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Fosamprenavir

pronounced as(fos' am pren a veer)

Why is this medication prescribed?

Fosamprenavir is used along with other medications to treat human immunodeficiency virus (HIV) infection. Fosamprenavir is in a class of medications called protease inhibitors. It works by decreasing the amount of HIV in the blood. Although fosamprenavir does not cure HIV, it may decrease your chance of developing acquired immunodeficiency syndrome (AIDS) and HIV-related illnesses such as serious infections or cancer. Taking these medications along with practicing safer sex and making other life-style changes may decrease the risk of transmitting the HIV virus to other people.

How should this medicine be used?

Fosamprenavir comes as a tablet and a suspension (liquid) to take by mouth. It is usually taken once or twice a day. The tablets can be taken with or without food. In patients at least 18 years old, the suspension should be taken without food. In patients younger than 18 years old, the suspension should be taken with food. To help you remember to take fosamprenavir, take it around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take fosamprenavir exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

If you are taking the suspension, shake it well before each use to mix the medication evenly.

If you vomit less than 30 minutes after you take fosamprenavir, you should take another full dose of fosamprenavir.

Fosamprenavir controls HIV infection but does not cure it. Continue to take fosamprenavir even if you feel well. Do not stop taking fosamprenavir without talking to your doctor. If you miss doses or stop taking fosamprenavir, your condition may become more difficult to treat.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Other uses for this medicine

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This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What special precautions should I follow?

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Before taking fosamprenavir,

  • tell your doctor and pharmacist if you are allergic to fosamprenavir, amprenavir (Agenerase), sulfa medications, any other medications, or any of the ingredients in fosamprenavir tablets or suspension. Ask your pharmacist for a list of the ingredients.
  • tell your doctor if you are taking alfuzosin (Uroxatral); cisapride (Propulsid) (not available in the US); delavirdine (Rescriptor); ergot medications such as dihydroergotamine (D.H.E. 45, Migranal), ergoloid mesylates (Hydergine, Gerimal), ergonovine (Ergotrate), ergotamine (Bellamine, Cafergot, Migergot), methylergonovine (Methergine), and methysergide (Sansert); lovastatin (in Advicor, Altoprev, Mevacor); midazolam (Versed); pimozide (Orap); rifampin (Rimactane, Rifadin, in Rifater, in Rifamate); sildenafil (only Revatio brand used for lung disease); simvastatin (in Simcor, in Vytorin, Zocor);or triazolam (Halcion). Your doctor will probably tell you not to take fosamprenavir if you are taking one or more of these medications.
  • do not take flecainide (Tambocor) or propafenone (Rhythmol) if you are taking fosamprenavir and ritonavir (Norvir) together.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, and nutritional supplements you are taking. Be sure to mention any of the following: anticoagulants ('blood thinners') such as warfarin (Coumadin, Jantoven); antidepressants such as amitriptyline (Elavil), imipramine (Tofranil), paroxetine (Paxil), and trazodone; atorvastatin (Lipitor); benzodiazepines such as alprazolam (Xanax), clorazepate (ClorazeCaps, Tranxene), diazepam (Valium), and flurazepam (Dalmane); bosentan (Tracleer); calcium channel blockers such as amlodipine (Lotrel, Norvasc), diltiazem (Cardizem, Dilacor, Tiazac), felodipine (Lexxel, Plendil), isradipine (DynaCirc), nicardipine (Cardene), nifedipine (Adalat, Nifedical, Procardia), nimodipine (Nimotop), nisoldipine (Sular), and verapamil (Calan, Covera, Isoptin, Verelan); colchicine (Colcrys); dexamethasone (Decadron); fluticasone (in Advair, Flonase, Flovent); histamine H2-receptor blockers such as cimetidine (Tagamet), famotidine (Pepcid), nizatidine (Axid), and ranitidine (Zantac); itraconazole (Sporanox); ketoconazole (Nizoral); medications for irregular heartbeat such as amiodarone (Cordarone, Pacerone), lidocaine (Xylocaine), and quinidine (Quinidex); medications for seizures such as carbamazepine (Tegretol), phenobarbital (Luminal, Solfoton), and phenytoin (Dilantin); medications that suppress the immune system such as cyclosporine (Gengraf, Neoral, Sandimmune), sirolimus (Rapamune), or tacrolimus (Prograf); methadone (Dolophine, Methadose); other medications to treat HIV including efavirenz (Sustiva), indinavir (Crixivan), lopinavir (Kaletra), nelfinavir (Viracept), nevirapine (Viramune), ritonavir (Norvir), and saquinavir (Fortovase, Invirase); certain phosphodiesterase inhibitors (PDE-5 inhibitors) used for erectile dysfunction such as sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra); rifabutin (Mycobutin); salmeterol (in Advair, Serevent); and tadalafil (Adcirca). Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Many other medications may also interact with fosamprenavir, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
  • tell your doctor what herbal products you are taking, especially St. John's wort. You should not take St. John's wort during your treatment with fosamprenavir.
  • tell your doctor if you have or have ever had diabetes, hemophilia (a disease in which the blood does not clot normally), high cholesterol or triglycerides, kidney or liver disease, or if you smoke or if you drink or have ever drunk large amounts of alcohol.
  • tell your doctor if you are pregnant or plan to become pregnant. If you become pregnant while taking fosamprenavir, call your doctor. You should not breast-feed if you are infected with HIV or are taking fosamprenavir.
  • if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking fosamprenavir.
  • you should know that fosamprenavir may decrease the effectiveness of oral contraceptives (birth control pills). Talk to your doctor about other ways to prevent pregnancy while you are taking this medication.
  • you should know that your body fat may increase or move to different areas of your body such as your breasts and upper back.
  • you should know that you may experience hyperglycemia (increases in your blood sugar) while you are taking this medication, even if you do not already have diabetes. Tell your doctor immediately if you have any of the following symptoms while you are taking fosamprenavir: extreme thirst, frequent urination, extreme hunger, blurred vision, or weakness. It is very important to call your doctor as soon as you have any of these symptoms, because high blood sugar that is not treated can cause a serious condition called ketoacidosis. Ketoacidosis may become life-threatening if it is not treated at an early stage. Symptoms of ketoacidosis include: dry mouth, nausea and vomiting, shortness of breath, breath that smells fruity, and decreased consciousness.
  • you should know that while you are taking medications to treat HIV infection, your immune system may get stronger and begin to fight other infections that were already in your body. This may cause you to develop symptoms of those infections. If you have new or worsening symptoms at anytime during your treatment with fosamprenavir, be sure to tell your doctor.

