FORMULATION AND EVALUATION OF LIDOCAINE-ETHYLCELLULOSE PSEUDOLATICES FOR TOPICAL APPLICATION

SERAP BUYUKYAYLACI, Purdue University

Abstract

This investigation was undertaken to assess the potential use of a new class of polymeric colloidal dispersions and film forming agents as unique topical vehicles. The study also involved determining the feasibility of employing molecular scale drug entrapment in these polymeric pseudolatices as a method of producing clear films on the skin, from a completely aqueous vehicle, with drug being dispersed in solution phase in the film. The local anesthetic drug lidocaine was employed as a model drug in the study. Previously formulated ethylcellulose pseudolatex dispersions developed for tablet film coating were modified, using tissue compatible and nonirritating nonionic surfactants, nontoxic solvents and other approved ingredients. A drug entrapment method was developed in which the lidocaine was incorporated in the pseudolatex particles during the preparation of the colloidal dispersions. Various formulation studies were directed to identify plasticizers and other components which would produce physically stable dispersions which in turn would form highly substantive, clear and virtually invisible, water resistant and protective films on the skin. X-ray diffraction studies indicated that lidocaine was molecularly dispersed in the film structures. The lidocaine-ethylcellulose pseudolatices were evaluated for their physical and chemical stability by periodic measurements of solids content, sediment height, particle size, surface tension, viscosity and pH. Most of the formulations were found to be physically and chemically stable. The formulations which formed continuous and flexible films on drying were evaluated for their general film properties as formed in petri dishes and on human skin. Water vapor transmission studies were conducted on free films, as an indication of the occlusivity of the films. In vitro diffusion and in vivo pin prick studies were also performed on selected pseudolatex formulations to assess the effect of formula ingredients on drug release and on local anesthetic activity. Commercially available lidocaine products were compared to the pseudolatex formulations, and the amount of drug released from the pseudolatices in a diffusion study was found to be several times higher than from the commercially available products.

Degree

Ph.D.

Subject Area

Pharmaceuticals

COinS