Pronunciation(s): IN-ver-ase; sa-KWIH-nuh-veer
|What is Invirase?
- Invirase is an HIV medication. It is in a category of HIV medications called protease inhibitors (PIs). Invirase prevents CD4 cells that have been infected with HIV from producing new HIV.
- Invirase is manufactured by Genentech. The U.S. Food and Drug Administration (FDA) approved it for the treatment of HIV infection in 1995.
- Invirase should be taken with low doses of Norvir (ritonavir), another protease inhibitor that boosts Invirase levels in the body (Invirase suffers from absorption problems, meaning that only a small amount of the drug is absorbed into the bloodstream from the gut). Invirase (1,000mg twice daily) combined with Norvir (100mg twice daily) was approved by the FDA in December 2003 for this purpose.
- Genentech has established a patient assistance program (PAP) for people with HIV who have no public or private health insurance and who cannot afford to cover the cost of Invirase. For more information about the PAP call 877-757-6243.
What is known about Invirase?
- The recommended dose of Invirase with Norvir (ritonavir) is two 500mg Invirase tablets, plus one 100mg Norvir tablet, every 12 hours (twice a day).
- Invirase should be taken with food, preferably a full nutritious meal (e.g., breakfast and dinner). Taking Invirase with food increases the amount of drug in the bloodstream, which makes Invirase more effective against the virus.
- Invirase is not yet recommended for HIV-positive children.
- Clinical trials have determined that Invirase, combined with Norvir, is safe and effective when combined with other drugs, most notably two nucleoside reverse transcriptase inhibitors (NRTIs).
- For HIV-positive adults beginning anti-HIV drug therapy for the first time, Invirase combined with Norvir is listed as an "alternative" protease inhibitor option by the United States Department of Health and Human Services in its treatment guidelines. Norvir-boosted Reyataz (atazanavir) and norvir-boosted Prezista (darunavir) are "preferred" protease inhibitor options. To learn more about these recommendations and options, click here.
- If your viral load becomes detectable while taking a drug regimen that contains Invirase, your doctor can order a drug-resistance test to see which drugs your virus are becoming less sensitive to.
- Many of the currently available protease inhibitors are affected by cross-resistance. This means that, if you've tried and failed a drug regimen in the past that contained a protease inhibitor, your virus might be resistant to Invirase. Similarly, if you take an HIV drug regimen that contains Invirase and your virus becomes resistant to the drug, your virus might also be resistant to many of the other protease inhibitors available. This is why it is very important to use drug-resistance testing to determine which drugs your virus are no longer responding to if you experience a rebound in your viral load while taking an HIV drug regimen. Drug-resistance testing can also help you figure out which protease inhibitors your virus is still sensitive to.
What about drug interactions?
- Invirase is broken down (metabolized) by the liver, like many medications used to treat HIV and AIDS. This means that Invirase can interact with other medications. Invirase can lower or raise the levels of other medications in the body. Similarly, other medications can lower or raise the levels of Invirase in the body. While many interactions are not a problem, some can cause your medications to be less effective or increase the risk of side effects.
- Tell your doctors and pharmacists about all medicines you take. This includes those you buy over-the-counter and herbal or natural remedies, such as St. John’s Wort. Bring all your medicines when you see a doctor, or make a list of their names, how much you take, and how often you take them. Your doctor can then tell you if you need to change the dosages of any of your medications.
