Atropine relative anticholinergic activity

Anticholinergics. Antagonists at muscarinic cholinoceptors such as benztropine and bi-periden (p. 110) can be used to suppress the sequelae of the relative predominance of cholinergic activity in the striatum (in particular, tremor). Atropine-like peripheral side effects and impairment of cognitive function limit the tolerable dosage. Complete disappearance of symptoms cannot be achieved. 

The great avidity of mitochondria from rat brain for 3-qulnuclldlnyl benzllate has been mentioned previously (56). Lareson et al. (192) recorded the Infrared spectra of seven esters of benzllic acid, of ei t esters of 3-qulnuclidlnol, and of atropine and scopolamine and attempted to correlate the relative strengths of the intramolecular hydrogen bond with the threshold doses of the various compounds in producing psychotomimetic effects in dogs. The data of Albanus (42) on the psychotomimetic activities of anticholinergic compounds were used for the comparison. Of the esters of benzllic acid. 

It can be concluded from such structure-activity studies, which are based on extensive psychopharmacologlc stests in both animals and human volunteers, that BZ is the most representative of the most potent anticholinergics. However, atropine and methylatropine are the most representative of the relatively Inactive anticholinergics and could serve as control drugs, particularly because atropine is equlpotent, although of shorter duration, to BZ in peripheral anticholinergic effects. 

The mydriatic and cycloplegic activities of anticholinergics in humans are listed in Table 3.18. Atropine is recommended in situations requiring complete and prolonged relaxation of the sphincter of iris and the ciliary muscle. Mydriatics, like cyclopentolate, eucatropine, and homatropine bromide, with a shorter duration of action, are usually preferred for measuring refractive errors because of the relative rapidity with which their cycloplegic effects are terminated. 

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