Process for preparing pharmaceutical composition having an increased active substance dissolution rate, and the compositions obtained

A process for preparing a pharmaceutical tablet having a controlled active principle dissolution rate which contains an active principle selected from the group consisting of nifedipine and carbamazepine, said process consisting of co-grinding or mixing said active principle with an agent which provides a controlled active principle dissolution rate and consists of cross-linked sodium carboxymethylcellulose and a hydrophilic polymer which forms a gel on contact with water, said hydrophilic polymer being selected from the group consisting of hydroxypropylmethylcellulose, hydroxylpropylcellulose, sodium carboxymethylcellulose, scleroglucan and polyvinyl alcohol, to form a mixture wherein the quantity of said active principle used is between 1 to 90% by weight of the whole mixture, and thereafter tableting said mixture.