In the dermatological field, the first choice route of administration is undoubtedly the topical one and melatonin represents a good candidate for thetranscutaneous absorption, considering its low molecular weight (MW = 232.27), the short half-life in plasma and a favorable octanol: water partition coefficient (log P = 1.20).
With the'oral intake the active substance undergoes a marked first pass hepatic metabolism which results in a reduced half-life in the blood (<45 min), while with skin application, in addition to having a better patient compliance, it is possible to avoid hepatic metabolization .
Furthermore, it is believed that melatonin is well absorbed through it stratum corneum, at the level of which it deposits and spreads slowly and continuously in the dermis and blood vessels, affecting, even if not by much, the physiological levels of endogenous melatonin [2].
Bangha et al. observed the plasma levels of melatonin after applying 20 and 100 mg of active dispersed in ethanol to 70% on the scalp of six young healthy volunteers, making measurements at different times of the day and concluded by stating that the absorption of melatonin through the skin is dose-dependent, the active is deposited quickly in the stratum corneum, from which it diffuses over time reaching the bloodstream.
In 2004 Fischer & coll. compared the transcutaneous penetration of melatonin contained in a semisolid preparation or in an alcoholic solution by evaluating the plasma levels of 15 healthy volunteers over the course of twenty-four hours and ascertained that the active in question penetrates the skin differently depending on the vehicle in question. which is missing. There melatonin in the semi-solid preparation it has a more rapid absorption through the stratum corneum, but its release to the bloodstream during the observation period is reduced compared to that of melatonin in solution.
In light of these observations, melatonin has found wide interest in the field of dermatology.
Applications of melatonin in dermatology
Skin tumors: as already mentioned, melatonin has been shown to possess properties oncostatics against various forms of cancer that can affect humans, including metastasizing malignant melanomas [3].
In vitro tests demonstrate the inhibitory effect of melatonin on cell proliferation in cultures of abnormal melanocytes and clinical studies report positive results on the use of melatonin, in mono- or polytherapy, in patients with malignant melanoma [3, 2].
In one of these researches, conducted by Gonzalez et al. on forty-two patients with advanced melanoma, the effect of oral administration of melatonin was examined, in doses ranging from 5 to 700 mg / m2/ day. After five weeks, a significant reduction in tumor size was observed in six patients, while in six others there was stabilization of tumor growth. In other clinical studies, performed by Lissoni & coll., MELATONIN was administered in combination with interleukin-2 (IL-2), as it is assumed to emphasize its stimulatory effect on the immune system against tumor progression, and with chemotherapeutic drugs, such as naltrexone and cisplatin. The results obtained showed that melatonin, in addition to having an immunostimulating effect, additive to that of IL-2, improves the cytotoxicity of chemotherapy drugs against cancer cells [2].
BIBLIOGRAPHY:
- Solominski A., Wortsman J & Tobin DJ The cutaneous serotoninergic / melatoninergic system: securing place under the sun FASEB J 2005; 19: 176-194
- Solominski A., Fisher TW, Zmijewski M, A, Wortsman J, Semac I., Zbytek B., Slominski RM & Tobin DJ on the role of melatonin in skin physiology and pathology Endocrine 2005; 27 (2): 137-148.
- Reiter RJ & Robinson J. Melatonin; Bantam Books 1995
- Podda M & Grundmann-Kollmann M. Low molecular weight antioxidants and their role in skin aging Clin and Exp Dermatol 2001; 26: 578-82
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