Investigation of water mobility and diffusivity in hydrating micronized low-substituted hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and hydroxypropyl cellulose matrix tablets by magnetic resonance imaging (MRI).
The water mobility and diffusivity in the gel-layer of hydrating low-substituted hydroxypropyl cellulose (LH41) tablets with or without a drug were investigated by magnetic resonance imaging (MRI) and compared with those properties in the gel-layer of hydroxypropylmethyl cellulose (HPMC) and hydroxypropyl cellulose (HPC) tablets. For this purpose, a localized image-analysis method was newly developed, and the spin-spin relaxation time (T(2)) and apparent self-diffusion coefficient (ADC) of water in the gel-layer were visualized in one-dimensional maps. Those maps showed that the extent of gel-layer growth in the tablets was in the order of HPC>HPMC>>LH41, and there was a water mobility gradient across the gel-layers of all three tablet formulations. The T(2) and ADC in the outer parts of the gel-layers were close to those of free water. In contrast, these values in the inner parts of the gel-layer decreased progressively; suggesting that the water mobility and diffusivity around the core interface were highly restricted. Furthermore, the correlation between the T(2) of (1)H proton in the gel-layer of the tablets and the drug release rate from the tablets was observed.
Kojima
Masazumi
M
Tokyo Pharmaceutical Research Center, Pharmaceutical Technology Research Laboratories, Daiichi Pharmaceutical Co, Ltd, Edogaea-ku, Japan. kojimsnr@daiichipharm.co.jp
Nakagami
Hiroaki
H
D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004337:Drug Carriers / Q000737:chemistry; D004339:Drug Compounding; D005782:Gels; D065347:Hypromellose Derivatives; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008747:Methylcellulose / Q000031:analogs & derivatives* / Q000737:chemistry*; D011342:Procainamide / Q000737:chemistry; D013607:Tablets; D013806:Theophylline / Q000737:chemistry; D014867:Water / Q000737:chemistry*
D004337:Drug Carriers; D005782:Gels; D013607:Tablets; D014867:Water; D065347:Hypromellose Derivatives; D002482:Cellulose; D008747:Methylcellulose; C008079:hydroxypropylcellulose; D013806:Theophylline; D011342:Procainamide