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MEDICINAL CHEMISTRY

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Tocainide Hydrochloride (±)-2-Amino-N-(2,6-dimethyl-phenyl) propionamide<br />

hydrochloride (157) is another lidocaine congener, similar to mexiletine its electiophysiologic<br />

properties and antiarrhythmic action; A low incidence of bone marrow<br />

depression has caused this drug to be used less frequently than mexiletine.<br />

Class IC Antiarrhythmic Drugs<br />

F 3CCH 2O<br />

CONHCH 2<br />

OCH 2CF 3<br />

HN<br />

CONH<br />

CH 2CH 2<br />

H 3C<br />

H 3C<br />

H 3C<br />

N<br />

CHNHCH2CH2CH2 CONH2 OCH3 Flecainide (163) Encainide (164)<br />

Indecainide (165)<br />

Synthesis of Flecainide (163):<br />

HO<br />

COOH<br />

(166)<br />

OH<br />

CF 3SO 2OCH 2CF 3<br />

K 2CO 3<br />

Flecainide (163)<br />

H 2<br />

PtO 2<br />

OCH 2CF 3<br />

OCH2CF3 (167)<br />

CO 2CH 2CF 3<br />

OCH 2CF 3<br />

OCH 2CF 3<br />

N<br />

CONHCH 2<br />

(168)<br />

N<br />

CH 2NH 2<br />

Flecainide Acetate: (±)-N-(2-piperidinylmethyl)-2, 5bis(2,2,2-trifluoroethoxy)<br />

benzamide (163) represents the first fluorine containing newer group of antiarrhythmic<br />

drugs. It is indicated for use in patients with life-threatening arrhythmias such as<br />

sustained ventricular tachycardia. It is able at precipitate cardiac arrest. Other side<br />

effects include headache, dizziness and nausea. The major metabolites, meta-O-dealkyl<br />

flecainide and meta-O-dealkyl flecainide lactam are inactive. The most potent<br />

compounds were having two trifluoroethoxy groups, one of which was ortho to the<br />

carboxamide function. The parasubstituted derivatives were less active. Replacement of<br />

trifluoro-ethoxy group with 5-CH3, 5-Cl, 5-F resulted in loss of activity. A two-carbon<br />

link between amide and amine nitrogen atoms appears to be optimal. Branching at the<br />

positions adjacent to the basic nitro-en is responsible for prolonged elimination half-life<br />

due to reduced N-dealkylation.

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