Lexiva – brand name

Fosamprenavir calcium – generic name

Lexiva belongs to a class of HIV drugs called protease inhibitors (PIs). Lexiva is a newer version of another protease inhibitor called Agenerase (amprenavir). Because Lexiva is easier to take, it is now preferred to Agenerase. If you are taking Agenerase, speak to your doctor about taking Lexiva instead.

The PIs block protease, a protein that HIV needs to make more copies of itself. This may slow down HIV disease.

The Food and Drug Administration (FDA) has approved Lexiva for use in combination with other HIV drugs for the treatment of HIV infection in adults. Lexiva can be used to treat children but there are very specific instructions, please discuss carefully with your doctor.

Lexiva comes in 700 milligram (mg) tablets for adults.  A new oral suspension formula (50 mg) has been FDA approved for children.

Lexiva can be combined with a small booster dose of Norvir (ritonavir) to increase its potency.

The recommended doses of Lexiva are as follows:

• People who are taking HIV drugs for the first time:
  • Two 700 mg Lexiva tablets twice daily (without Norvir)
  • Two 700 mg Lexiva tablets plus two 100 mg Norvir capsules once daily

  • One 700 mg Lexiva tablet plus one 100 mg Norvir capsule twice daily

• People who have taken protease inhibitors before:
  • One 700 mg Lexiva tablet plus one 100 mg Norvir capsule twice daily
• A liquid version of Lexiva was approved by the FDA in June 2007. There are three dosing options for children, depending on their body weight and age:
  • Children between 2 and 5 years of age: 30 milligrams of liquid Lexiva per kilogram (mg/kg) of body weight twice daily. Only for 2- to 5-year-olds starting HIV treatment for the first time (treatment naive); combining Lexiva with Norvir is not recommended.
  • Treatment-naive children 6 years of age or older: 30 mg/kg of body weight twice daily, or 18 mg/kg liquid Lexiva plus 3 mg/kg liquid Norvir twice daily.
  • Treatment-experienced children 6 years of age or older: 18 mg/kg Lexiva plus 3 mg/kg Norvir twice daily.

Lexiva must be used with other medications to treat HIV.

Lexiva can be taken with or without food.

Tell your doctor if you have liver or kidney problems, hemophilia, diabetes, or are allergic to sulfa drugs before taking this medication.

As with all HIV drugs, it is important to take Lexiva as prescribed. Missing or skipping doses can cause your blood levels of the drug to fall too low and resistance can develop. When your virus becomes resistant to an HIV medication, that drug may stop working.

Lexiva (with or without Norvir) may be used for people being treated for the first time.

Lexiva combined with Norvir may work against HIV that is resistant to some of the other PIs, so it may be a good option for people who need to switch therapies due to PI drug failure.

Lexiva is very similar to Agenerase and will likely not be effective in patients who are resistant to Agenerase.

Your doctor can run a resistance test to help determine whether Lexiva is likely to work for you.

If your virus develops resistance to Lexiva then it may stop working or not work as well for you. You also may not get as much benefit from the other PIs.

Sometimes taking more than one medication can cause drug interactions. Taking certain drugs with Lexiva can change the amount of each drug in your blood. Your doctor may need to adjust the doses of your drugs to avoid under- or overdosing.

If you are taking drugs to treat erectile dysfunction such as Viagra, TB drugs, cholesterol-lowering drugs called statins, or methadone, your doctor may need to adjust doses or switch drugs.

Certain medications (including Agenerase, Kaletra, Rescriptor, some acid reflux/heartburn medications, antibiotics, antimigraine medications, antihistamines, calcium channel blockers, antipsychotics, and sedatives) should not be taken with Lexiva.

Lexiva increases the levels of some antidepressant drugs like Elavil and Tofranil. Talk to your doctor about these and other antidepressant drugs you might be taking.

Some birth control pills may not work if you are taking Lexiva. Talk to your doctor about how to prevent an unwanted pregnancy.

The herb St. John's wort lowers the blood levels of some protease inhibitors. Do not take it while taking Lexiva.

Be sure your doctor knows about all the medications you are taking (including over-the-counter, prescription, street drugs, and herbs), even if you only use them occasionally.

For more information and additional resources to check interactions between the particular drugs you are taking, see our info sheet on drug interactions.

Most people find Lexiva easy to tolerate, but it is possible that unexpected long-term side effects could show up later.

