The buccal absorption of ascorbic acid and its passage through lipoid membrane.

Ascorbic acid concentration was measured in centrifuged and uncentrifuged saliva from normal young adult men and women. The salivary ascorbic acid content of uncentrifuged saliva was significantly higher in women on account of the ascorbic acid contained in the cellular sediment. Ascorbic acid absorption into the buccal mucosa was measured from solutions of pH range 3.4-9.0 held in the mouth for periods of 1-9 minutes. For a constant mouth contact time, increase in pH of the loading solutions resulted in reduction of buccal absorption, and diminishing transfer into the buccal epithelium. Percentage absorption was greater in males than females throughout the pH range. At pH 5, 80% of the loading solution was absorbed after 5 minutes. Diffusion of ascorbic acid through the lipoid membrane was more rapid in males. Female buccal cells had significantly higher ascorbic acid concentrations than male cells. Absorption of laevo and dextro ascorbic acid in human beings can be considered as partitioning into, or passage through, a lipoid phase into the buccal cells. The rate of passage of ascorbic acid into the buccal lining cells under controlled conditions of pH and buccal contact time is pH and concentration dependent in human beings.