Melatonin oral solution – new licensed product
Melatonin 1mg/ml oral solution (150ml) is now available as a licensed medicine and it is marketed by Colonis Pharma Ltd.
The General Medical Council (GMC) requires prescribers to always use a licensed medicine in preference to unlicensed products as this is safer practice. So other unlicensed melatonin liquid preparations should no longer be routinely prescribed.
The licensed indication for Colonis Melatonin 1mg/ml oral solution is for the short-term treatment of jet-lag in adults. So if it is prescribed to treat insomnia, or for young people and children under 18-years, or for a duration of more than a few days, then this would be off-license (or off-label) use and the GMC provides guidance for off-license prescribing.
It is a clear strawberry-flavoured liquid and is lactose- and sugar-free. There is a trace of alcohol (0.00045mg per 1ml) which is present as a non-active excipient. To put this into context, this low concentration of alcohol would fall within the definition of an ‘alcohol-free’ beverage and some naturally occurring fruit juices can contain low levels of alcohol.
The Ashtons Formulary is available to support the prescribing decision-making process for melatonin, and patient information leaflets can be obtained from Choice and Medication via Ashtons Live View.
Key prescribing points
Melatonin should not be taken within two hours of eating food.
Caution is advised when prescribing to people aged under 18 years as interference with the function of endogenous melatonin on the development of the hypothalamic-pituitary-gonadal axis cannot be excluded.
Melatonin may promote or increase seizure incidence and so the medication should be used with caution in patients who have epilepsy or multiple neurological defects as a co-morbidity.
Significant adverse drug interactions with melatonin
Cimetidine, fluvoxamine, methoxypsoralen, quinolones and patients receiving oestrogen therapy (oral contraceptives and HRT) can increase melatonin levels by inhibiting metabolism.
Cigarette smoking, carbamazepine and rifampicin may decrease melatonin plasma levels.
Food can enhance the increase in plasma melatonin concentration. Intake of melatonin and carbohydrate-rich meals may impair blood glucose control for several hours. It is recommended that food is not consumed two hours before or after intake of Melatonin 1mg/ml oral solution, and diabetic patients should take melatonin at least three hours after meals.
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