Drug transfer through mucus

Mucus is a complex aqueous mixture of glycoprotein. lipid. salts and cellul ar debris covering many epithelial surfaces in the human body. It affords p rotection for the underlying tissues from various environmental insults and the effects of enzymes or other chemical agents. In performing its functio ns, mucus may adversely affect the absorption or action of drugs administer ed by the oral, pulmonary, vaginal, nasal or other routes. The nature of mu cous in normal and diseased states is summarized and discussed in this revi ew. The study of the permeability of native or purified mucous gels is also important to understanding how it may alter the action or absorption of dr ugs that come in contact with epithelial surfaces. Various methods for stud ying mucous permeability and models for analyzing permeation data are discu ssed. A compilation of drug permeability data through various types of mucu s is included. Drug binding to mucus is also important to understanding the relative importance of hindered diffusion versus drug binding to altered p ermeability through mucous layers. This is discussed with methods for and r esults of drug-mucus binding studies. (C) 2001 Elsevier Science B.V. All ri ghts reserved.