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Low Risk, Patient
Friendly Microneedle Arrays: An Emerging
Medical Device for Enhanced Local/Systemic, Transdermal
Drug Delivery
Hollow MNs have also
been used as a conduit for drug diffusion into the skin
from a non-pressurized drug reservoir.
Dissolvable
microneedle
In contrast to coated
MNs, polymer MNs have been developed to completely
dissolve in the skin and thereby leave behind no
bio-hazardous sharps waste after use (Figure 5,
drug-loaded MNs).
These MNs are typically
made solely of safe, inert, water-soluble materials, such
as polymers and sugars that will dissolve in the skin
after insertion. While dissolving MNs can be used as a
skin pretreatment to increase permeability, drugs are
often encapsulated inside the microneedle for release into
the skin similarly to coated MNs.
All these types of
microneedle mostly suitable for delivery of biomolecule
and fabricated via different technique like solvent
casting, photolithography, ion etching etc. The most
usable technique is solvent casting technique by means of
centrifugation, pressure or vacuum as driving force to
fabricate MNs.
Application of
microneedle based transdermal patch system :
Microneedles have been
explored for varied applications ranging from systemic and
local drug delivery to cosmetic applications. Owing to
benefit of minimal skin invasion and pain free delivery,
MNs serve as an alternative to conventional hypodermic
therapy and have been employed for ocular, systemic and
intracellular drug delivery. Varied applications are MNs
are briefly summarized below :
1. Delivery of
immunobiologicals:
Microneedles have an
edge over conventional vaccination delivery systems with
associated needle phobia and the pain associated with
insertion of needle into the skin and chances of
occurrence of infectious diseases. MNs can be used for the
administration of immunobiologicals via the subcutaneous,
intramuscular or intradermal route.
2. Delivery of
biopharmaceuticals:
Owing to the harsh
gastric environmental conditions including acidic pH,
proteolytic degradation and hindered absorption, bioactive
macromolecules such as heparin, insulin, growth hormones
are not administered orally. The majority of
biopharmaceuticals are administered via the parenteral
route. Microneedles can be used for systemic delivery of
biopharmaceuticals via skin with no associated pain or
chances of infection.
3. Delivery of small
molecule synthetic drug substance:
It is essential for a
drug molecule to possess necessary physico-chemical
properties like lipophilicity and low molecular weight to
cross the skin barrier. Transport of a drug molecule
through the skin and also the rate of transportation are
governed by these physico-chemical properties like
hydrophilic-lipophilic balance, solubility, molecular
weight, etc. These challenges posed in transdermal drug
delivery can be overcome by use of microneedles based drug
delivery.
4. Diagnosis:
The use of microneedles
along with quantum dots can be employed in the field of
diagnosis. Hollow microneedles acts as channels for
delivery of nano scale crystals with a light-emitting
property which in turn would help in medical diagnosis.
5. Cosmeceuticals:
Treatment of skin
conditions like ageing (wrinkles, lax skin), scarring
(acne, surgical), photo damage, hyperpigmentation (age/
brown spots) and hair loss (alopecia) can be easily and
effectively done with the aid microneedle technology.
CONCLUSION:
Microneedle patch based
transdermal systems have evolved as an alternative to
conventional hypodermic injections for a number of
clinical applications. MNs based technology can offer
pain-free drug delivery also eradicating the chances of
infection. Microneedle based technology would be
beneficial particularly in paediatric vaccinations where
it can help dispel anxiety and actually enhance
participation. Microneedle based patch systems are
emerging as promising technology and can be foreseen as a
complete replacement of injectables.
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