Formulation of aspirin-magaldrate double-layer tablets: in vitro evaluation and cytoprotective activity in rats.

Double layer 325 mg oral aspirin tablets buffered with magaldrate antacid, 100, 150, 175 and 200 mg (F1, F2, F3 and F4, respectively) were prepared by direct compression. The new formulae were of remarkable hardness and friability. The tablets complied with the requirements of the acid neutralizing capacity, uniformity of dosage units, disintegration and dissolution tests (USP XXIII) for buffered aspirin tablets. The in vitro release pattern of F1 and F1 followed first order kinetics (r = 0.999), while F3 and F4 were released according to a zero order model (r = 0.993). Formulations F2, F3 and F4 as well as the marketed preparations, pure Aspro tablets (Acetylsalicylic acid 320 mg per tablet), or Ascriptin tablets (aspirin 325 mg plus 150 mg Maalox per tablet) were administered to fasted rats by gavage at doses that provided 400 mg aspirin kg-1 and the extent of the induced gastric damage was quantified 6 h later. Ascriptin, F3 and F4 preparations produced significantly less gastric damage (p < 0.05, n = 6) when compared with pure Aspro tablets. There was a clear dose-dependent decrease in the gastric damage following treatment with F2, F3 and F4 preparations, but there was no significant difference between the effects of F3 and F4 which were equipotent with Ascriptin.