Anhydrous Crystal Form Research Articles

Micellar Solubilization of Testosterone III: Dissolution Behavior of Testosterone in Aqueous Solutions of Selected Surfactants

The solution behavior of testosterone was studied with a view toward explaining an anomalous initial supersaturation observed in solubilized systems containing testosterone. This anomalous behavior was related to the conversion of an anhydrous crystal form of testosterone to a hydrate crystal form. The solution behavior of the anhydrous form was studied in several concentrations of polysorbate 20, dodecyltrimethylammonium bromide, and potassium laurate. In low concentrations of polysorbate 20 and potassium laurate, the time required to attain the solubility peak was less than that in distilled water. An increase in surfactant concentration resulted in a decrease in the solubility peak time. At higher concentrations, dodecyltrimethylammonium bromide exhibited a pattern similar to that of polysorbate 20 and potassium laurate; at a low concentration, however, a prolongation of the peak solubility time was noted.

Dissolution Kinetics of Certain Crystalline Forms of Prednisolone II: Influence of Low Concentrations of Sodium Lauryl Sulfate

The crystal behavior, solubilities, and dissolution rates of three crystalline forms of prednisolone were investigated in dilute sodium lauryl sulfate solutions. A solubilization effect was noted at concentrations considerably below the critical micelle concentration. Also, at a concentration of 0.1 per cent sodium lauryl sulfate the release from supersaturation of a metastable anhydrous crystal form was more rapid than in purely aqueous solutions. Substantial dissolution rate increases were observed in the surface-active media. It appeared that these increases could be accounted for by the solubilization effect and an apparent increase in the interfacial reaction rate.