Structure guanethidine

Fig. 26. Chemical structure of f llMIBG, a single photon emission computed tomography (SPECT)-radiopharmaceutical for cardiac neuronal imaging, and its lead structure guanethidine.

Table 3.6. THE ACTIVITY OF DIAZACYCLOALKANE ANALOGUES OF GUANETHIDINE AND RELATED STRUCTURES...

The available information on the relationship between structure and potency in preventing guanethidine-mduced ptosis in mice is summarized semi-quantitatively in Table 3.23. The most active compounds are aralkylguanidines Table 3.23. ANTAGONISM BY GUANIDINE DERIVATIVES OF... 

The noradrenaline normally contained in the storage granules can be partly or completely replaced by structurally related sympathomimetic amines, either by injection of the amine itself, or of suitable precursors such as a-methyl-DOPA or a-methyl-w-tyrosine. These amines can be depleted from the heart by guanethidine in the same way as the noradrenaline which they had replaced. a-Methylnoradrenaline [337] and metaraminol [338] are depleted less readily than noradrenaline from rabbit or rat hearts, whereas dopamine, octopamine and w-octopamine are depleted more readily than noradrenaline [339]. The more rapid depletion of these last three compounds was attributed to weaker binding in the storage granules [339], but could equally well be due to their greater susceptibility to destruction by monoamine oxidase, since both a-methyl-noradrenaline and metaraminol are resistant to attack by monoamine oxidase. 

LXXXVI) [342] of guanethidine and 3-hydroxyphenethylguanidine (LXXXVII) [264]. Guanoxan (V) has about equal activity, on acute administration, to that of guanethidine [94, 254]. Structure-activity relationships are summarized in... 

The spectrum of activity of a-methyldopa (Aldomet) lies between those of the more potent agents, such as guanethidine, and the milder antihypertensives, such as reserpine. a-Methyldopa is a structural analogue of di-hydroxyphenylalanine (dopa) and differs from dopa only by the presence of a methyl group on the a-carbon of the side chain. 

Part I of a review on guanethidine covering the discovery, development, chemical structure, physical properties and pharmacological actions of this drug has appeared. ... 

Examples of such structures with regularly increasing ring si2es are found for guanethidine (see Chapter 14), or for enalaprilat analogues (Fig. 12.2). In the latter example, a... 

B. Guanabenz is structurally similar to guanethidine, a ganglionic blocker. Guanfacine is related closely to guanabenz and has more selective alpha-2-agonist activity than clonidine. 

The guanyl-benzoxazepine (III) [206] was found in the dog to be approximately one-third as active as guanethidine. The substance displays both the partial structure of the benzylguanidines and the partial structure, described in the next section, of the oxyalkylguanidines. 

Tricyclic antidepressants and structurally similar drugs may block the antihypertensive action of guanethidine and may enhance the seizure risk in patients taking tramadol. 

Guanethidine-like Compounds - Structure activity relationships for a series of branched alkyl guanidines were reported, t-Octylguanldine was found to show fewer side effects and less toxicity clinically than guanethidine, but its h otensive effect was not as good or consistent as the latter. 

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