Pharmaceutical dosage forms contain both pharmacologically-active compounds and excipients, which have been added to aid the formulation and manufacture of the dosage form. The properties of the final dosage form are highly dependent on the excipients chosen, their concentration and interaction with both the active compound and each other. Excipients cannot be regarded as inert or inactive ingredients and a detailed understanding of their physiochemical properties, safety and handling, and regulatory status is essential for pharmaceutical scientists.¹

There has been increasing interest in the use of bioadhesive polymers as excipients in the design of drug delivery systems. One of the advantages of using these materials is that they can maintain contact with mucosal surfaces for longer periods than nonbioadhesive polymers. Because polymers possessing bioadhesive properties can retain drugs in close proximity to membranes rich in underlying vasculature, they may offer a solution to the poor bioavailability of some drugs and a method to avoid enzymatic degradation of others.

Figure 1 Conversion of PMVE/MA to its corresponding acid by hydrolysis.

Materials and MethodsMaterials. Gantrez AN-139, a copolymer of MVE and MA was provided by ISP Co. Ltd (UK). Glycerol, tripropyleneglycol methyl ether (TPM [Dowanol]) and methylene blue were obtained from Sigma Aldrich (UK). All other chemicals used were of analytical reagent quality.