Page 426 - Feline Cardiology

Generic Name Indications/Drug Dosage and Comments Available sizes
(Brand Name) Type Possible Routes
of Admin.

Hydralazine Direct arterio- 2.5 mg/cat PO Second- or third-line treatment for systemic 10,25,50,
(Apresoline [H]) dilator q 12–24h hypertension. Almost completely replaced by 100 mg Tab
amlodipine due to amlodipine’s superior 20 mg/ml Liq
efficacy and fewer adverse effects in cats. HM
Hydrochloro- Thiazide diuretic 1–2 mg/kg PO Second diuretic, generally added when 25,50,100mg
thiazide q 12h; usually long-term furosemide treatment is no longer Tab
(HydroDiuril [H]) decrease to adequate (relapse of congestive heart failure HM
0.5– despite high-dose furosemide). Begun when
1 mg/kg PO q inpatient is stable and preparing to be
12h discharged, or when relapse of CHF
when stable produces minimal clinical signs (cat is still
comfortable). Monitor renal function and
electrolytes as for other diuretics (e.g., 1–2
weeks after starting treatment, then q4–12
weeks depending on stability, patient comfort/
tractability, etc.)
Imidapril (Prilium Angiotensin- 0.5 mg/kg PO Adjunctive treatment of congestive heart 5,10 mg/ml
[V]) converting q 24h failure (with concurrent diuretic treatment). Liq
enzyme (ACE) Veterinary formulation is lyophilized powder VM
inhibitor reconstituted into oral solution (increased
dosage accuracy) and stored refrigerated.
Theoretical additional benefits of ACE
inhibition (e.g., reduction of myocardial
fibrosis) and loss of efficacy over time (ACE
inhibitor tolerance) unproven in clinical feline
cardiology at present. Therefore, no proven
benefit to treatment prior to congestive heart
failure. Available in Europe and Canada (for
dogs; as for many drugs, feline use is off-label).

Inderal—see
Propranolol

Intropin—see
Dopamine
Isoproterenol Beta adrenergic 0.04–0.08 mcg/ Indicated for severe/critical bradycardia, 0.2 mg/ml
(Isuprel [H]) agonist kg/min notably sinus bradycardia that fails to respond Inj
IV CRI, to atropine, or third-degree AV block during HM
adjusted stabilization for pacemaker implantation.
PRN Begin at low infusion rate and increase
gradually to desired effect; sudden high dose
may cause excess effect (extreme tachycardia).
Sample formulation for 0.04 mcg/kg/min:
place 1 ml (0.2 mg) in 100 ml 5%
dextrose = 2 mcg/ml. Administration at half
maintenance rate = 30 ml/kg/d = 1.25 ml/
kg/h = 0.02 ml/kg/min = 0.04 mcg/kg/min.

Isoptan—see Drug Formulary
Verapamil
Continued

451