• Patchless Transdermal Drug Delivery ... - Ecn5.com ecn5

10
MARCH 2011 • TransDermal
philic, it also helps to moisturize the skin, an added
benefit.
PharmaDur film on the skin serves as a matrix for
the drug and other nonvolatile excipients for the
product formulation. The skin retains the polymer
film and the drug contained therein for 24+ hours,
and the film provides continuous release of the drug
by a process of diffusion for transdermal delivery to
the body (Figure 2). The formed polymer film is not
removed by perspiration or articles of clothing or
transferred by touch. Thus, it functions as a virtual
patch without the limitations of plastic patches.
Formation of an invisible hydrogel patch for time
release of medications is an attractive concept for the
Figure 2
Schematic Diagram of PharmaDur Virtual
Patch on Skin
Figure 3
Comparison of Flux of Caffeine with Oleic Acid
Formulations (controls) and with Added 2%
PharmaDur Polymer
consumer. A cosmetically elegant and invisible virtual
patch is a unique concept for transdermal delivery
of drugs, such as nonsteroidal, anti-inflammatory
drugs (NSAIDs) for systemic activity. The
virtual patch provides the following key advantages:
• Delivers drugs requiring a high dosage or those
with low skin permeability effectively since
patients can apply the product over a large area of
skin (~ 300 to 500 cm2).
• Provides all-day, sustained therapeutic efficacy
with a once-a-day application due to its long-lasting
retention on skin, which also improves convenience
for and compliance by consumers.
• Reduces undesirable side effects due to avoidance
of peaks and valleys in systemic drug concentrations
as are typically found with oral drug
administration.
• Delivers many drugs that are not suitable for
transdermal administration using conventional
plastic patches and semisolid dosage forms.
Furthermore, our studies have shown that the Pharma
Dur polymer acts synergistically with skin-penetration
enhancers in maximizing the rate of transdermal
drug delivery. For example, Michniak et al
(28) previously reported the effect of PharmaDur
polymer on transdermal permeation of caffeine in
the presence of the enhancer oleic acid. The re -
searchers studied the skin-permeation rate of caffeine
with and without the PharmaDur polymer,
using human cadaver skin and Franz diffusion cells.
The presence of the PharmaDur polymer almost
doubled the skin-permeation rate of caffeine compared
to that of the control formulation consisting of
caffeine and oleic acid (Figure 3).
The researchers postulate that the PharmaDur polymer
film provides controlled release of both caffeine
and the enhancer, thereby maximizing the enhancement
in the caffeine permeation rate.
Conclusion
Patchless TDD is emerging as a convenient and
patient-friendly means for extending the scope of
transdermal delivery of drugs. Several new products
and technologies using this approach for eliciting
both local and systemic therapeutic effects have
emerged in the last decade.