- The following medications should not be taken while you are being treated with Invirase:
Acid reflux/heartburn medications: Propulsid (cisapride)
Antibiotics: Rifadin (rifampin)
Antimigraine medications: Methergine, Methylergometrine (methylergonovine); Ergostat, Cafergot, Ercaf, Wigraine (ergotamine); Ergotrate, Methergine (ergonovine); or D.H.E. 45, Migranal (dihydroergotamine)
Corticosteroids: Flovent o Flonase (fluticasone)
Pulmonary hypertension medications: sildenafil (Revatio)
Cholesterol-lowering drugs (statins): Zocor (simvastatin) and Mevacor (lovastatin)
Heart medications: Cordarone (amiodarone), Vascor (bepridil), Tambocor (flecainide), Rythmol (propafenone), or Quinaglute/Quinidex (quinidine)
Antipsychotics: Orap (pimozide)
Antidepressants: Desyrel (trazadone)
Sedatives: Versed (midazolam) and Halcion (triazolam)
Herbal products: St. John's wort, garlic capsules
Enlarged prostate: Uroxatral (alfuzosin)
- Anticonvulsants, such as Tegretol ( carbamazepine), Luminal (phenobarbital), and Dilantin (phenytoin), may decrease the amount of Invirase in the bloodstream. Invirase/Norvir should be used with caution if combined with these medications.
- HIV protease inhibitors can interact with invirase. Crixivan (indinavir), Viracept (nelfinavir), Reyataz (atazanavir), Lexiva (fosamprenavir) and Aptivus (tipranavir) can increase Invirase levels in the bloodstream. If Invirase is combined with Norvir, the dose should be two 500 mg Invirase capsules plus one 100mg Norvir capsule twice a day. If Invirase is combined with Kaletra, the dose should be two 500mg Invirase capsules plus the usual Kaletra dose. No dosing has been recommended for Invirase plus either Crixivan, Reyataz, Agenerase, or Lexiva. Invirase/Norvir should not be combined with Aptivus.
- Anti-HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs) can also interact with Invirase. Sustiva (efavirenz) can decrease the amount of Invirase in the bloodstream. A third NNRTI, Rescriptor (delavirdine), significantly increases the amount of Invirase in the bloodstream. Recommendations for dosing adjustments have not been issued.
- Invirase can interact with some medications used to treat TB, MAC, and other bacterial infections. Rifadin (rifampin) decreases Invirase levels in the bloodstream; these two drugs should not be used together. Mycobutin (rifabutin) also decreases Invirase levels in the bloodstream. The dose of Mycobutin should be significantly lowered if it is combined with Invirase/Norvir. Invirase can increase Biaxin (clarithromycin) levels and Biaxin can increase Invirase levels in the bloodstream. This can result in serious side effects in people with impaired kidney function. People with kidney problems who combine Invirase/Norvir with Biaxin should reduce the Biaxin dose. People without kidney problems do not need to adjust their dose of Biaxin.
- Several antibiotics— E-mycin (erythromycin), Halfan (halofantrine) and Nebupent (pentamidine)—can interact with Invirase/Norvir and increase the risk for heart rhythm disturbances. Caution is warranted when using these drugs together.
- Invirase/Norvir can increase the blood levels of several drugs used to suppress the immune system, generally after transplants. Therapeutic drug monitoring of these drugs—which include Gengraf (cyclosporine), Prograf (tacrolimus), Sirolimus (rapamycin)—is recommended.
- Invirase can interact with some medications used to treat thrush (candidiasis) and other fungal infections. Invirase/Norvir can increase blood levels of (ketoconazole) or Sporanox (itraconazole) and doses higher than 200 mg of Nizoral or Sporanox should not be used if they are combined with Invirase/Norvir.
- Invirase/Norvir can decrease the amount of methadone in the bloodstream, a drug commonly used to treat heroin addiction. It may be necessary to monitor blood levels of methadone and increase the dose, if needed. Also, methadone may increase blood levels of Invirase, thus increasing the risk of heart rhythm disturbances. Caution should be used when combining these drugs.
- Invirase/Norvir can significantly increase the dose of a number of sedatives. For this reason, oral administration of Versed (midazolam) is not recommended. Versed may be given intravenously, but caution is warranted. The significance of higher blood levels of Xanax (alprazolam), Tranxene (clorazepate), Valium (diazepam) and Dalmane (flurazepam) is unknown.
