Evaluation of 14-day Concentration-time Curves of Vitamin D3 and 25-Hydroxyvitamin D3 in Healthy Adults With Varying Body Mass Index

Background/Aim: To analyze the concentration-time curves of single-dose oral 25(OH)D3 in comparison with vitamin D3 in healthy adults. Patients and Methods: The pharmacokinetics observed over two weeks after orally administering single 900 mu g doses of vitamin D3 and 25(OH)D3 to six otherwise healthy vitamin D insufficient/deficient adults participating in a broader randomized, double-blind, crossover, single center trial was analyzed. The study protocol was approved by the institutional review board (H-37167). Results: Individual concentration-time curves revealed that vitamin D3 took longer than 25(OH)D3 to reach its maximal concentration after ingestion in five participants. After 25(OH)D3 ingestion, 25(OH)D3 reached its maximal concentration, dropped rapidly, and plateaued before starting to decrease slowly. There were observable inter-individual variations in the bioavailability of vitamin D3 and 25(OH)D3 and the pattern of changes in 25(OH)D3 concentration after their ingestion. Conclusion: Pharmacokinetics of 25(OH)D3 in comparison with vitamin D3 was illustrated and described in this study.

Automated summary

This study analyzed the concentration-time curves of single-dose oral 25(OH)D3 and vitamin D3 in healthy adults, showing that vitamin D3 took longer to reach peak concentration than 25(OH)D3 in most participants. Individual variations in bioavailability and concentration changes were observed after ingestion of both compounds.