In Vitro Analysis of the Degradation of Calcium Hydroxylapatite Dermal Filler: A Proof-of-Concept Study.

[BACKGROUND] A dissolving agent for calcium hydroxylapatite (CaHA, Radiesse) soft-tissue filler would be of value should inadvertent intravascular injection, vascular compromise, nodule formation, or overcorrection occur.

[METHODS] In a prospective, single-center, proof-of-concept study, 12 cadaveric porcine skin samples were injected with CaHA (0.4-0.8 mL). Samples were then randomized to intralesional injection of 0.2-mL sodium thiosulfate (STS, 12.5 g/50 mL); 1 to 2 g of topical sodium metabisulfite (SMB, 25% SMB in 120-mL gel) applied with occlusion, or both intralesional STS and topical SMB. Control samples were not treated after CaHA injection. A 4-mm punch biopsy was obtained 24 hours after treatment, and tissue sections were stained with hematoxylin and eosin and prepared for light microscopy. A board-certified dermatopathologist estimated the amount of CaHA present in each sample.

[RESULTS] Intralesional STS alone or combined with topical SMB completely dissolved CaHA in the porcine skin samples. Topical SMB treatment reduced, but did not entirely clear CaHA from the tissue samples. The control samples contained easily identifiable CaHA microspheres.

[CONCLUSION] This proof-of-concept study illustrates the potential reversibility of CaHA filler with intralesional STS, topical SMB, and the combination of both agents. Larger, in vivo, studies are now warranted to provide further insight.