Fos-amprenavir gets marketing approval in US, but once daily dose not recommended for PI-experienced

Michael Carter
Estimated reading time 2 minutes
This article is more than 21 years old.

The US Food and Drug Administration (FDA) has granted marketing approval for the protease inhibitor fos-amprenavir (US tradename LexivaTM). The drug has been developed by GlaxoSmithKline and Vertex Pharmaceuticals.

Fos-amprenavir is a pro-drug of amprenavir, which means that it is converted into amprenavir in the body, so that fewer capsules need to be taken and the drug reaches higher blood concentrations. It can also be boosted by taking 100mg of ritonavir.

The marketing approval was granted after analysis of clinical trials evaluating the safety and efficacy of one and twice-daily dosing of the drug. On the basis of these studies (which have been reported on aidsmap, see links below), fos-amprenavir/ritonavir has not been recommended for once-daily dosing in protease inhibitor-experienced individuals.

Glossary

Food and Drug Administration (FDA)

Regulatory agency that evaluates and approves medicines and medical devices for safety and efficacy in the United States. The FDA regulates over-the-counter and prescription drugs, including generic drugs. The European Medicines Agency performs a similar role in the European Union.

pro-drug

A drug that is broken down into another active form inside the body.

expanded access scheme

A programme that allows access to an experimental drug outside clinical trials for people in particular need.

efficacy

How well something works (in a research study). See also ‘effectiveness’.

boosting agent

Booster drugs are used to ‘boost’ the effects of protease inhibitors and some other antiretrovirals. Adding a small dose of a booster drug to an antiretroviral makes the liver break down the primary drug more slowly, which means that it stays in the body for longer times or at higher levels. Without the boosting agent, the prescribed dose of the primary drug would be ineffective.

Three doses of fos-amprenavir/ritonavir are recommended:

  • Fos-amprenavir 1400mg twice daily (two tablets)

  • Fosamprenavir 1400mg once daily (two tablets) with 200mg of ritonavir (2 capsules)

  • Fosamprenavir 700mg twice daily (one tablet) with 100mg of ritonavir (one capsule).

For patients with experience of protease inhibitors, the recommended dose is 700mg twice daily together with 100mg of ritonavir.

A chief advantage of fos-amprenavir is, that unlike other protease inhibitors, the drug does not have any food or water restrictions. It can be taken with food, or without food.

Marketing approval in Europe is expected early in 2004. Until then, the drug is available on an expanded access scheme in the UK.

Further information on this website

Fos-amprenavir, UK early access

Amprenavir - overview

Fos-amprenavir (433908) shows signs of weakness in Kaletra comparison - news story on CONTEXT study

New amprenavir formulation equal to nelfinavir - news story on the NEAT study

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