Hyaluronic acid gel based on CPM ® technology with and without lidocaine: Is there a difference?

BACKGROUND: In 2011, a cohesive polydensified matrix (CPM® ) hyaluronic acid (HA) gel filler was approved by the USA Food and Drug Administration. In 2014, lidocaine was added to the gel during its manufacturing process.

OBJECTIVES: To compare the behavior and rheological properties of a CPM® HA gel with and without lidocaine.

METHODS: In our office, we performed simple tests to document the cohesiveness and resistance to traction force of both gels. In two different laboratories, the rheological properties of both gels were measured. We used comparative data of the gel without lidocaine collected from over 6 years. We also observed the gels' behavior when injected into the superficial and mid-reticular dermis, comparing their distribution using both ultrasonography and histology.

RESULTS: Over more than 10 years, we observed no difference between both gels, even if clinically we felt a difference in the gels' viscosity upon injection. Their behaviors during injection were similar. Using more sophisticated tests measuring the gels' rheological properties with different techniques, namely sheer sweeps, a difference was, however, noted between the two gels.

CONCLUSIONS: Adding lidocaine to CPM® HA gel renders it more viscous. Whether this means a difference in the clinical results, however, would require a comparative clinical study over an extended time period.