Key rheological properties of hyaluronic acid fillers: from tissue integration to product degradation

Abstract

Aim: Over the last 15 years, hyaluronic acid (HA) fillers have become the most popular injectable biomaterial for soft tissue correction. With the increasing number of available HA fillers and the multiplication of facial treatments all over the world, there has been a need from physicians to better understand the HA fillers science. There is especially a growing interest in the science-based evaluation of rheological characteristics which represents an essential tool to guide physicians in the selection of the most appropriate HA fillers, administration techniques and depths of injection for their clinical applications. Methods: Four key rheological parameters (viscosity η, elasticity G', normal force F N and elasticity E') are measured and discussed on five HA fillers. Results: These four key rheological parameters are demonstrated to play a pivotal role, in combination with the cohesivity, for better predicting the clinical behavior of HA fillers at different stages of their lifetime. Conclusion: This article discusses the importance of four key rheological parameters during the main steps of the clinical HA fillers' lifetime, from the product injection to the loss of clinical effects. A better knowledge of these HA fillers' rheological parameters can help the physicians to optimize their aesthetic outcomes, safety and patient satisfaction.

Evaluation of the Rheologic and Physicochemical Properties of a Novel Hyaluronic Acid Filler Range with eXcellent Three-Dimensional Reticulation (XTR™) Technology

“…Crosslinking enables the HA molecules to have stable viscoelastic properties and allows for a low extrusion force when injecting the filler. It also improves filling properties and enhances the durability of the injectate [6]. Optimization of the cross-linking process enables minimal to almost zero free HA chains [3].…”

“…Crosslinked HAs are viscous, so in order to facilitate extrusion of this material through a thin gauged needle, manufacturers have purposely produced low viscosity HA fillers with high shear rates. When extruded through a 30 G or 27 G needle, the fillers then become easier to inject [6].…”

“…These properties influence the physical properties of the HA filler product and their variants, often referred to as 'ranges', which in turn affect their clinical effects. The most recognized of these formulae are the non-animal stabilized HA (NASHA ® , (Galderma Pharma S.A., Lausanne, Switzerland)), Vycross ® (Allergan Inc., Irvine, CA, USA), cohesive polydensified matrix (CPM ® , (Merz Pharmaceuticals GmbH, Frankfurt am Main, Germany)) and resilient HA (RHA ® , (Teoxane Laboratories, Geneva, Switzerland)), among others [4][5][6].…”

“…Inherently, as the market for these products continues to grow, so does the need for a better understanding of the basic science of HA fillers [6]. No individual product can be used for every indication; hence, the clinician's experience, as well as the specific guiding principles provided by the originating company, are often used as the bases for choosing the type of HA fillers that are appropriate for certain indications and for injection into specific anatomical layers.…”

Oral Gel Loaded by Fluconazole‒Sesame Oil Nanotransfersomes: Development, Optimization, and Assessment of Antifungal Activity

“…The ηmin for the FS-NTF-loaded hyaluronic acid hydrogel was recorded as 132,318 cp, a number much higher than that for the ηmin for the blank hyaluronic acid hydrogel (110,016 cp). Therefore, application of this formulation within the oral cavity might promote in increasing shear rate during talking, eating, or smiling [ 33 ]. This increasing shear rate might promote longer retention of the formulation at the site of application for the effective healing of the ulcers.…”