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Abstract
Detection of normal and pathologic parathyroid glands often is difficult due to their variability in number and location. The intraoperative identification of parathyroid glands is challenging yet very important, which is one of the main reasons for postoperative hypoparathyroidism. The feasibility and efficacy of fluorescence diagnosis using the photosensitizer aminolevulinic acid (ALA) has already been proven to identify parathyroid glands in experimental settings. Mostly, modifications of ALA aimed at improving its cellular permeability, increased stability in physiologic pH, increased selectivity and limiting side effects are important challenges in order to extend its clinical use. The present study represents ALA in delivery systems such as conventional liposomes and stealth liposomes and study the feasibility and efficacy of these forms for identifying parathyroids in a fluorescence technique and evaluates fluorescence differences between these delivery forms and the free ALA solution used before.ALA loaded conventional liposomal and stealth liposomal samples were prepared and they were characterized for drug encapsulation %, vesicle size, Zeta potential, in vitro drug release profile and thermal analysis. Seventy rats were randomized into seven groups; a peritoneal lavage was performed with either 1.5 or 3.0% ALA solution in free, conventional or stealth liposomal forms, the photosensitization times of each formula was calculated. After surgical exposure of thyroid and parathyroid glands the operative site was examined under wood{u2019}s light, the identified parathyroid glands were observed and confirmed by histological study, different forms and concentrations of ALA were compared through measuring fluorescence intensities of parathyroid glands by spectrometry