Abstract
is considered to be small, since this pathway occupies less than 0.1% of the total surface area of the intestinal epithelium, and the presence of tight junctions (TJ) between the epithelial cells limits drug absorption. These drugs have low intrinsic membrane permeability, probably because of their low lipophilicity and zwit- terion character at physiological pH or act as a substrate to drug efflux pumps like p-glycoprotein, ionic charge and high molecular weight. WHO listed out the BCS class III drugs, they are shown in below Table-1 Abstract Penetration enhancers are present in a large number of transdermal, dermatological, and cosmetic products to aid dermal absorption of curatives and aesthetics. Delivery of hydrophilic drug by per oral route has always fascinated the researchers. Hydrophilic drugs show low bioavailability through oral administration because of their poor intestinal permeation & absorption. In the last few years there has been great interest focused on search of different intestinal permeation enhancers for the oral delivery of BCS class III drugs, small polar molecules, vaccines, hormones, peptides and proteins, which are well suitable for the delivery of the above products to give enhanced bio- availability by increasing intestinal permeability. This review targets to discuss functioning, anatomy and physiology of the intestinal barrier, drug absorption from intestinal tract, mechanism of intestinal drug permeability, detail information about intestinal permeation enhancers and its mechanism of action, invitro methods for studying drug permeability, and importantly the advantages and applications of newer permeation enhancers
Highlights
To optimize bioavailability of orally administrated drug is one of the most important aims for the pharmaceutical research arena
In the last few years there has been great interest focused on search of different intestinal permeation enhancers for the oral delivery of BCS class III drugs, small polar molecules, vaccines, hormones, peptides and proteins, which are well suitable for the delivery of the above products to give enhanced bioavailability by increasing intestinal permeability
The drugs which are small and lipophilic in nature are permeated through the intestinal barrier whereas oral administration of macromolecules are restricted by the intestinal epithelial barrier which results in greatly reduced bioavailability .A great number of currently available drugs fall under the class III of the biopharmaceutical classification system1, possess high therapeutic potential but cannot be delivered by oral route because of its poor permeation across the GIT epithelia
Summary
To optimize bioavailability of orally administrated drug is one of the most important aims for the pharmaceutical research arena. Transport across mucosal membranes is a fundamental step for oral absorption and systemic availability. In genera[1], these are hydrophilic compounds, of medium to high-molecular weight, and sometimes containing strongly charged functional groups implying that transport across the intestinal barrier occurs essentially via the paracellular pathway. The contribution of the latter to intestinal absorption dC/ dt = D d2C/dx2 ---------- (1) Where,.
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