Arrhythmia cinchona

QuinidJne. Quinidine, an alkaloid obtained from cinchona bark (Sinchona sp.), is the dextrorotatory stereoisomer of quinine [130-95-0] (see Alkaloids). The first use of quinidine for the treatment of atrial fibrillation was reported in 1918 (12). The sulfate, gluconate, and polygalacturonate salts are used in clinical practice. The dmg is given mainly by the oral (po) route, rarely by the intravenous (iv) route of adniinistration. It is the most frequentiy prescribed po antiarrhythmic agent in the United States. The clinical uses of quinidine include suppression of atrial and ventricular extrasystoles and serious ventricular arrhythmias (1 3). 

Hypersensitivity or idiosyncrasy to quinidine or other cinchona derivatives manifested by thrombocytopenia, skin eruption or febrile reactions myasthenia gravis history of thrombocytopenic purpura associated with quinidine administration digitalis intoxication manifested by arrhythmias or AV conduction disorders complete heart block left bundle branch block or other severe intraventricular conduction defects exhibiting marked QRS widening or bizarre complexes complete AV block with an AV nodal or idioventricular pacemaker aberrant ectopic impulses and abnormal rhythms due to escape mechanisms history of drug-induced torsade de pointes history of long QT syndrome. 

It is used in the treatment of malaria Cinchona bark is also the source of quinidine, used to treat cardiac arrhythmias (see Chapter 22). 

Quinidine is the current drug of choice in the treatment of auricular arrhythmias. The other Cinchona alkaloids, the cryptopine-like compounds, sparteine and related substances, and the Rauwolfia alkaloids are primarily of interest in these arrhythmias. Quinidine or digitalis occasionally prove of therapeutic merit in preventing the ventricular arrhythmias. 

Quinidine (Fig. 26.10) is wideiy used for acute and chronic treatment of ventriouiar and supraventricuiar arrhythmias, especiaiiy supraventriouiar tachycardia, it is a member of a famiiy of aikaioids found in Cinchona bark Cinchona officinalis L.) and is the diastereomer of quinine. 

Cinchona A genus of rubiaceous South American trees that yields the toxic cinchona alkaloids from their bark quinine, quinidine, chinconine, cinchonidine and others are used to treat malaria and cardiac arrhythmias. [NIH]... 

The structures of two antiarrhythmic agents, quinidine, a natural product, and disopyramide (Searle Roussel, 1972) are shown in Figure 4.2. Quinidine was first isolated from cinchona bark but is now made by the epimerization of quinine at the carbon bearing the hydroxyl group. Its effects on arrhythmias were first noted more than 200 years ago when the drug was being used as an anti-malarial agent. 

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