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Drug Interactions between ritonavir and Strattera

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

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Interactions between your drugs

Moderate

ritonavir atomoxetine

Applies to: ritonavir and Strattera (atomoxetine)

MONITOR: Coadministration with drugs that are inhibitors of CYP450 2D6 may increase the plasma concentrations of atomoxetine, which is primarily metabolized by the isoenzyme. In patients who are extensive metabolizers of CYP450 2D6 (approximately 93% of Caucasians and more than 98% of Asians and individuals of African descent), potent inhibitors of the isoenzyme such as fluoxetine and paroxetine have been shown to increase atomoxetine systemic exposure (AUC) by 6- to 8-fold and peak plasma concentration (Cmax) by 3- to 4-fold. These higher concentrations are similar to those observed in CYP450 2D6 poor metabolizers given the drug alone. In vitro studies suggest that coadministration of CYP450 2D6 inhibitors to poor metabolizers will not further increase atomoxetine plasma concentrations.

MANAGEMENT: Pharmacologic response to atomoxetine should be monitored more closely whenever a CYP450 2D6 inhibitor is added to or withdrawn from therapy, as dosage adjustment of atomoxetine may be necessary in extensive metabolizers. During coadministration, patients should be advised to contact their physician if they experience excessive adverse effects of atomoxetine such as dizziness, dry mouth, anorexia, sleep disturbances, and palpitations.

References

  1. Belle DJ, Ernest CS, Sauer JM, Smith BP, Thomasson HR, Witcher JW (2002) "Effect of potent CYP2D6 inhibition by paroxetine on atomoxetine pharmacokinetics." J Clin Pharmacol, 42, p. 1219-27
  2. (2002) "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company
  3. (2021) "Product Information. Qelbree (viloxazine)." Supernus Pharmaceuticals Inc

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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

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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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