[Soft tissue filling with hyaluronic acid].
PHYSIOLOGY AND PHARMACOLOGY: Hyaluronan was discovered by Karl Meyer in 1934 in the vitreous humor of cattle eye. Hyaluronic acid, (AH), is a natural polysaccharide and a ubiquitous component of the extra cellular matrix. It is largely biocompatible and has a short half life. In the early 1990's, preceded by the use of bovine collagen, AH started to be employed in the fields of Dermatology and Plastic Surgery; currently it is a major intervention product in both soft tissue augmentation and facial volume loss treatments. Often well tolerated, AH, has high water retention properties and is an effective tissue volumizer. Industry first attempted to extract AH from rooster comb, then through bacterial fermentation and succeeded in increasing its lifespan by cross linking. However, industrially produced AH can contain residues from the manufacturing process. It thus appears critical to us to be informed of the process used in manufacturing AH including the reticulant utilized. Manufacturers should be legally required to publish this data as well as to conduct physiochemical follow-up studies over the short, mid and long terms.
In Europe, CE marking is a prerequisite to market injectable products. However, a CE marking does not necessarily imply that the product's efficacy and side effects have been assessed objectively in clinical studies. However, this marking is expected to fall into line with the US legislation, where the marketing of any medicinal product is subject to FDA approval, based on comprehensive animal and clinical studies and on more systematic and better centralised side effect reporting. We have examined most of the products used in Europe and internationally in 2004, whether of animal or bacterial origin, reticulated or non-reticulated, and used to restore, increase volume or as a product vector. Before injecting these products, it is essential to have a thorough understanding of their absolute and relative contraindications and anaesthetic requirements, differences between types of wrinkles to fill in and indicated techniques, differences between concerned regions or tissues, and the impact of associated cosmetic treatments. These resorbable injectable products have mild and, more importantly, short-lived side effects. However, in patients with a relative contraindication, a double test is justified, as allergic reactions are known to occur in 1 to 3% of patients. It is also advisable not to inject HA in a site previously injected with a non-resorbable product. More precise statistics on results and side effects based on double-blind randomised studies are still wanting, due to the lack of legal requirement and effective centralisation of data. Therefore, all side effects must be reported to improve our knowledge as well as the safety of injections.


CONCLUSIONS
Although their duration of effect is limited, HA products are the most commonly used fillers, before collagens. Many questions have yet to be answered, but they produce very significant results in filling procedures. Both clinicians and patients praise these products for their tolerance, resorbable nature, and limited side effects.
Ascher
B
B
Clinique IENA, 11, rue Fresnel, 75116 Paris, France. benjaminascher@wanadoo.fr
Cerceau
M
M
Baspeyras
M
M
Rossi
B
B
D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use*; D016907:Adverse Drug Reaction Reporting Systems; D002986:Clinical Trials as Topic; D004340:Drug Contamination; D006801:Humans; D006820:Hyaluronic Acid / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use*; D011640:Public Policy; D019651:Plastic Surgery Procedures / Q000379:methods*; D015361:Rhytidoplasty / Q000379:methods*
D000276:Adjuvants, Immunologic; D006820:Hyaluronic Acid