indinavir sulfate

Action

Inhibits replication, function, and maturation of human immunodeficiency virus (HIV) protease, an enzyme essential to formation of infectious virus. As a result, further spread of virus is prevented.

Availability

Capsules: 100 mg, 200 mg, 333 mg, 400 mg

Indications and dosages

➣ HIV infection

Adults: 800 mg P.O. q 8 hours

Dosage adjustment

• Mild to moderate hepatic insufficiency secondary to cirrhosis

Contraindications

• Hypersensitivity to drug or its components

• Concurrent use of amiodarone, ergot derivatives, cisapride, pimozide, or oral midazolam, triazolam, alprazolam, alfuzosin, sildenafil

Precautions

Use cautiously in:

• renal or severe hepatic impairment, history of renal calculi

• pregnant or breastfeeding patients

• children.

Administration

• Know that drug is usually given with other antiretrovirals.

• Give with full glass of water on empty stomach 1 hour before or 2 hours after meals.

• If GI upset occurs, give with a light meal.

See Don't give concurrently with alfuzosin, amiodarone, sildenafil, cisapride (not available in U.S.), ergot derivatives, midazolam, pimozide, or triazolam.

Adverse reactions

CNS: depression, dizziness, headache, drowsiness, malaise, asthenia

CV: angina, myocardial infarction

EENT: oral paresthesia

GI: nausea, vomiting, diarrhea, abdominal pain or distention, dyspepsia, acid regurgitation, pancreatitis

GU: dysuria, crystalluria, nephrolithiasis or urolithiasis leading to renal insufficiency or failure, interstitial nephritis

Hematologic: anemia, acute hemolytic anemia, increased spontaneous bleeding (in hemophiliacs)

Hepatic: jaundice, hepatic dysfunction, hepatic failure

Metabolic: new onset or exacerbation of diabetes mellitus, hyperglycemia

Musculoskeletal: joint or back pain

Respiratory: cough, dyspnea

Skin: urticaria, rash, pruritus

Other: abnormal taste, increased or decreased appetite, body fat redistribution or accumulation, fever, anaphylactoid reactions

Interactions

Drug-drug. Azole antifungals, delavirdine, interleukins: elevated indinavir blood level, greater risk of toxicity

Cisapride, ergot derivatives, midazolam, pimozide, triazolam: CYP3A4 inhibition by indinavir, leading to increased blood levels of these drugs and dangerous reactions

Didanosine, efavirenz, rifamycins: decreased indinavir effects

Drug-diagnostic tests. Alanine aminotransferase, amylase, aspartate aminotransferase, bilirubin, cholesterol, glucose, triglycerides: increased values

Hemoglobin, neutrophils, platelets: decreased values

Drug-food. Any food: decreased indinavir absorption

Drug-herbs. St. John's wort: decreased indinavir blood level

Patient monitoring

• Assess fluid intake and output to ensure adequate hydration and help prevent nephrolithiasis or urolithiasis.

• Monitor for adverse GI and CNS effects.

• Evaluate liver function test results. Assess for hyperbilirubinemia.

• Monitor cholesterol, glucose, and CBC with white cell differential.

Patient teaching

• Tell patient to take 1 hour before or 2 hours after meals with a full glass of water.

• If GI upset occurs, advise patient to take with a light meal.

See Instruct patient to report severe nausea or diarrhea, fever, chills, flank pain, urine or stool color changes, yellowing of skin or eyes, or personality changes.

• Tell patient that drug doesn't cure HIV infection and that its long-term effects are largely unknown.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, and herbs mentioned above.