Formulation and Ex Vivo Evaluation of Membrane Permeation Properties of a Mixed Acetaminophen Gel for Rectal Administration

The purpose of this work was to evaluate the permeation of a mixed native starch-based gel of Ipomoea batatas (Convolvulaceae), using acetaminophen as a tracer through a rat rectal membrane (ex vivo method). The formulated gel was composed of a 10 g solution of poloxamer 407 at 20% and 2.5 g of glycerolized potato starch. The gel obtained was a smooth, homogeneous mixed gel with no foam, air bubbles or lumps, there was no characteristic odor, and the gel was whitish in color. This gel was characterized at the physicochemical and rheological level by means of the viscosimeter KINEXUS, pH- meter EUTECH and the study of the permeation was carried out by means of the Ussing chamber of horizontal type (the dual chamber). The formulated mixed gel is thermogelling, rheofluidifying and viscoelastic with a gelling temperature of 23.83; the permeation study gave a relatively low permeation percentage of 0.16% but which can be improved. The different viscoelastic, rheofluidizing and thermogelling characteristics contained in this mixed gel as well as the pH did not influence the permeation of the active ingredient (AP) through the rat rectal mucosa.