title: Efficacy and toxicity of tocainide for the treatment of ventricular tachyarrhythmias in Doberman pinschers with occult cardiomyopathy.
abstract: Tocainide was administered to 23 cardiomyopathic Doberman Pinschers at doses of 15 to 25 mg/kg tid. These doses produced peak (2-hour) serum concentrations of 6.2 to 19.1 mg/L and trough (8-hour) serum concentrations of 2.3 to 11.1 mg/L. Anorexia and gastrointestinal disturbances occurred in 8 dogs (35%) at doses (15.6 to 25.0 mg/kg) that were not different from those (16.0 to 26.0 mg/kg) received by dogs that did not experience toxicity. Doses producing peak serum concentrations that were either greater or less than 14 mg/L were not different. Likewise, doses producing trough values that were either greater or less than 6 mg/L were not different. The mean dose that produced peak serum concentrations of 10 to 13.6 mg/L and trough concentrations of 4.2 to 10.0 mg/L was 17.9 mg/kg, and was associated with anorexia in 4 dogs. Mean peak serum concentrations associated with toxicity (14.4 mg/L) were significantly higher (P = .02) than dogs not experiencing toxicity (11.8 mg/L). Serious adverse effects occurred in 7 of 12 dogs (58%) receiving tocainide for longer than 4 consecutive months. Progressive corneal endothelial dystrophy occurred in 3 dogs. Although a causal effect could not be proven, 6 dogs experienced renal dysfunction during treatment. Drug doses in these 7 dogs were similar to those received by other dogs. At least a 70% reduction of the total numbers of ventricular premature contractions occurred in 80% of dogs treated, and ventricular tachycardia was eliminated in 90% of affected dogs by the time of the first posttreatment Holter recording. Long-term control of ventricular tachyarrhythmias was difficult to achieve in some dogs when the left ventricular shortening fraction was less than approximately 17%.
authors.affiliation: Department of Small Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Calvert
authors.forename: C W
authors.initials: CW
authors.lastname: Pickus
authors.forename: G J
authors.initials: GJ
authors.lastname: Jacobs
mesh_terms: D000818:Animals; D000855:Anorexia; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use*; D009202:Cardiomyopathies / Q000188:drug therapy / Q000503:physiopathology / Q000662:veterinary*; D004283:Dog Diseases; D004285:Dogs; D015716:Electrocardiography, Ambulatory / Q000662:veterinary; D012189:Retrospective Studies; D013045:Species Specificity; D017180:Tachycardia, Ventricular / Q000188:drug therapy / Q000209:etiology / Q000662:veterinary*; D016677:Tocainide / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use*
chemical_list: D000889:Anti-Arrhythmia Agents; D016677:Tocainide