Pseudolatex topical therapeutic systems for hydrocortisone

Glen Gary Lawrence, Purdue University

Abstract

In these studies, stable hydrocortisone and placebo pseudolatex systems were manufactured using only polymeric, nonionic surfactants to achieve the processes of emulsification and stabilization. These systems did not employ sodium lauryl sulfate or cetyl alcohol as emulsifiers or stabilizers which had been used in previous pseudolatex systems. Hydrocortisone and placebo pseudolatex systems were evaluated by a series of physical and chemical investigations. These studies were concluded by conducting a physical stability evaluation on six pseudolatex systems. The criteria for selection of the systems were: the surfactant system employed (Pluronic F68 or a 1:1 mixture of Pluronic F38 and F127), and the inclusion/exclusion of both benzyl alcohol and hydrocortisone within the pseudolatex systems. Physical methods included ultracentrifugation to examine the distribution of drug within the product and the use of a fiber optic Doppler anemometer to measure the particle size of the pseudolatex beads. The particle size remained fairly constant over a one year period. The particle size studies confirmed by SEM studies on an unplasticized cast film. The hydrodynamic diameters of beads exhibiting Brownian motion were on the order of 250 nanometers. The partially coalesced, deformed beads in the cast films of an unplasticized system had measured particle sizes on the order of 300 nanometers. Both methods yielded relatively narrow particle size distributions. Negligible sediment formed over a year. Viscosities of the systems were very consistent over the same period. The rheologic studies were conducted by pipet flow viscometry and confirmed by a cup and bob viscometer. The systems manufactured were Newtonian and maintained their viscosity within a range of 5 to 15 cps over a year. Chemical evaluations centered on measuring hydrocortisone concentrations in the product, as well as monitoring the product pH. The hydrocortisone concentrations were measured by a stability indicating HPLC assay developed for these studies. These studies indicated that approximately 70 to 80 percent of the drug resides within the bead phase. The hydrocortisone pseudolatex products exhibited decreases in hydrocortisone concentration and product pH as a function of time and temperature.

Degree

Ph.D.

Advisors

Peck, Purdue University.

Subject Area

Industrial engineering

COinS