RESUMO
OBJECTIVE: There is a growing interest in psychiatry regarding melatonin use both for its soporific and chronobiotic effects. This study aimed to evaluate factors impacting the daily-dose. METHODS: In a university department of psychiatry in Paris (France), we conducted a posteriori naturalistic observational study from April 03, 2017 to January 31, 2018. We assessed links between sociodemographic and clinical characteristics and daily dose of melatonin (the daily-dose of melatonin initiation and the daily-dose at Hospital discharge). A survey of drug interactions was performed regarding metabolic inducers and inhibitors of the cytochrome P450 1A2. RESULTS: Forty patients were included and treated with immediate-release melatonin. For patients with no history of melatonin use, the initiation dose of was 2 or 4mg, with no effects of age, weight, BMI, melatonin indication, cause of hospitalization. We found that higher discharge dose was associated with higher BMI (P=0.036) and more reevaluations of melatonin dose (P=0.00019). All patients with a moderate inducer (n=3, here lansoprazole) were significantly more associated with the discontinuation melatonin group (P=0.002). CONCLUSION: The BMI and the number of reevaluations impact the daily dose of melatonin. Two mechanisms may explain that BMI may need higher doses: (i) melatonin diffuses into the fat mass, (ii) the variant 24E on melatonin receptor MT2, more frequent in obese patients, leads to a decrease of the receptor signal.