Fosamprenavir (patient information)

Why this medication is prescribed

Fosamprenavir is used with other medications to treat human immunodeficiency virus (HIV) infection in patients with or without acquired immunodeficiency syndrome (AIDS). Fosamprenavir is in a class of medications called protease inhibitors. It works by slowing the spread of HIV in the body. Fosamprenavir does not cure HIV infection and may not prevent you from developing HIV-related illnesses. Fosamprenavir does not prevent you from spreading HIV to other people.

How this medication should be used

Fosamprenavir comes as a tablet to take by mouth. It is usually taken with or without food once or twice a day. 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.

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.

Other uses for this medicine

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

Special precautions

Before taking fosamprenavir:

• tell your doctor and pharmacist if you are allergic to fosamprenavir, amprenavir (Agenerase), sulfa medications, or any other medications.
• do not take fosamprenavir if you are taking cisapride (Propulsid); 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); midazolam (Versed); pimozide (Orap); or triazolam (Halcion).
• 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); antidepressants such as amitriptyline (Elavil), amoxapine (Asendin), clomipramine (Anafranil), desipramine (Norpramin), doxepin (Adapin, Sinequan), fluoxetine (Prozac), fluvoxamine (Luvox), imipramine (Tofranil), nefazodone (Serzone), nortriptyline (Aventyl, Pamelor), paroxetine (Paxil), protriptyline (Vivactil), trazodone, and trimipramine (Surmontil); benzodiazepines such as alprazolam (Xanax), clorazepate (ClorazeCaps, Tranxene), diazepam (Valium), and flurazepam (Dalmane); buspirone (BuSpar); calcium channel blockers such as amlodipine (Lotrel, Norvasc), diltiazem (Cardizem, Dilacor, Tizac), felodipine (Lexxel, Plendil), isradipine (DynaCirc), nicardipine (Cardene), nifedipine (Adalat, Nifedical, Procardia), nimodipine (Nimotop), nisoldipine (Sular), and verapamil (Calan, Covera, Isoptin, Verelan); chlorpheniramine (antihistamine in cough and cold medicines); cholesterol-lowering medications (statins) such as atorvastatin (Lipitor), fluvastatin (Lescol), lovastatin (Altocor, Mevacor), and simvastatin (Zocor); clarithromycin (Biaxin); danazol (Danocrine); dexamethasone (Decadron); erythromycin (E.E.S., E-mycin, Erythrocin); fluconazole (Diflucan); histamine H2-receptor blockers such as cimetidine (Tagamet), famotidine (Pepcid), nizatidine (Axid), and ranitidine (Zantac); isoniazid (INH, Nydrazid); itraconazole (Sporanox); ketoconazole (Nizoral); medications for irregular heartbeat such as amiodarone (Cordarone, Pacerone), bepridil (Vascor), flecainide (Tambocor), propafenone (Rhythmol), and quinidine (Quinidex); medications for seizures such as carbamazepine (Tegretol), ethosuximide (Zarontin), phenobarbital (Luminal, Solfoton), and phenytoin (Dilantin); medications that suppress the immune system such as cyclosporine (Neoral, Sandimmune), sirolimus (Rapamune), or tacrolimus (Prograf); methadone (Dolophine, Methadose); metronidazole (Flagyl); other medications to treat HIV including amprenavir (Agenerase), delavirdine (Rescriptor), efavirenz (Sustiva), indinavir (Crixivan), lopinavir (Kaletra), nelfinavir (Viracept), nevirapine (Viramune), saquinavir (Fortovase, Invirase), and ritonavir (Norvir); proton-pump inhibitors such as esomeprazole (Nexium), lansoprazole (Prevacid), omeprazole (Prilosec), pantoprazole (Protonix), and rabeprazole (AcipHex); quinine; rifabutin (Mycobutin); rifampin (Rifadin, Rimactane); tamoxifen (Nolvadex); terfenadine (Allegra); troleandomycin (TAO); vincristine (Vincasar); and zafirlukast (Accolate). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if you are taking medications for erectile dysfunction such as sildenafil (Viagra), tadalafil (Cialis), or vardenafil (Levitra). You should know that fosamprenavir may increase the chance that you will experience serious side effects from these medications. If you are taking any of these medications and you experience dizziness, fainting, upset stomach, changes in vision, or a painful erection that lasts for several hours, call your doctor right away.
• tell your doctor what herbal products you are taking, especially St. John's wort.
• 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 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 breastfeed 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.

Special dietary instructions

Talk to your doctor about drinking grapefruit juice while taking this medicine.

What to do if you forget a dose

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.

Side effects

Minor side effects

Fosamprenavir may cause hyperglycemia (high blood sugar). Call your doctor immediately if you have any of the following symptoms of hyperglycemia:

• extreme thirst
• frequent urination
• extreme hunger
• weakness
• blurred vision

Severe side effects

If high blood sugar is not treated, a serious, life-threatening condition called diabetic ketoacidosis could develop. Call your doctor immediately if you have any of the these symptoms:

• dry mouth
• upset stomach and vomiting
• shortness of breath
• breath that smells fruity
• decreased consciousness

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

• diarrhea
• upset stomach
• 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:

• skin rash
• itching
• hives
• difficulty breathing or swallowing
• sore throat, fever, chills, cough, and other signs of infection

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

Laboratory animals who 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/MedWatch/report.htm] or by phone [1-800-332-1088].

Storage conditions needed for this medication

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). 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

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.

Other information

Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests 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.

Brand names

• Lexiva