Topical Gel: A Novel approach for drug delivery - Journal of ...

Formulation...Sudhir Bharadwaj et al.b. It should be stable at storage condition.c. It should be free from microbial contamination.d. It should maintain all rheological properties of gel.e. Economical.f. It should be washable with water and free from staining nature.g. It should not affect biological nature of drug.h. It should be convenient in handling and its application.i. It should possess properties such as thixotropic, greaseless, emollient, non-staining etc.1.1.5. Desirable Properties of Gellants 11a. It should be inert, compatible with addition and non-toxic.b. It should produce gels at low concentration.c. It should help gel formation.d. It should be economical.e. It should be free from microbial contamination.1.2 ANATOMY OF THE HUMAN SKIN 12The skin of an average adult body covers a surface area of approximately 2 sq.m. and receives about onethird of the blood circulating through the body and serves as a permeability barrier against the topicalabsorption of various chemical and biological agents to achieve a localized pharmacological action in theskin tissues in the various forms i.e., ointment, paste, creams, gels etc. When topical gels are applied tothe skin, the drug molecules are considered to diffuse to a target tissue and produce therapeutic effectprior to its systemic distribution for elimination. It is one of the most readily available organs of the bodywith a thickness of only a few millimeters (2.97 0.28 mm). The skin• Separates the underlying blood circulation network from the outside environment.• Serves as a barrier against physical, chemical & microbiological attacks.• Acts as a thermostat in maintaining body temperature.• Plays role in the regulation of blood pressure.• Protects against the penetration of UV rays.As skin is major factor in determining the various drug delivery aspects like permeation and absorptionof drug across the dermis. The diffusional resistance of the skin is greatly dependent on its anatomy andultra structure. The skin is capable of metabolizing many substances and through its microvasculature,limits the transport of most substances into regions below the dermis. Although the flux of solutesthrough the skin should be identical for different vehicles when the solute exists as a saturated solution,the fluxes vary in accordance with the skin penetration enhancement properties of the vehicle. It istherefore desirable that the regulatory standards required for the bio-equivalence of topical products860 J. Chem. Bio. Phy. Sci. Sec.B, 2012, Vol.2, No.2,856-867