indinavir (Crixivan)

Indinavir is an oral medication that is used for treating infections with the human immunodeficiency virus (HIV). It is in a class of drugs called protease inhibitors which also includes ritonavir (Norvir), nelfinavir (Viracept) and saquinavir (Invirase, Fortovase). During infection with HIV, the HIV virus multiplies within the body's cells. Viruses are released from the cells and spread throughout the body where they infect other cells. In this manner, HIV infection is perpetuated among new cells that the body produces continually. During the production of the viruses, new proteins are made. Some of the proteins are structural proteins, that, is, proteins that form the body of the virus. Other proteins are enzymes which manufacture DNA and other components for the new viruses. Protease is the enzyme that forms the new structural proteins and enzymes. Indinavir blocks the activity of protease and results in the formation of defective viruses that are unable to infect the body's cells. As a result, the number of viruses in the body (the viral load) decreases. Nevertheless, indinavir does not prevent the transmission of HIV among individuals, and it does not cure HIV infections or AIDS. Indinavir was approved by the FDA in March 1995.

What brand names are available for indinavir?

Crixivan

Is indinavir available as a generic drug?

GENERIC AVAILABLE: No

Do I need a prescription for indinavir?

Yes

The most common side effects of indinavir are:

• abdominal pain,
• weakness,
• nausea,
• diarrhea,
• vomiting,
• headache,
• insomnia and
• abnormal taste sensation.

Other important side effects include:

• anemia (break-down of red blood cells),
• liver failure and
• kidney stones.

Like other protease inhibitors, use of indinavir may be associated with:

• redistribution or accumulation of body fat,
• increased blood cholesterol, and
• worsening of diabetes.

Kidney stones may be prevented by adequate fluid intake. Adequate fluid intake can be achieved by consuming at least 48 ounces of fluid daily. Immune reconstitution syndrome which is an inflammatory response to infection may occur in patients treated with combination antiretroviral therapy.

The recommended dose for adults is 800 mg every eight hours. Food reduces the absorption of indinavir. Therefore, for optimal absorption, indinavir should be taken with water one hour before or two hours after a meal; however, it may administered with skim milk, juice, coffee, tea or with a light meal such as dry toast or corn flakes.

The dose of indinavir should be reduced to 600 mg every 8 hours when it is combined with delaviridine (Rescriptor), itraconazole (Sporanox), ketoconazole (Nizoral), or in patients with liver failure. The dose of indinavir should be increased to 1000 mg every 8 hours when it is combined with rifabutin (Mycobutin).

Indinavir interacts with many drugs. Some of the important interactions are mentioned below. Patients should consult their health care professional before combining any drugs with indinavir.

Triazolam (Halcion), midazolam (Versed), alprazolam (Xanax), pimozide, lovastatin (Mevacor), simvastatin (Zocor), ergot derivatives (for example, ergotamine, dihydroergotamine), and amiodarone (Cordarone) should not be combined with indinavir due to the risk of serious adverse effects resulting from indinavir increasing the blood levels of these drugs.

Indinavir increases blood concentrations of stavudine (Zerit), alfuzosin (Uroxatral), oral contraceptives, and clarithromycin (Claritin). Increased blood levels may result in more frequent side effects.

Indinavir decreases the blood concentration of didanosine (Videx) in the body and can thereby reduce the effectiveness of didanosine. Therefore, when didanosine and indinavir are both being used for treatment, their ingestion should be separated by one hour.

Indinavir also may inhibit the break-down of the cholesterol-lowering drugs lovastatin (Mevacor), simvastatin (Zocor), and atorvastatin (Lipitor). This may increase the risk of muscle breakdown (rhabdomyolysis) that may be seen when these drugs accumulate in the body.

Ketoconazole (Nizoral), itraconazole (Sporanox), delavirdine (Rescriptor) and clarithromycin (Claritin) can increase blood levels of indinavir and result in more frequent or severe side effects from indinavir.

Rifampin (Rifadin), rifabutin (Mycobutin), St. John's Wort and efavirenz (Sustiva) decrease the blood levels of indinavir and thus can reduce the effect of indinavir.

Indinavir increases blood levels of sildenafil (Revatio) and the risk of side effects such as low blood pressure, prolonged erection, and fainting.

Use of indinavir during pregnancy has not been adequately evaluated.

It is not known whether indinavir is excreted in breast milk. Nevertheless, HIV-infected mothers should not breastfeed because of the potential risk of transmitting HIV to an infant that is not infected.

What preparations of indinavir are available?

Capsules: 100, 200, and 400 mg

How should I keep indinavir stored?

Indinavir should be stored at room temperature, 15 C to 30 C (59 F to 86 F), in the original container and kept away from moisture. The desiccant (drying agent) in the original bottle should not be discarded.