RELEASE OF ISOSORBIDE DINITRATE FROM POLYMER FILM DOSAGE FORMS AND ABSORPTION OF THIS DRUG THROUGH THE ORAL-MUCOSA OF RATS

In vitro release tests and in vivo absorption measurements of oral cav ity dosage forms of isosorbide dinitrate (ISDN) prepared from mixed po lymer film systems were conducted. Hydroxypropylcellulose (HPC) and hy droxypropylmethylcellulose phthalate (HPMCP) were used to make the fil ms, and the tests were conducted with films made from various ratios o f these two polymers. The effects of the addition of the accelerator g lycyrrhizic acid (GL), on dissolution and absorption were also examine d. The mean dissolution time (MDT) in the in vitro dissolution tests v aried with the nature of the polymers and drug, as well as with the pH of the testing solution. The MDT for the polymer film system with GL was smaller than that without GL. In the in vivo absorption tests usin g rats, the absorption of ISDN through the oral mucosa was observed in all the systems. In the mixed polymer film systems, the mean residenc e time (MRT) increased with increasing the ratio of HPMCP/HPC. The val ues of the area under the curve (AUC) for the systems with GL was larg er than for those without GL. A good correlation was demonstrated betw een the absorption rate constant, k(n) and the dissolution rate consta nt, k(d).