Comparing Water Absorption of Food and Drug Administration–Approved Hyaluronic Acid Fillers

Abstract

BACKGROUNDTo compare the water absorption of 12 FDA-approved hyaluronic acid (HA) facial fillers in vitro in conditions relevant to in vivo injection.OBJECTIVEThe goal of this study was to provide long-term insight into an improved, tailored facial rejuvenation approach and to understand sequelae that could affect preoperative surgical planning.METHODSIn 2 experiments, 12 FDA-approved HA fillers were loaded into test tubes with nonpreserved normal saline and then placed in a 94.5°F–96°F environment for 1 month to allow water absorption by passive diffusion. The test tubes were centrifuged so that the hydrated filler could pass to the bottom of the tube. The tubes were centrifuged for 12 minutes at 1,200 revolutions per minute in the first experiment and for 7 minutes in the second experiment. A blue dye was then instilled to demarcate the filler/saline interface.RESULTSThere was variation in the water absorption of different HAs. Low absorption occurred in non–animal-stabilized hyaluronic acid.CONCLUSIONThe pattern of water absorption was similar in the 2 experiments. The results inform us about in vivo conditions and provide guidance for filler selection.

Evaluation of the Hydrophilic, Cohesive, and Physical Properties of Eight Hyaluronic Acid Fillers: Clinical Implications of Gel Differentiation

“…In a later study, investigators rotated the centrifuge at 1200rpm for twelve minutes (total of 14,400 revolutions) and raised concerns that longer durations could potentially compress the saline out of the hydrated HA. 10 To ensure our results could be compared to these earlier works and account for the aforementioned concerns regarding the potential compression of the sample, we arbitrarily reduced the centrifuging time to five minutes since our centrifuge rotated at the same speed as that used in the first paper (total of 17,500 revolutions). After the centrifugation was completed, 10 μL of blue dye (DipQuick counter stain # 3) was gently pipetted onto the top surface of the sample.…”