The use of injectable materials for filling or plumping up
facial lines and wrinkles dates back to 1981 in the U.S.
when collagen injections became available. From 1981 to
2003, for over twenty years, injectable collagen was the
only available facial filler. While the injection process
was easy, the popularity of collagen injections was limited
as its effects were very short-lived usually lasting around
6 weeks or so. Because the collagen material was
bovine-derived (from cows), a skin test was required prior
to injection and a small percent of patients had allergic
reactions, thus not being capable of treatment. Since 2003,
a new synthetic material has become commercially available
and collagen is now 'a material of historic interest'
primarily. This new material is hyaluron or hyaluronic acid.
Hyaluron (HA) is produced today by fermentation in cultures
of equine streptococci. The fermented material is then
stabilized via epoxidic cross-links of the
glycosaminoglycan chains. As a result of this processing
method, the HA material does not cause immunologic
sensitization and virtually no risk of allergic reactions.
Hyaluronan is a polysaccharide that is an essential
component of the extracellular matrices in which all human
tissues differentiate. In certain tissues, such as the
vitreous cavity of the eye and synovial joint fluid, it is
the major constituent. Unlike collagen, it is identical
across all animal species and microbes. The largest amount
of hyaluronan resides in skin, where it is present in both
dermis and epidermis. Hyaluronan's high capacity for
holding water and high viscoelasticity give it some unique
properties that are useful in various medical and
pharmaceutical applications.
Because it retains moisture, hyaluronan is used in some
cosmetics to keep skin young and fresh-looking. As we age,
the water-holding capacity of our skin decreases as
hyaluronan depolymerizes. Therefore, the retention or
insertion of hyaluronan into the skin is theoretically
helpful in wrinkle reduction. HA can be rather rapidly
degraded and is ultimately metabolized in the liver. Modern
processing methods have produced more stable forms of HA
that have much longer in vivo retention times. As
degradation occurs over time, water is attracted to the
material at the site of implantation. As the HA
concentration decreases, more water bonds to it thus
helping with cosmetic persistence. This feature is what
probably accounts for its longer volume retention effects
than bovine collagen. (isovolemic degradation)
A variety of differing grades of transparent gels are
available, based on the same type gel from highly
concentrated (20mg/ml)stabilized HA, which varies in
particle size and subsequent indication. Restylane has a
particulate size of 100,000 gel particles/ml, flows through
a 27 gauge needle, and is indicated for mid-dermal
applications such as deeper wrinkle reduction, as well as
lip augmentation, nasolabial folds, and glabellar creases.
Restylane Fine Lines has the highest concentration at
200,000 gel particles/ml. It can be injected through a 30
gauge needle, and is indicated for thin superficial
wrinkles. The lowest concentration gel is Perlane at 8,000
gel particles/ml which is injected through a 27 gauge
needle and is intended for shaping facial contours,
correcting deep folds, and for lip augmentation. Restylane
was FDA-approved in December 2003, Perlane received its
approval in 2007. There are numerous manufacturers of HA
injectable fillers which, in addition to Restylane,
includes Captique and Juvaderm.
The universal HA composition makes the need for
pre-injection skin testing unnecessary as the risk for
hypersensitivity reactions is minimal. It is easily
injected and flows nicely through small-gauge needles.
While not permanent, its persistence is reported to exceed
bovine collagen with estimates of between 4 and 6 months
post-injection.Rare side effects, that I have not yet seen,
include injection site inflammation at an incidence of
0.02% and local hypersensitivity reactions (swelling,
erythema, and induration) at an incidence of 0.02% lasting
a mean of 15 days.
As of today in 2008, HA injectable soft tissue fillers are
the gold standard by which all future injectable filler
materials will be compared.
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Dr Barry Eppley runs a private plastic surgery practice
through his hospital-based medspa locations at Clarian
Health in Indianapolis. To learn more about the latest
trends in plastic surgery, spa therapies, or skin care, go
to his daily blog, http://www.exploreplasticsurgery.com .
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