Effects of hardness on the disintegration time and the dissolution rate of uncoated caffeine tablets

The effects of hardness on disintegration and dissolution characteristics of uncoated caffeine tablets made at eight different pressure levels were studied. The disintegration times were determined using the J.P. VIII procedure with disks and the dissolution rate measurements were performed with the U.S.P.XVIII procedure (U.S.P. method) and the J.P. VIII disintegration test apparatus (J.P. method). A good correlation between the hardness and the disintegration times was obtained. The dissolution rate constants were determined from the equation of Noyes & Whitney (1897) and a good correlation between the hardness and the dissolution rate constants was obtained. The hardness governed the dissolution over all the stages from tablet to the smallest particles after the breakage by disintegration. The dissolution rates of the J.P. method were greater than those of the U.S.P. method.