Journal of Bioequivalence & Bioavailability

Abstract

Bioavailability of a New Oral Spray Melatonin Emulsion Compared with a Standard Oral Formulation in Healthy Volunteers

Antonella Natalia Bartoli, Simona De Gregori, Mariadelfina Molinaro, Monica Broglia, Carmine Tinelli and Roberto Imberti

Background and Objective: Melatonin, a pineal gland hormone secreted at night, is involved in the sleep-wake cycle and has been extensively used in the treatment of primary sleeping disorders. Up to 90% of blood melatonin is cleared by the liver in a single passage, thus its half-life is very short (30-60 minutes). To avoid the first pass effect responsible for up to 90% loss of the melatonin oral dosage and to ensure rapid onset of activity, a new food grade liquid emulsion has been formulated in a spray form, which assures an additional increase of the contact surface and the possibility of efficient mucosal absorption.

The purpose of the present study was to investigate the bioavailability profile of this new food grade liquid emulsion compared with a standard melatonin formulation in commercially available oral tablets.

Methods: In a single-dose, open-label, crossover study, eight subjects were randomly assigned to receive 5 mg of oral spray or oral melatonin (tablet). After a washout of one week, plasma was collected at six hours post dosing and assayed by a validated liquid chromatography tandem mass spectrometry method to determine the main pharmacokinetic parameters.

Results and Discussion: The student t Test for paired data highlighted a significant difference between Cmax values (p=0.021) and the AUC (p=0.045). The absorption rate (Tmax) of the two melatonin formulations did not show statistically significant differences (Friedman test). The amount of melatonin reaching the systemic circulation after oral spray administration was significantly higher than after oral tablet administration.