Is there an interaction between melatonin and cyclosporine, calcitriol, prednisolone, furosemide or

Fråga: Is there an interaction between melatonin and cyclosporine, calcitriol, prednisolone, furosemide or candesartan?

A 35-year-old woman with a renal transplant is being treated with Sandimmun (cyclosporine), Rocatrol (calcitriol), prednisolone, Lasix Retard (furosemide) and Atacand (candesartan). Medication with melatonin is being considered as a non-conventional treatment for insomnia. Are there any known interactions between melatonin and the other substances?

Sammanfattning: There is no documentation on interactions between melatonin and the patient´s current medication, nor would interactions be expected from what is known about the pharmacokinetics of these substances. The lack of information calls for caution when melatonin is added.

Svar: No information about interactions between melatonin and the substanses mentioned above was found in Medline, Drugline or in standard pharmacological literature.

It has been shown that blocking of the adrenergic beta-receptors decrease the nocturnal endogenous production of melatonin (1). Fluvoxamin causes a two- to threefold rise in endogenous melatonin plasma concentration (2) and unpublished studies indicate that this is due to an interaction on the cytochrome P450 enzyme CYP1A2 (3). There is no reason to expect a pharmacokinetic or pharmacodynamic interaction between melatonin and the other substances by these mechanisms. 1 Stoschitzky K, Sakotnik A, Lercher P, Zweiker R, Maier R, Liebmann P, Lindner W: Influence of beta-blockers on melatonin release. Eur J Clin Pharmacol 1999; 55: 111-115 2 Skene DJ, Bojkowski CJ, Arendt J: Comparison of the effects of acute fluvoxamine and desipramine administration on melatonin and cortisol production in humans. Br J Clin Pharmacol 1994; 37: 181-186 3 Personal communication with professor Leif Bertilsson, Department of Clinical Pharmacology, Huddinge University Hospital