POSSIBILITIES OF CONVEYING A CATIONIC DRUG IN CARBOMER HYDROGELS

A drug with cationic characteristics such as procaine can be conveyed in a Carbomer hydrogel in two different ways: (i) in the form of salt in solution in the aqueous phase, and (ii) in the base form salified w ith the same polymer. Introduction of the drug into the hydrogel with different concentrations of polymer produced, in both cases, a reducti on in viscosity in relation to drug concentration. The gels with proca ine salified with the polymer shelved greater viscosity. The drug rele ase rate, in general, diminished with the increase in polymer concentr ation. Nevertheless, when this concentration was maintained, there was no variation in release rate when the viscosity produced as a consequ ence of drug concentration was changed. Gels with procaine salified wi th the carboxyvinylic polymer had a faster release rate than those wit h procaine in the hydrochloride form dissolved in the aqueous phase. T hese results have also been confirmed by a simulated absorption test.