No abstract

Thirty-two alpha-amino anilides with various substituents in the aromatic ring and in the alpha position are described. Their abilities to protect mice against chloroform-induced fibrillation and to elicit toxicity were determined. Substitution of an alkyl or aryl group in the alpha position enhanced the antifibrillatory activity. In most cases, increased potency was accompanied by increased toxicity. Eleven compounds were tested in dogs with surgically induced myocardial infarction; most showed antiarrhythmic activity. 2-Aminopropiono-2',6'-xylidide, tocainide, was chosen for clinical investigation.

The synthesis and pharmacological evaluation of primary and tertiary aminoxylidides with the amino group in the 2-7 position of the acyl chain are described. 2,6-Xylidine was acylated with haloacyl halides and converted to the target compounds by direct amination or by the Gabriel procedure. Alternatively, 2,6-xylidine was coupled with keto acids, and the ketoxylidides were converted to the amines by reductive amination. The target compounds were evaluated in mice both for antiarrhythmic efficacy against chloroform-induced tachycardia and for central nervous system toxicity. Experimentally determined values of partition coefficients and pKa values were used for quantitative structure-activity analyses. While the antiarrhythmic activity could be described as a function of log P alone, the CNS toxicity was best described as a function of both log P and pKa. The results suggest that antiarrhythmic potency can be increased by increasing lipophilicity, while the therapeutic index can be improved by increasing the pKa.

The synthesis of a series of N-alkyl 2-amino 2',6'-xylidides is described. The method involved coupling of the N-alkyl-2',6'-xylidine with the appropriate 2-haloacyl halide, followed by ammonolysis. Alternatively, alkylation of the 2-phthalimido 2',6'-xylidide with NaH and the alkyl halide followed by hydrazinolysis was used. All compounds were evaluated for their ability to protect mice against chloroform-induced ventricular fibrillation. The compounds were generally more potent antifibrillatory agents than the corresponding secondary amides. All were more potent than tocainide and several showed less CNS toxicity. Five compounds were further evaluated in dogs with ventricular arrhythmias resulting from myocardial infarction. N-Ethyl-2-aminoaceto-4'-propoxy-2',6'-xylidide was as potent as lidocaine and produced less CNS toxicity.

The synthesis and pharmacologic evaluation of primary beta-amino anilides, as well as comparisons with tocainide, lidocaine, and its beta homologue, are described. Substituted anilines were acylated with 3-bromoacyl chlorides and converted to the title compounds by direct amination or via 3-phthalimido anilides and subsequent hydrazinolysis. Alternatively, anilines were acylated with substituted acryloyl chlorides and the amines prepared by addition of ammonia to the double bond. The target compounds were evaluated for their ability to protect against chloroform-induced fibrillation in mice. All were found to have some antifibrillatory activity; several were more potent than tocainide, a compound in clinical trials as an oral antiarrhythmic drug. Four compounds were tested for their effects against ventricular arrhythmias in dogs with myocardial infarction. 3-Amino-2',6'-butyroxylidide (38) was found to be more potent and less CNS toxic than tocainide.