2.2.3. Randomization and Group
The method of centralized random grouping was adopted, and each research center competed to be included in the group. During the first 48 h of the study period subjects were randomized in a 1 : 1 : 1 ratio to the IVIB 400 mg group (diluted to 200 ml 0.9% NaCl), the IVIB 800 mg group (diluted to 200 ml 0.9% NaCl), and the placebo group (200 ml 0.9% NaCl) using a double-blind, simple randomization protocol. The first dose of ibuprofen or placebo was administered 30 minutes before the end of the procedure. Subsequently, interventions were performed every 6 h until the end of the whole clinical trial, with a total of 8 doses (