Comparison of the in vitro release characteristics of mucosal freeze-dried wafers and solvent-cast films containing an insoluble drug

Abstract

Drug release characteristics of freeze-dried wafers and solvent-cast films prepared from sodium carboxymethylcellulose have been investigated and compared. In vitro drug dissolution studies were performed using an exchange cell and drug release was measured by UV spectroscopy at 272 nm using distilled water. The dissolution profiles of hydrochlorothiazide from the wafers and films were compared by determining the rates of drug release, estimated from the % release versus time profiles and calculating their difference (f₁) and similarity (f₂) factors. The effects of drug loading, polymer content and amount of glycerol (GLY) (films) on the drug release characteristics of both formulations were investigated. Both the wafers and films showed sustained type release profiles that were best explained by the Korsmeyer–Peppas equation. Changes in the concentration of drug and GLY (films) did not significantly alter the release profiles whilst increasing polymer content significantly decreased the rate of drug release from both formulations. The rate of release was faster from the wafers than the corresponding films which could be attributed to differences in the physical microstructure. The results show the potential of employing both formulations in various mucosal drug delivery applications.

Keywords::

• Carboxymethylcellulose
• drug dissolution
• hydrochlorothiazide
• mucosal delivery
• release mechanism

Acknowledgements

The authors are grateful to Pfizer Ltd., UK, for funding this project and to Hercules Inc. for donating carboxymethylcellulose.

Declaration of interest

This project was funded by Pfizer UK. The authors report no declarations of interest.