Active Ingredients

Fosamprenavir – Effect, Application & Risks


The medicinal substance fosamprenavir is a so-called antiviral from the family of HIV protesis inhibitors. It is used to treat HIV infections and is intended to prevent the development of the disease AIDS (short for: Acquired Immune Deficiency Syndrome). Fosamprenavir is sold under the trade name Telzir® and is manufactured by GlaxoSmithKline plc. based in London, UK.

What is fosamprenavir?

The drug fosamprenavir is an antiviral. This is a group of drugs that stop viruses from multiplying. The drug belongs to the family of HIV protease inhibitors. This refers to active ingredients that specifically inhibit the activity of the protein-splitting enzymes of the HI virus . In addition to fosamprenavir, this group also includes the preparations nelfinavir and lopinavir .

By preventing protein splitting, the replication of the HI virus is considerably slowed down.

Fosamprenavir is used in tablet form and as a suspension. A suspension is a suspension of small particles that are placed in liquid but are not soluble. Medicines containing fosamprenavir require a prescription across Europe. Independent consumption without a doctor’s prescription is prohibited. In Germany there is also a pharmacy obligation.

Pharmacological action

As an antiviral, fosamprenavir inhibits the multiplication of the HI virus in the human body. Unlike bacteria , viruses do not have their own metabolism that could be interfered with by medication. As a result, the therapy of viruses is fundamentally made considerably more difficult. Because the metabolism usually offers an easily accessible target for destroying a bacterium.

The drug fosamprenavir therefore starts with the protein splitting of the HI viruses contained in the body. The cleavage of proteins (enzymes) is inhibited by fosamprenavir and similar HIV protease inhibitor drugs. As a result, no further infectious viruses are formed in the host cell of the body affected by the virus, since HI viruses depend on the enzyme (protease) they produce in order to be able to infect healthy blood cells (CD-4 cells).

Fosamprenavir is primarily broken down or excreted in the liver or faeces . The half-life until the active ingredient is completely excreted is about 7 hours on average.

Medical Application & Use

Fosamprenavir is only used in combination with other drugs as part of a comprehensive HIV therapy that is fully monitored by a doctor ( combination therapy ). It is only indicated if low-dose ritonavir or similar antiretroviral drugs are used at the same time. Ritonavir increases drug levels of fosamprenavir.

The recommended daily amount of fosamprenavir is one film-coated tablet, each containing 700 mg of the active substance, twice a day. In addition to these two tablets, the other HIV preparations (e.g. 100 g ritonavir) should be taken. In total, a patient takes four tablets a day (two tablets of fosamprenavir and two tablets of ritonavir). Compared to treatments with the predecessor drug amprenavir , there is a significant reduction in the number of tablets taken daily.

Fosamprenavir is not used for preventive HIV treatment as part of a so-called PrEP (pre-exposure prophylaxis). The area of ​​application remains limited to HIV combination therapy.

Risks & side effects

Fosamprenavir must be used concomitantly with low-dose ritonavir or other antiretroviral drugs. Only in this way can the intended purpose be effectively achieved. Each application must therefore be discussed with a doctor or pharmacist. Taking fosamprenavir is prohibited if you are hypersensitive ( allergic ) to fosamprenavir, amprenavir or other components of the HIV medication.

Drugs containing fosamprenavir must not be taken with the following preparations:

Fosamprenavir can cause side effects. The following side effects have been reported so far:

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.