Aciclovir Effects and Side Effects

Products

Aciclovir is commercially available as film-coated tablets, cream, aciclovir lip cream, injectable, and suspension (Zovirax, generic). This article refers to the film-coated tablets. Aciclovir eye ointment is currently no longer marketed in many countries. Aciclovir was developed in the 1970s by the British company Burroughs Wellcome (Elion et al. 1977). It has been approved in many countries since 1982 and is also known as acyclovir.

Structure and properties

Aciclovir (C8H11N5O3, Mr = 225.2 g/mol) exists as a white crystalline powder that is sparingly soluble in water. It is the prodrug of the active aciclovir triphosphate. Aciclovir is an analog of the nucleoside deoxyguanosine – hence the active ingredient name. -vir refers to virus.

Effect

Aciclovir (ATC J05AB01) has antiviral properties against herpes simplex virus types 1 and 2 (HSV-1, HSV-2) and against varicella zoster virus (VZV). It is a prodrug that is converted to aciclovir triphosphate in virus-infected cells by viral thymidine kinase and subsequently by cellular kinases. Aciclovir triphosphate is used by viral polymerase as a false substrate in DNA synthesis. This leads to chain termination in nucleic acid formation and inhibition of viral replication. Because the viral enzyme is involved in activation, aciclovir has high selectivity for infected cells. Aciclovir has a low bioavailability of about 10 to 30% and a short half-life of 2.9 hours. Therefore, frequent administration is necessary. For this reason, the drug is also administered in the form of the more readily available prodrug valaciclovir.

Indications

For the prevention and treatment of herpes simplex virus type 1 and 2 infections:

  • Genital herpes (genital herpes), cold sores (herpes labialis).
  • Herpes simplex encephalitis
  • Prevention in immunosuppression.
  • Herpes simplex keratitis

Varicella zoster virus:

Dosage

According to the professional information. Treatment should be started as early as possible. For therapy, tablets are taken up to five times daily (every 4 hours) with a night break of 8 hours. So, for example, at 8:00, 12:00, 16:00, 20:00 and 24:00. Or at 6:00, 10:00, 14:00, 18:00 and 22:00. Ensure adequate fluid intake (drink plenty of fluids). For detailed instructions, please refer to the professional information. In case of preventive intake, the dosing interval is longer.

Contraindications

Aciclovir is contraindicated in cases of hypersensitivity. For complete precautions, see the drug label.

Interactions

Aciclovir passes unchanged to the kidney, where it undergoes active tubular secretion. Other agents (organic anions) that are also secreted or inhibit this process may cause an increase in plasma concentration. A typical example is probenecid.

Adverse effects

The most common possible adverse effects include headache, dizziness, gastrointestinal disturbances (nausea, vomiting, diarrhea, abdominal pain), and skin reactions such as a rash and itching. Very rarely, the intake may lead to kidney dysfunction, kidney pain and kidney failure.