Vascular benefit of the use of mepivacaine as an anaesthetic in resilient hyaluronic acid® injectables

The use of lidocaine (0.3% w/w) for pain management in hyaluronic acid-based soft-tissue injectables has been standard for two decades. Given lidocaine's well-known vasodilatory activity it may contribute to the incidence of post-treatment adverse events including bruising in patients. This study seeks to compare these vasodilatory properties of lidocaine with that of another anaesthetic candidate, mepivacaine. Rat aortic rings and human skin resistance arteries (diameter between 200–400 μm) were mounted on an isolated organ bath or myograph, respectively, and exposed to progressively increasing concentrations of lidocaine or mepivacaine from a solution or released from a gel. The concentration-dependent vascular response and kinetics were systematically compared in tissue originating from 3 biological donors. Additionally, tissue perfusion changes induced by 0.3% w/w anaesthetic solutions were assessed using laser Doppler imaging in rabbit ears. Systematically, lidocaine exhibited a greater vasodilatory activity than mepivacaine in clinically relevant concentration ranges in both animal and human models. In contrast to lidocaine, mepivacaine did not have a significant impact on blood vessel vasodilation. In clinical practice, formulation of hyaluronic acid (HA) injectables with mepivacaine may potentially reduce the risk of common adverse events. This characteristic highlights its potential advantages in the practice of hydrogel injections.