Design and ethics
BLIND
This was a prospective randomized, double blind, single dose, placebo-controlled, parallel group, single-centre, outpatient, and fixed-dose study. The design included a screening period (at least 14 days before surgery), surgical period, qualification period waiting for local anaesthesia to wear off (up to 6 h after surgery), and an observation period of 6 h. Patients provided written informed consent prior to any screening- and study-related procedures. The patients did not receive remunerations.