Skip to main content

Drug Interactions between caffeine and fenfluramine

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

Edit list (add/remove drugs)

Interactions between your drugs

Moderate

caffeine fenfluramine

Applies to: caffeine and fenfluramine

MONITOR: Coadministration with inhibitors of CYP450 1A2 or 2D6 may increase the plasma concentrations of fenfluramine. Over 75% of fenfluramine is metabolized to norfenfluramine prior to elimination, primarily by CYP450 1A2, 2B6 and 2D6, but also to a minor extent by CYP450 2C9, 2C19 and 3A4/5. When a single 0.35 mg/kg dose of fenfluramine oral solution was coadministered with 50 mg once daily fluvoxamine (a potent CYP450 1A2 inhibitor) at steady state in healthy volunteers, fenfluramine peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 22% and 102%, respectively, while the Cmax and AUC of norfenfluramine decreased by 44% and 22%, respectively. Coadministration with 30 mg once daily paroxetine (a potent CYP450 2D6 inhibitor) at steady state in healthy volunteers increased the Cmax and AUC of fenfluramine by 13% and 81%, respectively, and decreased Cmax and AUC of norfenfluramine by 29% and 13%, respectively. Coadministration with repeated doses of cannabidiol (a weak CYP450 1A2 inhibitor with the potential to also inhibit CYP450 2B6, 2C8, 2C9, and 2C19 at clinically relevant concentrations) increased the Cmax and AUC of fenfluramine by 10% and 59%, respectively, and decreased Cmax and AUC of norfenfluramine by 33% and 22%, respectively. Elevated plasma levels of fenfluramine may increase the risk of serious adverse effects such as valvular heart disease, pulmonary arterial hypertension, blood pressure increases, and serotonin syndrome.

MANAGEMENT: Caution is advised when fenfluramine is used with CYP450 1A2 or 2D6 inhibitors. Patients should be monitored for increased adverse effects, and the dosage of fenfluramine adjusted as necessary.

References (2)
  1. (2020) "Product Information. Fintepla (fenfluramine)." Zogenix, Inc
  2. (2023) "Product Information. Fintepla (fenfluramine)." UCB Pharma Ltd, SUPPL-13

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 (3)
  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
Minor

caffeine food

Applies to: caffeine

The effect of grapefruit juice on the pharmacologic activity of caffeine is controversial. One report suggests that grapefruit juice increases the effect of caffeine. The proposed mechanism is inhibition of cytochrome P-450 metabolism of caffeine. However, a well-conducted pharmacokinetic/pharmacodynamic study did not demonstrate this effect. The clinical significance of this potential interaction is unknown.

References (2)
  1. (1995) "Grapefruit juice interactions with drugs." Med Lett Drugs Ther, 37, p. 73-4
  2. Maish WA, Hampton EM, Whitsett TL, Shepard JD, Lovallo WR (1996) "Influence of grapefruit juice on caffeine pharmacokinetics and pharmacodynamics." Pharmacotherapy, 16, p. 1046-52

Therapeutic duplication warnings

Therapeutic duplication is the use of more than one medicine from the same drug category or therapeutic class to treat the same condition. This can be intentional in cases where drugs with similar actions are used together for demonstrated therapeutic benefit. It can also be unintentional in cases where a patient has been treated by more than one doctor, or had prescriptions filled at more than one pharmacy, and can have potentially adverse consequences.

Duplication

Stimulants

Therapeutic duplication

The recommended maximum number of medicines in the 'stimulants' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'stimulants' category:

  • caffeine
  • fenfluramine

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.

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