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We are pleased to enclose the article “Initiating Antiretroviral Therapy in Treatment-Naive Patients” by Charles B. Hicks, as published as the first monograph in the Clinical Guide series New Treatment Goals for Adult HIV Infection, a special publication of the Journal of Clinical Outcomes Management. CRIXIVAN® (indinavir sulfate) in combination with other antiretroviral agents is indicated for the treatment of HIV infection. This indica-tion is based on 2 clinical trials of approximately 1 year’s duration that demonstrated (1) a reduction in the risk of AIDS-defining illness or death and (2) a prolonged suppression of HIV RNA.
IMPORTANT SAFETY INFORMATION
Contraindications
CRIXIVAN is contraindicated in patients with clinically significant hypersensitivity to any of its components. Drug Interactions With CRIXIVAN: Contraindicated Drugs
Drug Class
Drugs Within Class That are
Potential Serious and/or Life-Threatening Reactions due to
Contraindicated With CRIXIVAN
Inhibition of CYP3A4 by CRIXIVAN Resulting in Elevated
Plasma Concentrations of These Drugs
Acute ergot toxicity characterized by peripheral vasospasm and ischemia of the extremities and other tissues Prolonged or increased sedation or respiratory depression Selected Warnings
• ALERT: Find out about medicines that should NOT be taken with CRIXIVAN.
• Nephrolithiasis/urolithiasis has occurred in clinical studies in adult patients (12.4%; range across individual trials, 4.7% to 34.4%) and in pediatric patients (29%) receiving CRIXIVAN. The cumulative frequency of nephrolithiasis events increases with increasing exposure
to CRIXIVAN; however, the risk over time remains relatively constant. In some cases, nephrolithiasis/urolithiasis has been associated
with renal insufficiency or acute renal failure and pyelonephritis with or without bacteremia. If signs or symptoms of nephrolithiasis/
urolithiasis occur (including flank pain with or without hematuria or microscopic hematuria), temporary interruption (eg, 1 to 3 days)
or discontinuation of therapy may be considered. Adequate hydration (at least 48 ounces daily for adults) is recommended in all
patients treated with CRIXIVAN.
• In patients treated with CRIXIVAN, acute hemolytic anemia, including death in some patients, and hepatitis, including hepatic failure • There have also been reports of hyperglycemia and new onset or exacerbation of preexisting diabetes mellitus in patients receiving pro- • Concomitant use of CRIXIVAN with lovastatin or simvastatin is not recommended. Caution should be exercised if HIV protease inhib- itors, including CRIXIVAN, are used concurrently with other HMG-CoA reductase inhibitors metabolized by the CYP3A4 pathway (eg, atorvastatin).
• Particular caution should be used when prescribing sildenafil, tadalafil, or vardenafil in patients receiving indinavir. Coadministration of CRIXIVAN with these medications is expected to substantially increase plasma concentrations of sildenafil, tadalafil, and vardenafil and may result in an increase in adverse reactions, including hypotension, visual changes, and priapism, which have been associated with sildenafil, tadalafil, and vardenafil.
Selected Drug Interactions
Additional Drugs That Should NOT be Coadministered With CRIXIVAN® (indinavir sulfate)
Drug Class
Drug Name
Clinical Comment
Warning: Shown to substantially decrease con- centrations of CRIXIVAN and may lead to loss of virologic response and possible resistance to CRIXIVAN or to the class of protease inhibitors.
Precaution: May lead to loss of virologic response and possible resistance to CRIXIVAN or to the class of protease inhibitors or other coadministered antiretroviral agents.
Warning: Not recommended. Potential for seri-ous reactions, such as risk of myopathy including rhabdomyolysis, may be increased.
Precaution: Both CRIXIVAN and atazanavir are associated with indirect (unconjugated) hyperbilirubinemia. Combinations of these drugs have not been studied, and coadministration of CRIXIVAN and atazanavir is not recommended.
Selected Precautions
• Indirect hyperbilirubinemia has occurred frequently (in approximately 14% of patients treated with CRIXIVAN in clinical studies) and has infrequently been associated with increases in serum transaminases. • Reports of tubulointerstitial nephritis with medullary calcification and cortical atrophy have been observed in patients with asymptomatic severe leukocyturia (>100 cells/high-power field). • There have been reports of spontaneous bleeding in patients with hemophilia A and B treated with protease inhibitors. • In patients with hepatic insufficiency due to cirrhosis, the dosage of CRIXIVAN should be lowered because of decreased metabolism of CRIXIVAN. Patients with renal insufficiency have not been studied.
• Redistribution/accumulation of body fat, including central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, facial wasting, breast enlargement, and cushingoid appearance, has been observed in patients receiving antiretroviral therapy. The mechanism and long-term consequences of these events are currently unknown. A causal relationship has not been established.