- Invirase/Norvir can increase blood levels of cochicine, which is used to treat gout. Lower doses of colchicine are recommended, and these drugs should not be used together in people with liver or kidney impairment.
- The corticosteroid Decadron (dexamethasone) can lower the blood levels of Invirase. The two should be combined with caution.
- Invirase/Norvir can increase blood levels of Advair, Flovent, or Flonase (fluticasone), an inhaler that is used to treat allergies and asthma, and this can significantly increase the risk of serious side effects from Flonase. The two should not be combined unless the benefits outweigh the risks.
- Some patients with asthma, bronchitis, or emphysema also take a drug called salmeterol (found in Serevent and Advair), a long-acting beta2-adrenergic receptor agonist that is inhaled. Using salmeterol and Invirase/Norvir together is not recommended, as salmeterol levels can become increased and cause heart rhythm abnormalities.
- Antacids from the proton pump inhibitor class, including Prilosec (omeprazole), can increase Invirase levels in the blood. If Invirase/Norvir are combined with proton pump inhibitors, providers should monitor for Invirase side effects.
- Invirase/Norvir decreases the amount of oral contraceptives (taken by women to help avoid pregnancy) in the bloodstream. This means that there may be a higher risk of becoming pregnant if Invirase/Norvir and oral contraceptives are taken at the same time. To reduce the risk of pregnancy, barrier protection (e.g., condoms) should be used.
- Invirase/Norvir can interact with calcium channel blockers, medications that are used to treat heart disease. Studies of Invirase/Norvir in combination with calcium channel blockers have not been completed. Providers should use caution when combining Invirase/Norvir with Cardizem (diltiazem), Plendil/Lexxel (felodipine), Cardene (nicardipine), Adalat/Nifedical/Procardia (nifedipine), Nimotop (nimopidine), Sular (nisoldipine), Calan/Verelan (verapamil), Norvasc (amiodarone) or Dynacirc (isradepine). Invirase/Norvir can also significantly reduce blood levels of Lanoxin (digoxin). Providers should start with the lowest dose of Lanoxin and monitor Lanoxin blood levels.
- Tracleer (bosenstan) is another type of drug used to treat pulmonary arterial hypertension, called an endothelin receptor antagonist. Kaletra can increase Tracleer blood levels, so the dose of Tracleer should be reduced.
- Cholesterol-lowering drugs, also known as "statins," can interact with Invirase. There are two statins that should not be used with Invirase: Zocor (simvastatin) and Mevacor (lovastatin). Levels of these two drugs can become significantly increased in the bloodstream if they are combined with Invirase, which increases the risk of side effects. The two statins that are considered to be the safest in combination with Invirase are Pravachol (pravastatin) and Lescol (fluvastatin). It is also possible to take Invirase with Lipitor (atorvastatin) or Crestor (rosuvastatin), although Invirase can increase Lipitor or Crestor levels in the bloodstream. If Lipitor or Crestor is prescribed, it's best to begin treatment with the lowest possible dose of the drug and then increase the dose if necessary.
- There is a class of drugs, known as PDE-5 inhibitors that are used to treat both erectile dysfunction and pulmonary arterial hypertension. Their brand names differ, depending on their use. Invirase/Norvir can significantly increase blood levels of these drugs.
When used to treat erectile dysfunction, it is best to use a lower dose of Viagra (sildenafil), Levitra (vardenafil) and Cialis (tadalafil) in order to reduce the risk of side effects. When used to treat pulmonary arterial hypertension, the dose of tadalafil (Adcirca) must be reduced if combined with Invirase/Norvir. Revatio (sildenafil) and Invirase/Norvir should not be used together.
- Invirase/Norvir can increase blood levels of the antidepressant Desyrel (trazadone), which can increase the possibility of experiencing Desyrel side effects. The two should not be used together. Invirase/Norvir can also increase the blood levels of the tricyclic antidepressants Elevil (amitriptyline) and Tofranil (imipramine). Providers should monitor blood levels of these antidepressants if combined with Invirase/Norvir.
