In vitro and in vivo evaluation of cellacephate microcapsules of sodium salicylate prepared by pan coating.

Within various organic solvent based coating systems examined, one containing cellacephate and hydrogenated castor oil as cofilm formers was found to produce microcapsules of sodium salicylate by pan coating with optimum enteric properties, as determined by in vitro evaluation by scanning electron microscopy and dissolution studies. Scintiscans showed that such microcapsules packed in an outer hard gelatin capsule shell lodged temporarily in the oesophagus and tended to form aggregates on liberation in the stomach of the dog. Because of their rapid clearance from the stomach, single dosage with these microcapsules only prolonged appearance of the plasma peak by about 1.5 h in comparison to a conventional form. The microcapsules showed no decrease in bioavailability and only slight faecal blood loss during acute toxicity testing for gastrointestinal bleeding.