An often unforgotten drug that we must be aware of in ESRD patients is acyclovir.
Acyclovir can accumulate in ESRD if not dosed appropriately and can lead to neurotoxicities- leading to confusion, tremors and coma.
Initial study of 7 patients with end stage kidney disease receiving hemodialysis looked at levels following hemodialysis with each patient received a single 800-mg tablet of acyclovir. Plasma acyclovir levels were monitored over the next 48 h as well as before and after the next routine dialysis. Peak plasma levels were achieved at 3 h (12.54 +/- 1.76 microM, range 8.5-17.5 microM) with the half-life calculated to be 20.2 +/- 4.6 h. Mean plasma level of 6.29 +/- 0.94 microM were within the quoted range to inhibit herpes zoster virus (4-8 microM) at 18 h. Hemodialysis (4-5 h) eliminated 51 +/- 11.5% of the acyclovir which remained at 48 h. Computer modelling of various dose modifications suggests that a loading dose of 400 mg and a maintenance dose of 200 mg twice daily is sufficient to maintain a mean plasma acyclovir level of 6.4 +/- 0.8 microM. A further loading dose (400 mg) after dialysis would raise the residual acyclovir concentration by 6.1 +/- 1.0 microM.
Acute acyclovir neurotoxicity can be treated in CKD and ESRD patients with dialysis. The drug is water soluble, not albumin bound and small- hence an ideal dialysis candidate for removal. It is important to keep this toxicity in mind as many might come in to your office with non renal dosing of this agent on ESRD and CKD patients and can lead to neurotoxicity. PD is not an option; HD is preferred mode for removal of acyclovir.
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