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Results for “FOLIC ACID ANTAGONISTS”

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PubMed1988

Effect of antacid and H2 receptor antagonists on the intestinal absorption of folic acid.

Intestinal folic acid transport is a saturable process with a pH optimum of 5.5 to 6.0. Because of the possible effects of antacids and acid-lowering drugs on the pH of the proximal small intestine, the influence of these drugs on folic acid absorption was studied by using tritium-labeled pteroylmonoglutamic acid (PGA) in 30 subjects (21 women, nine men) of 56 to 89 years of age. Both cimetidine and an antacid containing aluminum and magnesium hydroxide reduced folate absorption from a liquid formula meal (p less than 0.01, p less than 0.001, respectively). Although ranitidine also caused a fall in folic acid absorption from the liquid meal, the change was not statistically significantly different from when PGA was given with the meal alone. Both histamine receptor antagonists tended to maintain a high intraluminal pH in the proximal small intestine after meals, which in part could explain the inhibition of folate absorption. However, neither drug was found to chemically interact with folic acid, and neither drug inhibited the dihydrofolate reductase. The antacid was found to precipitate folic acid at a pH of greater than 4.0, thus removing it from the aqueous phase. This appears to be the explanation for the lowered folate absorption in the presence of antacid. Although the effects of these drugs on reducing folic acid absorption were relatively small, such reductions could become clinically significant in chronic antacid or H2 receptor antagonist use or intensive antacid or H2 receptor antagonist use by individuals eating diets that are marginal in folate content.

Aged↗
PubMed1999

[Antagonism of folic acid on the toxicity of aspirin in yolk sac of rats].

The antagonistic effects of folic acid to aspirin on the development of rat yolk sac and embryos were studied during early organogenesis by using whole embryo culture technique and electron microscopy. The results showed that when treated with aspirin, the diameter of yolk sac and the body length of embryo were much shorter, the frequencies of abnormal embryos were significantly higher, and the yolk sac became thinner than those without treatment. The number of blood islands and capillaries decreased, the differentiation and development of blood vessel were retarded in the treated group. Ultrastructure observation also showed that the numbers of microvilli and capillaries were greatly decreased, and the structure and the numbers of lysosomes, endoplasmic reticula and ribosomes significantly changed in the treated group. When aspirin was added with high folic acid serum, the toxicity on yolk sac decreased or disappeared. The results suggested that the protection of yolk sac would be related to the antagonism of folic acid to aspirin.

Animals↗