Ritonavir

Brand Name(s):

• Norvir®

Other Name(s):

• RTV

IMPORTANT WARNING:

[Posted 3/1/2012]ISSUE:FDA notified healthcare professionals of updates to the prescribing information concerning interactions between protease inhibitors and certain statin drugs. Protease inhibitors and statins taken together may raise the blood levels of statins and increase the risk for muscle injury (myopathy). The most serious form of myopathy, called rhabdomyolysis, can damage the kidneys and lead to kidney failure, which can be fatal.

BACKGROUND:Statins are a class of prescription drugs used together with diet and exercise to reduce blood levels of low-density lipoprotein (LDL) cholesterol (''bad cholesterol''). HIV protease inhibitors are a class of prescription anti-viral drugs used to treat HIV. HCV protease inhibitors are a class of prescription anti-viral drugs used to treat hepatitis C infection.

RECOMMENDATION:Healthcare professionals should follow the recommendations in the prescribing information (drug labels) when prescribing HIV or HCV protease inhibitors with statins. See the FDA Drug Safety Communication for additional information, including a data summary. For more information visit the FDA website at: Web Siteand Web Site.

[Posted 02/09/2012]ISSUE:FDA notified healthcare professionals and patients that drug interactions between the hepatitis C virus (HCV) protease inhibitor boceprevir (Victrelis) and certain ritonavir-boosted human immunodeficiency virus (HIV) protease inhibitors (atazanavir, lopinavir, darunavir) can potentially reduce the effectiveness of these medicines when they are used together.

A drug interaction study showed that taking boceprevir (Victrelis) with ritonavir (Norvir) in combination with atazanavir (Reyataz) or darunavir (Prezista), or with Kaletra (lopinavir/ritonavir) reduced the blood levels of the HIV medicines and boceprevir in the body. FDA will be updating the boceprevir drug label to include information about these drug interactions.

BACKGROUND:Boceprevir is a hepatitis C virus (HCV) protease inhibitor used with the medicines peginterferon alfa and ribavirin to treat chronic (long-lasting) hepatitis C infection in adults. HIV protease inhibitors are a class of anti-viral drugs used to treat HIV infection. Ritonavir is an HIV protease inhibitor used to boost other HIV protease inhibitors, increasing their levels in the blood and making them more effective.

RECOMMENDATION:Patients should not stop taking any of their medicines without talking to their healthcare professional. Patients should contact their healthcare professional if they have any questions or concerns.

Healthcare professionals who have started patients infected with both chronic HCV and HIV on boceprevir and antiretroviral therapy containing a ritonavir-boosted protease inhibitor should closely monitor patients for HCV treatment response and for potential HCV and HIV virologic rebound. For more information visit the FDA website at: Web Siteand Web Site.

IMPORTANT WARNING

Taking ritonavir with certain other medications may cause serious or life-threatening side effects. Tell your doctor if you are taking any of the following medications: ergot medications such as dihydroergotamine (D.H.E. 45, Migranal), ergotamine (Ergomar, in Cafergot, in Migergot), ergonovine, and methylergonovine (Methergine); medications for irregular heartbeat such as amiodarone (Cordarone, Pacerone), bepridil (Vascor) (not available in the U.S.), flecainide (Tambocor), propafenone (Rhythmol), and quinidine; and sedatives or sleeping pills such as midazolam (Versed) and triazolam (Halcion). Your doctor will probably tell you not to take ritonavir if you are taking any of these medications.

WHY is this medicine prescribed?

Ritonavir is used with other medications to treat human immunodeficiency virus (HIV) infection. Ritonavir is in a class of antiviral medications called protease inhibitors. It works by slowing the spread of HIV infection in the body. Ritonavir does not cure HIV and may not decrease the number of HIV-related illnesses. Ritonavir does not prevent the spread of HIV to other people.

HOW should this medicine be used?

Ritonavir comes as a capsule, a tablet, and a solution (liquid) to take by mouth. It is usually taken twice a day with meals. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take ritonavir exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Your doctor will probably start you on a low dose of ritonavir and gradually increase your dose, not more often than once every 2 to 3 days. Follow these directions carefully.

Swallow ritonavir tablets whole. Do not split, chew, or crush them.

If you are taking the oral solution, use a dose measuring spoon, syringe, or cup to measure the correct amount of liquid needed for each dose. Do not use a regular household spoon. You may take the solution by itself, or you may improve the taste by mixing it with 8 ounces of chocolate milk or Ensure or Advera brand dietary supplements. If you mix the medication with once of these liquids, you must drink the mixture no longer than one hour after you mix it.

If your doctor tells you to stop taking ritonavir capsules and start taking the tablets instead, you may experience more side effects such as nausea, vomiting, stomach pain, and diarrhea shortly after you switch. These symptoms may improve as your body adjusts to the tablets.

Continue to take ritonavir even if you feel well. Do not stop taking ritonavir without talking to your doctor. If you miss doses, take less than the prescribed dose, or stop taking ritonavir, your condition may become more difficult to treat.

