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Drug Interactions between ivacaftor and torsemide

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

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Interactions between your drugs

Moderate

torsemide ivacaftor

Applies to: torsemide and ivacaftor

MONITOR: Coadministration with inhibitors of CYP450 2C9 may increase the plasma concentrations of torsemide. The interaction has not been evaluated in pharmacokinetic studies; however, torsemide has been shown to undergo metabolism by CYP450 2C9.

MANAGEMENT: Caution is advised when torsemide is prescribed with CYP450 2C9 inhibitors. Patients should be monitored for potentially increased adverse effects such as dehydration, hypotension, electrolyte imbalances, hyperglycemia, tinnitus, and hearing loss.

References

  1. "Product Information. Demadex (torsemide)." Boehringer Mannheim
  2. Miners JO, Rees DLP, Valente L, Veronese ME, Birkett DJ (1995) "Human hepatic cytochrome p450 2c9 catalyzes the rate-limiting pathway of torsemide metabolism." J Pharmacol Exp Ther, 272, p. 1076-81
  3. Miners JO, Birkett DJ (1998) "Cytochrome P4502C9: an enzyme of major importance in human drug metabolism." Br J Clin Pharmacol, 45, p. 525-38
  4. Vormfelde SV, Engelhardt S, Zirk A, et al. (2004) "CYP2C9 polymorphisms and the interindividual variability in pharmacokinetics and pharmacodynamics of the loop diuretic drug torsemide." Clin Pharmacol Ther, 76, p. 557-66
View all 4 references

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Drug and food interactions

Moderate

ivacaftor food

Applies to: ivacaftor

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of ivacaftor. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Elexacaftor and tezacaftor are also CYP450 3A4 substrates in vitro and may interact similarly with grapefruit juice, whereas lumacaftor is not expected to interact.

ADJUST DOSING INTERVAL: According to prescribing information, systemic exposure to ivacaftor increased approximately 2.5- to 4-fold, systemic exposure to elexacaftor increased approximately 1.9- to 2.5-fold, and systemic exposure to lumacaftor increased approximately 2-fold following administration with fat-containing foods relative to administration in a fasting state. Tezacaftor exposure is not significantly affected by administration of fat-containing foods.

MANAGEMENT: Patients treated with ivacaftor-containing medications should avoid consumption of grapefruit juice and any food that contains grapefruit or Seville oranges. All ivacaftor-containing medications should be administered with fat-containing foods such as eggs, avocados, nuts, meat, butter, peanut butter, cheese pizza, and whole-milk dairy products. A typical cystic fibrosis diet will satisfy this requirement.

References

  1. (2012) "Product Information. Kalydeco (ivacaftor)." Vertex Pharmaceuticals
  2. (2015) "Product Information. Orkambi (ivacaftor-lumacaftor)." Vertex Pharmaceuticals
  3. (2022) "Product Information. Symdeko (ivacaftor-tezacaftor)." Vertex Pharmaceuticals
  4. (2019) "Product Information. Trikafta (elexacaftor/ivacaftor/tezacaftor)." Vertex Pharmaceuticals
View all 4 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.

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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