Interactions with Melatonin

Melatonin impaired the efficacy of both methoxamine and clonidine by relaxing vascular smooth muscle through an undetermined mechanism in an ex-vivo experiment using thoracic aorta excised from male rats (Weekley 1991). It is not known whether exogenous melatonin can antagonize the effects of methoxamine and clonidine in humans.

Desipramine; Fluoxetine

In an experimental rat study, exogenous melatonin (0.25 mg/kg/day) abolished the antidepressant effects of desipramine and fluoxetine possibly through interference with tryptophan-2,3-dioxygenase activity (Walsh and Daya 1998). More research is needed to determine if exogenous melatonin counteracts the effects of antidepressants in humans.

Tamoxifen

Preliminary research suggests that tamoxifen plus high-dose melatonin may be of benefit in patients with metastatic solid tumors or breast cancer (Lissoni et al. 1995A; Lissoni et al. 1996). More research is needed to confirm these effects.

Triazolam

The combination of melatonin (100 mg/day) with triazolam improved subjective sleep quality in healthy subjects (Ferini-Strambi et al. 1993). Another case study reported that melatonin (1 mg/day controlled release) improved sleep quality and enabled a patient to cease long-term benzodiazepine therapy (Dagan et al. 1997).

References

Dagan Y, Zisapel N, Nof D, et al. Rapid reversal of tolerance to benzodiazepine hypnotics by treatment with oral melatonin: a case report. Eur Neuropsychopharmacol. 1997;7(2):157-160.

Ferini-Strambi L, Zucconi M, Biella G, et al. Effect of melatonin on sleep microstructure: preliminary results in healthy subjects. Sleep. 1993;16(8):744-747.

Lissoni P, Barni S, Meregalli S, et al. Modulation of cancer endocrine therapy by melatonin: a phase II study of tamoxifen plus melatonin in metastic breast cancer patients progressing under tamoxifen alone. Br J Cancer. 1995A;71(4):854-856.

Lissoni P, Paolorossi F, Tancini G, et al. A phase II study of tamoxifen plus melatonin in metastic solid tumour patients. Br J Cancer. 1996;74(9):1466-1468.

Walsh HA, Daya S. Influence of the antidepressants desipramine and fluoxetine on tryptophan-2,3-dioxygenase in the presence of exogenous melatonin. Life Sci. 1998;62(26):2417-2423.

Weekley LB. Melatonin-induced relaxation of rat aorta: Interaction with adrenergic agonists. J. Pineal Res. 1991;11:28-34.

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