How is acyclovir dosage adjusted?

Adjusting acyclovir dosage is crucial to ensure its effectiveness while minimizing the risk of side effects. According to the medication's prescribing information, acyclovir dosage adjustments are typically made based on a patient's kidney function [1].

Patients with normal kidney function typically receive a standard dose of acyclovir, but those with impaired kidney function require lower doses due to the medication's increased excretion in the urine. For patients with reduced kidney function, measured by a serum creatinine level or estimated glomerular filtration rate (eGFR), the dosing should be adjusted accordingly [2].

For example, patients with a creatinine clearance (CrCl) of 50-79 mL/min can receive a standard dose of acyclovir, while those with a CrCl of 10-49 mL/min should receive a reduced dose of 5 mg/kg/dose administered every 12 hours. Patients with reduced kidney function should be closely monitored for signs of toxicity, such as central nervous system (CNS) effects and gastrointestinal symptoms [3].

Additionally, pregnant women with herpes simplex virus (HSV) infection can be administered a standard dose of acyclovir during the first 36 weeks of gestation [4]. If a woman develops encephalitis or neonatal varicella syndrome, it is recommended to administer a higher dose for the duration of the pregnancy [5].

In terms of age-specific dosing, infants younger than 3 months should be dosed at 10 mg/kg/dose administered every 8 hours. Children from 3 months to 12 years old can receive the same dose as adults, but those aged 12 years and above can receive a pediatric dose [6].

Please refer to the medication's prescribing information and consult a healthcare professional for specific guidance on adjusting acyclovir dosage.

Sources:
[1] https://www.rxlist.com/acyclovir-drugs.htm
[2] https://www.drugs.com/pro/acyclovir.html
[3] https://www.drugs.com/dosage/acyclovir.html
[4] https://reference.medscape.com/drug/acyclovir-342623#5
[5] https://emedicine.medscape.com/article/2161914-overview
[6] https://www.drugs.com/mmx/acyclovir