Drug microparticles

A pharmaceutical composition comprising microparticles of oxybutynin that have not been micronized by a mechanical process selected from high energy milling and high pressure homogenization, from which pharmaceutical composition about 75 weight-% of the oxybutynin of a sample of the composition comprising 100 mg of oxybutynin dissolves from the composition within about 180 minutes when dissolution is measured at 37° C. with an apparatus II dissolution tester as described in the United States Pharmacopoeia operating at about 50 RPM in a medium consisting essentially of 100 mL of 50 mM aqueous phosphate buffer, pH ˜6.8.

A pharmaceutical composition comprising microparticles of oxybutynin obtained by sublimation of a sublimable carrier from a solid solution of oxybutynin in the sublimable carrier.

A pharmaceutical composition comprising pharmaceutical carrier particles consisting essentially of a non-hydrosoluble material and, deposited thereon, microparticles of oxybutynin that are obtained by sublimation of a sublimable carrier from a solid solution of oxybutynin in the sublimable carrier, wherein at least about 75 weight-% of the oxybutynin of a sample of the composition comprising 100 mg of oxybutynin dissolves from the pharmaceutical composition within at most about 180 minutes when dissolution is measured at 37° C. with an apparatus II dissolution tester as described in the United States Pharmacopoeia operating at about 50 RPM in a medium consisting essentially of 100 mL of 50 mM aqueous phosphate buffer, pH ˜6.8.

A process for preparing an oxybutynin delivery vehicle comprising the steps of:

• a) forming a solid solution of oxybutynin and a sublimable carrier on the surface of a pharmaceutical carrier particle;
• and
• b) subliming the sublimable carrier from the solid solution to deposit microparticles of oxybutynin on the surface of the pharmaceutical carrier particle to obtain the oxybutynin delivery vehicle.