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Other Names: FAPV, Lexiva ®
Manufacturer: GlaxoWellcome

What is it?

Fosamprenavir is an antiretroviral medication that belongs to a group of drugs known as protease inhibitors. It is used to treat HIV, a retrovirus. Retroviruses use the genetic material in the body’s cells to produce more virus which can infect other cells.

How does it work?

Fosamprenavir interferes with the life cycle of HIV to stop it from producing more virus. Specifically, Fosamprenavir ties up the protease enzyme, which slows the production of new virus to prevent other cells from becoming infected.

How do I take it?

  • Fosamprenavir is available as 700 mg tablets.
  • The dose being studied is 1400mg (2 tablets) twice daily.
  • Fosamprenavir is also taken with ritonavir in 700mg/100mg twice daily dose.
  • Fosamprenavir may be taken with or without food.

It is extremely important that you take Fosamprenavir and your other antiretroviral medications exactly as directed. You should set up a system that will help you remember to take your medicines so that you do not miss any doses. If you miss a dose, take it as soon as possible; however, if you skip a dose, do not take two doses at once. Do not stop taking the medication for any reason at any time unless you are directed to do so by your study clinician. If you are unable to continue taking your medication due to side effects, you should contact your study clinician immediately.

Special Considerations

  • Fosamprenavir should be stored at controlled room temperature in a dry place, out of reach of children.
  • Please bring your medication bottles (empty and partially used) to each study visit.


Some drugs taken together may have interactions that cause illness or impair the effectiveness of the drugs. Since Fosamprenavir is a new drug, studies are being done to determine what interactions there might be with other medications. Always check with your study clinician before taking any other medications, prescription or otherwise, to be sure it will not interact with Fosamprenavir.

Fosamprenavir should not be administered if you are taking the following medications:

  • Cisapride (Propulsid®)
  • dihydroergotamine
  • ergotamine
  • Midazolam (Versed®)
  • Terfenadine (Seldane®)
  • Triazolam (Halcion®)

Many other drugs may interact with Fosamprenavir so you must tell your provider about all medications you are currently taking. This includes any medications that you may take on an ‘as needed’ basis, such as sleeping pills or pain medications and herbal or natural medicines.

Fosamprenavir should not be taken with vitamin E supplements because the capsule formulation contains a substantial amount of vitamin E.

If you are taking oral contraceptives with Fosamprenavir, an alternate form of birth control should be used.

Side Effects

Not everyone experiences side effects. When they do occur, they may be mild, moderate or severe. Some side effects cannot be felt by the patient but can be found through laboratory tests, so it is important to see the doctor regularly for checkups so that side effects can be detected early and treated.

The most common side effects of amprenaivr include diarrhea/loose stools, nausea/vomiting, abdominal pain/discomfort, gas, skin rash, fatigue and headache. Other side effects which may occur include circumoral paresthesia (tingling sensation around the mouth), and changes in liver function, which can be detected and monitored with laboratory tests.

Increases in blood sugar or the development of diabetes has been reported in a small number of patients taking protease inhibitors. Symptoms include increased thirst or hunger, weight loss, increased need to urinate, fatigue, or dry, itchy skin. Please contact your study clinician if any of these side effects occur.

Also, a condition called lipodystrophy (abnormal use of fats in the body) has been reported in patients taking protease inhibitors. Symptoms vary among individuals, but they may include accumulation of fat tissue in the stomach area or the upper back, and a loss of mass in other areas of the body. Some people have experienced increases in cholesterol and triglycerides that have required the use of lipid lowering medications.

The benefits of taking protease inhibitors far outweigh the risk of developing lipodystrophy or diabetes. Therefore, at this time, we strongly encourage you to take your medications exactly as prescribed. Notify your study clinician if any of these side effects are bothersome and may prevent you from taking your medication.

Because Fosamprenavir is still experimental, it is very important that you report any side effects to the clinic staff, regardless of suspected cause.


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