Laudanosine, a potentially epileptogenic metabolite of the neuromuscular relaxant atracurium besylate with potentially toxic effects. Laudanosine is a non-competitive and voltage-dependent inhibitor of alpha7, alpha4beta2 or alpha4beta4 nicotinic acetylcholine receptors, opioid mu 1 type receptors and possesses a low-affinity to the GABA receptors, but didn’t interact with the benzodiazepine or muscarinic receptors.

Benzenesulfonic acid (conjugate base benzenesulfonate) is the simplest aromatic sulfonic acid, that is soluble in water and ethanol, slightly soluble in benzene and insoluble in nonpolar solvents like diethyl ether. Benzenesulfonic acid was first obtained, together with diphenyl sulfone, by E. MITSCHERLICH in 1834 by heating benzene with fuming sulfuric acid. The industrially important reaction of benzenesulfonic acid with alkali hydroxide to form phenol (alkali fusion) was developed by A. WURTZ and A. KEKUL_e in 1867 and by P. O. DEGENER in 1878. Until the early 1960s benzenesulfonic acid was used chiefly in the manufacture of phenol. Benzenesulfonic acid has the characteristic reactions of a strong aromatic sulfonic acid. Acid hydrolysis at 175 C splits it into benzene and sulfuric acid. Additional sulfonation with fuming sulfuric acid gives 1,3-benzenedisulfonic acid, which reacts further to 1,3,5-benzenetrisulfonic acid, and also diphenyl sulfone disulfonic acid. Benzenesulfonic acid is used as an acid catalyst. The sodium salt is used to standardize dyes. A variety of pharmaceutical drugs are prepared as benzenesulfonate salts and are known as besilates (INN) or besylates (USAN).

Cisatracurium is a cis-cis isomer of atracurium and five time as potent as atracurium. The drug is approved by FDA and marketed under the name Nimbex. It is indicated as an adjunct to general anesthesia, to facilitate tracheal intubation, and to provide skeletal muscle relaxation due to its antagonistic properties toward nicotinic acetylcholine receptors.