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Drug Interactions between Fortovase and Gentlax Tablet

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

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Interactions between your drugs

Moderate

bisacodyl saquinavir

Applies to: Gentlax Tablet (bisacodyl) and Fortovase (saquinavir)

MONITOR: Bowel cleansing as well as overuse of certain laxatives may cause electrolyte loss and increase the risk of torsade de pointes ventricular arrhythmia in patients treated with drugs that prolong the QT interval. Electrolyte disturbances including hypokalemia and hypomagnesemia have been reported with laxative abuse and are known risk factors for torsade de pointes associated with QT interval prolongation.

MANAGEMENT: Patients treated with drugs that prolong the QT interval should exercise caution when self-medicating with laxatives. The recommended dosage and duration of use should not be exceeded. Patients treated with lactulose for more than six months should be monitored periodically for electrolyte imbalance. Patients should be advised to seek prompt medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitation, irregular heart rhythm, shortness of breath, or syncope.

References

  1. Chin RL "Laxative-induced hypokalemia." Ann Emerg Med 32 (1998): 517-8
  2. Muller-Lissner SA "Adverse effects of laxatives: fact and fiction." Pharmacology 47 (1993): 138-45
  3. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  4. Canadian Pharmacists Association "e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink" (2006):
  5. Cerner Multum, Inc. "Australian Product Information." O 0
  6. Schaefer DC, Cheskin LJ "Constipation in the elderly." Am Fam Physician 58 (1998): 907-14
View all 6 references

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Drug and food interactions

Moderate

saquinavir food

Applies to: Fortovase (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. "Product Information. Invirase (saquinavir)." Roche Laboratories PROD (2001):
  2. Kupferschmidt HHT, Fattinger KE, Ha HR, Follath F, Krahenbuhl S "Grapefruit juice enhances the bioavailability of the HIV protease inhibitor saquinavir in man." Br J Clin Pharmacol 45 (1998): 355-9
  3. Bailey DG, Malcolm J, Arnold O, Spence JD "Grapefruit juice-drug interactions." Br J Clin Pharmacol 46 (1998): 101-10
  4. Eagling VA, Profit L, Back DJ "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 (1999): 543-52
  5. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  6. Cerner Multum, Inc. "Australian Product Information." O 0
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

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

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