Swelling and ketoprofen release characteristics of thermo- and pH-responsive copolymer gels.
Swelling-controlled drug delivery copolymer gels were newly synthesized by introducing thermo- and pH-responsive methacryloyl-glycine (MA-Gly) or pH-responsive methacrylic acid (MA-Ac) for comparison with thermoresponsive acryloyl-L-proline ethyl ester (A-ProOEt). A homopolymer gel of A-ProOEt was kept at degrees of swelling that were less than 0.5 at a pH from 2.5 to 7.5 at 37 degrees C. The thresholds of swelling for copolymer gels consisting of A-ProOEt/MA-Gly and A-ProOEt/MA-Ac with a composition of 40/60 mol% were found to be pH 3.0 and pH 5.5, respectively, in buffer solutions at 37 degrees C. The diffusion characteristics of 2-(3-benzoylphenyl)propionic acid (ketoprofen) from such copolymer gels was evaluated in buffer solutions at pH's more than 5.5, and it was found that A-ProOEt/MA-Gly gel possesses a case II transport mechanism that is completely linear time dependent in both the amount diffused and the penetrating swelling front position. On the other hand, A-ProOEt/MA-Ac gel exhibited a non-Fickian (or anomalous) diffusion behavior under the same conditions.
Negishi
M
M
Department of Pharmaceutical Research, Zeria Pharmaceutical Company, Ltd., Saitama, Japan.
Hiroki
A
A
Horikoshi
Y
Y
Miyajima
M
M
Asano
M
M
Katakai
R
R
Yoshida
M
M
D004058:Diffusion; D016503:Drug Delivery Systems; D005782:Gels / Q000138:chemical synthesis / Q000737:chemistry*; D005998:Glycine / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D007660:Ketoprofen / Q000493:pharmacokinetics*; D008855:Microscopy, Electron, Scanning; D011108:Polymers; D011109:Polymethacrylic Acids / Q000737:chemistry*; D011392:Proline / Q000032:analysis*; D013696:Temperature; D013997:Time Factors
D005782:Gels; D011108:Polymers; D011109:Polymethacrylic Acids; D007660:Ketoprofen; D011392:Proline; D005998:Glycine