INTERACTIONS BETWEEN FOOD COMPONENTS AND DRUGS .4. INFLUENCE OF PECTINS AND BILE-SALTS ON PROPRANOLOL ABSORPTION

Influence of dietary fiber components on drug absorption was studied i n vitro using artificial membranes and mucosa preparations from guinea pig in 2-compartment model systems (permeation model and equilibrium dialysis). Well defined pectin preparations with different structural properties were used as food components and propranolol (P) as basic m odel drug. The retardation of drug was increased with decreased degree of esterification (DE) of pectin. Pectins with a blockwise distributi on of free carboxyl groups possessed a more intensive effect than pect ins with a random arrangement. It was found that P transport across th e artificial lipid membrane was significantly decreased by pectins wit h a blockwise (DE less than or equal to 54%) or statistical (DE = 36%) distribution of free COOH. Pectins with lower molecular weight giving low viscosities in the medium showed only a small effect on permeatio n of the drug. Furthermore, the influence of bile acids without and wi th pectins on P absorption was studied. The bile salts did only influe nce P transport when they were applied above the critical micellar con centration (CMC). P transport across the lipid membranes increased sli ghtly when pectins were additionally used to the bile salts above the CMC. Transport of P across the guinea pig mucosa was less than the per meation through the artificial lipid membranes. However, the transport of P across the mucosa was significantly reduced by glycocholic acid (GC), by pectin BL-3 as well as by BL-3 and GC in the same way as foun d using the artificial lipid membranes.