The pharmacological research of cisatracurium and the other individual isomers was then developed further primarily by R. Brandt Maehr and William B. Wastila, PhD (both of whom were pharmacologists within the Division of Pharmacology at Burroughs Wellcome Co.) in collaboration with John J. Savarese MD (who at the time was an anesthesiologist in the Dept. of Anesthesia, Harvard Medical School at the Massachusetts General Hospital, Boston, MA). Thereafter, the entire clinical development of cisatracurium was completed in a record short period from 1992 to 1994: the team of scientists was led by J. Neal Weakly PhD, Martha M. Abou-Donia PhD, and Steve Quessy PhD, in the Division of Clinical Neurosciences at Burroughs Wellcome Co., Research Triangle Park, NC. By the time of its approval for human use, in 1995, by the US Food and Drug Administration, Burroughs Wellcome Co. had merged with Glaxo Inc., and cisatracurium was approved to be marketed as Nimbex by GlaxoWellcome Inc. The trade name "Nimbex" was derived from inserting an "i" to the original proposal "Nmbex," which stood for excellent Neuromuscular blocker. Preclinical pharmacology
In vitro studies using human plasma indicated that cisatracurium spontaneously degrades at physiological pH via Hofmann elimination to yield laudanosine and the quaternary monoacrylate. Subsequent ester hydrolysis of the monoacrylate generates the monoquaternary alcohol, although the rate-limiting step is Hofmann elimination. In rat plasma, cisatracurium is also metabolized by non-specific carboxylesterases (a rate-limiting step) to the monoquaternary alcohol and the monoquaternary acid.
Laudanosine – Epileptic foci
Cisatracurium undergoes Hofmann elimination as a primary route of chemodegradation: consequently one of the metabolites from this process is laudanosine, a tertiary amino alkaloid reported to be a modest CNS stimulant with epileptogenic activity and cardiovascular effects such as low blood pressure and a slowed heart rate. As a tertiary amine, Laudanosine is unionised and readily crosses the blood–brain barrier. Presently, there is little evidence that laudanosine accumulation and related toxicity will likely ever be seen with the doses of cisatracurium that are administered in clinical practice especially given that the plasma concentrations of laudanosine generated are lower with cisatracurium than those seen with atracurium. Research
A recent study showed that cisatracurium pretreatment effectively decreases the incidence and severity of pain induced by propofol general anaesthesia. Another study showed that hiccups accompanied by vomiting, insomnia, shortness of breath can also be relieved by the nondepolarizing muscle relaxant, cisatracurium, during total intravenous anesthesia. Synthesis
Treatment of 1,5-Pentanediol with 3-bromopropionyl chloride gives the corresponding ester; dehydrohalogenation of the ester with triethylamine then gives the bis-acrylate (2). Reaction of that unsaturated ester with tetrahydropapaverine (3) leads to conjugate addition of the secondary amine and formation of the intermediate (4). Alkylation with methyl benzenesulfonate forms the bis-quaternary salt, affording cisatracuronium (5). References
Further reading
Caldwell JE (1995). "New skeletal muscle relaxants". Int Anesthesiol Clin. 33 (1): 39–60. doi:10.1097/00004311-199500000-00003. PMID 7635557. Hull CJ (1995). "Pharmacokinetics and pharmacodynamics of the benzylisoquinolinium muscle relaxants". Acta Anaesthesiol Scand. 106 Suppl: 13–17. doi:10.1111/j.1399-6576.1995.tb04302.x. PMID 8533537. S2CID 43784865. Savarese JJ, Wastila WB (1995).