Abstract: Paricalcitol, a synthetic vitamin D analog, is purified to a purity greater than 99.7% by crystallization from solution in isopropyl acetate solvent, followed by filtration and vacuum drying. Isopropyl acetate appears to be unique among commonly available and pharmaceutically acceptable solvents in its ability to precipitate paricalcitol in this high purity, essentially free of isomers thereof. In addition, paricalcitol of purity of at least 99.9% has been shown to have exceptional storage stability.

Abstract: Paricalcitol, a synthetic vitamin D analog, is purified to a purity greater than 99.7% by crystallization from solution in isopropyl acetate solvent, followed by filtration and vacuum drying. Isopropyl acetate appears to be unique among commonly available and pharmaceutically acceptable solvents in its ability to precipitate paricalcitol in this high purity, essentially free of isomers thereof.

Abstract: Paricalcitol, a synthetic vitamin D analog, is purified to a purity greater than 99.7% by crystallization from solution in isopropyl acetate solvent, followed by filtration and vacuum drying. Isopropyl acetate appears to be unique among commonly available and pharmaceutically acceptable solvents in its ability to precipitate paricalcitol in this high purity, essentially free of isomers thereof.

Abstract: Paricalcitol, a synthetic vitamin D analog, is purified to a purity greater than 99.7% by crystallization from solution in isopropyl acetate solvent, followed by filtration and vacuum drying. Isopropyl acetate appears to be unique among commonly available and pharmaceutically acceptable solvents in its ability to precipitate paricalcitol in this high purity, essentially free of isomers thereof. In addition, paricalcitol of purity of at least 99.9% has been shown to have exceptional storage stability.

Abstract: An individual tetrahydrocannabinol isomer of interest is separated from a mixture containing two or more such isomers, by treating the mixture with an isocyanate or isothiocyanate of formula I: R—(CH2)n—N?C?X??(I) where R represents an aromatic ring optionally substituted with one or more electron withdrawing groups, n=0 or 1 and X is oxygen or sulphur; so as to produce a crystallizable THC carbamate of formula II: wherein X and R are as defined above, R? is a C3-C10 alkyl group and the dotted lines indicate optional unsaturation including aromatic, separating the compound of formula II from solution in isolation of other THC derivatives, and hydrolyzing the compound of formula II to form the individual tetrahydrocannabinol isomer of interest.