International harmonization of generic drugs: in vitro dissolution tests for Japanese and American generic tablets.

Ibuprofen tablets on the market in Japan and the USA were compared by manual- and automatic-dissolution tests according to USP24 criteria. Dissolution test were performed in 900 ml of phosphate buffer of pH 7.2 at 37.0+/-0.5 degrees C at 50 rpm for 60 min, and the time required for 70% dissolution (T70%) and 5% dissolution after 60 min (A60) were evaluated. The dissolution profiles of both Japanese and American tablets by the automatic-method showed almost the same profiles as those of the manual method. T70% of the American and Japanese tablets by the manual method were not significantly different (p>0.05) from the automatic-method at various sampling positions. The A60 of the American and Japanese tablets by the manual-method was not significantly different (p>0.05) except at one position. The results indicate that the automatic-method was more reproducible than the manual-method, and also that systematic error was negligible. The T70% and A60 of the American tablets were significantly different (p<0.05) from the Japanese tablets. The American tablets were a film-coated over-the-counter drug and the Japanese tablets were a sugar-coated prescription drug. There was a difference in dissolution behavior between the dosage forms of the two countries.