Dermal Fillers: A Comprehensive Explanation
Hyaluronic acid fillers are used for the majority of soft tissue procedures in the clinic and their properties are well understood.
Fundamentally, hyaluronic acid is a mucopolysaccharide, a repeating unit of N-acetylglucosamine and glucuronic acid, existing in a hydrated gel within a number of structures in the human body.
It is found in the vitreous fluid of the eye, the synovial fluid in joints and in the skin.
In physiological solution, HA displays conformational stiffness due to B-glycosidic bonds, internal hydrogen bonds and interaction with solvent.
This combined with a high molecular weight, makes even dilute HA solutions behave highly in a non- Newtonian, gel- like manner.
Chong (2005) These are the rheological and pharmacological properties which lend to its usefulness, but also the problems arising from intravascular injection.
Cross linking the bonds improves product viscosity half life insitu and current HA fillers have demonstrated longevity to 12months or more.
Natively, the half-life of HA in cartilage is 2-3 weeks, in epidermis it is less than one day, 11 and in blood it is only a few minutes.
Evidence for rapid degradation was provided by the identification of 3H2O in urine.
Calculations from the specific activity of urinary 3H2O indicated that approximately 55% of the acetyl content of the injected HA was completely oxidized within 3hrs, and 85% within the first day.
Fraser (2007) The final metabolic fate of the constituent N-acetylglucosamine and glucuronic acid has not been established as yet.
Synthetic HA is manufactured globally by a number of companies in the aesthetics industry.
The source of the filler Perlane is NASHA (non - animal stabilized hyaluronic acid) manufactured by Q-Med AG.
(Sweden) Exogenous HA like Perlane demonstrate a limited biosignature, meaning it is not readily recognised by the immune system, lending to the enhanced longevity of the product.
Companies have begun to vary the degree of cross linking to enhance longevity with balancing the effect of visible biosignature.
Hyaluronidase is an enzyme that breaks down both endogenous hyaluronic acid and synthetically made dermal fillers.
It is a bovine testicular protein that hydrolyses hyaluronic acid, a structural component of the intercellular matrix.
It is commonly used as a spreading factor in order to improve diffusion of other drugs or related compounds.
Typical applications are as an adjunct to local anaesthesia, especially in nerve blocks and ophthalmic anaesthesia (e.
g.
during cataract surgery), hypodermoclysis (infusion of relatively large volumes of fluid subcutaneously), as a spreading factor of chemotherapeutic agents, and as an adjunct in SC urography for improving resorption of radiopaque agents.
It is used for the treatment of allergic reactions to HA fillers or when hyaluronic acid fillers have been placed erroneously or where there is a cosmetic or medical need for dissolution of HA material.
Fundamentally, hyaluronic acid is a mucopolysaccharide, a repeating unit of N-acetylglucosamine and glucuronic acid, existing in a hydrated gel within a number of structures in the human body.
It is found in the vitreous fluid of the eye, the synovial fluid in joints and in the skin.
In physiological solution, HA displays conformational stiffness due to B-glycosidic bonds, internal hydrogen bonds and interaction with solvent.
This combined with a high molecular weight, makes even dilute HA solutions behave highly in a non- Newtonian, gel- like manner.
Chong (2005) These are the rheological and pharmacological properties which lend to its usefulness, but also the problems arising from intravascular injection.
Cross linking the bonds improves product viscosity half life insitu and current HA fillers have demonstrated longevity to 12months or more.
Natively, the half-life of HA in cartilage is 2-3 weeks, in epidermis it is less than one day, 11 and in blood it is only a few minutes.
Evidence for rapid degradation was provided by the identification of 3H2O in urine.
Calculations from the specific activity of urinary 3H2O indicated that approximately 55% of the acetyl content of the injected HA was completely oxidized within 3hrs, and 85% within the first day.
Fraser (2007) The final metabolic fate of the constituent N-acetylglucosamine and glucuronic acid has not been established as yet.
Synthetic HA is manufactured globally by a number of companies in the aesthetics industry.
The source of the filler Perlane is NASHA (non - animal stabilized hyaluronic acid) manufactured by Q-Med AG.
(Sweden) Exogenous HA like Perlane demonstrate a limited biosignature, meaning it is not readily recognised by the immune system, lending to the enhanced longevity of the product.
Companies have begun to vary the degree of cross linking to enhance longevity with balancing the effect of visible biosignature.
Hyaluronidase is an enzyme that breaks down both endogenous hyaluronic acid and synthetically made dermal fillers.
It is a bovine testicular protein that hydrolyses hyaluronic acid, a structural component of the intercellular matrix.
It is commonly used as a spreading factor in order to improve diffusion of other drugs or related compounds.
Typical applications are as an adjunct to local anaesthesia, especially in nerve blocks and ophthalmic anaesthesia (e.
g.
during cataract surgery), hypodermoclysis (infusion of relatively large volumes of fluid subcutaneously), as a spreading factor of chemotherapeutic agents, and as an adjunct in SC urography for improving resorption of radiopaque agents.
It is used for the treatment of allergic reactions to HA fillers or when hyaluronic acid fillers have been placed erroneously or where there is a cosmetic or medical need for dissolution of HA material.
