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Drug Interactions between indinavir and saquinavir

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

saquinavir indinavir

Applies to: saquinavir and indinavir

GENERALLY AVOID: Coadministration of indinavir with unboosted saquinavir may lead to increased plasma concentrations of saquinavir, while coadministration with ritonavir-boosted saquinavir may lead to increased plasma concentrations of indinavir. Administration of indinavir (800 mg three times a day for two days) with single dose saquinavir (600 mg to 1200 mg, soft gel capsules) in 6 healthy volunteers led to a 4.6 to 7.2-fold increase in systemic exposure (AUC) of saquinavir without a clinically significant change in indinavir concentration. In addition, coadministration with indinavir may increase the plasma concentration of indinavir; however, data are not available. Increased indinavir plasma concentration may increase the risk of urological complications, such as nephrolithiasis.

MANAGEMENT: Coadministration of ritonavir-boosted saquinavir and indinavir is not recommended. Appropriate doses of this combination and of unboosted saquinavir with indinavir in terms of safety and efficacy have not been established. Unboosted saquinavir is not indicated as the sole protease inhibitor in the treatment of HIV-infected adults; it should only be given with low-dose ritonavir in combination with other antiretroviral agents.

References

  1. (2001) "Product Information. Invirase (saquinavir)." Roche Laboratories
  2. (2001) "Product Information. Crixivan (indinavir)." Merck & Co., Inc
  3. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  4. Cerner Multum, Inc. "Australian Product Information."
View all 4 references

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Drug and food interactions

Moderate

saquinavir food

Applies to: saquinavir

ADJUST DOSING INTERVAL: Food significantly increases the absorption of saquinavir.

MONITOR: Coadministration with grapefruit juice may increase the plasma concentrations of saquinavir. The primary mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. In eight healthy volunteers, ingestion of 400 mL of grapefruit juice prior to administration of a 600 mg dose of saquinavir mesylate increased the area under the plasma concentration-time curve and oral bioavailability of saquinavir by 50% and 100%, respectively, compared to water; however, the increase is not considered clinically relevant. A high degree of intersubject variability in the grapefruit juice effect was also observed. The extent to which this interaction may occur with the saquinavir free base soft gelatin capsule is unknown. However, the saquinavir soft gelatin capsule formulation is no longer commercially available.

MANAGEMENT: Saquinavir mesylate should be taken with meals or within 2 hours after eating to enhance bioavailability. Patients should be advised to avoid the consumption of large amounts of grapefruit and grapefruit juice during saquinavir therapy unless otherwise directed by their doctor, as the interaction is unreliable and subject to a high degree of interpatient variation.

References

  1. (2001) "Product Information. Invirase (saquinavir)." Roche Laboratories
  2. Kupferschmidt HHT, Fattinger KE, Ha HR, Follath F, Krahenbuhl S (1998) "Grapefruit juice enhances the bioavailability of the HIV protease inhibitor saquinavir in man." Br J Clin Pharmacol, 45, p. 355-9
  3. Bailey DG, Malcolm J, Arnold O, Spence JD (1998) "Grapefruit juice-drug interactions." Br J Clin Pharmacol, 46, p. 101-10
  4. Eagling VA, Profit L, Back DJ (1999) "Inhibition of the CYP3A4-mediated metabolism and P-glycoprotein-mediated transport of the HIV-I protease inhibitor saquinavir by grapefruit juice components." Br J Clin Pharmacol, 48, p. 543-52
  5. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  6. Cerner Multum, Inc. "Australian Product Information."
View all 6 references

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Moderate

indinavir food

Applies to: indinavir

ADJUST DOSING INTERVAL: According to the manufacturer, coadministration with a meal high in calories, fat, and protein reduces the absorption of indinavir. In ten patients given indinavir in this manner, the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of indinavir decreased by an average of 84% and 77%, respectively. In contrast, grapefruit juice may have only minor effects on the oral bioavailability of indinavir. The manufacturer's package labeling states that administration of a single 400 mg dose of indinavir with 8 oz. of grapefruit juice decreased indinavir AUC by an average of 26%. Likewise, a study consisting of 14 HIV-infected subjects found no uniform nor significant changes in steady-state indinavir AUC during administration with double-strength grapefruit juice compared to water. There was, however, a delay in absorption (Tmax) due to grapefruit juice that is unlikely to be of clinical significance.

MANAGEMENT: To ensure maximal oral absorption, indinavir should be administered without food but with water 1 hour before or 2 hours after a meal. Alternatively, indinavir may be administered with other liquids such as skim milk, juice, coffee, or tea, or with a light meal (e.g., dry toast with jelly, juice, and coffee with skim milk and sugar; corn flakes, skim milk and sugar).

References

  1. (2001) "Product Information. Crixivan (indinavir)." Merck & Co., Inc
  2. Yeh KC, Deutsch PJ, Haddix H, Hesney M, Hoagland V, Ju WD, Justice SJ, Osborne B, Sterrett AT, Stone JA, Woolf E, Waldman S (1998) "Single-dose pharmacokinetics of indinavir and the effect of food." Antimicrob Agents Chemother, 42, p. 332-8
  3. Shelton MJ, Wynn HE, Newitt RG, DiFrancesco R (2001) "Effects of grapefruit juice on pharmacokinetic exposure to indinavir in HIV-positive subjects." J Clin Pharmacol, 41, p. 435-42

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Therapeutic duplication warnings

Therapeutic duplication is the use of more than one medicine from the same drug category or therapeutic class to treat the same condition. This can be intentional in cases where drugs with similar actions are used together for demonstrated therapeutic benefit. It can also be unintentional in cases where a patient has been treated by more than one doctor, or had prescriptions filled at more than one pharmacy, and can have potentially adverse consequences.

Duplication

Protease inhibitors

Therapeutic duplication

The recommended maximum number of medicines in the 'protease inhibitors' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'protease inhibitors' category:

  • indinavir
  • saquinavir

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.

See also

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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