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Hyaluronidase
Hyaluronidase
Hyaluronidase is an enzyme that breaks down hyaluronic acid,5 an acid mucopolysaccharide present in the dermis. When added to local anesthesia, hyaluronidase facilitates diffusion of the anesthetic through soft tissues. This results in a wider field of local anesthesia, faster onset of action, less tissue distortion, and easier tissue undermining.26 In ophthalmology, hyaluronidase additives allow the surgeon to minimize injection sites, decrease the volume of anesthesia used, and lessen the bruising risks for the patient.5 Doses in cutaneous surgery vary. Some authors recommend that 150 units of hyaluronidase be mixed in 20 to 30 mL of lidocaine for a concentration of 7.5 units/mL.27
There are some risks with using hyaluronidase, including decreased anesthetic duration and a greater risk of toxicity due to enhanced absorption.27 Hyaluronidase also contains the preservative thimerosal,5 which is a contact allergen. Preoperative skin testing in highly sensitive patients is recommended prior to its use.5,27 Hyaluronidase should also not be used in those with a documented bee venom allergy.28