RODD preparation
Ropivacaine (200 mg) was added to benzyl alcohol. After the ropivacaine was dissolved, benzyl benzoate and soybean oil were added to the ropivacaine solution up to 10 mL. Then, the mixture was heated and stirred until the solution was clear. After being filtered and sterilized with a filter, the bulk solution, i.e., RODD, was obtained, divided into vials, filled with nitrogen and sealed. The concentration of RODD was 20 mg·mL