Transfer of alcohols and ureas across the oral mucosa measured using streaming potentials and radioisotopes.

The permeability of the oral mucosa to an alcohol and a urea series was studied using radioisotope transfer and the measurement of streaming potentials. Both methods yielded similar quantitative estimates of permeability. The rate of transfer of the smallest member of both series (methanol and urea) was greater than the second member (ethanol and methylurea). In the alcohol series, permeability increased as the chain length increased from ethanol to butanol. In contrast, the permeability of the oral mucosa to ethylurea and propylurea was less than to methylurea. However, butylurea had a greater rate of transfer than either propylurea or ethylurea.