If you do experience any side effects from Lexiva, they are likely to be temporary and go away as your body adjusts to the medication. If you experience any of the side effects listed below, call your doctor for advice. Do not just stop taking your medication.

• Diarrhea
• Nausea
• Vomiting
• Abdominal pain
• Intestinal gas (flatulence)
• Headaches
• Skin rash
• Tingling or numbness around the mouth

More serious side effects:

• In rare cases Lexiva can cause a life-threatening hypersensitivity reaction (Stevens-Johnson syndrome). Symptoms may include a severe rash, blisters, mouth sores, swelling, fever, and weakness.  Swelling of the face, lips, and tongue (angioedema) has also been reported. Tell your doctor if you get a rash or develop facial swelling after starting LEXIVA.
• Liver toxicity: This may be indicated by elevated liver enzymes or yellowing of the skin or eyes (jaundice).
• Lipodystrophy, which may include elevated blood sugar (glucose), elevated lipid levels ( cholesterol and triglycerides), and fat gain or loss in certain areas. The exact causes of lipodystrophy are not known, but may include HIV and/or HIV drugs. It is unclear if Lexiva will cause or impact symptoms of lipodystrophy. For more information on lipodystrophy, see our info sheet.

• Hypersensitivity reaction: Lexiva contains an ingredient called sulfa, which can cause an allergic reaction in some people. If you are allergic to Bactrim or Septra, you have a sulfa allergy and should use caution with Lexiva.

If you are experiencing persistent, unusual, or serious side effects, call your doctor right away.

Lexiva is a newer protease inhibitor, and has not been studied in as many people as the older HIV drugs. Studies of Lexiva pharmacokinetics (how the drug is processed by the body) show that the drug behaves similarly in the bodies of women and men.

Some studies suggest that the metabolic side effects (lipodystrophy) associated with PIs may be somewhat different in women and men. However, it is still unclear if women are more likely to gain or lose body fat in certain areas than men.

The NEAT study (APV30001) included 249 participants starting HIV treatment for the first time, 31 percent (or about 77) of whom were women. After 48 weeks, Lexiva plus Ziagen (abacavir) and Epivir (lamivudine or 3TC ) was about as effective as Viracept (nelfinavir) plus Ziagen and Epivir overall, but Lexiva worked better in people with high viral loads.

In the SOLO study (APV30002), Lexiva boosted with Norvir worked about as well as Viracept when taken with Ziagen plus Epivir. This study, also in people starting HIV treatment for the first time, included 27 percent women, or about 175 women out of 649 total participants.

In the CONTEXT study (APV30003), twice-daily Lexiva boosted with Norvir worked about as well as Kaletra (lopinavir/ritonavir) in people who had stopped responding to treatment with other PIs. This study included 15 percent women, or about 47 women out of 315 total participants.

Studies have shown that pregnant women who use HIV drugs can greatly reduce the risk of passing HIV on to their babies. There have been no formal studies on the use of Lexiva during pregnancy.

Check with your doctor about the best treatment options for you and your baby if you are thinking of getting pregnant.

Click this link for more information about pregnancy.

 People who are starting HIV treatment for the first time may develop Immune Reconstitution Syndrome or IRS (also called Immune Reconstitution Inflammatory Syndrome or IRIS). IRS can happen as a result of the immune system getting stronger and responding to an HIV-related infection such as Mycobacterium avium infection (MAC), cytomegalovirus (CMV), Pneumocystis jirovecii pneumonia (PCP), or tuberculosis (TB). People may have been treated for these infections in the past or not even know they have them. If you notice any unusual symptoms soon after starting HIV drugs for the first time, let your doctor know right away so you can be evaluated and, if necessary, treated.

1		DeJesus E., et al. (2003). The Context study: Efficacy and safety of GW433908/RTV in PI-experienced subjects with virological failure (24 week results). 10th Conference on Retroviruses and Opportunistic Infections. Abstract 178.
2		Rodriguez-French A., et al. (2004). The NEAT study: A 48-week open-label study to compare the antiviral efficacy and safety of GW433908 versus nelfinavir in antiretroviral therapy-naive HIV-1-infected patients. J Acquir Immune Defic Syndr,35. 22-32.
3		Schürmann D., et al. (2002). Efficacy and safety of GW433908/ritonavir once daily in therapy naive subjects, (the SOLO study): 48 week results. 6th International Congress on Drug Therapy in HIV Infection. Abstract PL14.4.