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Gastric and intestinal absorption of monofluorophosphate and fluoride in the rat
A Rigalli1, M A Cabrerizo, A D Beinlich
1Laboratorio de Biologia Osea, Facultad de Medicina, Rosario, Argentina.
Abstract:
This paper reports data indicating that, in the rat, sodium monofluorophosphate (MFP, CAS 10163-15-2) is absorbed without hydrolysis through the stomach. This phenomenon and the fact that MFP binds to plasma globulins produce a prompt increase in protein-bound MFP concentration, significantly greater than the increase in plasma ultrafilterable fluoride. Intestinal absorption of MFP was investigated with the isolated duodenal loop in situ. The drug was hydrolyzed to fluoride at the intestinal lumen with a rate of approx. 3 times greater than that for fluoride absorption. After filling the duodenal loop with a MFP solution, ultrafiltrable fluoride accounts for the increase in plasma fluoride concentration, with no evidence of protein-bound MFP. This report also includes analytical techniques for the measurement of MFP in test solutions and in plasma.
Insights
Sodium monofluorophosphate (MFP) is absorbed intact through the stomach, binding to plasma proteins. In the intestine, MFP rapidly hydrolyzes to fluoride, which then enters the bloodstream.
Area of Science:
- Pharmacokinetics
- Toxicology
- Biochemistry
Background:
- Sodium monofluorophosphate (MFP) is a compound used in dental products.
- Understanding MFP absorption and metabolism is crucial for assessing its safety and efficacy.
Purpose of the Study:
- To investigate the absorption and hydrolysis of sodium monofluorophosphate (MFP) in rats.
- To differentiate between MFP and fluoride absorption in the gastrointestinal tract.
Main Methods:
- In vivo gastric absorption studies in rats.
- In situ isolated duodenal loop experiments.
- Analysis of plasma for protein-bound and ultrafilterable fluoride and MFP.
Main Results:
- MFP is absorbed intact through the stomach, leading to increased protein-bound MFP.
- Intestinal absorption involves rapid hydrolysis of MFP to fluoride.
- Plasma fluoride increase is primarily due to absorbed fluoride, not intact MFP, after intestinal exposure.
Conclusions:
- Gastric absorption of MFP occurs without hydrolysis, with subsequent binding to plasma proteins.
- Intestinal absorption of MFP is characterized by rapid hydrolysis to fluoride.
- The route of administration significantly influences the form of fluoride absorbed into circulation.