Indinavir is a potent inhibitor of the HIV protease enzyme which is used in the replication of the virus that causes AIDS.  Protease inhibitors work by disabling the enzyme protease which is essential for replication of the AIDS virus.  Clinical trials have shown that the indinavir boosts the immune system by increasing the CD4 cell counts and suppresses the amount of circulating virus in the bloodstream.  Significant antiviral effects of indinivir have been shown through decreasing levels of p24 antigen which is used to measure HIV levels in the blood.  Indinivir has also been shown to increase the strength of the immune system by increasing CD4 counts.

    Indinavir, known by the Merck brand name of Crixivan, was approved by the Food and Drug Administration on March 13, 1996. The drug can be taken alone or in combination with other anti-HIV therapies.  A Merck study in early 1996 showed that the drug, when used in combination with two other reverse transcriptase inhibitors, reduced the amount of HIV in the bloodstream to nearly undetectable levels in 86% of the patients.  Of the patients showing lowered viral levels in the bloodstream, an additional 86% were able to maintain the viral suppression for up to 68 weeks. This drug is now being marketed all over the world as a protease inhibitor.  It is estimated that more than 125,000 patients are taking the drug.

    Indinavir capsules are formulated as a sulfate salt and are administered orally.  The capsule strengths range from 200, 333 and 400 mg of indinavir. Each capsule contains the inactive ingredients anhydrous lactose and magnesium stearate. The capsule shell contains inactive ingredients and dyes including gelatin, titanium dioxide, silicon dioxide, and sodium lauryl sulfate.

    Approximatly 9% of patients receiveing indinavir at the recommended dose experience nephrolithiasis, including flank pain with or without hematuria.  Some clinical cases have shown an association between the nephrolithiasis  and renal insufficiency or acute renal failure. Proper hydration intake of no less than 48 ounces daily is recommended.  Some studies show that  hyperglycemia, onset or exacerbation of diabetes mellitus, and spontaneous bleeding in patients with hemophilia are associated with the use of protease inhibitors.  Other less serious side effects include fever nausea, headache, fatigue,  abdominal pain, difficulty breathing, cough, vomiting, back pain, and diarrhea.