Authors Kiran Sharma, Ashu Mittal, Nitesh Chauhan
Skin penetration enhancers, enhancing drug penetration into the skin through transdermal drug delivery system or topical administration, skin penetration enhancers are molecules which reversibly remove the barrier resistance of the stratum corneum and allow drugs to penetrate more readily to the viable tissues and thus enter the systemic circulation, A. vera gel increased the in vitro skin penetration of compounds depending on their molecular weights, with an apparent inverse correlation between enhancement ratio and molecular weight of the compound, penetration enhancement effect of the aloe gel, pull effect of complexes formed between the compound and the enhancing agent within the aloe gel, administer drugs through skin is transdermal patch, delivery rates tend to be below therapeutic levels due to the barrier function of the skin, Transdermal delivery of drugs , oral or intravenous administration, though human skin, human skin provides an effective barrier to the permeation of most drugs in the form of stratum corneum, drugs must breach this barrier and permeate the skin at a rate sufficient to attain effective plasma concentration, enhance the skin permeation rate of active moieties, use of chemical penetration enhancers such as DMSO, DMF, azone, ionic surfactants, but their use are also associated with unpleasant and toxic side effects, natural compounds as permeation enhancers to improve drug permeation that also exhibit low toxicity while maintaining their enhancing activity, natural absorption promoters documented so far include essential oils, terpenes, terpenoids, fatty acid esters, fatty acid glycols, and herbal extracts, herbal penetration enhancers which have received much attention and an enhancement system based upon a product is Aloe Vera, which appears as an attractive prospect due to its purported skin friendly and humectant properties, Aloe Vera also possess skin penetrative property, is a good vehicle for transport other substances, aloe Vera is responsible for increased skin penetration of co-formulated drugs, Aloe Vera Gel promotes wound healing by directly stimulating the activity of macrophages and fibroblasts, Fibroblast activation by Aloe Vera Gel has been reported to increase collagen and proteoglycan synthesis, thereby promoting tissue repair, polysaccharides composed of several monosaccharides, predominantly mannose. It has been suggested that mannose 6-phosphate, the principal sugar component of Aloe Vera Gel, may be partly responsible for the wound healing properties of the gel. Mannose 6-phosphate can bind to the growth factor receptors on the surface of the fibroblasts and thereby enhance their activity, mechanism of action of acemannan appears to be twofold. First, acemannan is a potent macrophage-activating agent and therefore may stimulate the release of fibrogenic cytokines. Second, growth factors may directly bind to acemannan, promoting their stability and prolonging their stimulation of granulation tissue, The higher the molecular weight of the co-applied compound, the less of the gel components were transported across the skin, displacement of Aloe vera components from the penetration pathways and thereby it inhibits, permeation of the gel components more effectively than the smaller compounds, intestinal drug absorption enhancement, Aloe Vera has an element called Lignin which helps it to penetrate right down to the cellular level, rate of vitamin C absorption- bioavailability of vitamin C was 3 times higher when administered with the aloe gel, For vitamin E, the bioavailability was 3.7 times higher when administered with aloe gel, he mechanism of action of the aloe products to improve the bioavailability of the vitamins was explained to be a possible protection effect against the degradation of the vitamins in the intestinal tract as well as binding of the polysaccharides to the vitamins and thereby slowing down the absorption rate, A. vera gel and whole leaf extract could decrease the transepithelial electrical resistance of intestinal epithelial cell monolayers (Caco-2), thereby indicating opening of the tight junctions between adjacent epithelial cells, aloe vera able to significantly increase the transport of the macromolecular peptide drug, insulin, across the Caco-2 cell monolayers, Drug absorption enhancers are compounds capable of reversibly removing the resistance of the outer layers in the body with minimum tissue damage, thus allowing the drug to enter the blood circulation in sufficient quantities, Drug absorption enhancers are compounds capable of reversibly removing the resistance of the outer layers in the body with minimum tissue damage, thus allowing the drug to enter the blood circulation in sufficient quantities, functional excipients in dosage forms, which include binders, disintegrants, emulsifiers, suspending agents, gelling agents and sustaining agents in modified release tablets, some natural gums and mucilages have been reported to modify the release of drugs from modified release dosage forms such as matrix type tablet, Skin penetration properties: Penetration enhancers work by means of two possible mechanisms: (1) the penetration enhancer increases the solubility of the drug within the SC by altering the partitioning of the drug into the SC and/or (2) the penetration enhancer influences the diffusion of the drug across the SC by disrupting the ordered nature of the skin lipids. Lignins as structural material of cellulose content allows for penetration properties, Aloe Vera can soak into all the layers of the skin and this may be helpful in increasing the penetration of certain drug molecules across the skin, as lignins can penetrate the toughened areas of the skin
