Is the prolonged-release formulation really needed? What about fast / immediate-release melatonin?

The prolonged-release formulation is needed to ensure continuous melatonin action throughout the night, mimicking the body’s physiological pattern, whereas fast-release melatonin would act only for 2-3 hours.

Full-night melatonin levels are ensured via the continued production and release of melatonin throughout the night. With the onset of darkness, melatonin levels increase, even the small increase is sufficient to induce fatigue in healthy individuals. Melatonin levels are then sustained during sleep, and fall off again at the end of the sleeping period, thus melatonin acts as a signal for the entire night.

Exogenous (fast / immediate-release) melatonin, unless modified in a prolonged-release formulation such as Circadin^®, will not provide continuous melatonin throughout the night²³. Immediate-release melatonin reaches maximum levels shortly after being taken at the beginning of the night and, due to the very short half-life¹⁵, melatonin levels will diminish within a short period thereafter. Thus, in the later part of the night, immediate-release melatonin will already have been cleared from the body. Further, there has been no thorough clinical development programme to demonstrate the effects of immediate-release formulations of melatonin on Quality of Sleep, morning alertness and Quality of Life or on patients’ safety.

Circadin^®, the prolonged-release formulation of melatonin, circumvents the fast clearance of the hormone and provides a melatonin profile in the blood more closely matched to normal physiological release²⁴. It has been studied extensively in clinical trials to show its efficacy and safety profiles.