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Tocainide (Tonocard) is a class Ib
antiarrhythmic agent
Antiarrhythmic agents, also known as cardiac dysrhythmia medications, are a class of drugs that are used to suppress abnormally fast rhythms (tachycardias), such as atrial fibrillation, supraventricular tachycardia and ventricular tachycardia.
M ...
. It is no longer sold in the United States.
Synthesis
Pharmacokinetics
Tocainide is alidocaine
Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia and ventricular fibrillation. When used for local anae ...
derivative, that undergoes very less first pass metabolism. It occurs as two enantiomer
In chemistry, an enantiomer (Help:IPA/English, /ɪˈnænti.əmər, ɛ-, -oʊ-/ Help:Pronunciation respelling key, ''ih-NAN-tee-ə-mər''), also known as an optical isomer, antipode, or optical antipode, is one of a pair of molecular entities whi ...
s. The R isomer is three times more potent than the S isomer. Tocainide's oral bioavailability is almost 100%. Plasma half-life generally lasts for 11.5-15.5 hours (13.5 ± 2 hours). In the blood, tocainide is 10-20% protein bound. The volume of distribution is 2.8-3.2 L/kg. 31-45% is excreted unchanged in the urine. The more active R-isomer is cleared faster in anephric patients (without kidneys) or those with severe kidney dysfunction. The main metabolite is tocainide carbamoyl ester glucuronlde.
Drug interactions
Rifampicin
Rifampicin, also known as rifampin, is an ansamycin antibiotic used to treat several types of bacterial infections, including tuberculosis (TB), ''Mycobacterium avium'' complex, leprosy, and Legionnaires' disease. It is almost always used tog ...
increases conversion of tocainide into its main metabolite, tocainide carbamoyl ester glucuronlde, by inducing the glucuronosyl transferase enzyme that catalyzes glucuronidation
Glucuronidation is often involved in drug metabolism of substances such as drugs, pollutants, bilirubin, androgens, estrogens, mineralocorticoids, glucocorticoids, fatty acid derivatives, retinoids, and bile acids. These linkages involve gly ...
of tocainide to produce that metabolite. Rifampicin also increases elimination rate and decreases oral clearance of tocainide. Tocainide decreases plasma clearance of theophylline.
References
Further reading
*External links
* Antiarrhythmic agents Sodium channel blockers Anilides {{cardiovascular-drug-stub