Quaternary ammonium group, effect

There is a wide variety of dyes unique to the field of hair coloring. Successive N-alkylation of the nitrophenylenediamines has an additive bathochromic effect on the visible absorption to the extent that violet-blue dyes can be formed. Since the simple A/-alkyl derivatives do not have good dyeing properties, patent activity has concentrated on the superior A/-hydroxyalkyl derivatives of nitrophenylenediamines (29,30), some of which have commercial use (31). Other substituents have been used (32). A series of patents also have been issued on substituted water-soluble azo and anthraquinone dyes bearing quaternary ammonium groups (33). 

The cationic acrylamide polymers may contain either tertiary amine or quaternary ammonium groups. Because of their positive charge, they are self-retaining on pulp fibers therefore, they can be used effectively in nonalum systems. 

Cation units usually contain a sulphonic acid resin whilst anion resins fall into the two main categories of strongly basic, with quaternary ammonium groupings and weakly basic, with tertiary amine groups. The final unit is the mixed bed in which, by a mixture of cation and anion resins in the same vessel, the effect is achieved of a multiplicity of separate cation and anion units. Resin separation is necessary for regeneration purposes. Considerable improvements in water quality are obtainable by these means. 

Inhibition of AChE can increase the stimulation of both muscarinic and nicotinic receptors produced by synaptically released ACh. Nicotinic receptors can also be stimulated directly by AChE inhibitors with a quaternary ammonium group, and this can potentiate their cholinomimetic effect. Finally, although inhibition of true AChE is most important for potentiating the synaptic activity of ACh, several AChE inhibitors also inhibit the pseudo-ChE in plasma. This can permit plasma concentrations of ACh to rise markedly and activate endothelial muscarinic receptors. 

Antimuscarinics having a quaternary ammonium group are incompletely absorbed from the gut since these are completely ionized. The tertiary amine antimuscarinics are readily absorbed from the gut. The presence of food may reduce absorption. Quaternary ammonium antimuscarinics exhibit poor lipid solubility, do not cross the blood-brain barrier, and thus exhibit minimal central nervous system (CNS) effects. Also due to their poor lipid solubility they do not penetrate the eye and are unlikely to appear in the milk. Atropine and other tertiary amines are capable of crossing the CNS. Atropine is capable of crossing the placenta and has been stated to distribute into milk in small quantities. It is oxidized primarily in the liver. Atropine is apparently metabolized in the liver to tropic acid, tropine, and possibly esters of tropic acid and glucuronide conjugate. 

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