In vivo-in vitro correlations with various aspirin formulations.

In vivo evaluation of gastric irritation as determined by gastric transmural potential difference (GPD) and in vitro characterization of four formulations have been made. The four formulations were: (A) highly buffered, (B) cytoprotective, (C) microencapsulated and (D) a plain tablet. The GPD results showed C to be much less irritating than A or D, and slightly less-irritating than B. The release from all formulations was well represented by dissolution efficiency (DE%) and mean time of dissolution. When correlation coefficients were calculated, significant relationships were found between DE% and the GPD parameters area under the baseline (AUB) and the Reiz Index (RI), and between the mean time of dissolution and the GPD parameters AUB, mean potential drop (MD) and RI.