Throughout the past three decades, there have been
significant advances in understanding the function
of skin as an active biological barrier. Research in
this field has been motivated to a large extent by the
desire to develop the transdermal route for systemic
drug delivery. Despite many feasibility studies, few
drugs today have been proven safe and effective using
this route. The major reason for this limitation is the
inherent barrier characteristics of the outermost
layer of skin, the stratum corneum.

Early attempts to overcome the barrier were centered on the use of simple
solvents or solvent mixtures, surface-active agents and fatty acids. These
materials, although capable of increasing the penetration of many chemicals
across the skin, often caused undesirable side effects, mostly centered on their
interaction with plastic polymers making up the delivery device. However, this
early work did serve to motivate the search for compounds capable of producing
skin permeation enhancement without adverse side effects.

TransDermal Technologies Inc. (TTI) has developed a patented and patent-pending
process, TDS®, which has been shown to be able to formulate unique, rapid-acting
drug-and-dose-specific delivery systems that possess broad-spectrum absorption-
enablement activity and have been very well tolerated at effective concentrations.
Extensive chemical, pharmacology, toxicology and carcinogenicity studies have
demonstrated that TDS® is composed of excipients that are generally regarded as
safe (GRAS) and which are formulated so that they do not chemically interact or
otherwise alter any known drug or compound with which they have been combined.

This overview briefly describes the chemistry, activity, and mode of action aspects
of TDS®, and why TTI believes it to be a desirable method of encouraging different
degrees of skin penetration. TTI believes TDS® holds potential for a wide range of
applications, ranging from local and systemic delivery of organic and inorganic
drugs to moving peptides and small proteins through the skin.