چکیده (انگلیسی):

The aim of the present study was to prepare surfactant-free
pseudolatexes of various methacrylic acid copolymers. These
aqueous colloidal dispersions of polymeric materials for oral
administration are intended for film coating of solid dosage
forms or for direct manufacturing of nanoparticles. Nanoparticulate
dispersions were produced by an emulsificationdiffusionmethod
involving the use of partially water-miscible
solvents and the mutual saturation of the aqueous and organic
phases prior to the emulsification in order to reduce the initial
thermodynamic instability of the emulsion. Because of the
self-emulsifying properties of the methacrylic acid copolymers,
it was possible to prepare aqueous dispersions of colloidal
size containing up to 30% wt/vol of Eudragit RL, RS,
and E using 2-butanone or methyl acetate as partially watermiscible
solvents, but without any surfactant. However, in the
case of the cationic Eudragit E, protonation of the tertiary
amine groups by acidification of the aqueous phase was necessary
to improve the emulsion stability in the absence of
surfactant and subsequently to prevent droplet coalescence
during evaporation. In addition, a pseudolatex of Eudragit E
was used to validate the coating properties of the formulation
for solid dosage forms. Film-coated tablets of quinidine sulfate
showed a transparent glossy continuous film that was
firmly attached to the tablet. The dissolution profile of quinidine
sulfate from the tablets coated with the Eudragit E pseudolatex
was comparable to that of tablets coated with an
acetonic solution of Eudragit E. Furthermore, both types of
coating ensured similar taste masking. The emulsificationevaporation
method used was shown to be appropriate for
the preparation of surfactant-free colloidal dispersions of
the 3 types of preformed methacrylic acid copolymers; the
dispersions can subsequently be used for film coating of
solid dosage forms.