Also, a number of anti-psychotic drugs can increase Invirase blood levels. These include: Clozaril (clozapine), Haldol (haloperidol), (mesoridazine), phenothiazines—which include Mellaril (thioridazine) Thorazine (chlorpromazine) and Compazine (prochlorperazine)—and Geodon (ziprasidone). Caution is warranted when combining these drugs with Invirase/Norvir.
- Herbal products can also interact with Invirase. St. John's wort should not be used with Invirase, since it can greatly reduce the amount of Invirase in the bloodstream. HIV-positive people should also be cautious about using garlic supplements or milk thistle with Invirase—test tube studies suggest that both herbal products can interact with the same liver enzyme system (cytochrome P450 3A4) responsible for metabolizing Invirase. This may alter the amount of Invirase in the bloodstream. These and other herbal products should be used with caution, until further studies are conducted.
- Garlic capsules can decrease Invirase blood levels. The two should not be used together.
- A number of other negative drug interactions are possible if Invirase is combined with Norvir. To learn more about these drug interactions, click here.
What about side effects?
- Short-term side effects include appetite loss, headaches, feeling crummy (malaise), diarrhea, nausea, and vomiting. Very often, these side effects improve within a few months/weeks of starting Invirase.
- HIV drug regimens containing protease inhibitors, including Invirase, can cause increased fat levels (cholesterol and triglycerides) in the blood, abnormal body-shape changes (lipodystrophy; including increased fat around the abdomen, breasts, and back of the neck, as well as decreased fat in the face, arms, and legs), and diabetes. These side effects of HIV drug therapy are reviewed in our lessons on Lipodystrophy, Facial Lipoatrophy, and Risks To Your Heart (Hyperlipidemia).
- In rare cases, Invirase/Norvir can increase the risk of heart rhythm disturbances, called QT interval prolongation or a condition called torsades de pointes. The abnormalities—which can be detected using an electrocardiogram—can also lead to interrupted electrical impulses to the heart muscle, technically referred to as heart block. Both conditions can lead to lightheadedness, fainting or abnormal heart beats. In some cases, torsades de pointes can progress to life-threatening irregular heart beat known as ventricular fibrillation. People who already have these conditions should not use Invirase/Norvir.
- Invirase/Norvir should not be used in people with severe liver disease.
Can pregnant women take Invirase?
- Invirase is classified by the FDA as a pregnancy category B drug. Pregnancy category B means that animal studies have failed to demonstrate a risk to the fetus, but there are no adequate and well-controlled studies in pregnant women. Little is known about how pregnancy may affect blood levels of Invirase. Therefore, federal guidelines on the treatment of HIV-positive pregnant women recommend that low dose Norvir (ritonavir) be used to boost blood levels of Invirase. HIV-positive women who become pregnant should discuss the benefits and possible side effects of anti-HIV treatment to help protect their babies from HIV (see our lesson called Family Planning, Pregnancy & HIV).
- It is not known whether Invirase passes into breast milk and what effects it may have on a nursing baby. However, to prevent HIV transmission of the virus to uninfected babies, it is recommended that HIV-positive mothers not breast-feed.
Who should not take Invirase?
- Before taking this medication, tell your doctor if you have diabetes, liver disease, hemophilia or cardiovascular disease . You may require a dosage adjustment or special monitoring during treatment if you have any of these conditions.
- Invirase has not been studied in children.
- Other side effects may occur in addition to those listed. Talk to your doctor if you experience any unusual side effects or if any side effects persist.
Where can I learn more about clinical trials that are using Invirase?
- If you would like to find out if you are eligible for any clinical trials that include Invirase, visit ClinicalTrials.gov, a site run by the U.S. National Institutes of Health. The site has information about all HIV-related clinical studies in the United States. For more info, you can call their toll-free number at 1-800-HIV-0440 (1-800-448-0440) or email email@example.com.