Page 119 - Small Animal Internal Medicine, 6th Edition

CHAPTER 4 Cardiac Arrhythmias and Antiarrhythmic Therapy 91

TABLE 4.2
VetBooks.ir Dosage of Antiarrhythmic Drugs—cont’d

AGENT
DOSAGE
Class IV
Diltiazem Dog: Acute IV for rapid rate control of AF: 0.05-0.10 mg/kg IV over 2-5 minutes, can repeat if needed.
Acute IV for SVT: 0.1-(0.2) mg/kg over 2-5 minutes IV, can repeat to cumulative IV dose of
0.3-0.4 mg/kg; monitor blood pressure. CRI (if frequent SVT recurrence): 0.002-0.006 mg/kg/min
(or 0.12-0.35 mg/kg/h)
PO loading dose: 0.5 mg/kg PO followed by 0.25 mg/kg PO q1h to a total of 1.5(-2.0) mg/kg or
conversion
Oral maintenance: initial dose 0.5-1 mg/kg (up to 2-3 mg/kg) PO q8h
Extended release (diltiazem ER): 1-4 (up to 6) mg/kg PO q12h
Cat: Same?; Or 1.5-2.5 mg/kg (or 7.5-10 mg/cat) PO q8h; sustained-release preparations: diltiazem
ER, 30 mg/cat/day (one half of a 60 mg controlled-release tablet within the 240-mg gelatin
capsule), can increase to 60 mg/day in some cats if necessary
Cardizem-CD, 10 mg/kg/day (45 mg/cat ≅ 105 mg of Cardizem-CD ≅ amount that fits into small end
of No. 4 gelatin capsule)
Verapamil Dog: initial dose, 0.02-0.05 mg/kg slowly IV, can repeat q5min up to a total of 0.15(-0.2) mg/kg;
0.5-2 mg/kg PO q8h. (Note: diltiazem preferred instead)
Cat: initial dose, 0.025 mg/kg slowly IV, can repeat q5min up to a total of 0.15(-0.2) mg/kg;
0.5-1 mg/kg PO q8h. (Note: diltiazem preferred instead)
Anticholinergic
Atropine Dog: 0.02-0.04 mg/kg IV, IM, SC; 0.04 mg/kg PO q6-8h
Cat: same
Atropine challenge test: 0.04 mg/kg IV (see text, p. 97)
Glycopyrrolate Dog: 0.005-0.01 mg/kg, IV or IM; 0.01-0.02 mg/kg SC
Cat: same
Propantheline Dog: 0.25-0.5 mg/kg or 3.73-7.5 (-15) mg/dog PO q8-12h
Cat: —
Hyoscyamine Dog: 0.003-0.006 mg/kg PO q8h
Cat: —
Sympathomimetic
Isoproterenol Dog: 0.04-0.08 mcg/kg/min CRI
Cat: same
Theophylline Dog: 10 mg/kg PO q12h
(extended rel.) Cat: 10-15 mg/kg q24h
Terbutaline Dog: 0.14 mg/kg, or 2.5-5 mg/dog, PO q8-12h
Cat: 0.1-0.2 mg/kg, or 0.625-1.25 mg/cat, PO q12h
Other Agents
Digoxin See Table 3.3 for PO dosing; see Box 3.1 and p. 85 for IV
Edrophonium Dog: 0.05-0.1 mg/kg IV (have atropine and endotracheal tube available)
Cat: same?
Phenylephrine Dog: 0.004-0.01 mg/kg IV
Cat: same?

CRI, Constant-rate infusion; —, effective dosage not known.

slow the drug’s metabolism. Drugs that decrease liver blood Procainamide
flow (such as propranolol, cimetidine, and chloramphenicol) Procainamide HCl has electrophysiologic effects similar to
also slow lidocaine’s metabolism and predispose to toxicity. those of quinidine. These include both direct and indirect
Animals with heart failure could have reduced hepatic blood (vagolytic) effects. Procainamide is indicated for the treat-
flow and so might require a lower dosage of the drug. ment of premature ventricular (and sometimes atrial)