fosamprenavir
Fosamprenavir (Lexiva) is an oral tablet or suspension that's used as part of an antiretroviral (ARV) regimen to treat human immunodeficiency virus (HIV) infections. It's typically taken twice daily, usually in combination with a "booster," like ritonavir (Norvir), to help fosamprenavir (Lexiva) work better against the virus. Fosamprenavir (Lexiva) isn't a first-choice option for HIV anymore because it can cause serious side effects (e.g., rash, diarrhea, and nausea) and can interact with many other medications.
What is Fosamprenavir (Lexiva)?
What is Fosamprenavir (Lexiva) used for?
- Treatment of HIV infection
How Fosamprenavir (Lexiva) works
Fosamprenavir (Lexiva) is a protease inhibitor, which means it blocks a protein called protease. Normally, protease helps to process viral proteins so that the HIV virus can infect healthy cells. By blocking protease from working, fosamprenavir (Lexiva) prevents the virus from making copies of itself and spreading.
Drug facts
| Common Brands | Lexiva |
|---|---|
| Drug Class | HIV ARV |
| Controlled Substance Classification | Not a controlled medication |
| Generic Status | Lower-cost generic available |
| Availability | Prescription only |
Side effects of Fosamprenavir (Lexiva)
The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.
Common Side Effects
- Diarrhea (5-13%)
- Higher levels of fats in the body (up to 11%)
- Higher liver labs (6-8%)
- Rash (3-8%)
- Nausea (3-7%)
Please note: The side effects above include those reported by people who also took ritonavir (Norvir) with fosamprenavir (Lexiva) during clinical trials.
Less Common Side Effects
- Vomiting
- Belly pain
- Feeling tired
- Headache
Fosamprenavir (Lexiva) serious side effects
Contact your healthcare provider immediately if you experience any of the following.
- Severe allergic reactions: facial swelling, hives, rash, itchy skin, welts, body aches, trouble breathing
- Severe skin reactions: fever, cough, sore throat, body aches, peeling or blistering skin rash
- Serious liver problems: nausea, vomiting, not feeling hungry, pain in the right side of the stomach, yellowing of the whites of the eyes or skin, dark-colored urine, light-colored stool
The following Fosamprenavir (Lexiva) side effects have also been reported
Side effects that you should report to your care team as soon as possible:
- Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
- Hemolytic anemia—unusual weakness or fatigue, dizziness, headache, trouble breathing, dark urine, yellowing skin or eyes
- High blood sugar (hyperglycemia)—increased thirst or amount of urine, unusual weakness or fatigue, blurry vision
- Kidney stones—blood in the urine, pain or trouble passing urine, pain in the lower back or sides
- Liver injury—right upper belly pain, loss of appetite, nausea, light-colored stool, dark yellow or brown urine, yellowing skin or eyes, unusual weakness or fatigue
- Redness, blistering, peeling, or loosening of the skin, including inside the mouth
Side effects that usually do not require medical attention (report to your care team if they continue or are bothersome):
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Pros and cons of Fosamprenavir (Lexiva)
Pros
- Available in a liquid form for people who have difficulty swallowing pills
- Can be used in children age 4 weeks and older
- Tablets can be taken with or without food
Cons
- Interacts with many medications
- Requires regular blood work and lab tests to make sure your liver is healthy
- Likely to cause high blood sugar and cholesterol levels
Pharmacist tips for Fosamprenavir (Lexiva)
- Fosamprenavir (Lexiva) tablets can be taken with or without food.
- Fosamprenavir (Lexiva) can interact with many medications. Some medications might need to be stopped or the dose changed before you start HIV ARV regimen. Let your provider or pharmacist know what medications you're taking, including over-the-counter products and supplements.
- Tell the provider if your child experiences any changes in weight while taking fosamprenavir (Lexiva) because the dose might need to be changed.
- Get your routine blood tests done on time while you’re taking fosamprenavir (Lexiva). Lab work is important to make sure that fosamprenavir (Lexiva) works against the virus, and that the medication isn't causing unwanted effects.
- Fosamprenavir (Lexiva) might raise your blood sugar levels. This can lead to or worsen diabetes. If you have diabetes, it's important that you check your blood sugar while taking this medication. Talk to your provider to see if you need additional medications to help control your sugar levels during treatment with fosamprenavir (Lexiva).
