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Drug Interactions between atazanavir / cobicistat and saquinavir

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

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Interactions between your drugs

Major

saquinavir atazanavir

Applies to: saquinavir and atazanavir / cobicistat

CONTRAINDICATED: Saquinavir in combination with ritonavir has been shown to prolong the PR interval of the electrocardiogram in some patients. Theoretically, coadministration with other agents that prolong the PR interval, such as atazanavir, may result in elevated risk of conduction disturbances and atrioventricular block. However, clinical data are lacking. There is also potential for a pharmacokinetic interaction due to CYP450 3A4 inhibition by atazanavir. In a study of 18 HIV patients, coadministration of atazanavir (300 mg once a day) and saquinavir mesylate hard gelatin capsule (HGC)/ritonavir (1600 mg/100 mg once a day) resulted in an increase in saquinavir systemic exposure (AUC), peak plasma concentration (Cmax), and trough plasma concentration (Cmin) of 60%, 42%, and 112%, respectively. Ritonavir AUC and Cmax were increased by 41% and 34% respectively, while atazanavir pharmacokinetics was unchanged. Data are not available for saquinavir HGC/ritonavir given in a dosage of 1000 mg/100 mg twice a day with atazanavir 300 mg once a day.

MANAGEMENT: Due to the increased risk for life-threatening cardiac arrhythmia, the use of ritonavir-boosted saquinavir with atazanavir is considered contraindicated.

References

  1. (2001) "Product Information. Invirase (saquinavir)." Roche Laboratories
  2. Haas DW, Zala C, Schrader S, et al. (2003) "Therapy with atazanavir plus saquinavir in patients failing highly active antiretroviral therapy: a randomized comparative pilot trial." AIDS, 17, p. 1339-1349
  3. (2003) "Product Information. Reyataz (atazanavir)." Bristol-Myers Squibb
  4. Boffito M, Kurowski M, Kruse G, et al. (2004) "Atazanavir enhances saquinavir hard-gel concentrations in a ritonavir-boosted once-daily regimen." AIDS, 18, p. 1291-7
  5. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  6. EMEA. European Medicines Agency (2007) EPARs. European Union Public Assessment Reports. http://www.ema.europa.eu/ema/index.jsp?curl=pages/includes/medicines/medicines_landingpage.jsp&mid
  7. Cerner Multum, Inc. "Australian Product Information."
  8. FDA. U.S. Food and Drug Administration (2010) FDA drug safety communication: Ongoing safety review of Invirase (saquinavir) and possible association with abnormal heart rhythms. http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm201221.htm
  9. Biondi L (2010) Health Canada endorsed important safety information on Invirase (saquinavir mesylate). http://hc-sc.gc.ca/dhp-mps/alt_formats/pdf/medeff/advisories-avis/prof/2010/invirase_hpc-cps-eng.pdf
View all 9 references

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Moderate

saquinavir cobicistat

Applies to: saquinavir and atazanavir / cobicistat

GENERALLY AVOID: Cobicistat may increase the plasma concentrations of antiretroviral agents. The plasma concentrations of cobicistat may also be increased or reduced in the presence of antiretroviral agents. The proposed mechanism is cobicistat inhibition of the CYP450 3A4 isoenzyme, of which antiretroviral agents may be substrates, and the inhibition or induction of CYP450 3A4 by concomitant antiretroviral medications. Cobicistat is a mechanism-based inhibitor and substrate of CYP450 3A4 with no antiretroviral activity of its own. Rather, it is indicated in its capacity as a pharmacokinetic booster of CYP450 3A4 to increase the systemic exposure of some antiretroviral medications such as atazanavir, darunavir, and elvitegravir, which are substrates of this isoenzyme. Concomitant use of other antiretroviral agents with cobicistat may also increase the plasma levels and risk of side effects associated with these medicines. In contrast, concomitant use of cobicistat-boosted atazanavir or darunavir with CYP450 3A4 inducers nevirapine, etravirine, or efavirenz may reduce the plasma concentrations of cobicistat, darunavir, and atazanavir, leading to a potential loss of therapeutic effect and development of resistance to darunavir and atazanavir. Pharmacokinetic data are not available.

MANAGEMENT: Cobicistat is not intended for use with more than one antiretroviral medication that requires pharmacokinetic enhancement, such as two protease inhibitors or elvitegravir in combination with a protease inhibitor. In addition, cobicistat should not be used concomitantly with ritonavir due to their similar effects on CYP450 3A4. According to some authorities, use of the antiretroviral combinations of atazanavir-cobicistat or darunavir-cobicistat concomitantly with the CYP450 3A4 inducers efavirenz, etravirine, or nevirapine is also not recommended. Other authorities consider the administration of atazanavir-cobicistat with efavirenz or nevirapine to be contraindicated. Since dosing recommendations have only been established for a number of antiretroviral medications, product labeling and current antiretroviral treatment guidelines should be consulted.

References

  1. (2001) "Product Information. Viramune (nevirapine)." Boehringer-Ingelheim
  2. (2001) "Product Information. Sustiva (efavirenz)." DuPont Pharmaceuticals
  3. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  4. (2006) "Product Information. Prezista (darunavir)." Ortho Biotech Inc
  5. (2008) "Product Information. Intelence (etravirine)." Ortho Biotech Inc
  6. Cerner Multum, Inc. "Australian Product Information."
  7. (2012) "Product Information. Stribild (cobicistat/elvitegravir/emtricitabine/tenofov)." Gilead Sciences
  8. (2014) "Product Information. Tybost (cobicistat)." Gilead Sciences
  9. (2014) "Product Information. Prezcobix (cobicistat-darunavir)." Janssen Pharmaceuticals
  10. (2015) "Product Information. Evotaz (atazanavir-cobicistat)." Bristol-Myers Squibb
View all 10 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

atazanavir food

Applies to: atazanavir / cobicistat

ADJUST DOSING INTERVAL: Administration of atazanavir with food enhances oral bioavailability and reduces pharmacokinetic variability. According to the manufacturer, administration with a light meal increased the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of a single 400 mg dose of atazanavir by 57% and 70%, respectively, relative to the fasting state. Administration with a high-fat meal resulted in a mean increase of 35% in atazanavir AUC and no change in Cmax compared to fasting. The coefficient of variation of AUC and Cmax decreased by approximately one-half when given with either a light or high-fat meal compared to the fasting state.

MANAGEMENT: To ensure maximal oral absorption, atazanavir should be administered with or immediately after a meal.

References

  1. (2003) "Product Information. Reyataz (atazanavir)." Bristol-Myers Squibb

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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:

  • atazanavir/cobicistat
  • 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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