Quinidine pharmacological action

Quinicine (quinotoxine), 419,425, 442,448 Quinidine, 419, 424 configuration, 443 constitntion, 435 isomerides, 453-4 pharmacological action, 479 transformaticn products 448 Quinidine, 419, 4 ... 

Other pharmacological effects - Clinical effects, in addition to antidepressant effects, include sedation, anticholinergic effects, mild peripheral vasodilator effects and possible quinidine-like actions. 

Quinidine is used mainly in the therapy of atrial fibrillation and certain other cardiac arrhythmias. Its pharmacological actions, especially cardiac activities, as well as its toxic reactions and therapeutic uses, are adequately illustrated in a recent edition of The Pharmacological Basis of Therapeutics by Goodman and Gilman (54). 

This highly unsaturated indole alkaloid (CVI) which, like ajmaline, incorporates skeletal pattern XXI, has similar pharmacological properties to ajmaline, producing a brief hypotension [1136,1139-1142] which is due to a diminished cardiac output resulting from its quinidine-like action on the heart [1105, 1106, 1108-1110, 1143, 1144]. However, the unpredictable frequency of response and untoward side effects militate against clinical application of serpentine [1145] or its synthetic analogues [1146]. 

Quinidine Quinidex) was one of the first clinically used antiarrhythmic agents. Because of the high incidence of ventricular proarrhythmia associated with its use and numerous other equally efficacious agents, quinidine is now used sparingly. Quinidine shares all of the pharmacological properties of quinine, including an-timalarial, antipyretic, oxytocic, and skeletal muscle relaxant actions. 

In pharmacodynamic interactions, the pharmacological effect of a drug is changed by the action of a second drug at a common receptor or bioactive site. For example, low-potency antipsychotics and tertiary amine TCAs have anticholinergic, antihistaminic, a-adrenergic antagonist, and quinidine-Kke effects. Therefore, concurrent administration of chlorpromazine and imipramine results in additive sedation, constipation, postural hypotension, and depression of cardiac conduction. 

Propranolol has been reported to exhibit quinidine-like antiarrhythmic actions which are quiet independent of beta-adrenergic blockade. Hence, these pharmacological properties are usually employed to suppress ventricular tachycardia, digitalis-induced tachyarrhythmias, paroxysml atrial tachycardia, and lastly ventricular and atrial extra-systoles. It is also currently receiving a lot of attention in the treatment and management of essential hypertension. 

Akbarov ZS, Aliev KhU, Sultanov MB (1972) Antieurhythmic action of thalisopine, novocainamide, and quinidine on experimented eurhyth-mia models. Farmakol. In Sultanov MB (ed) Farmakologiia Alkaloidov i Ikh Proizvodnikh (Pharmacology of alkaloids and their derivatives). FAN, Tashkent, pp 129-133 (in Russian)... 

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