Date of Award

1997

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Pharmaceutical Sciences

First Advisor

M. Serpil Kislalioglu

Abstract

In this study, six different types of cellulose acetate butyrate (CAB) were used to microencapsulate ascorbyl palmitate. Their molecular weight ranged from 53,937 to 264,362. They have varying acetyl, butyryl and hydroxyl contents. By using nonsolvent addition microencapsulation method, ascorbyl palmitate microcapsules were prepared with each fraction and their physical chemical properties including yield, mean particle size, size distribution, degree of aggregation, drug loading and release characteristics were evaluated. The relationship between the formulation variable responses including rnicrocapsule yield, microcapsule size, size distribution, drug loading and degree of aggregation and the polymer molecular weight, viscosity of the polymer solution and polydispersity of the polymer were evaluated by Stepwise Regression Analysis. The effects of molecular weight of cellulose acetate butyrate on the formulation variables but drug loading were significant. The mean particle size and size distribution of microcapsules increased with increasing molecular weight. Solution viscosity and polydispersity of the polymer also affected the mean particle size. The microcapsules made with lower molecular weight polymer caused more aggregation. Drug loading was affected by the solution viscosity and polydispersity. Stepwise Regression Analysis also indicated that viscosity and polydispersity of the polymer were also influenced by polymer molecular weight. Higher molecular weight of the polymer results in the higher viscosity and larger polydispersity. The burst release was influenced by both the solution viscosity and polydispersity of the cellulose acetate butyrate. Higher viscosity of the polymer solution and smaller degree of polydispersity resulted in the smallest burst effect. The steady state release profiles fitted equally well to both HIGUCHI and Zero Order Equations. However, there is no significant difference between the steady state release rates of the six polymers. Lower viscosity of the polymer solution resulted in larger amount of release in one and eight hours. Polydispersity also affected the total amount release in one hour. The total release in one hour increased with larger degree of polydispersity.

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