Transfersomes — A Nanoscience in Transdermal Drug Delivery and Its Clinical Advancements

The convenient nanotransdermal delivery system is always likely to have some ideal and unique characteristics, predominantly for safety, desired actions, clinical efficacy, enriched with a therapeutic index with minimal adverse occurrence. One of the most challenging tasks for the formulators is to transfer the medicament, especially macromolecules, through the skin. Some of the ways to achieve this is the use of a painful needle or some other methods which also have economical constraints. A new technology has been developed, that is ultradeformable liposomes, also called as transfersomes. These are an elastic type of lipid vesicle aggregates capable of delivering wide range of active moieties including various biomolecules. It can be manufactured by evaporation, vortexing, reverse-phase evaporation, ethanol injection or freeze-thaw methods, where phospholipids and edge activators are the major ingredients that contribute the main role in their unique mechanism of permeation through less permeable stratum corneum. This review mainly focuses on the clinical trial studies and patents accessible on transfersomal products worldwide, highlights the recent work on transfersomes with various therapeutic agents. An effort to explain the deeper penetration of transfersomes across the epidermis layer by its pharmacokinetics and dynamic properties has been taken.

Two-dimensional pollutant migration in soils of finite depth

A technique for analyzing two-dimensional migration of contaminant from a landfill into a homogeneous clayey layer is described. The analysis takes acount of the fact that the concentration of contaminant in the landfill will decrease as contaminant is transported into the soil. The analysis also allows for advective–dispersive transport within a permeable stratum (aquifer), which underlies the homogeneous layer. Consideration is given to chemical retardation arising from sorption/desorption of contaminant in the clayey layer. Some of the more important effects arising from the use of a 2-D analysis are illustrated by means of a limited parametric study. It is shown that the diffusion of contaminant from the aquifer into the clayey layer will substantially reduce the concentrations of contaminant in the groundwater away from the landfill. It is also shown that there is a critical velocity in the aquifer at which the maximum concentration at a point occurs. At greater or lesser velocities, significantly smaller concentrations may result. Thus design for limiting velocities is not necessarily conservative. Finally, the results of the 2-D analysis are compared with those from a 1-D analysis and the applicability of 1-D solutions is discussed. Key words: contaminant migration, analysis, soil, diffusion, advection, pollutant.