The effect of bambuterol (carbamylated terbutaline) on plasma cholinesterase activity and suxamethonium-induced neuromuscular blockade in genotypically normal patients.

Bambuterol (the bisdimethylcarbamate prodrug of terbutaline) is a new bronchodilator with a prolonged duration of action due to its inhibition of plasma cholinesterase during metabolism. The effect of bambuterol on suxamethonium-induced neuromuscular blockade was studied in 10 patients undergoing elective laparotomy. Thirty mg of bambuterol was given 2 h before anaesthesia, which was performed with thiopentone, fentanyl, halothane and nitrous oxide in oxygen. Neuromuscular function was monitored using supramaximal train-of-four stimulation of the ulnar nerve and a force displacement transducer. Suxamethonium 1 mg.kg-1 was given i.v. for endotracheal intubation. Plasma cholinesterase activity was measured before and after intake of bambuterol and during anaesthesia. The results from the 10 patients were compared with those of 41 patients not given bambuterol but otherwise studied during the same conditions. Following bambuterol, all patients had a significant decrease of plasma cholinesterase activity (P less than 0.001) and the suxamethonium-induced blockade was 3-4 times prolonged compared to patients not given bambuterol (P less than 0.001). Five patients with very low plasma cholinesterase activity developed a long-lasting phase II block.