Atracurium besilate

Chemical compound

Atracurium besilate, also known as atracurium besylate, is a medication used in addition to other medications to provide skeletal muscle relaxation during surgery or mechanical ventilation. Prolonged paralysis may occur in people with conditions like myasthenia gravis. Atracurium is available as a generic medication.

Atracurium is a medication used in addition to other medications in to provide skeletal muscle relaxation during surgery or mechanical ventilation.<! There are some exceptions to this rule; cisatracurium (Nimbex), for example, is one such agent that does not elicit histamine release even up to 5×ED95 doses. The liberation of histamine is a dose dependent phenomenon such that, with increasing doses administered at the same rate, there is a greater propensity for eliciting histamine release and its ensuing sequelae. Most commonly, the histamine release following administration of these agents is associated with observable cutaneous flushing (facial face and arms, commonly), hypotension and a consequent reflex tachycardia. These sequelae are very transient effects: the total duration of the cardiovascular effects is no more than one to two minutes, while the facial flush may take around 3–4 minutes to dissipate. Because these effects are so transient, there is no reason to administer adjunctive therapy to ameliorate either the cutaneous or the cardiovascular effects.

Bronchospasm has been reported on occasion with the use of atracurium. However, this particular undesirable effect does not appear to be observed nearly as often as that seen with rapacuronium, which led to the latter's withdrawal of approval for clinical use worldwide. The issue of bronchospasm acquired prominence in the neuromuscular blocking agents arena after the withdrawal from clinical use of rapacuronium (Raplon a steroidal neuromuscular blocking agent marketed by Organon) in 2001 after several serious events of bronchospasm, including five unexplained fatalities, following its administration. Bronchospasm was not an unknown phenomenon prior to rapacuronium: occasional reports of bronchospasm have been noted also with the prototypical agents, tubocurarine and succinylcholine, as well as alcuronium, pancuronium, vecuronium, and gallamine.

Seizures rarely occur. and cardiovascular effects such a hypotension and bradycardia. As part of the then fierce marketing battle between the competing pharmaceutical companies (Burroughs Wellcome Co. and Organon, Inc.) with their respective products, erroneous information was quickly and subtly disseminated very shortly after the clinical introduction of atracurium that the clinical use of atracurium was likely to result in a terrible tragedy because of the significant clinical hazard by way of frank seizures induced by the laudanosine by product Fortunately, both for the public and for atracurium, rapid initial investigations irrefutably failed to find any overt or EEG evidence for a connection between atracurium administration and epileptogenic activity. Indeed, because laudanosine is cleared primarily via renal excretion, a cat study modelling anephric patients went so far as to corroborate that EEG changes, when observed, were evident only at plasma concentrations 8 to 10 times greater than those observed in humans during infusions of atracurium. Thus, the cat study predicted that, following atracurium administration in an anephric patient, laudanosine accumulation and related CNS or cardiovascular toxicity were unlikely a prediction that correlated very well with a study in patients with kidney failure and undergoing cadaveric renal transplantation. Furthermore, almost a decade later, work by Cardone et al confirmed that, in fact, it is the steroidal neuromuscular blocking agents pancuronium and vecuronium that, when introduced directly into the CNS, were likely to cause acute excitement and seizures, owing to accumulation of cytosolic calcium caused by activation of acetylcholine receptor ion channels. Unlike the two steroidal agents, neither atracurium nor laudanosine caused such accumulation of intracellular calcium. Just over two decades later with availability of atracurium, there is little doubt that laudanosine accumulation and related toxicity will likely never be seen with the doses of atracurium that are generally used. The initial in vitro studies appeared to indicate a major role for ester hydrolysis

Hofmann elimination is a temperature and pH dependent process, and therefore atracurium's rate of degradation in vivo is highly influenced by body pH and temperature: An increase in body pH favors the elimination process, age, or by the status of renal or hepatic function. On the other hand, excretion of the metabolite, laudanosine, and, to a small extent, atracurium itself is dependent on hepatic and renal functions that tend to be less efficient in the elderly population. a pharmacist and a medicinal chemistry doctoral candidate in John B. Stenlake's medicinal chemistry research group in the Department of Pharmacy at Strathclyde University, Scotland. Dewar first named this compound "33A74" also a pharmacist and a postdoctoral researcher in Stenlake's research group. Atracurium was licensed by Strathclyde University to the Wellcome Foundation UK, which developed the drug (then known as BW 33A) and its introduction to first human trials in 1979, and then eventually to its first introduction (as a mixture of all ten stereoisomers) into clinical anesthetic practice in the UK, in 1983, under the tradename of Tracrium. The premise to the design of atracurium and several of its congeners stemmed from the knowledge that a bis quaternary structure is essential for neuromuscular blocking activity: ideally, therefore, a chemical entity devoid of this bis quaternary structure via susceptibility to inactive breakdown products by enzymic independent processes would prove to be invaluable in the clinical use of a drug with a predictable onset and duration of action. Hofmann elimination provided precisely this basis: It is a chemical process in which a suitably activated quaternary ammonium compound can be degraded by the mildly alkaline conditions present at physiological pH and temperature. In effect, Hofmann elimination is a retro Michael addition chemical process. It is important to note here that the physiological process of Hofmann elimination differs from the non physiological Hofmann degradation process: the latter is a chemical reaction in which a quaternary ammonium hydroxide solid salt is heated to 100 °C, or an aqueous solution of the salt is boiled. Regardless of which Hofmann process is referenced, the end products in both situations will be the same: an alkene and a tertiary amine. The approach to utilizing Hofmann elimination as a means to promoting biodegradation had its roots in much earlier observations that the quaternary alkaloid petaline (obtained from the Lebanese plant Leontice leontopetalum) readily underwent facile Hofmann elimination to a tertiary amine called leonticine upon passage through a basic (as opposed to an acidic) ion exchange resin. Stenlake's research group advanced this concept by systematically synthesizing numerous quaternary ammonium β aminoesters and β aminoketones and evaluated them for skeletal muscle relaxant activity: one of these compounds, eventually led to further clinical development, and came to be known as atracurium.