Products
Tenofovir is commercially available in the form of film-coated tablets (Viread, combination products, generics). It has been approved in many countries since 2002. It is also used to treat chronic hepatitis B. This article refers to HIV.
Structure and properties
Tenofovir (C9H14N5O4P, Mr = 287.2 g/mol) is present in drugs in the form of the prodrug tenofovirdisoproxil and as the fumarate salt tenofovirdisoproxil fumarate, a white crystalline powder that is soluble in water. Tenofovirdisoproxil is rapidly metabolized in the body to tenofovir and intracellularly to the active ingredient tenofovir diphosphate. It is an analog of adenosine 5′-monophosphate (see also under Nucleic Acids). Some drugs also contain the new prodrug tenofoviralafenamide (see there). Generic drugs may contain other salts (e.g., succinate, maleate).
Effects
Tenofovir (ATC J05AF07) has antiviral properties against HIV. The effects are due to inhibition of the viral enzyme reverse transcriptase, which transcribes viral RNA into DNA and is important in viral replication. The activated agent is incorporated into DNA and leads to chain termination.
Indications
- For treatment of infection with HIV as part of combination antiretroviral therapy.
- HIV pre-exposure prophylaxis (see there).
- Chronic hepatitis B (this article refers to HIV).
Dosage
According to the professional information. The tablets are taken once daily with a meal. This increases the bioavailability.
Contraindications
- Hypersensitivity
- Renal insufficiency
- Patients requiring dialysis
Full precautions can be found in the drug label.
Interactions
Tenofovir interacts poorly with CYP450, so interactions via this pathway seem unlikely. However, other interactions are possible (see FI).
Adverse effects
The most common possible adverse effects include a rash, diarrhea, headache, pain, depression, weakness, and nausea. Rarely, dangerous lactacidosis may occur.
