PROGRAMMABLE DRUG-RELEASE OF HIGHLY WATER-SOLUBLE PENTOXIFYLLINE FROM DRY-COATED WAX MATRIX TABLETS

The programmable release of pentoxifylline from a dry-coated wax matrix tablet containing behenic acid as wax matrix was investigated at 37 degrees C in Japanese Pharmacopeia XII 1st (PR 1.2) and 2nd (pH 6.8) fluids. The dry-coated tablet consisted of a low drug concentration (33% w/w) in the outer layer tablet and a high concentration (50-67% w/w) in the core. The drug release from the wax matrix significantly increased after penetrating the core; therefore, the drug release profiles showed specific biphasic curves. Because the contact angle of the wax matrix tablet increased with a decrease in the drug concentration, the fluid penetration in wax matrix tablet increased with an increase of the drug concentration. The time required for 75% drug release (T-75) decreased with an increasing drug concentration in the core, and the T-75 at PH 6.8 was slightly longer than that in pH 1.2. The larger core tablet had a shorter T-75, indicating that the drug release rate was controlled by regulating the drug concentration and/or the weight of the core tablet.