Doxacurium chloride (formerly recognized as BW938U80 or BW A938U) is a

neuromuscular-blocking drug Neuromuscular-blocking drugs, or Neuromuscular blocking agents (NMBAs), block transmission at the neuromuscular junction, causing paralysis of the affected skeletal muscles. This is accomplished via their action on the post-synaptic acetylcho ...

skeletal muscle relaxant A muscle relaxant is a drug that affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia. The term "muscle relaxant" is used to refer to two major therapeu ...

in the category of non-depolarizing

neuromuscular-blocking drugs Neuromuscular-blocking drugs, or Neuromuscular blocking agents (NMBAs), block transmission at the neuromuscular junction, causing paralysis of the affected skeletal muscles. This is accomplished via their action on the post-synaptic acetylcho ...

, used adjunctively in

anesthesia Anesthesia (American English) or anaesthesia (British English) is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prev ...

to provide

skeletal muscle Skeletal muscle (commonly referred to as muscle) is one of the three types of vertebrate muscle tissue, the others being cardiac muscle and smooth muscle. They are part of the somatic nervous system, voluntary muscular system and typically are a ...

relaxation during

surgery Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery s ...

mechanical ventilation Mechanical ventilation or assisted ventilation is the Medicine, medical term for using a ventilator, ventilator machine to fully or partially provide artificial ventilation. Mechanical ventilation helps move air into and out of the lungs, wit ...

. Unlike a number of other related skeletal muscle relaxants, it is rarely used adjunctively to facilitate endotracheal

intubation Intubation (sometimes entubation) is a medical procedure involving the insertion of a tube into the body. Most commonly, intubation refers to tracheal intubation, a procedure during which an endotracheal tube is inserted into the trachea to supp ...

Chemistry

Doxacurium is a symmetrical molecule because it is a diester of

succinic acid Succinic acid () is a dicarboxylic acid with the chemical formula (CH2)2(CO2H)2. In living organisms, succinic acid takes the form of an anion, succinate, which has multiple biological roles as a metabolic intermediate being converted into fum ...

. The pharmacological action of doxacurium is a function of its competitive antagonism to acetylcholine receptors of the nicotinic type. The drug is marketed worldwide under the tradename of Nuromax, and it is classified as a long-duration non-depolarizing neuromuscular blocking agent in a class of compounds commonly and most erroneously referred to as "benzylisoquinolines" when, in fact, it is a ''bis''benzyltetrahydroisoquinolinium agent. The pharmaceutical preparation comprises the three trans-trans isomers (a meso structure ''R'',''S''-''S'',''R''-doxacurium and an enantiomeric pair ''R'',''S''-''R'',''S''-doxacurium and ''S'',''R''-''S'',''R''-doxacurium)

Availability

Doxacurium is available worldwide although, for a number of years, its use has not been popular because of considerably long duration of action. Its decline from clinical use was even further hastened when the sister molecule, mivacurium chloride, was introduced into the clinic very shortly after doxacurium's debut. The only perceived advantage of doxacurium over that of mivacurium is its superior cardiovascular profile, with particular reference to the lack of histamine release when administered as a rapid bolus dose.

History

Doxacurium represents the second generation of tetrahydroisoquinolinium neuromuscular blocking drugs in a long lineage of nicotinic acetylcholine receptor antagonists synthesized by Mary M. Jackson and James C. Wisowaty, PhD (both chemists within the Chemical Development Laboratories at Burroughs Wellcome Co., Research Triangle Park, NC) in collaboration with John J. Savarese MD (who at the time was an anesthesiologist in the Dept. of Anesthesia,

Harvard Medical School Harvard Medical School (HMS) is the medical school of Harvard University and is located in the Longwood Medical and Academic Area, Longwood Medical Area in Boston, Massachusetts. Founded in 1782, HMS is the third oldest medical school in the Un ...

at the

Massachusetts General Hospital Massachusetts General Hospital (Mass General or MGH) is a teaching hospital located in the West End neighborhood of Boston, Massachusetts. It is the original and largest clinical education and research facility of Harvard Medical School/Harvar ...

Boston Boston is the capital and most populous city in the Commonwealth (U.S. state), Commonwealth of Massachusetts in the United States. The city serves as the cultural and Financial centre, financial center of New England, a region of the Northeas ...

, MA). Specifically, doxacurium was first synthesized in 1980. Early structure-activity studies had confirmed that the bulky nature of the "benzylisoquinolinium" entity provided a non-depolarizing mechanism of action. Partial saturation of the benzylisoquinoline ring to the tetrahydroisoquinoline ring provided an even further increase in potency of the molecules without detrimental effects to other pharmacological properties: this key finding led to the rapid adoption of the tetrahydroisoquinolinium structures as a standard building block (along with a 1-benzyl attachment), and it is the primary reason why the continued unwarranted reference to "benzylisoquinolinium" is a complete misnomer for all clinically introduced and currently used neuromuscular blocking agents in this class because they are all, in fact, tetrahydroisoquinoline derivatives. By definition, therefore, there has never been, in the history of clinical anesthetic practice, the use of a ''benzylisoquinoline'' neuromuscular blocking agent. The heritages of doxacurium and mivacurium hark back to the synthesis of numerous compounds following structure-activity relationships that drove researchers to find the ideal replacement for succinylcholine (suxamethonium). Both doxacurium and mivacurium are descendants of early vigorous attempts to synthesize potent non-depolarizing agents with pharmacophoric elements derived from cross-combinations of the non-depolarizing agent, laudexium, and the well-known depolarizing agent,

succinylcholine Suxamethonium chloride (brand names Scoline and Sucostrin, among others), also known as suxamethonium or succinylcholine, or simply sux in medical abbreviation, is a medication used to cause short-term paralysis as part of general anesthesia. T ...

( suxamethonium). Ironically, laudexium itself was invented by a cross-combination between the prototypical non-depolarizing agent, d-tubocurarine and the depolarizing agent,

decamethonium Decamethonium (Syncurine) is a depolarizing muscle relaxant or neuromuscular blocking agent, and is used in anesthesia to induce paralytic, paralysis. Pharmacology Decamethonium, which has a short action time, is similar to acetylcholine and ...

. In the 1950s and 1960s, the present-day concept of a neuromuscular blocking agent with a rapid onset and an ultra-short duration of action had not taken root: researchers and clinicians were still on the quest for potent but non-depolarizing replacements devoid of the histamine release and the dreaded "recurarizing" effects seen with tubocurarine and, more importantly, the absence of a depolarizing mechanism of action as seen with

and

References

{{DEFAULTSORT:Doxacurium Chloride Quaternary ammonium compounds Muscle relaxants Nicotinic antagonists Norsalsolinol ethers Pyrogallol ethers Chlorides Succinate esters Neuromuscular blockers