Biopharmaceutic approach in designing a controlled release tablet of sodium monofluoro phosphate. Characterization of absorption sites and evaluation of modified dosage form
Vattikonda, C.S.; Ritschel, W.A.; Herbert, C.
International Journal of Clinical Pharmacology and Therapeutics 32(10): 559-566
1994
ISSN/ISBN: 0946-1965 PMID: 7834164 Document Number: 431654
Based on the results from in vivo study in dogs, it was decided to characterize the absorption sites of sodium monofluoro phosphate (NaMFP). It was hypothesized that bioavailability upon p.o. administration can be improved for controlled release dosage forms if the drug release is confined to segments of gastrointestinal tract responsible for absorption. To characterize the principal sites of absorption of NaMFP, in situ segmental absorption studies were carried out in rats. It was found that NaMFP is predominantly absorbed from the small intestine. The larger surface area and presence of alkaline phosphatase enzymes, are attributed to the higher absorption from the small intestine. Based on these results the delivery time was limited to 6 h to restrict the release of the drug within the principal sites of absorption. The dose was adjusted to 160 mg of NaMEP. After studying in vitro release profiles, the drug to polymer ratio was adjusted to 1:1.1. The modified dosage form was finally subjected to bioavailability studies in humans. An immediate release dos age form was used to compare the efficacy in a two-period crossover study. The extent of bioavailability was 99% and the dosage form was effective in reducing the fluctuations.