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|Invirase Invirase

Invirase

Generic name: Saquinavir
Brand names: Invirase, Fortovase

Why is Invirase prescribed?

Invirase is used in the treatment of advanced human immunodeficiency virus (HIV) infection. HIV causes the immune system to break down so that it can no longer fight off other infections. This leads to the fatal disease known as acquired immune deficiency syndrome (AIDS).

Invirase belongs to a class of HIV drugs called protease inhibitors, which work by interfering with an important step in the virus"s reproductive cycle. Invirase is used in combination with other HIV drugs called nucleoside analogues (Retrovir or Hivid, for example). The combination produces an increase in the immune system"s vital CD4 cells (white blood cells) and reduces the amount of virus in the bloodstream. Invirase should not be used by itself.

The active ingredient in Invirase is saquinavir mesylate, and although it"s similar to the active ingredient in Invirase, the two drugs are not interchangeable (see "Most important fact about Invirase"). However, the drug information provided here about Invirase also applies to Invirase.

Most important fact about Invirase

Invirase will not cure an HIV infection. You will continue to face the possibility of complications, including opportunistic infections (rare infections that develop only when the immune system falters, such as certain types of pneumonia, tuberculosis, and fungal infections). Therefore, it is important that you remain under the care of a doctor and keep all your follow-up appointments.

Although they contain a similar ingredient, Invirase and Invirase are not interchangeable. When using saquinavir as the sole protease inhibitor in a combination drug regimen, Invirase is the recommended brand. Invirase may be used only if it is combined with ritonavir (Norvir). Any switch from Invirase to Invirase or vice versa should be made only under the supervision of your doctor.

How should you take Invirase?

Take Invirase exactly as prescribed by your doctor. Do not share Invirase with anyone and do not exceed your recommended dosage. Take Invirase with a meal or within 2 hours afterwards. This allows the drug to be properly absorbed by your body. Your doctor will perform laboratory tests before you start therapy with Invirase and at regular intervals during your therapy to see how you are reacting to the medication.

--If you miss a dose...

Take it as soon as possible. If it is almost time for your next dose, skip the one you missed and go back to your regular schedule. Never take a double dose.

--Storage instructions...

Store Invirase in the refrigerator in a tightly closed bottle. The capsules should be used within 3 months if they"ve been allowed to reach room temperature.

What side effects may occur?

Side effects cannot be anticipated. If any develop or change in intensity, tell your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking Invirase.

• More common side effects may include:
  Abdominal discomfort and pain, appetite disturbance, depression, diarrhea, dizziness, fatigue, gas, headache, indigestion, mouth sores, muscle and bone pain, nausea, numbness in the arms and legs, tingling or "pins and needles" sensation, vomiting, weakness

Why should Invirase not be prescribed?

You should not use Invirase if you have severe liver impairment. Also, you should not take certain medications while using Invirase (see "Possible food and drug interactions when taking Invirase").

If you suffer an allergic reaction to Invirase or any of its components, you will not be able to use Invirase.

Invirase may be used only when it"s combined with ritonavir (Norvir); it cannot be added to regimens that don"t contain Norvir.

Special warnings about Invirase

Invirase may increase blood sugar levels. If you have diabetes, be sure to let the doctor know. Your dosage of diabetes medication may need adjustment.

Invirase may aggravate mild-to-moderate liver problems and should be used with caution if you have such liver disorders as hepatitis or cirrhosis. Also use the drug with caution if you have severe kidney problems.

Invirase may cause bleeding in people with hemophilia type A or B.

Patients taking protease inhibitors such as Invirase sometimes undergo a redistribution of body fat, gaining weight around the waist, developing a pad of fat on the upper back, and losing weight in the arms and legs. The long-term health effects of these changes are still unknown.

High cholesterol and triglyceride levels have been observed in people taking Invirase or Invirase combined with ritonavir (Norvir). If you"re taking Invirase combination, the doctor will do periodic blood tests to check for problems.

This medication does not reduce the risk of transmission of HIV to others through sexual contact or blood contamination. Therefore, you should continue to avoid practices that could give HIV to others.

Possible food and drug interactions when taking Invirase

Combining certain medications with Invirase could cause serious or life-threatening reactions. The following drugs should never be used while you"re taking Invirase:

Amiodarone (Cordarone)
Astemizole
Bepridil
Certain migraine drugs, including D.H.E. 45 injection, Cafergot, Ergostat, and Migranal Nasal Spray
Cisapride
Flecainide (Tambocor)
Midazolam (Versed)
Pimozide
Propafenone (Rythmol)
Quinidine (Quinidex)
Terfenadine
Triazolam (Halcion)

The manufacturer also warns against combining Invirase with the following:

Cholesterol-lowering drugs known as statins, such as Lipitor, Mevacor, and Zocor
Garlic
Rifampin (Rifadin)
St. John"s wort

If Invirase is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Invirase with the following:

Antidepressants known as tricyclics, such as Elavil and Tofranil
Carbamazepine (Tegretol)
Calcium channel blockers, including Cardene, Cardizem, and Verelan
Delavirdine (Rescriptor)
Dexamethasone (Decadron)
Erectile dysfunction medications such as Cialis, Levitra, and Viagra
Efavirenz (Sustiva)
Immunosuppressants such as Rapamune, Prograf, and Sandimmune
Lidocaine
Methadone
Nevirapine (Viramune)
Oral contraceptives
Other protease inhibitors such as Crixivan, Norvir, and Viracept
Phenobarbital (Donnatal)
Phenytoin (Dilantin)
Rifabutin (Mycobutin)
Sedatives such as Tranxene, Valium, and Xanax
Warfarin (Coumadin)

Be sure to tell your doctor and pharmacist about all the medications (both prescription and over-the-counter) that you are presently taking. Alert them, too, whenever you stop taking a medication.

Special information if you are pregnant or breastfeeding

The effects of Invirase during pregnancy have not been adequately studied. If you are pregnant or plan to become pregnant, tell your doctor immediately. Do not breastfeed. HIV appears in breast milk and can be passed to a nursing infant.

Recommended dosage

ADULTS AND CHILDREN 16 YEARS AND OLDER

Invirase Combined with Other Anti-HIV Drugs

The recommended dosage is 1,200 milligrams (six 200-milligram capsules), taken 3 times a day with a meal or within 2 hours afterwards. Daily doses lower than 1,200 milligrams 3 times a day are not recommended, since they will not have the same antiviral activity. You should also be taking Retrovir, Hivid, or another antiviral drug as directed.

Invirase Combined with Ritonavir

The recommended dosage is 1,000 milligrams (five 200-milligram capsules) taken 2 times a day with a meal or within 2 hours afterwards. Ritonavir (Norvir) should be taken at the same time as Invirase. Daily doses lower than 1,000 milligrams (along with 100 milligrams of Norvir) 2 times a day are not recommended, since they will not have the same antiviral activity.

CHILDREN LESS THAN 16 YEARS OLD

Invirase and Invirase have not been studied in children younger than 16 years old.

Overdosage

There have been no reports of Invirase poisoning. However, any medication taken in excess can have serious consequences. If you suspect an overdose, seek emergency medical treatment immediately.