Rheological Properties of Several Hyaluronic Acid-Based Gels: A Comparative Study
September 2018 | Volume 17 | Issue 9 | Original Article | 948 | Copyright © September 2018
Patrick Micheels MDa and Martinien Obamba Engb
aPrivate practice, Geneva, Switzerland bCompany Rheonova, Saint-Martin-d'Hères, France
Background: Adding lidocaine to hyaluronic acid (HA)-based gels appeared to modify their rheological properties, in the view of the first author.
Objective: This paper sought to compare the rheological properties of three CE-marked and FDA-approved gels, administered with and without lidocaine, along with two other newly FDA-approved gels.
Methods: The tested gels were as follows: NASHA® Restylane® with and without lidocaine; CPM®; Belotero® Balance with and without lidocaine; 3-D Matrix®; Surgiderm® 30XP (without lidocaine) and Juvederm® Ultra 3- Juvederm® Ultra Plus XC (with lidocaine); Preserved Network® RHA®2 (with lidocaine); Vycross® Volbella® (with lidocaine). For rheological analyses, viscoelastic data were collected with plate-plate geometry of 25mm, temperature regulated by a Peltier-effect plate, and the following assessed: Strain sweep from 0.01% to 3000% strain at 1Hz over frequency sweep from 0.1 to 100 Hz.
Results: NASHA Restylane gels with and without lidocaine exhibited similar viscoelastic characteristics, with very similar tan δ values, but the elastic modulus G’ proved significantly higher when the gel was injected with lidocaine vs without. 3D-Matrix Surgiderm 30XP gel without lidocaine and Juvéderm Ultra 3 with lidocaine exhibited similar viscoelastic characteristics, as well as tan δ values, yet the elastic modulus G’ of Surgiderm 30XP proved significantly higher than that of Juvederm Ultra 3-Juvederm Ultra Plus XC. CPM Belotero Balance gels with and without lidocaine exhibited similar G’ and G’’ values. tan δ was somewhat higher when the gel was administered without lidocaine. VYCROSS Volbella gel exhibited a higher elastic modulus G’ than the other Allergan gels, roughly nearing the NASHA gel values. Preserved Network RHA 2 gel exhibited values that were close to its partially cohesive "competitors", except for Vycross.
Conclusion: Adding lidocaine to HA gels does modify their rheological properties yet this, to a variable extent depending on the
J Drugs Dermatol. 2018;17(9):948-954.
For over 23 years, hyaluronic acid (HA)-based gels have found application in esthetic medicine across the world as an optimal product to provide soft tissue augmentation, improve facial rejuvenation and wrinkles, and correct tissue de- fects.1,2 This ubiquitous use of HA gels is primarily accounted for by its specific features, such as its lacking organ or species specificity prior to cross-linking, in addition to being non-immu- nological, highly biocompatible, and able to bind 1,000 times its volume in water. Therefore, there are no significant risks of allergic reactions when exogenous HA is directly injected into the skin, nor have there been reports of other major adverse events.3 Whereas most complications are mild and self-limiting, late reactions to HA-based fillers have been reported to occur at a rate of 0.02%, and according to the authors, their inci- dence appears to vary depending on the product applied.4 It may, however, be assumed that in daily practice, the rate of adverse events encountered following HA injections likely ex- ceeds the figures reported in scientific literature. But what are the reasons for this assumption? The point is that once crosslinked, HA is no longer a natural product and may thus be rec- ognized as a foreign body by our organism, notably the dermis, this specific layer that houses our innate host defenses. 5 Over the past decades, numerous HA fillers have been devel- oped and are now available on the EU market, with most of them likewise FDA-approved and also available on the US mar- ket. Features that differentiate the various HA fillers are particle size, crosslinking agent used, type and degree of crosslinking, gel viscosity, percentage of cross-linked HA, amount of unmod- ified HA, extrusion force, as well as elastic modulus termed G’, the latter being a measure of the gel hardness. These physical and chemical attributes have been demonstrated to influence the filler’s clinical characteristics, thereby reflecting the gel’s clinical indication, ease of injection, degree of tissue filling, longevity, clinical appearance, as well as undesirable effects. This paper sought to compare the rheological properties of three CE-marked and FDA-approved gels, given with and with- out lidocaine, along with two other newly FDA-approved gels.