Abstract
Purpose. The objective of this study was to evaluate in vitro and invivo the melanogenic activity of one-month duration Melanotan-I(MT-I) implants prepared using poly (D,L lactide-co-glycolide) polymer.
Methods. The biological activity of the samples of MT-I released invitro from the non-irradiated or gamma irradiated implants wasmeasured using a frog skin bioassay. The effect of MT-I on skinpigmentation was measured using a Chroma meter (reflectometer) aftersubcutaneous administration of implants containing 4 mg MT-I toguinea pigs. Eumelanin, the black/brown melanin pigment, wasquantified in skin biopsies as pyrrole-2, 3, 5-tricarboxylic acid using HPLC.
Results. The MT-I released in vitro from implants after 24 hoursexhibited 100% melanotropic activity in frog skins compared to an identicalconcentration of a freshly prepared MT-I standard. The reflectancereadings demonstrated a prolonged skin darkening for up to threemonths as evidenced by the decrease in the luminance values from 0to −4.82. A 2.5-fold increase in eumelanin levels was observed afterone month and the increased pigmentation lasted for 3 months.
Conclusions. The melanogenic response to MT-I implants persisted forthree months and the increase in pigmentation, especially the increasedeumelanin levels, could provide protection from ultraviolet radiation.
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Bhardwaj, R., Hadley, M.E., Dorr, R.T. et al. Pharmacologic Response of a Controlled-Release PLGA Formulation for the Alpha-Melanocyte Stimulating Hormone Analog, Melanotan-I. Pharm Res 17, 593–599 (2000). https://doi.org/10.1023/A:1007525117894
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DOI: https://doi.org/10.1023/A:1007525117894