Medication Description and Uses

Aciclovir is an antiviral medication used primarily to manage infections caused by herpes viruses, including herpes simplex virus types 1 and 2, varicella-zoster virus, and Epstein-Barr virus. It is effective in treating genital herpes, cold sores, shingles, and chickenpox. The mechanism of action involves inhibiting viral DNA replication, which helps in controlling viral outbreaks and reducing their severity.

Dosage Forms and Strengths

Aciclovir is available in various forms, including tablets, capsules, suspensions, creams, and ointments. Tablets and capsules typically come in strengths of 200 mg, 400 mg, and 800 mg. The cream and ointment formulations are for topical application, with a standard concentration of 5%. The oral suspension is an option for patients with difficulty swallowing pills and is typically available in a concentration of 200 mg/5 ml.

Pharmacokinetics and Absorption

After oral administration, aciclovir is absorbed in the gastrointestinal tract with bioavailability between 10% and 20%. Food may slightly delay absorption but does not significantly affect the extent of absorption. Peak plasma concentrations are reached within 1.5 to 2 hours after dosing. When applied topically, systemic absorption is minimal. The drug is excreted primarily through renal pathways as unchanged drug and metabolites.

Recommended Dosage and Administration

For herpes simplex infections, the usual adult dose is 200 mg orally every 4 hours, five times a day for ten days. For treatment of shingles, 800 mg orally every 4 hours, five times daily for seven to ten days is recommended. In the case of chickenpox, the dosage for children and adults can vary, with specific instructions provided by healthcare professionals based on patient age and weight. For optimal results, initiate treatment at the first sign or symptom of the infection.

Special Populations Considerations

Patients with renal impairment may require dose adjustments, as aciclovir is primarily eliminated by the kidneys. Reduced doses should be used, and frequent monitoring of renal function is recommended to prevent accumulation and potential toxicity. In elderly patients, consideration of renal function is particularly important. For pregnant or breastfeeding women, consult healthcare providers to weigh potential benefits against risks before starting treatment.

Potential Side Effects

Common side effects of oral and systemic aciclovir include nausea, diarrhea, headache, dizziness, and fatigue. Topical application may cause localized effects such as itching, burning, or skin rash. Serious reactions like renal dysfunction, neurotoxicity, and thrombocytopenia are rare but have been reported. Immediate medical attention is advised if patients experience severe adverse effects or signs of hypersensitivity.

Drug Interactions and Precautions

Concomitant use of aciclovir with other nephrotoxic drugs may increase the risk of renal impairment. Probenecid can increase aciclovir plasma concentrations, requiring monitoring for potential toxicity. Ensure adequate hydration during treatment to minimize the risk of renal adverse events. Avoid alcohol as it could amplify side effects like dizziness or sedation.

Monitoring and Follow-up

Regular follow-up is suggested to evaluate therapeutic progress and the occurrence of adverse effects. Monitor renal function, particularly in patients with pre-existing renal issues or those receiving high doses. Patients are advised to report any unusual symptoms promptly to their healthcare provider for adjustment in therapy. Continuous review of potential new or recurring symptoms can help tailor ongoing treatment.

Storage and Handling

Store aciclovir tablets and capsules at room temperature, away from moisture and heat. The suspension should be kept in a tightly closed container and shaken well before use. Cream and ointment formulations should be stored at a cool temperature, avoiding direct sunlight. Ensure medications are kept out of reach of children and disposed of appropriately once they are no longer needed or have expired.