**Abstract**

Melatonin (N-acetyl-5-methoxytryptamine) is an antioxidant active pharmaceutical ingredient with numerous applications as medicine and nutraceutical. Melatonin, a hormone synthesized by the pineal gland, has a significant role in the regulation of the circadian biological clock. The aim of this chapter is to present the conventional solid and liquid forms (i.e., tables, capsules, suspensions, etc.) and the nanoformulations (i.e., liposomes, niosomes, polymeric nanoparticles, chitosomes, calcium alginate beads, etc.) of melatonin and to give special attention to its release kinetics from the pharmaceutical vehicle. These systems have been designed and developed as platforms for the delivery and release of melatonin. In all cases, the controlled release of melatonin is the main goal of its loading into drug delivery platforms. Fractal analysis is a mathematical tool to quantify nature and physical systems' complexity. These systems have been characterized as fractal objects, due to their fractional dimensions. In this chapter, we are probing the interrelationship between the fractal dimension of pharmaceutical vehicle and the release profile of melatonin. Several examples will be given in order to understand in depth the reason of controlledrelease profile of melatonin and its added value for the development of a new medicine and/or nutraceutical.

**Keywords:** nanosystems, drug delivery, kinetics, release, fractals
