Acyclovir Contraindications and Precautions
- breast-feeding
- children
- dehydration
- elderly
- ganciclovir hypersensitivity
- neurological disease
- pregnancy
- renal failure
- renal impairment
- seizure disorder
Acyclovir Contraindications and Precautions
Since acyclovir is excreted primarily by glomerular filtration and tubular secretion, use caution when administering systemic acyclovir to patients with renal dysfunction. Patients with renal impairment or renal failure should receive lower doses of acyclovir at longer intervals (see Dosage). Patients with renal dysfunction are at increased risk of acyclovir-induced neurotoxicity due to high levels of acyclovir. In order to prevent crystalluria, patients should be well-hydrated to maintain a high urine volume and avoid dehydration, especially during therapy with parenteral acyclovir.
Acyclovir should be used with caution in patients with a preexisting seizure disorder or other neurological disease due to a possible increased risk of adverse effects.
The duration of pain after healing was longer in elderly patients >= 65 years compared to younger patients. Renal adverse events, nausea, vomiting, and dizziness are more frequently in elderly subjects. Elderly patients are more likely to have reduced renal function and require dose reduction. Elderly patients are also more likely to have CNS adverse events (e.g., somnolence, hallucinations, confusion, or coma) possibly related to changes in renal function.
Acyclovir should be used with caution in patients with valacyclovir or ganciclovir hypersensitivity. These drugs have similar chemical structures and there may be cross sensitivity.
Oral, intravenous and topical acyclovir products are classified as FDA pregnancy risk category B. No complete or well-controlled pregnancy studies have been performed in humans. Acyclovir was not found to be teratogenic in standard animal studies. A prospective epidemiologic registry of acyclovir use during pregnancy was established in 1984 and completed in April 1999. There were 756 pregnancies followed in women exposed to systemic acyclovir during the first trimester of pregnancy. The occurrence rate of birth defects approximates that found in the general population. However, the small size of the registry is insufficient to evaluate the risk for specific defects or to permit definitive conclusions regarding the safety of acyclovir in pregnant women. Systemic acyclovir should be avoided during pregnancy unless the potential benefits outweigh the possible risks to the fetus.
Following oral administration of acyclovir, breast milk concentrations 1-4 times that of those found in maternal plasma were observed. These concentrations would potentially expose the nursing infant to a dose of acyclovir as high as 0.3 mg/kg/day. The effect of acyclovir on breast-feeding infants has not been established; systemic acyclovir should be used with caution in women breast-feeding their infants. Exposure of the infant after maternal use of topical administration of acyclovir is minimal. Women who have active herpetic lesions on or near the breast should avoid nursing.
The safe and effective use of acyclovir ointment in children has not been established. Oral formulations of acyclovir are not recommended by the manufacturer for use in children < 2 years of age.
[ Last revised: 10/31/2003 1:54:00 PM ]
Related entries
Syndicate
|
