title: Prolongation of succinylcholine block by metoclopramide.
abstract: Laboratory and clinical evidence of the inhibition of plasma cholinesterase by metoclopramide was demonstrated. When succinylcholine is used as the substrate and the product choline assayed by choline oxidase-peroxidase-quinone dye colorimetry, the rate of the choline production as optical density change was reduced to 50% by 19.5 X 10(-6) M metoclopramide at 20 degrees C. Prolongation of neuromuscular blockade produced by concurrent administration of succinylcholine and metoclopramide was studied in 22 patients aged between 18 and 40 years undergoing elective gynecological surgery. EMG activity in the adductor pollicis muscle was recorded in response to a train-of-four (TOF) stimulus delivered every 10 s. Patients were randomly divided into two groups: A and B. In both groups, anesthesia was induced with thiopental and maintained with sufentanil and nitrous oxide. Tracheal intubation followed intravenous succinylcholine. Intraoperatively, after returning of neuromuscular function, patients in both groups received 20 mg succinylcholine for the determination of duration of neuromuscular blockade. Time from 95% suppression of baseline twitch following a 20 mg increment of succinylcholine until recovery to 25% of control activity was determined. Thereafter, in group A, patients receive metoclopramide (10 mg iv) followed by succinylcholine 20 mg iv, and patients in group B received succinylcholine 20 mg iv alone. Recovery times were again measured and found to be prolonged in patients receiving metoclopramide compared with those not receiving metoclopramide (P less than 0.05). Metoclopramide has no intrinsic neuromuscular blocking activity, but its ability to inhibit plasma cholinesterase probably is the mechanism by which it prolongs succinylcholine block. Reducing the dose of succinylcholine may be appropriate when metoclopramide is given concurrently.
authors.affiliation: Department of Anesthesiology, Texas Tech University Health Sciences Center, Lubbock 79430.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Kao
authors.forename: D R
authors.initials: DR
authors.lastname: Turner
mesh_terms: D000328:Adult; D002802:Cholinesterases / Q000097:blood; D002986:Clinical Trials as Topic; D004357:Drug Synergism; D005260:Female; D005836:Genitalia, Female / Q000601:surgery; D006801:Humans; D008787:Metoclopramide / Q000494:pharmacology*; D009469:Neuromuscular Junction / Q000187:drug effects*; D011897:Random Allocation; D013390:Succinylcholine / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D002802:Cholinesterases; D013390:Succinylcholine; D008787:Metoclopramide