title: Preparation of novel cationic copolymer microspheres and evaluation of their function by in vitro and in vivo tests as pH-sensitive drug carrier systems.
abstract: Novel pH-sensitive copolymer microspheres containing methylacrylic acid and styrene cross-linking with divinylbenzene were synthesized by free radical polymerization. The microspheres that were formed were then characterized by Fourier-Transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), size analysis, and X-ray analysis. The copolymer microspheres showed pulsatile swelling behavior when the pH of the media changed. The pH-sensitive microspheres were loaded with diltiazem hydrochloride (DH). The release characteristics of the free drug and the drug-loaded microspheres were studied under both simulated gastric conditions and intestinal pH conditions. The in vivo evaluation of the pulsatile preparation was subsequently carried out using beagle dogs as experimental subjects. The results demonstrated that the drug release exhibited a pulsatile character both in vitro and in vivo.
authors.affiliation: Department of Pharmaceutics, Shenyang Pharmaceutical University, Shenyang, 110016, People's Republic of China.
authors.forename: C
authors.initials: C
authors.lastname: Sun
authors.forename: H
authors.initials: H
authors.lastname: Liu
authors.forename: S
authors.initials: S
authors.lastname: Zhang
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: W
authors.initials: W
authors.lastname: Pan
mesh_terms: D000818:Animals; D004110:Diltiazem / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics; D004285:Dogs; D004337:Drug Carriers; D006863:Hydrogen-Ion Concentration; D008297:Male; D008863:Microspheres; D010316:Particle Size; D011109:Polymethacrylic Acids / Q000008:administration & dosage; D011137:Polystyrenes / Q000008:administration & dosage; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D004337:Drug Carriers; D011109:Polymethacrylic Acids; D011137:Polystyrenes; D004110:Diltiazem