Are there OTHER USES for this medicine?

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

What SPECIAL PRECAUTIONS should I follow?

Before taking ritonavir,

• tell your doctor and pharmacist if you are allergic to ritonavir, any other medications, or any of the ingredients in ritonavir tablets, capsules, or solution. Ask your pharmacist for a list of the ingredients.
• tell your doctor if you are taking any of the medications in the IMPORTANT WARNING section or any of the following: alfuzosin (Uroxatral), cisapride (Propulsid), lovastatin (Mevacor, in Advicor), pimozide (Orap), sildenafil (Revatio brand only), simvastatin (in Simcor, in Vytorin, Zocor), or voriconazole (Vfend). Your doctor will probably tell you not to take ritonavir if you are taking one or more of these medications.
• also tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, and nutritional supplements you are taking or plan to take. Be sure to mention any of the following: anticoagulants ('blood thinners') such as warfarin (Coumadin); antidepressants such as bupropion (Wellbutrin, Zyban), desipramine (Norpramin), nefazodone, and trazodone (Oleptro); atovaquone (Mepron); beta-blockers such as metoprolol (Toprol) and timolol; bosentan (Tracleer); buspirone (Buspar); calcium channel blockers such as diltiazem (Cardizem, Dilacor, Tiazac), nifedipine (Adalat, Procardia), verapamil (Calan, Covera, Verelan); cholesterol-lowering medications such as atorvastatin (Lipitor) and rosuvastatin (Zocor); clarithromycin (Biaxin); clorazepate (Tranxene); colchicine (Colcrys); dexamethasone (Decadron); diazepam (Valium); digoxin (Lanoxin); dronabinol (Marinol); estazolam; itraconazole (Sporanox); fluticasone (Flovent, in Advair); ketoconazole (Nizoral); lidocaine; other medications for HIV such as atazanvir (Reyataz), darunavir (Prezista), delavirdine (Rescriptor), fosamprenavir (Lexiva), indinavir (Crixivan), maraviroc (Selzentry), saquinavir (Invirase), and tipranavir (Aptivus); medications for erectile dysfunction such as sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra); medications that suppress the immune system such as cyclosporine (Neoral, Sandimmune), sirolimus (Rapamune) and tacrolimus (Prograf); certain medications for seizures such as carbamazepine (Epitol, Equetro, Tegretol), clonazepam (Klonopin), divalproex (Depakote), ethosuximide (Zarontin), lamotrigine (Lamictal), and phenytoin (Dilantin); meperidine (Demerol); methadone (Dolobid); methamphetamine (Desoxyn); mexiletine; nefazodone; perphenazine; prednisone; quinine (Qualaquin); rifabutin (Mycobutin); rifampin (Rifadin, Rimactane); risperidone; salmeterol (Serevent, in Advair); theophylline (Theo-Dur); thioridazine; vinblastine; vincristine; and zolpidem (Ambien). Many other medications may also interact with ritonavir, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• if you are taking ritonavir oral suspension, also tell your doctor if you are taking disulfiram (Antabuse) or metronidazole (Flagyl).
• tell your doctor and pharmacist what herbal products you are taking, especially St. John's wort.
• tell your doctor if you have or have ever had a prolonged QT interval (a rare heart problem that may cause irregular heartbeat, fainting, or sudden death), diabetes, hemophilia, high cholesterol or triglycerides (fats) in the blood, or heart or liver disease.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking ritonavir, call your doctor immediately. You should not breast-feed if you are infected with HIV or if you are taking ritonavir.
• you should know that ritonavir may decrease the effectiveness of hormonal contraceptives (birth control pills, patches, rings, or injections). Talk to your doctor about using another form of birth control.
• you should be aware that your body fat may increase or move to different areas of your body, such as your upper back, neck (''buffalo hump''), breasts, and around your stomach. You may notice a loss of body fat from your face, legs, and arms.
• 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 ritonavir: 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 after starting treatment with ritonavir, be sure to tell your doctor.

What SPECIAL DIETARY instructions should I follow?

Unless your doctor tells otherwise, continue your normal diet.

What should I do IF I FORGET to take a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What SIDE EFFECTS can this medicine cause?

What should I know about STORAGE and DISPOSAL of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store the tablets and solution at room temperature. Do not refrigerate the solution and do not let it get too hot or too cold. It is best to refrigerate ritonavir capsules, but you may also store them at room temperature for up to 30 days. Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

What should I do in case of 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.

It is especially important to get medical help right away if a child drinks more than the usual dose of the solution. The solution contains a large amount of alcohol that could be very harmful to a child.

Symptoms of overdose may include:

• numbness, burning, or tingling of the hands or feet

What OTHER INFORMATION should I know?

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your response to ritonavir.

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.

AHFS® Consumer Medication Information. © Copyright, 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.

Selected Revisions: March 15, 2012.