What special dietary instructions should I follow?

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Unless your doctor tells you otherwise, continue your normal diet.

What should I do if I forget a dose?

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If you miss a dose and remember after less than 4 hours have passed, take the missed dose immediately. However, if you remember after more than 4 hours have passed, call your doctor to find out if you should skip the missed dose. Do not take a double dose to make up for a missed dose.

What side effects can this medication cause?

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Fosamprenavir may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • diarrhea

  • nausea

  • vomiting

  • headache

  • extreme tiredness

Some side effects can be serious. The following symptoms are uncommon, but if you experience any of them, call your doctor immediately or get emergency medical treatment:

  • skin rash

  • itching

  • hives

  • difficulty breathing or swallowing

  • sore throat, fever, chills, cough, and other signs of infection

  • back or side pain

  • blood in urine

  • pain when urinating

Fosamprenavir may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

Laboratory animals that were given amprenavir (Agenerase), a medication similar to fosamprenavir, developed tumors. It is not known if fosamprenavir increases the risk of tumors in humans. Talk to your doctor about the risks of taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online [at http://www.fda.gov/Safety/MedWatch] or by phone [1-800-332-1088].

What should I know about storage and disposal of this medication?

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Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). The suspension may also be stored in the refrigerator. Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

In case of emergency/overdose

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In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

What other information should I know?

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Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests before and during your treatment to be sure it is safe for you to take fosamprenavir and to check your body's response to fosamprenavir.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

Brand names

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  • Lexiva®

Last Revised - 09/15/2012

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AHFS® Consumer Medication Information. © Copyright, 2014. The American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.