Fluoride absorption: the influence of gastric acidity

Area of Science:

• Pharmacokinetics
• Gastroenterology
• Toxicology

Background:

• Gastric acidity plays a role in drug and nutrient absorption.
• Understanding fluoride absorption is crucial for managing toxicity and therapeutic uses.

Purpose of the Study:

• To investigate the influence of gastric acidity on intragastric fluoride absorption in rats.
• To explore the mechanism of fluoride absorption in the stomach.

Main Methods:

• Rats were pretreated with acid secretion inhibitors (atropine, cimetidine) or given fluoride in a bicarbonate solution.
• Fluoride absorption was compared between different gastric pH conditions using plasma fluoride concentrations and AUC.
• In situ isolated stomach studies compared absorption rates at pH 2.1 and pH 7.1.

Main Results:

• Reduced gastric acidity markedly decreased fluoride absorption rates.
• Plasma fluoride concentrations and AUC were lower in animals with reduced gastric acidity.
• Fluoride absorption was significantly faster from a pH 2.1 buffer compared to a pH 7.1 buffer in isolated stomachs.

Conclusions:

• Gastric acidity is a critical factor influencing fluoride absorption.
• Fluoride is likely absorbed from the gastric lumen primarily as undissociated hydrogen fluoride (HF).
• Findings may inform understanding of fluoride toxicity, dental fluorosis, and osteoporosis treatment.