Muscarine pharmacological properties

Carbachol is a powerful cholinic ester that stimulates both muscarinic and nicotinic receptors, as well as exhibits all of the pharmacological properties of acetylcholine while in addition resulting in vasodilation, a decrease in heart rate, an increase in tone and con-tractability of smooth muscle, stimulation of salivary, ocular, and sweat glands as well as autonomic ganglia and skeletal muscle. For this reason, use of carbachol, like acetylcholine, is limited. The exception is that it is used in ophthalmological practice and post-operational intestines and bladder atony. Upon administration in the eye, the pupil constricts and the intraocular pressure is reduced. It is used for severe chronic glaucoma. Synonyms of this drag are doryl and miostat. 

SSRIs were developed in an attempt to formulate reuptake-blocking drugs that lacked the troublesome side effects of TCAs. Of the five pharmacological properties of TCAs—blockade of muscarinic receptors, blockade of histamine Hj receptors, blockade of aj-adrenergic receptors, norepinephrine reuptake blockade, and serotonin reuptake inhibition—only the last remains intact in SSRIs. This selectivity has... 

Propantheline bromide (Pro-banthine) resembles methantheline chemically (isopropyl groups replace the ethyl substituents on the quaternary N atom). Its pharmacological properties are also similar to those of methantheline, but it is two to five times more potent. It is one of the more widely used of the synthetic muscarinic receptor antagonists. Very high doses block the skeletal neuromuscular junction. The usual clinical dose (15 mg) acts for about 6 h. 

Bethanechol Chloride, USP. Bethanechol. jS-mcthyl-choline chloride carbamate. (2-hydroxypropyl)trimethylam-monium chloride carbamate, carbamylmelhylcholinc chloride (Urecholinc), is nonspecific in its action on muscarinic receptor. subtypes but appears to be more effective at eliciting pharmacological action of M> receptors. It has pharmacological properties similar to those of methacholinc. Both are esters of nicthylcholine and have feeble nicotinic activity. Bethanechol is inactivated more slowly by AChE in vivo than is mcthacholine. It is a carbamyl ester and is expected to have stability in aqueous solutions similar to that of carbachol. 

A major problem in ct receptor research is the lack of specific ligands as most of these agents bind at other receptor systems including serotonin 5-HT2, dopamine D2, PCP, and muscarinic receptors, thus making it unclear whether their pharmacological properties are due to the interaction with cr sites. Some specific compounds are emerging here two examples are quoted NE 100, which also displays an cr,/o 2 selectivity ratio of 55, reported to... 

Quinolizidines have antiarrhythmic, CNS-depressant, hypotensive, and hypoglycemic effects. Their toxicity and some of their pharmacological properties can be explained through inhibition of Na and K channels and interaction with nicotinic and muscarinic acetylcholine receptors. Sparteine from broom (Cytisus sco-parius) is used as antiarrhythmic. However, its medicinal use is declining and restricted because about 10% of all patients are unable to metabolize this alkaloid and suffer from intoxication (Wink, 2003). 

The methyl ester of P-trimethylammoniopropionate (13.62) may be regarded as acetylcholine in which the order of the ethereal and carbonyl oxygen atoms has been reversed. It is a very poor substrate for acetylcholinesterase, and does not inhibit this enzyme. However, it has strong muscarinic and moderate nicotinic properties, as well as some small measure of individuality in the pharmacological properties (Bass et al., 1950)-The resemblance between this structure and that of arecoline (13.57) is noteworthy. 

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