The parenteral administration of proteins and peptides is necessary for achieving a therapeutic outcome. However, low patient acceptability and tolerance towards continuous intramuscular, intravenous or subcutaneous injections have led to poor patient compliance and increased interest in alternative extra-parenteral protein and peptide delivery systems (Zhou, 1994). Permeation enhancers, enzyme inhibitors and appropriate formulation vehicles are essential in the application of non-invasive routes as the absence thereof makes them much less effective as compared to the parenteral route of administration