- Fosamprenavir (Lexiva) might also raise your cholesterol (fat) levels. This can raise your risk of a heart attack or stroke. If you have a history of high cholesterol, talk to your provider to see if you need additional medications to help control your cholesterol levels during treatment with fosamprenavir (Lexiva).
- People with a "sulfa" allergy might also be allergic to fosamprenavir (Lexiva). Let your provider or pharmacist know if you've had allergic reactions to any medications in the past.
- Always follow the directions on your medications. This is extra important for HIV ARV medications. Talk to your provider before stopping fosamprenavir (Lexiva) or any of your HIV medications. Doing so can cause the virus to spread and become harder to treat.
More tips for Lexiva (fosamprenavir) oral suspension:
- Store Lexiva (fosamprenavir) suspension in its original container and at room temperature or in the refrigerator. Remember to shake it before each dose. And use the dosing cup provided to take your dose.
- Adults should take Lexiva (fosamprenavir) suspension on an empty stomach.
- Children should take Lexiva (fosamprenavir) suspension with food. Since vomiting is a common side effect in children who take fosamprenavir (Lexiva), taking this medication with food can help to prevent nausea and vomiting. If your child throws up within 30 minutes of taking fosamprenavir (Lexiva) oral suspension, you can give them another dose right away to make sure the full dose is absorbed by the body.
Risks and warnings for Fosamprenavir (Lexiva)
Fosamprenavir (Lexiva) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Interactions with other medications
Some medications can interfere with how well your body gets rid of fosamprenavir (Lexiva) from your system. This can affect the amount of fosamprenavir (Lexiva) in your body, how well it works, and the risk of side effects.
Taking certain supplements (e.g., St. John's Wort) or tuberculosis medication (e.g., rifampin (Rifadin)) can lower the amount of fosamprenavir (Lexiva) in your body. This can make fosamprenavir (Lexiva) not work as well to treat your HIV. So this combination must be avoided.
Fosamprenavir (Lexiva) also interferes with how your body gets rid of other medications. For example, taking fosamprenavir (Lexiva) with medications like alfuzosin (Uroxatral) can raise the amount of alfuzosin in your body. This can lead to dangerously low blood pressure. In addition, taking fosamprenavir (Lexiva) with some statins (e.g., lovastatin (Altoprev), simvastatin (Zocor)) can cause your body to absorb more of these statins and raise your risk for serious muscle problems.
Because of the potential for serious interactions with fosamprenavir (Lexiva) and various medications, tell your provider and pharmacist about all the medications you take or plan to take. They can make sure your medications are safe to take together.
Severe skin and allergic reactions
- Risk factor: Sulfa allergies | Taking fosamprenavir (Lexiva) with ritonavir (Norvir)
Fosamprenavir (Lexiva) can sometimes cause rash and other severe skin reactions. If you have a mild or moderate rash, continue to take fosamprenavir (Lexiva) and let your provider know. Oftentimes, the rash goes away on its own. If you have a severe rash or your rash gets worse, talk with your provider right away. In rare cases, if you experience a rash with fever, general discomfort, muscle or joint pain, mouth sores, blisters, or facial swelling, stop taking fosamprenavir (Lexiva) right away and get medical attention. These might be sign of a serious skin reaction called Stevens-Johnson Syndrome (SJS).
People with allergies to sulfa medications might experience similar reactions, including rash, with fosamprenavir (Lexiva). Make sure your provider and pharmacist know about all of your medication allergies, especially if they are severe.
Liver problems
- Risk factors: Hepatitis B or C | History of liver problems | Taking high dose of fosamprenavir (Lexiva) with ritonavir (Norvir)
Fosamprenavir (Lexiva) can cause liver problems. Your risk is higher if you've a history of hepatitis, liver problems, or if you take this medication with ritonavir (Norvir) at a higher dose. Your provider will order blood tests for you before and during treatment so they can make sure this medication is safe for your liver. Let your provider know immediately if you experience signs and symptoms of liver damage, such as feeling sleepy, nausea, loss of appetite, light-colored stool, upper right stomach pain, yellowing of the skin or eyes, or dark urine.
