RÉSUMÉ
OBJECTIVE: To study the local irritative response and cytotoxicity of glycerol in vivo and in vitro, and evaluate the safety of glycerol as an excipient in inhaled preparations preliminarily. METHODS: Local irritation test: rats were divided into two groups, the glycerol group received 20% glycerol by intratracheal atomization once a day, followed by 5 d, the control group was given the equal volume of 0.9% sodium chloride solutions in the same way. After administration, the throat, trachea and lung were taken for histopathological examination, and bronchoalveolar lavage was performed in each group, total protein (TP) content (BCA method) and alkaline phosphatase (ALP), lactate dehydrogenase (LDH) activity in the lavage fluid were detected (biochemical instrument). Cytotoxicity test: the toxic effects of glycerol on adenocarcinoma human alveolar epithelial-like cells (A549), human bronchial epithelial cells (16HBE) and rat tracheal epithelial cells (RTE) were studied by MTT assay. RESULTS: Local irritation test:the control group showed mild infiltration of inflammatory cells in the alveolar (1/8), glycerol group showed perivascular inflammation (2/8) and moderate mild to mild infiltration of inflammatory cells in the alveolar (6/8); bronchoalveolar lavage fluid test showed that, compared with the control group, the level of ALP in the glycerol group was elevated significantly (P<0.05). There was a dose-effect relationship between the cytotoxicity on A549, 16HBE and RTE cells with varying volume fraction of glycerol content in the range of 0.25%-10%, r2 values were 0.989, 0.981, 0.964, and IC50 were 4.28%, 4.40%, 4.31% respectively. CONCLUSION: The 20% glycerol has slight irritation to the lung in vivo, and in vitro glycerol has obvious toxic effect on A549 and 16HBE cells when the volume fraction reached 2.0%, when it reached 4.0%, it has significant toxic effect on RTE cells, suggesting that large dose of glycerol may cause mild irritation and toxicity to the lungs.