|Trade names||Zovirax, others|
|Other names||Acycloguanosine, acyclovir (BAN UK), acyclovir (USAN US)|
|Intravenous, by mouth, topical, eye ointment|
|Bioavailability||15–20% (by mouth)|
|Elimination half-life||2–4 hours|
|Excretion||Kidney (62–90% as unchanged drug)|
|CompTox Dashboard (EPA)|
|Chemical and physical data|
|Molar mass||225.208 g·mol−1|
|3D model (JSmol)|
|Melting point||256.5 °C (493.7 °F)|
Aciclovir (ACV), also known as acyclovir, is an antiviral medication. It is primarily used for the treatment of herpes simplex virus infections, chickenpox, and shingles. Other uses include prevention of cytomegalovirus infections following transplant and severe complications of Epstein-Barr virus infection. It can be taken by mouth, applied as a cream, or injected.
Common side effects include nausea and diarrhea. Potentially serious side effects include kidney problems and low platelets. Greater care is recommended in those with poor liver or kidney function. It is generally considered safe for use in pregnancy with no harm having been observed. It appears to be safe during breastfeeding. Aciclovir is a nucleoside analogue that mimics guanosine. It works by decreasing the production of the virus's DNA.
Aciclovir was patented in 1974, and approved for medical use in 1981. It is on the World Health Organization's List of Essential Medicines, the safest and most effective medicines needed in a health system. It is available as a generic medication and is marketed under many brand names worldwide. In 2018, it was the 151st most commonly prescribed medication in the United States, with more than 4 million prescriptions.
Even with the highest maternal dosages, the dosage of acyclovir in milk is only about 1% of a typical infant dosage and would not be expected to cause any adverse effects in breastfed infants