G A McLeod1, B Munishankar, M O Columb. 1. Department of Anaesthetics, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK. g.a.mcleod@dundee.ac.uk
Abstract
BACKGROUND: The physicochemical properties of diamorphine (3,6-diacetylmorphine) enhance its bioavailability compared with more lipid-soluble opioids when administered into the epidural space. However, the influence of concentration, volume or mass on the clinical efficacy of diamorphine is not known. METHOD: In this double-blind, randomized, prospective study, 62 women in active labour and </=5 cm cervical dilatation were recruited to determine whether the mode of action of diamorphine in the epidural space is concentration-dependent. After insertion of a lumbar epidural catheter, patients received epidural diamorphine 3 mg either as a high-volume, low-concentration solution (group A) or a low-volume, high-concentration solution (group B). The concentration of diamorphine was determined by the response of the previous patient in the same group using up-down sequential allocation. Pain corresponding to the previous contraction was assessed using a 100-mm visual analogue score and effective analgesia was defined as </=10 mm within 30 min of epidural injection. RESULTS: There was no significant difference in EC50 for diamorphine between the groups: the difference was 15.0 microg ml(-1) (95% CI -40.3 to 10.3). The EC50 for group A was 237.5 microg ml(-1) (95% CI 221.2 to 253.8) and the EC50 for group B was 252.5 microg ml(-1) (95% CI 232.2 to 272.8). The EC50 ratio was 0.95 (95% CI 0.87 to 1.06). The groups exhibited parallelism (P=0.98). The overall EC50 for all data was 244.2 microg ml(-1) (95% CI 230.8 to 257.2). CONCLUSION: We conclude that diamorphine provides analgesia in labour by a concentration-dependent effect.
RCT Entities:
BACKGROUND: The physicochemical properties of diamorphine (3,6-diacetylmorphine) enhance its bioavailability compared with more lipid-soluble opioids when administered into the epidural space. However, the influence of concentration, volume or mass on the clinical efficacy of diamorphine is not known. METHOD: In this double-blind, randomized, prospective study, 62 women in active labour and </=5 cm cervical dilatation were recruited to determine whether the mode of action of diamorphine in the epidural space is concentration-dependent. After insertion of a lumbar epidural catheter, patients received epidural diamorphine 3 mg either as a high-volume, low-concentration solution (group A) or a low-volume, high-concentration solution (group B). The concentration of diamorphine was determined by the response of the previous patient in the same group using up-down sequential allocation. Pain corresponding to the previous contraction was assessed using a 100-mm visual analogue score and effective analgesia was defined as </=10 mm within 30 min of epidural injection. RESULTS: There was no significant difference in EC50 for diamorphine between the groups: the difference was 15.0 microg ml(-1) (95% CI -40.3 to 10.3). The EC50 for group A was 237.5 microg ml(-1) (95% CI 221.2 to 253.8) and the EC50 for group B was 252.5 microg ml(-1) (95% CI 232.2 to 272.8). The EC50 ratio was 0.95 (95% CI 0.87 to 1.06). The groups exhibited parallelism (P=0.98). The overall EC50 for all data was 244.2 microg ml(-1) (95% CI 230.8 to 257.2). CONCLUSION: We conclude that diamorphine provides analgesia in labour by a concentration-dependent effect.
Authors: Henning Hermanns; Elke M E Bos; Mark L van Zuylen; Markus W Hollmann; Markus F Stevens Journal: CNS Drugs Date: 2022-07-15 Impact factor: 6.497