High blood sugar
- Risk factor: Taking certain HIV ARVs (e.g., protease inhibitors)
Taking fosamprenavir (Lexiva) and certain HIV ARVs can raise your blood sugar levels or worsen your diabetes. In some cases, your provider will need to adjust your dose of diabetic medications to make sure your blood sugar is under control. If you have a history of diabetes, let your provider know before starting fosamprenavir (Lexiva). Your provider might ask you to check your blood sugar at home to make sure this medication is safe for you.
Overactive immune system
Taking combination ARV therapy, such as fosamprenavir (Lexiva) with other HIV medications, can cause changes to your immune system called immune reconstitution syndrome. This condition happens when your immune system becomes overly active after you start combination therapy. So your immune system begins to fight off different infections that it was too weak to fight off before you started treatment. In rare cases, your immune response might improve too much with treatment that it starts to attack normal cells in your body (autoimmune). You can develop these conditions as early as during the first few weeks of treatment or many months later. Tell your healthcare provider right away if you start having any new symptoms, such as fever, pain, hair loss, bulging eyes, or sweating, after starting fosamprenavir (Lexiva).
Changes in body fat
Rarely, people taking HIV medications, such as fosamprenavir (Lexiva), have experienced changes in body fat. These changes include fat buildup in the back of the neck, breast, and around the middle of the body. Some people also lost fat from the legs, arms, and face. It's not clear whether fosamprenavir (Lexiva) causes these changes to body fat, why this happens, and whether it will affect your health in the future. Let your provider know if these changes occur while you're taking fosamprenavir (Lexiva).
Higher cholesterol levels
- Risk factor: Taking fosamprenavir (Lexiva) with ritonavir (Norvir)
Fosamprenavir (Lexiva) raises the amount of cholesterol and triglycerides (fats) in your blood, which can put you at higher risk for a heart attack or stroke. Your provider will monitor your blood tests before and during treatment with this medication to make sure it's safe for you. If your cholesterol levels are too high, your might need to take medications to help keep them under control. Keep in mind that certain cholesterol medications, such as lovastatin (Altoprev) or simvastatin (Zocor), should be avoided with fosamprenavir (Lexiva) to prevent serious side effects. Make sure to let your provider know all the medications you're taking before being prescribed new ones.
Risk of bleeding
- Risk factor: History of bleeding problems
Some people with a bleeding condition called hemophilia have reported more bleeding after treatment with a protease inhibitor, such as fosamprenavir (Lexiva). It's unclear whether or not protease inhibitors were the cause for the bleeding. Many people were able to continue treatment with the protease inhibitor. Let your provider know if you experience any sudden bleeds or bleeding that's difficult to stop.
Risk of kidney stone
Though rare, few people who took fosamprenavir (Lexiva) have reported developing kidney stones during treatment. Stop taking fosamprenavir (Lexiva) and let your provider know right away if you experience symptoms such as pain in the lower stomach or back, nausea, and vomiting.
Fosamprenavir (Lexiva) dosage
Tablet| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 700mg | 180 tablets | $572.44 | $3.18 |
Typical dosage for Fosamprenavir (Lexiva)
-
Adults: The typical dose ranges from 1,400 mg by mouth once daily, to 700 mg to 1,400 mg twice daily. Your provider will determine your dose based on different factors, such as what dose of ritonavir (Norvir) you're taking, and whether or not you've taken another protease inhibitor before.
-
Children (ages 4 weeks and older): Your child's provider will determine their dose of fosamprenavir (Lexiva) and ritonavir (Norvir) based on your child's body weight. The typical dose of fosamprenavir (Lexiva) ranges from 18 mg/kg to 45 mg/kg by mouth twice daily, along with ritonavir (Norvir).
Your dose might be different if you have liver problems.
How much does Fosamprenavir (Lexiva) cost?
Fosamprenavir (Lexiva) contraindications
Contraindications are specific health conditions or situations in which a person should not take a medication due to safety concerns. If you have any of the following conditions or if any of the following apply to you, let your healthcare provider know because Fosamprenavir (Lexiva) will not be safe for you to take.
- Taken with certain medications that can raise the risk for serious side effects (e.g., alfuzosin (Uroxatral), rifampin (Rifadin), St. John’s wort, lovastatin, simvastatin (Zocor), triazolam (Halcion))
