The crystal behavior, solubilities, and dissolution rates of three crystallide forms of prednisolone were investigated in dilute sodium lauryl sulfate solutions. A solubilization effFct 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.
INCE surface-active agents are commonly a S part of both liquid and solid pharmaceutical preparations, their effect on dissolution rates and crystal behavior in solution is of importance in determining the limits of physiological availability of the drug and the physical stability of the preparation. I n our previous study with different prednisolone crystal forms (l), complete diffusion or transport control of dissolution did not prevail in water under the employed intensities of agitation. It would be of considerable interest t o investigate the influence of a surfactant on dissolution in these systems because here dissolution may be affected in a different manner than expected for diffusion controlled systems.
PLAN OF STUDY
Crystal Behavior Studies.-The three crystalline forms of prednisolone used in this study and their crystal behavior in distilled water have been previously described (1). For comparisons to be made on the crystal behavior, studies using these same methods were carried out in sodium lauryl sulfate solutions with samples taken at specified time intervals. Since the hydrate crystal form was the only stable crystal form in aqueous solution, equilibrium solubilization studies could only be conducted with this crystal form.
Influence of Sodium Lauryl Sulfate on the Dissolution Rate.-Since a surface-active agent affects both the energy relationships at a solid-liquid interface and the solubility of a crystal form through a solubilization effect, an analysis of these phenomena