Electronic Theses and Dissertations

Date of Award


Document Type


Degree Name

Ph.D. in Pharmaceutical Sciences

First Advisor

S. Narasimha Murthy

Second Advisor

Michael A. Repka

Third Advisor

N. P. Dhammika Nanayakkara


University of Mississippi

Relational Format



Topical drug delivery such as creams and emulsions are most widely used in the treatment of skin diseases. It offers advantages such as non-invasiveness, direct drug delivery at the site of action, patient compliance and lower cost of treatment. However, topical formulation development faces challenges in the market in terms of critical evaluation parameters for understanding the effect of manufacturing process variables, the role of excipients and the effect of its compositions and skins buffering capacity. The main objective of the first project was to investigate the effect of different manufacturing process variables which can influence the microstructure thereby understanding the influence of process parameters on the performance of these creams. The custom-made formulation with the application of nile red for visualization of globule size in o/w creams was used for this study. The results revealed that the difference in globule size has influenced textural properties and yield stress. This study elucidated the relationship between the globule size and performance of creams. The second study was aimed to evaluate the influence of incremental change in the concentration of a surfactant on the quality attributes and performance of semisolid topical products. The critical quality attributes of these products did not differ significantly but there was a significant difference in their permeation flux-time profile. One of the major reasons was found to be due to the rate of change of thermodynamic activity during the process of evaporative metamorphosis. In the third project, we evaluated the buffer capacity of topical products as a critical quality attribute and impact of buffer capacity on the performance of topical products. In this project, we investigated the role of the buffering capacity of formulations as a critical quality attribute. Herein we found that skins buffering capacity can alter the pH of formulation on the application site. The results shothat the creams with poor buffer capacity would end up changing their pH and match with the skin’s pH. Whereas, the formulations with buffer restricted the physiological interaction of skin with the formulation pH and sustained the original pH of topical product for a longer time.

Available for download on Wednesday, August 31, 2022