HYDROGEL: A NEW
RADIATION-PROCESSED SURGICAL DRESSING
Dr.
Lalit Varshney*
The Bhabha Atomic
Research Centre, Mumbai has developed a new hydrogel wound dressing
technique as a spin off of basic research being pursued in its
Chemistry and Isotope Group in the fields of radiation chemistry
and radiation technology. It has proved highly effective in healing
almost all types of external wounds. Known as Hydrogel Dressings,
it is now available in the market under the brand name ‘HI-ZEL’.
Extensive clinical studies have established its safety and shown
that it is not only an excellent first aid for burns but also
cures other wounds which are difficult to heal like diabetic foot
ulcers, leprosy ulcers and animal bites. Its applications are
expected to be useful in more and more diseases. Hydrogel
dressings are gaining widespread acceptance abroad. But their
local use was restricted due to very high cost of imported dressings.
Radiation processing technology developed at BARC produces high
quality hydrogel dressings at a fraction of the market cost of
imported material.
The use of hydrogel
dressings has several applications in the medical field. Drug
delivery devices, contact lenses, wound dressing, artificial cartilage’s
or membranes, vascular prosthesis and gel-coated catheters are
some of the examples. Generally, hydrogels contain more than 50
per cent of water entrapped in a three-dimensional network structure
of a polymer. The high water content makes them highly biocompatible.
Natural skin is the
best functional cover to the wound but its use is not practical.
So second best dressings have to be used. Among the economical
dressings cotton gauze, sofra tulle, potato and banana peels are
currently in use. The list of expensive dressings consists of
collagen, amniotic membranes, elastogel, omniderm and burn free.
Depending on wound conditions, medicated as well as non-medicated
dressings are used.
A dressing should
ideally maintain moist environment at the wound -dressing interface.
It should be possible to use on infected wounds, below or non-adherent
and mechanically strong, transparent and flexible, provide mechanical
protection and cushioning effect, should not require frequent
changing, safe to use, good absorption characteristics, impermeable
to micro-organism, sterile, available in required size possibility
of delivering drugs without removing dressing and cost-effective
Normally, three to
four different types of dressings would be needed to meet all
these criteria. The new dressing developed by BARC meets almost
all requirements and hence is an ideal wound dressing. The unique
advantages of radiation processing technology is that it packs
most of the enlisted characteristics in a single-stage manufacturing
process. The technology is environment-friendly as it leaves no
residue or pollutant in the environment.
Technique
In the present process,
one of the most biocompatible polymers, polyvinyl alcohol (PVA)
and a mixture of naturally occurring polysaccharides like agar
and carrageenan are mixed together. The hot, aqueous solution
of this mixture is poured in disposable plastic trays and sealed
in polythene bags. These bags or pouches are then sent to ISOMED
for radiation sterilization resulting in ready-to-use hydrogel
dressing. The process is such that the dressing formation and
sterilization is achieved simultaneously due to the unique properties
of gamma radiation processing. This results in economic manufacturing
and a high quality of the hydrogel dressing.
The process does
not involve the use of initiators, plasticizers, antimicrobials
and mechanical support. It thus gives us a pure hydrogel dressing
free from chemical contaminants. The dressing contains about 90
per cent water. Yet it has the capacity to absorb further water,
almost equal to its weight. On its application on the wound, it
could reduce the skin temperature by 80 to 10 0 C and maintain
this differential for a very long time. This property is very
useful in reducing the depth of burning and restricting the burn
damage to the body surface. Hydrogel dressings reduce pain by
cooling and covering the open nerve endings and thus are very
useful in plastic surgery. The dressing is elastic in nature and
has high compression strength. It provides a good cushioning effect
and thus could be used in treating bedsores. Dry wounds can be
best treated with hydrogels. Hydrogel dressings hydrate the desiccated
wounds which is essential for healing. Absorption and hydration
properties of the dressing softens the wounds containing pus and
sucks out the slough, making the wound clean which helps in early
healing.
Utility
Most hydrogel dressings
available in the international market are not suitable for use
on infected wounds. The dressing produced by BARC on the other
hand, can also be converted into Iodine-hydrogel (antimicrobial-hydrogel)
by the user himself to get the best properties of germicidal iodine
and that of hydrogel. This antimicrobial hydrogel could be prepared
by simply dipping the dressing for a few seconds in an Iodine
solution. Available at a chemist’s shop, the tincture of iodine
or lugol solution (diluted 1 part in 4 parts of distilled water)
could be used as iodine source. The transparent gel changes into
blue-black coloured gel. On applying to the wound,
iodine in the gel is slowly released into it. Iodine has a tendency
of reacting much faster with bacterial proteins as compared to
human proteins and thus inactivate the microorganism. A complete
consumption of iodine is indicated by the gel reverting back to
its original colour. In the same way, other water-soluble drugs
can first be absorbed and applied across the wound. This allows
ample freedom to a practitioner to try different medications for
treatment.
Although self-adhesive,
it is preferable to have a secondary bandage as well to secure
the hydrogel dressing. The size of the dressing should be larger
than the wound perimeter. If dried on the wound, hydrogel dressing
should be rehydrated by first wetting the dressing, using boiled,
cooled or distilled water for 10 to15 minutes to ensure a painless
removal of the dressing. For exuding wounds, three to four parallel
cuts on the gel could be made using surgical knife before application.
The excess exudate could then be absorbed into the secondary bandage
such as absorbing cotton.
BARC hydrogel dressings
have so far been used for treating burns, leprosy ulcers, animal
bites, diabetic foot ulcers, cancer-related external wounds, herpes,
fresh scars, bullet injuries, boils, pimples, sun burns and abrasion
with excellent results. Its application and some of the examples
are shown in the pictures.
Recently, the technology
has been transferred to a Vadodara- based pharmaceutical firm
for commercial production of the dressing. Its dressing is now
available in the market under brand name HI-ZEL. (PIB Features)
*Senior Scientist,
ISOMED, Chemistry & Isotope Group, BARC, Mumbai Pictures can
be downloaded from www.pib.nic.in.
