A pharmaco-scintigraphy study of riboflavin 5'-phosphate sodium capsules (1 vs. 4)

The comparative in-vivo disintegration, gastric emptying and bioavailability of 41 mg radiolabeled riboflavin 5'-phosphate sodium capsules administered as a single hard gelatin capsule or as four capsules was evaluated in human subjects. A total of 41 mg of riboflavin 5'-phosphate sodium and 7 MBq of technetium sulfur colloid were incorporated in a single gelatin capsule or the same dose was administered in four capsules. A randomized crossover design was conducted in eight subjects under fasting conditions. Capsule disintegration and gastric emptying was measured by gamma scintigraphy and the relative amount of riboflavin excreted in the urine was measured by HPLC. The in-vivo disintegration time and gastric emptying of the four capsules was significantly faster 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 riboflavin excreted in the urine in the 0-2 h interval was significantly greater for the four versus one capsule. The in-vivo performance of one 41 mg riboflavin 5'-phosphate sodium capsule is significantly different than the equivalent dose administered in four capsules. Further studies are needed to understand the underlying mechanism for the difference between the regimens. (C) 1997 Elsevier Science B.V.