A PHARMACO-SCINTIGRAPHY STUDY OF RIBOFLAVIN 5'-PHOSPHATE SODIUM CAPSULES (1 VS 4)

The comparative in-vivo disintegration, gastric emptying and bioavaila bility of 41 mg radiolabeled riboflavin 5'-phosphate sodium capsules a dministered as a single hard gelatin capsule or as four capsules was e valuated in human subjects. A total of 41 mg of riboflavin 5'-phosphat e sodium and 7 MBq of technetium sulfur colloid were incorporated in a single gelatin capsule or the same dose was administered in four caps ules. A randomized crossover design was conducted in eight subjects un der fasting conditions. Capsule disintegration and gastric emptying wa s measured by gamma scintigraphy and the relative amount of riboflavin excreted in the urine was measured by HPLC. The in-vivo disintegratio n time and gastric emptying of the four capsules was significantly fas ter than for the one capsule. The bioavailability of the four capsule regimen was 16.5 versus 11.2% for the one capsule. The amount of ribof lavin excreted in the urine in the 0-2 h interval was significantly gr eater for the four versus one capsule. The in-vivo performance of one 41 mg riboflavin 5'-phosphate sodium capsule is significantly differen t than the equivalent dose administered in four capsules. Further stud ies are needed to understand the underlying mechanism for the differen ce between the regimens. (C) 1997 Elsevier Science B.V.