Thermal analysis of pharmaceutical compounds. VI: Thermal analysis of fluoride-containing steroids

Introduction of a 9-a-fluorine atom in some steroidal molecules was found to enhance their activity [1,2]. The presence of a 16-a-hydroxyl group eliminates the undesirable salt-retention activity [l]. Glucocorticoid and anti-inflammatory activities, in the case of flucinolone acetonide, are both enhanced by the formation of the ketal through condensation with acetone. This is thought to be due to the prevention of intermolecular hydrogen bonding with fluorine atoms [l]. In other cases, the introduction of a 16-P-methyl group appears to neutralize the unfavourable electrolyte properties without diminishing the anti-inflammatory effect [l]. Analysis of some fluoride-containing steroids (fludrocortisone acetate, fluorometholone and fluocinolone acetonide) was achieved by spectrophotometry, gas-liquid chromatography and high pressure liquid chromatography [3,41. The present work is a continuation of a series of studies by the author on the thermal analysis of pharmaceutical compounds [5-91, and records the thermal analysis of some fluoride-containing steroids. This was carried out using TG, DTG, and DTA. A thorough study of the thermal behaviour and different transformations was carried out in order to identify the compounds and emphasize their correlation, if any. The determination of some constants and characteristics by thermal analysis is also considered.