Products
Valaciclovir is commercially available in the form of film-coated tablets (Valtrex, generic). It has been approved in many countries since 1995.
Structure and properties
Valaciclovir (C13H20N6O4, Mr = 324.3 g/mol) is the ester of the natural amino acid valine and the antiviral drug aciclovir. It is present in drugs as valaciclovir hydrochloride, a white powder that is soluble in water. Valaciclovir was developed with the aim of increasing the deep bioavailability of aciclovir. It also achieves a higher plasma concentration and requires less frequent administration than aciclovir.
Effects
Valaciclovir (ATC J05AB11) has antiviral properties against herpesviruses. It is a prodrug that is rapidly biotransformed in the body to aciclovir. Aciclovir is itself also 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 during nucleic acid formation.
Indications
For the treatment of infections with herpes viruses. Valaciclovir is used to treat shingles, zoster ophthalmicus, herpes simplex infections of the skin and mucosa, genital herpes, and to prevent cytomegalovirus disease after kidney transplantation.
Dosage
According to the SmPC. The dosing regimen depends on the indication. In general, treatment should be started as early as possible and adequate fluid intake should be ensured.
Contraindications
- Hypersensitivity
For complete precautions, see the drug label.
Interactions
Valaciclovir is actively secreted at the kidney via OAT (organic anion transporter). At this level, interactions with other organic anions are possible, for example, probenecid. Valaciclovir should be combined with renal toxic agents only with caution.
Adverse effects
The most common possible adverse effects include headache, dizziness, nausea, vomiting, diarrhea, photosensitivity, and skin rash. Valaciclovir may rarely cause renal dysfunction and very rarely cause renal failure.
