Solid State Characterization of Stanozolol

Abstract

A study was undertaken to illustrate the ability to characterize various crystal forms of Stanozolol by by thermal analysis (differential scanning calorimetry-DSC), X-ray powder diffraction (XRPD), and Fourier transform infrared spectroscopy (FTIR). Mixtures of forms I and II were prepared and analyzed by each technique to investigate the strengths and weaknesses of the three methods. The detection of a contaminant polymorph in mixtures of forms I and II was possible by both FTIR and XRPD but not possible by DSC.Various solvated forms were prepared by recrystallization from methanol, ethanol, 2-propanol, and were shown by thermal gravimetric analysis to exist in a 1:1 stoichiometry with Stanozolol. XRPD analysis of solvates indicated that each solvated form (monohydrate, ethanol solvate, methanol solvate, 2-propanol solvate) exists in a crystal unique with respect to forms I and II.The concentration of drug in solution for the different crystal forms was determined at room temperature in 2% SLS at 5 and 24 hours. A significantly higher concentration was observed for the form II sample at 5 hours versus the form I and the monohydrate samples. It is likely that the form I sample had converted to the monohydrate form after 5 hours and a maximum concentration would be observed at an earlier time. At 24 hours, both the form I and II samples had converted to the monohydrate form and concentrations of 0.5–0.6 mg/mL were observed for each form. Due to the transformations to the hydrate during solubility studies, meaningful comparisons were difficult.