Effects of SZ1677, a new non-depolarizing steroidal neuromuscular blocking drug, and rocuronium on two laryngeal muscles and the anterior tibial muscle in guinea pigs

• Published in: Acta anaesthesiologica Scandinavica Vol. 50; no. 4; pp. 481 - 487
• Main Authors: Michalek-Sauberer, A., Nicolakis, E. M., Vizi, E. S., Gilly, H.
• Format: Journal Article
• Language: English
• Published: Oxford, UK; Malden, USA Blackwell Publishing Ltd 01.04.2006; Blackwell
• Subjects: Androstanes - pharmacology; Androstanols - pharmacology; Anesthesia; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; anterior tibial muscle; Biological and medical sciences; Electric Stimulation; Electromyography; guinea pig; Guinea Pigs; Hindlimb; laryngeal muscles; Laryngeal Muscles - drug effects; Laryngeal Muscles - physiology; Male; Medical sciences; Muscle, Skeletal - drug effects; Muscle, Skeletal - physiology; Neuromuscular Blockade; Neuromuscular Nondepolarizing Agents - pharmacology; posterior cricoarytenoid muscle; Recurrent Laryngeal Nerve - drug effects; Recurrent Laryngeal Nerve - physiology; rocuronium; Sciatic Nerve - drug effects; Sciatic Nerve - physiology; SZ1677; thyroarytenoid muscle; SZ1677; anterior tibial muscle; Rodentia; Vertebrata; Mammalia; Guinea pig; thyroarytenoid muscle; Animal; Anesthesia; rocuronium; Neuromuscular blocking; posterior cricoarytenoid muscle; laryngeal muscles
• ISSN: 0001-5172; 1399-6576
• DOI: 10.1111/j.1399-6576.2006.00983.x

Background:  SZ1677 is a new neuromuscular blocking drug structurally related to rocuronium. We compared the effect of an ED90 of SZ1677 (25 μg/kg) with that of rocuronium (100 μg/kg) in guinea pig laryngeal and peripheral muscles. Methods:  Electromyography was used to quantify neuromusc‐ular blockade at the posterior cricoarytenoid muscle, the thyroarytenoid muscle and the anterior tibial muscle after SZ1677 (n = 10) and rocuronium (n = 9). Results:  Maximum neuromuscular blockade was similar after SZ1677 and rocuronium (83 ± 11% vs. 89 ± 11%; thyroarytenoid muscle: 91 ± 8% vs. 97 ± 3%; anterior tibial muscle: 91 ± 15% vs. 96 ± 3%, respectively). Onset time of neuromuscular blockade at the laryngeal muscles was similar for the two neuromuscular blocking drugs; it was shorter at the thyroarytenoid muscle (67 ± 32 s vs. 42 ± 40 s) than at the posterior cricoarytenoid muscle (101 ± 26 s vs. 102 ± 108 s). Onset time at the anterior tibial muscle was longer after SZ1677 (114 ± 34 s) than after rocuronium (68 ± 46 s); P < 0.05. Neuromuscular recovery was faster after SZ1677 (interval 25%−75%: posterior cricoarytenoid muscle: 222 ± 66 s; thyroarytenoid muscle: 192 ± 92 s; tibial muscle 149 ± 55 s) than after rocuronium (450 ± 148 and 464 ± 183 s, 292 ± 86 s, respectively); P < 0.05. Conclusions:  In guinea pigs, SZ1677 offers a rapid onset of neuromuscular blockade at a laryngeal adductor muscle with a shorter duration than rocuronium. Regardless of the drug used, the course of neuromuscular blockade differs not only between peripheral muscles and the larynx but also between antagonistic laryngeal muscles. The differences seem to be species specific.