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Drug Interactions between atomoxetine and fenfluramine

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

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Interactions between your drugs

Moderate

fenfluramine atomoxetine

Applies to: fenfluramine and 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Pharmacologic response to atomoxetine should be monitored more closely whenever a CYP450 2D6 inhibitor is added to or withdrawn from therapy, as dosage adjustment of atomoxetine may be necessary in extensive metabolizers.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

fenfluramine food

Applies to: fenfluramine

GENERALLY AVOID: Alcohol may potentiate the central nervous system and cardiovascular effects of centrally-acting appetite suppressants. In one study, concurrent administration of methamphetamine (30 mg intravenously) and ethanol (1 gm/kg orally over 30 minutes) increased heart rate by 24 beats/minute compared to methamphetamine alone. This increases cardiac work and myocardial oxygen consumption, which may lead to more adverse cardiovascular effects than either agent alone. Subjective effects of ethanol were diminished in the eight study subjects, but those of methamphetamine were not affected. The pharmacokinetics of methamphetamine were also unaffected except for a decrease in the apparent volume of distribution at steady state.

MANAGEMENT: Concomitant use of centrally-acting appetite suppressants and alcohol should be avoided if possible, especially in patients with a history of cardiovascular disease. Patients should be counselled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

References

  1. Mendelson J, Jones RT, Upton R, Jacob P 3rd (1995) "Methamphetamine and ethanol interactions in humans." Clin Pharmacol Ther, 57, p. 559-68
  2. (2001) "Product Information. Didrex (benzphetamine)." Pharmacia and Upjohn
  3. (2012) "Product Information. Suprenza (phentermine)." Akrimax Pharmaceuticals

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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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