CrCl > 80: 200 - 800 mg 2-5 x day po.
CrCl 80-50: 5-12 mg/kg q 8 h iv.
CrCl 50-10: 5-12 mg/kg q 12-24 h iv.
CrCl < 10: 2.5 - 6 mg/kg q 24 h iv. Hemodialysis: 500 mg after dialysis. Peritoneal dialysis: 2.5 mg/kg/day.
Important side effects
Keep well hydrated, causes acute renal failure from IV acyclovir crystal deposition in the kidneys. Agitation, confusion, dizziness, hallucinations, somnolence (more common in the elderly)
Important drug interactions
Cyclosporine increases nephrotoxicity; aminoglycosides increases nephrotoxicity and/or neurotoxicity; cimetidine increases acyclovir toxicity; increases meperidine effect; decreases phenytoin effect; zidovudine increases neurotoxicity (drowsiness and lethargy (:the Grand Rounds Effect:))
Rants and Screeds
Herpes simplex 1 and 2; Varicella Zoster (aka shingles). CMV prophylaxis in the transplant patient, although it shouldn't work. In terms of MIC for herpes virus, from most to least sensitive: HSV 1 < HSV 2 < VZV.
Don't use for
Relevant links to my Medscape blog