Skip to main content

Drug Interactions between ritonavir and Tikosyn

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

Edit list (add/remove drugs)

Interactions between your drugs

Moderate

ritonavir dofetilide

Applies to: ritonavir and Tikosyn (dofetilide)

MONITOR: Coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations of dofetilide, which is partially metabolized by the isoenzyme. The use of dofetilide has been associated with dose-related prolongation of the QT interval, thus elevated plasma levels of the drug may potentiate the risk of ventricular arrhythmias such as ventricular tachycardia and torsade de pointes as well as cardiac arrest and sudden death.

MANAGEMENT: Close clinical and laboratory monitoring is recommended whenever a CYP450 3A4 inhibitor is added to or withdrawn from therapy, and the dosage of dofetilide adjusted accordingly as necessary. 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. (2001) "Product Information. Tikosyn (dofetilide)." Pfizer U.S. Pharmaceuticals

Switch to consumer interaction data

Drug and food interactions

Moderate

ritonavir food

Applies to: ritonavir

ADJUST DOSING INTERVAL: Administration with food may modestly affect the bioavailability of ritonavir from the various available formulations. When the oral solution was given under nonfasting conditions, peak ritonavir concentrations decreased 23% and the extent of absorption decreased 7% relative to fasting conditions. Dilution of the oral solution (within one hour of dosing) with 240 mL of chocolate milk or a nutritional supplement (Advera or Ensure) did not significantly affect the extent and rate of ritonavir absorption. When a single 100 mg dose of the tablet was administered with a high-fat meal (907 kcal; 52% fat, 15% protein, 33% carbohydrates), approximately 20% decreases in mean peak concentration (Cmax) and systemic exposure (AUC) were observed relative to administration after fasting. Similar decreases in Cmax and AUC were reported when the tablet was administered with a moderate-fat meal. In contrast, the extent of absorption of ritonavir from the soft gelatin capsule formulation was 13% higher when administered with a meal (615 KCal; 14.5% fat, 9% protein, and 76% carbohydrate) relative to fasting.

MANAGEMENT: Ritonavir should be taken with meals to enhance gastrointestinal tolerability.

References

  1. (2001) "Product Information. Norvir (ritonavir)." Abbott Pharmaceutical

Switch to consumer interaction data

Minor

dofetilide food

Applies to: Tikosyn (dofetilide)

In vitro data suggest that grapefruit juice may inhibit the CYP450 3A4 first-pass metabolism of dofetilide. Decreased first-pass metabolism may increase dofetilide concentrations and increase the risk of QT interval prolongation and arrhythmias. The clinical significance is unknown, since dofetilide has a high oral bioavailability and a low affinity for CYP450 3A4. The manufacturer recommends caution.

References

  1. (2001) "Product Information. Tikosyn (dofetilide)." Pfizer U.S. Pharmaceuticals

Switch to consumer interaction data

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

Report options

Loading...
QR code containing a link to this page

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.

Medical Disclaimer