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Drug Interactions between Invirase and Zagam

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

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Interactions between your drugs

Major

saquinavir sparfloxacin

Applies to: Invirase (saquinavir) and Zagam (sparfloxacin)

CONTRAINDICATED: Sparfloxacin may cause dose-related prolongation of the QT interval in some patients. Theoretically, coadministration with other agents that can prolong the QT interval may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death. Torsade de pointes has been reported in a few patients receiving sparfloxacin alone and with antiarrhythmic agents like amiodarone and disopyramide.

MANAGEMENT: Coadministration of sparfloxacin with other drugs that can prolong the QT interval is considered contraindicated.

References

  1. Thomas M, Maconochie JG, Fletcher E (1996) "The dilemma of the prolonged QT interval in early drug studies." Br J Clin Pharmacol, 41, p. 77-81
  2. Jaillon P, Morganroth J, Brumpt I, Talbot G (1996) "Overview of electrocardiographic and cardiovascular safety data for sparfloxacin. Sparfloxacin Safety Group." J Antimicrob Chemother, 37(suppl a), p. 161-7
  3. Zix JA, GeerdesFenge HF, Rau M, Vockler J, Borner K, Koeppe P, Lode H (1997) "Pharmacokinetics of sparfloxacin and interaction with cisapride and sucralfate." Antimicrob Agents Chemother, 41, p. 1668-72
  4. (2001) "Product Information. Zagam (sparfloxacin)." Rhone Poulenc Rorer
  5. Demolis JL, Charransol A, Funck-Brentano C, Jaillon P (1996) "Effects of a single oral dose of sparfloxacin on ventricular repolarization in healthy volunteers." Br J Clin Pharmacol, 41, p. 499-503
  6. Dupont H, Timsit JF, Souweine B, Gachot B, Wolff M, Regnier B (1996) "Torsades de pointe probably related to sparfloxacin." Eur J Clin Microbiol Infect Dis, 15, p. 350-1
  7. Lipsky BA, Dorr MB, Magner DJ, Talbot GH (1999) "Safety profile of sparfloxacin, a new fluoroquinolone antibiotic." Clin Ther, 21, p. 148-59
  8. Owens RC (2001) "Risk assessment for antimicrobial agent-induced QTc interval prolongation and torsades de pointes." Pharmacotherapy, 21, p. 301-19
  9. Iannini PB, Doddamani S, Byazrova E, Curciumaru I, Kramer H (2001) "Risk of torsades de pointes with non-cardiac drugs." BMJ, 322, p. 46-7
  10. Ball P (2000) "Quinolone-induced QT interval prolongation: a not-so-unexpected class effect." J Antimicrob Chemother, 45, p. 557-9
  11. Kang J, Wang L, Chen XL, Triggle DJ, Rampe D (2001) "Interactions of a series of fluoroquinolone antibacterial drugs with the human cardiac K+ channel HERG." Mol Pharmacol, 59, p. 122-6
  12. Oliphant CM, Green GM (2002) "Quinolones: a comprehensive review." Am Fam Physician, 65, p. 455-64
  13. Owens RC Jr, Ambrose PG (2002) "Torsades de pointes associated with fluoroquinolones." Pharmacotherapy, 22, 663-8; discussion 668-72
  14. Iannini PB (2002) "Cardiotoxicity of macrolides, ketolides and fluoroquinolones that prolong the QTc interval." Expert Opin Drug Saf, 1, p. 121-8
  15. Owens RC (2004) "QT Prolongation with Antimicrobial Agents : Understanding the Significance." Drugs, 64, p. 1091-124
  16. Katritsis D, Camm AJ (2003) "Quinolones: cardioprotective or cardiotoxic." Pacing Clin Electrophysiol, 26, p. 2317-20
  17. Stahlmann R (2002) "Clinical toxicological aspects of fluoroquinolones." Toxicol Lett, 127, p. 269-77
  18. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  19. Canadian Pharmacists Association (2006) e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink
  20. Falagas ME, Rafailidis PI, Rosmarakis ES (2007) "Arrhythmias associated with fluoroquinolone therapy." Int J Antimicrob Agents, 29, p. 374-9
  21. Cerner Multum, Inc. "Australian Product Information."
View all 21 references

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Drug and food interactions

Moderate

saquinavir food

Applies to: Invirase (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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Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

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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

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