The ScinTwelve Study: Pharmacoscintigraphic Evaluation and Pharmacokinetic Assessment of a Vitamin B12 Sustained-Release Tablet in Healthy Human Subjects

Background: Oral bioavailability of vitamin B12 is highly dependent on gastrointestinal transit and site-specific release, with optimal absorption occurring in the terminal ileum. Sustained-release formulations were designed to enhance targeted delivery and prolong systemic exposure. Objective: This study aimed to evaluate the in vivo disintegration pattern, gastric emptying, and gastrointestinal transit of a vitamin B12 sustained-release tablet using pharmacoscintigraphy and to correlate these findings with systemic bioavailability. Methods: An open-label, single-dose pharmacoscintigraphy study was conducted in six healthy adult male subjects. The investigational product (vitamin B12 1500 mcg sustained-release tablet) was radiolabeled with technetium-99m (99mTc) and administered orally. Sequential gamma imaging was performed up to eight hours post dose to determine the gastric residence, intestinal arrival, intestinal residence, and colon arrival time. Serum vitamin B12 levels were measured at predefined intervals up to 48 hours. Results: The upper placebo layer disintegrated rapidly in the stomach within 1.0 ± 0.0 minutes, with gastric emptying completed by 0.7 ± 0.2 hours. The lower sustained-release layer remained intact in the stomach and emptied at 120.00 ± 0.00 hours, followed by gradual intestinal disintegration between four and six hours. Colonic arrival occurred at 336.00 ± 53.67 hours. Serum vitamin B12 levels peaked at eight hours (296.00 ± 94.65 pg/mL), indicating delayed absorption corresponding to intestinal release. Sustained levels were maintained up to 48 hours, and no adverse events were reported. Conclusion: The vitamin B12 sustained-release tablet exhibited effective biphasic release with targeted intestinal delivery and sustained bioavailability, confirming its design intent and potential for improved therapeutic efficacy.