Equilibrium properties and mechanism of kinetics release of metoclopramide from carbomer hydrogels

ALVARO FEDERICO JIMENEZ KAIRUZ; DANIEL ALLEMANDI,; RUBEN MANZO,

INTERNATIONAL JOURNAL OF PHARMACEUTICS

Año: 2003 vol. 250 p. 129 - 129

0378-5173

quilibrium properties and kinetics of metoclopramide release of carbomer-metoclopramide (C-M) hydrogels are reported. A set of (C-M)X (x = moles percent of M = 50, 75, 100) that covers a pH range between 6.49 and 8.40 was used. Hydrogels exhibited a high negative electrokinetic potential (z). Concentrations of ion pair [R-COO-MH+] and free species [M] and [MH+] were determined by the selective extraction of M with 1,2-dichloroethane (DCE) together with pH measurements. The system (C-M) is characterized by a high proportion of drug present in the form of ion pairs and a negative z potential that attracts MH+ and H+ and repeals OH-, providing a microenvironment of higher acidity than the bulk medium. Delivery rates ofM were measured in a Franz type bi-compartimental device using water and NaCl 0.9% solution as receptor media. (C-M) hydrogels behave as a reservoir that releases the drug at a slow rate to water; the rate increases 14 times as water is replaced by NaCl solution. The pH eff