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

BACKGROUND

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.

METHODS

This was a multicentre, randomised, double-blind, positive-controlled trial. Patients were assigned randomly to receive a single dose of HYR-PB21 (150 mg or 300 mg) or bupivacaine HCl (75 mg) after surgery for prolapsing haemorrhoids. Postoperative pain was evaluated using a numeric rating scale at rest to calculate a cumulative pain score. Total rescue opioid usage and the proportion of subjects receiving rescue opioid were also assessed.

RESULTS

We enrolled 72 patients with haemorrhoidectomy, and 71 patients completed the study. The average cumulative pain score through 72 h after surgery in the 300 mg HYR-PB21 group (87 scores) was lower than in the bupivacaine HCl group (166 scores) in an intention-to-treat analysis (P<0.001). There was a dose-response effect in reducing total opioid usage and the proportion of rescue opioid use between the 150 mg and 300 mg HYR-PB21 groups, with bupivacaine HCl as a reference group. The HYR-PB21 groups did not show more adverse effects than the bupivacaine HCl group.

CONCLUSIONS

Local infiltration of a single dose of HYR-PB21 sustained-release bupivacaine had better efficacy in controlling postoperative pain, with similar adverse effects, compared with a single dose of bupivacaine HCl in patients after haemorrhoidectomy.

CLINICAL TRIAL REGISTRATION

ChiCTR2000041318 (Chinese Clinical Trial Registry).