• Indinavir is an inhibitor of the cytochrome P-450 isoform CYP3A4. Coadministration of CRIXIVAN and drugs primarily metabo- lized by CYP3A4 may result in increased plasma concentrations of the other drug, which could increase or prolong its therapeutic and adverse effects (see CONTRAINDICATIONS and WARNINGS). • Indinavir is metabolized by CYP3A4. Drugs that induce CYP3A4 activity would be expected to increase the clearance of indinavir, resulting in lowered plasma concentrations of indinavir. Coadministration of CRIXIVAN and other drugs that inhibit CYP3A4 may decrease the clearance of indinavir and may result in increased plasma concentrations of indinavir.
• Use of CRIXIVAN is not recommended in pregnant patients.
Established and Other Potentially Significant Drug Interactions
Alteration in dose or regimen may be recommended based on drug interaction studies or predicted interaction.
HIV Antiviral Agents
Drug Name
Effect on Concentration
Clinical Comment
Dose reductions of CRIXIVAN to 600 mg q8h should be considered when taking delavirdine 400 mg tid.
Indinavir and didanosine formulations containing buf-fer should be administered at least 1 hour apart on an empty stomach.
The optimal dose of indinavir, when given in combina-tion with efavirenz, is not known. Increasing the indi-navir dose to 1000 mg q8h does not compensate for the increased indinavir metabolism due to efavirenz.
The appropriate doses for this combination with respect to efficacy and safety have not been established.
The appropriate doses for this combination with respect to efficacy and safety have not been established.
The appropriate doses for this combination with respect to efficacy and safety have not been established. Preliminary clinical data suggest that the incidence of nephrolithiasis is higher in patients receiving indinavir in combination with ritonavir than in those receiving CRIXIVAN® (indinavir sulfate) 800 mg q8h.
The appropriate doses for this combination with respect to efficacy and safety have not been established.
Other Agents
Drug Name
Effect on
Clinical Comment
Concentration
Caution is warranted, and therapeutic concentration monitoring is recommended for antiarrhythmics when coadministered with CRIXIVAN.
Use with caution. CRIXIVAN may not be effective because of decreased indina- vir concentrations in patients taking these agents concomitantly.
Caution is warranted, and clinical monitoring of patients is recommended.
The appropriate doses for this combination with respect to efficacy and safety Concomitant use of fluticasone and CRIXIVAN may increase plasma concentra- tions of fluticasone, particularly for long-term use.
Use of fluticasone is not recommended in situations in which CRIXIVAN is coad-ministered with a potent CYP3A4 inhibitor such as ritonavir unless the potential benefit to the patient outweighs the risk of systemic corticosteroid adverse reac-tions.
Use lowest possible dose of atorvastatin with careful monitoring, or consider other HMG-CoA reductase inhibitors not primarily metabolized by CYP3A4, such as pravastatin, fluvastatin, or rosuvastatin, in combination with CRIXIVAN.
Plasma concentrations may be increased by CRIXIVAN.
Dose reduction of CRIXIVAN to 600 mg q8h is recommended.
Dose reduction of CRIXIVAN to 600 mg q8h should be considered.
Concomitant use of trazodone and CRIXIVAN may increase plasma concen-trations of trazodone. Nausea, dizziness, hypotension, and syncope have been observed after coadministration of trazodone and ritonavir. If trazodone is used with a CYP3A4 inhibitor such as CRIXIVAN, the combination should be used with caution, and a lower dose of trazodone should be considered.
Dose reduction of rifabutin to half the standard dose and dose increase of CRIXIVAN to 1000 mg (three 333-mg capsules) q8h are recommended when rifabutin and CRIXIVAN are coadministered.
The dose of these agents should not exceed maximum dose according to the respective Prescribing Information when receiving concomitant indinavir therapy.
In a study of 9 healthy volunteers, venlafaxine administered under steady-state conditions at 150 mg/day resulted in a 28% decrease in the AUC of a single 800-mg oral dose of indinavir and a 36% decrease in indinavir C not affect the pharmacokinetics of venlafaxine and ODV. The clinical significance of this finding is unknown.
Note: ↑ = increase; ↓ = decrease.
Selected Adverse Reactions
Selected adverse reactions of severe or life-threatening intensity and of unknown drug relationship reported by patients treated with CRIXIVAN® (indinavir sulfate)/AZT/3TC in ACTG 320 were fever (3.8%), nausea (2.8%), nephrolithiasis/urolithiasis (2.6%), headache (2.4%), asthenia/fatigue (2.4%), anemia (2.4%), abdominal pain (1.9%), difficulty breathing/dyspnea/shortness of breath (1.8%), cough (1.6%), vomiting (1.4%), rash (1.1%), back pain (0.9%), and diarrhea (0.9%).
Before prescribing CRIXIVAN, please read the enclosed Prescribing Information. For additional copies of the Prescribing
Information, contact the Merck National Service Center at 1-800-672-6372, visit crixivan.com, or contact your Merck professional repre-
sentative.
Bram Greenberg, MD, FAAP Executive Director, Medical Services Enclosure: Prescribing Information for CRIXIVAN CRIXIVAN is a registered trademark of Merck & Co., Inc.

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