Bioavailability of Pyridoxal Phosphate from Enteric-Coated Tablets. III. Correlations between Bioavailability in Humans and Beagle Dogs and between Bioavailability in Humans and in Vitro Dissolution Rates

抄録

The bioavailability of five enteric-coated tablets and one sugar-coated tablet of pyridoxal phosphate previously tested in humans was studied in beagle dogs, and the dissolution rates of the tablets were measured by various dissolution methods. The results in beagle dogs correlated significantly with those in humans, and beagle dogs can therefore be used as an animal model to predict the bioavailability in humans of enteric-coated tablets of pyridoxal phosphate. On the other hand, dissolution tests were not as useful as the bioavailability test in beagle dogs. Only the dissolution parameter obtained by the oscillating basket method using medium of pH 5.9 correlated significantly with the initial excretion rates of pyridoxic acid found in the human study. The oscillating basket method with pretreatment in the No. 1 medium (J. P. IX) failed to reject tablets having inferior bioavailabilities in humans. Pretreatment with acidic solution in dissolution or disintegration tests was considered to make the prediction of bioavailability less reliable.