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AIDSinfo Drug Database

AIDSinfo Drug Database

Drugs by class



Fosamprenavir  Audio icon

Brand Name: Lexiva
Other Names: fosamprenavir calcium, FOS-APV, FPV
Drug Class: Protease Inhibitors
Approved Use: Treatment of HIV Infection
Drug Images:
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Lexiva 700mg
Lexiva Oral
Chemical Image:
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fosamprenavir calcium
fosamprenavir calcium
Molecular Weight: 623.6736


Fosamprenavir can cause serious, life-threatening side effects. These include severe skin reactions or rash.

Stop taking fosamprenavir and contact your health care provider right away if you have a rash and have any of the following symptoms:

  • Hives or sores in your mouth, or your skin blisters and peels.
  • Trouble swallowing or breathing.
  • Swelling of your face, eyes, lips, tongue, or throat.

Taking fosamprenavir with certain other medicines may result in serious and/or life-threatening side effects. Tell your health care provider about other medicines you take.

While taking fosamprenavir, it is important to keep all of your appointments with your health care provider.

What is fosamprenavir?

Fosamprenavir is a prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of HIV infection in adults and children 4 weeks of age and older. Fosamprenavir is always used in combination with other HIV medicines.

Fosamprenavir belongs to a class (group) of HIV medicines called protease inhibitors (PIs). PIs block an HIV enzyme called protease. (An enzyme is a protein that starts or increases the speed of a chemical reaction.) By blocking protease, PIs prevent HIV from multiplying and can reduce the amount of HIV in the body.

HIV medicines can’t cure HIV/AIDS, but taking a combination of HIV medicines (called an HIV regimen) every day helps people with HIV live longer, healthier lives. HIV medicines also reduce the risk of HIV transmission.

What should I tell my health care provider before taking fosamprenavir?

Before taking fosamprenavir, tell your health care provider:

  • If you are allergic to fosamprenavir, sulfa medicines, or any other medicines.
  • If you have liver problems, including hepatitis B virus (HBV) or hepatitis C virus (HCV) infection.
  • If you have kidney problems.
  • If you have diabetes or high blood sugar (hyperglycemia).
  • If you have hemophilia.
  • If you have any other medical conditions.
  • If you are pregnant or plan to become pregnant. Whether fosamprenavir can harm an unborn baby is unknown. Talk to your health care provider about possible risks with taking fosamprenavir when pregnant.
  • If you are breastfeeding or plan to breastfeed. Do not breastfeed if you are infected with HIV or are taking fosamprenavir.
  • If you are using estrogen-based birth control (such as pills). Fosamprenavir may make these forms of birth control less effective. Your health care provider can help you decide how to adjust your birth control while you are taking fosamprenavir.
  • About other prescription and nonprescription medicines, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Fosamprenavir may affect the way other medicines or products work, and other medicines or products may affect how fosamprenavir works. Taking fosamprenavir together with certain medicines or products may cause serious and/or life-threatening side effects.

How should I take fosamprenavir?

Fosamprenavir comes in two forms:

  • 700-mg tablets (brand name: Lexiva).
  • 50-mg/mL oral suspension (brand name: Lexiva).

Take fosamprenavir according to your health care provider’s instructions.

Take fosamprenavir tablets with or without food. Adults should take the fosamprenavir oral suspension without food. Children should take the oral suspension with food. If your child vomits within 30 minutes after taking a dose of fosamprenavir, the dose should be repeated. Shake the oral suspension vigorously before each use.

Always take fosamprenavir in combination with other HIV medicines.

If you take too much fosamprenavir, contact your health care provider or local poison control center (1-800-222-1222) right away, or go to the nearest hospital emergency room.

For more information on how to take fosamprenavir, see the FDA drug label from DailyMed. (DailyMed is a federal website that includes the most recent drug labels submitted to FDA.)

What should I do if I forget a dose?

If you miss a dose of fosamprenavir, take the missed dose as soon as you remember it. But if it is almost time for your next dose, skip the missed dose and just take your next dose at the regular time. Do not take two doses at the same time to make up for a missed dose.

What side effects can fosamprenavir cause?

Fosamprenavir can cause serious, life-threatening side effects. These include severe skin reactions or rash. Taking fosamprenavir with certain other medicines may cause serious and/or life-threatening side effects. (See the WARNING above.)

Other possible side effects of fosamprenavir include:

  • Liver problems.
  • Diabetes and high blood sugar (hyperglycemia).
  • Changes in body fat (lipodystrophy).
  • Changes in the immune system (immune reconstitution inflammatory syndrome [IRIS]). Your immune system may get stronger and begin to fight infections that have been hidden in your body for a long time. Tell your health care provider if you start having new or worse symptoms of infection after you start taking fosamprenavir.
  • Changes in blood tests. These include increases seen in liver function tests, blood fat levels, and decreases in white blood cells.
  • Increased bleeding in some people with hemophilia.
  • Kidney stones. (Contact your health care provider right away if you have pain in your side, blood in your urine, or pain when you urinate.)

Tell your health care provider if you have any side effect that bothers you or that does not go away.

These are not all the possible side effects of fosamprenavir. To learn more about possible side effects of fosamprenavir, read the drug label or package insert or talk to your health care provider or pharmacist.

The AIDSinfo fact sheet on HIV Medicines and Side Effects also includes information that may apply to fosamprenavir.

You can also report side effects to FDA at 1-800-FDA-1088 (1-800-332-1088) or online at

How should fosamprenavir be stored?

  • Store fosamprenavir tablets at room temperature, 68°F to 77°F (20°C to 25°C). Keep the container tightly closed.
  • Store fosamprenavir oral suspension between 41°F and 86°F (5°C to 30°C). Refrigeration of fosamprenavir oral suspension may improve taste for some people. Do not freeze the oral suspension.
  • Follow FDA’s guidelines to safely dispose of fosamprenavir that is no longer needed or expired (out of date).
  • Keep fosamprenavir and all medicines out of reach of children.

Where can I find more information about fosamprenavir?

More information about fosamprenavir is available:

Manufacturer Information

ViiV Healthcare

The above Patient Version drug summary is based on the following FDA label(s): Suspension, tablet (film coated).

Last Reviewed: November 4, 2014

Last Updated: November 4, 2014

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