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Drug Interactions between 5-hydroxytryptophan / melatonin / pyridoxine and echinacea

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

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Interactions between your drugs

Moderate

melatonin echinacea

Applies to: 5-hydroxytryptophan / melatonin / pyridoxine and echinacea

MONITOR: Coadministration with echinacea may increase the plasma concentrations and the risk of adverse effects of drugs that are substrates of CYP450 1A2. The proposed mechanism is decreased clearance due to echinacea-mediated inhibition of CYP450 1A2. Echinacea has been shown to increase the plasma levels of caffeine, a CYP450 1A2 substrate, by approximately 30%. Due to limited data, the clinical consequences of this interaction are unknown.

MANAGEMENT: Caution is advised if echinacea is used concomitantly with drugs that are substrates of CYP450 1A2, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring should be considered whenever echinacea is added to or withdrawn from therapy with these drugs. Patients should be monitored for the development of adverse effects.

References

  1. Gorski JC, Huang SM, Pinto A, et al. (2004) "The effect of echinacea (Echinacea purpurea root) on cytochrome P450 activity in vivo." Clin Pharmacol Ther, 75, p. 89-100

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Drug and food interactions

Moderate

melatonin food

Applies to: 5-hydroxytryptophan / melatonin / pyridoxine

MONITOR: Oral caffeine may significantly increase the bioavailability of melatonin. The proposed mechanism is inhibition of CYP450 1A2 first-pass metabolism. After administration of melatonin 6 mg and caffeine 200 mg orally (approximately equivalent to 1 large cup of coffee) to 12 healthy subjects, the mean peak plasma concentration (Cmax) of melatonin increased by 137% and the area under the concentration-time curve (AUC) increased by 120%. The metabolic inhibition was greater in nonsmokers (n=6) than in smokers (n=6). The greatest effect was seen in subjects with the *1F/*1F genotype (n=7), whose melatonin Cmax increased by 202%. The half-life did not change significantly. The clinical significance of this interaction is unknown.

According to some authorities, alcohol may reduce the effect of melatonin on sleep. The mechanism of this interaction is not fully understood.

In addition, CYP450 1A2 inducers like cigarette smoking may reduce exogenous melatonin plasma levels. In a small clinical trial (n=8), habitual smokers had their melatonin plasma levels measured two times, each after a single oral dose of 25 mg of melatonin. They had smoked prior to the first measurement but had not smoked for 7 days prior to the second. Cigarette smoking significantly reduced melatonin plasma exposure (AUC) as compared to melatonin levels after 7 days of smoking abstinence (7.34 +/- 1.85 versus 21.07 +/- 7.28 nmol/L*h, respectively).

MANAGEMENT: Caution and monitoring are recommended if melatonin is used with inhibitors of CYP450 1A2 like caffeine or inducers of CYP450 1A2 like cigarette smoking. Consumption of alcohol should be avoided when taking melatonin.

References

  1. Hartter S, Nordmark A, Rose DM, Bertilsson L, Tybring G, Laine K (2003) "Effects of caffeine intake on the pharmacokinetics of melatonin, a probe drug for CYP1A2 activity." Br J Clin Pharmacol, 56, p. 679-682
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  3. Ursing C, Bahr CV, Brismar K, Rojdmark S (2005) "Influence of cigarette smoking on melatonin levels in man" Eur J Clin Pharmacol, 61, p. 197-201

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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

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.