Local infiltration of HYR-PB21, a sustained-release formulation of bupivacaine, provides analgesia and reduces opioid requirement after haemorrhoidectomy: a randomised controlled trial.

HYR-PB21 is a new sustained-release formulation of bupivacaine indicated for controlling postoperative pain. The objectives of this study were to investigate the analgesic efficacy and safety profile of HYR-PB21 in patients after haemorrhoidectomy.