acute renal failure) from acyclovir due to decreased drug clearance. Therapy with acyclovir should be administered cautiously in patients with renal impairment. Dosage adjustments are recommended in patients with moderate to severe renal dysfunction.

Acyclovir crystals may precipitate in the renal tubules, particularly when the drug is injected intravenously as a bolus. Abnormal renal function may occur, which is usually reversible but may infrequently progress to tubular damage and acute renal failure. Patients who are dehydrated may be at increased risk for nephrotoxicity from acyclovir administration. Intravenous acyclovir should be administered over a one-hour period accompanied by adequate hydration. The urine flow should be monitored, especially within the first two hours following infusion when maximum urine concentration occurs. The recommended urine output is a minimum of 500 mL per gram of drug infused.

Acyclovir is substantially removed by hemodialysis. Plasma levels of acyclovir have been shown to reduce by 60% following 6 hours of dialysis. Acyclovir should be administered after hemodialysis. Otherwise, an additional dose may be given after each hemodialysis session.

Acyclovir, particularly when administered intravenously in higher dosages, may occasionally produce neurotoxicity characterized by lethargy, obtundation, tremors, confusion, hallucinations, agitation, seizures, or coma. Therapy with acyclovir should be administered cautiously in the elderly and in patients with underlying neurologic abnormalities, severe renal or liver disease, or significant electrolyte abnormalities or hypoxia.