Medications Commonly Used for Heart Failure
This
information is not meant to be a substitute for veterinary care. Always follow
the instructions provided by your veterinarian.
Enalapril
(Enacard
®, Vasotec®),
benazepril (Lotensin®), lisinopril (Prinivil®, Zestril®).
These drugs are angiotensin converting enzyme (ACE) inhibitors. ACE
inhibitors dilate blood vessels and moderate excess hormone activity that occurs with heart failure,
resulting in less resistance in the blood vessels against which the heart must
pump. These drugs have improved
clinical signs of heart failure and prolonged survival in several studies. An
ACE inhibitor may be the only drug needed early in the disease process.
The specific drug used and the individual pet’s disease influence the dose
and frequency of administration recommended. Enalapril®, benazepril®, and
lisinopril® can be given either on an empty stomach or with food.
Adverse effects of ACE inhibitors could include vomiting or diarrhea,
deterioration of kidney function, elevation of blood potassium levels, or low
blood pressure (hypotension). Other adverse effects that have been reported in
people taking the drug include skin rash or itchiness, taste impairment, and
certain abnormalities in blood and urine tests.
Furosemide (Lasix®, Disal®, others)
Furosemide is the diuretic ("water pill") most often used to promote
the loss of excess fluid in patients with congestive heart failure. The dosage
varies depending on the clinical situation and the patient’s response, but
generally the lowest dose that controls signs of congestion is used for
chronic therapy. Signs of heart failure decompensation and congestion such
as a persistent increase in resting respiratory rate or recurrence of cough
may respond to an (often temporary) increase in furosemide dose. In most cases
(check with your veterinarian first), if your pet has been
doing well on heart failure medication but subsequently develops signs of
congestion again, you can increase the dose or add an extra dose of furosemide
for a day or so. If this becomes necessary, be sure to discuss each event with
your veterinarian – reevaluation additional tests, and/or other therapy
adjustments may be necessary.
Adverse effects of furosemide are usually related to excessive fluid and/or
electrolyte losses (especially potassium) resulting in dehydration and
weakness.
Digoxin (Lanoxin®, Cardoxin®, Cardoxin LS®)
Digoxin is a positive inotropic (refers to the ability to contract) agent that mildly strengthens heart
muscle contraction. It also moderates the excess neurohormonal activity that
occurs with heart failure and helps control certain heart rhythm
abnormalities. Digoxin is not necessarily indicated in every case of heart
failure.
Digoxin is best given on an empty stomach since food as well as antacids
and kaolin-pectin compounds decrease drug absorption.
The toxic effects of digoxin can be serious and even life threatening so the drug must be carefully
dosed. Monitoring of the drug concentration in the blood is recommended. This
is often done 7 to 10 days after starting the drug or after making a dosage change.
The blood sample is taken 8 to 10 hours after a dose of the drug has been
given. Reduced kidney function, dehydration, loss of lean muscle mass, low
blood potassium levels, and certain drugs increase the potential for digoxin
toxicity.
Adverse/toxic effects can include heart rhythm disturbances, loss of
appetite, vomiting, diarrhea, and depression. If you suspect digoxin toxicity,
stop giving the digoxin and contact your veterinarian immediately.
Diltiazem (Cardizem®, Cardizem CD®, Dilacor XR®)
Diltiazem is a calcium channel blocker that is used to help control
certain heart rhythm disturbances and to promote heart muscle relaxation in
hypertrophic cardiomyopathy (especially in cats). In dogs with atrial
fibrillation (a rapid, irregular, abnormal heart rhythm) it may be used with digoxin to slow the rate of the heartbeat.
Adverse effects are uncommon at standard doses but can include decreased
appetite, slow heart rate, and rarely, other stomach/intestinal or heart
effects.
Atenolol (Tenormin®) and propranolol (Inderal®)
These drugs, among others, are called beta-blockers. They antagonize
the effects of the sympathetic nervous system, and thereby slow the heart
rate, reduce the heart’s oxygen demand, and help control certain heart rhythm
disturbances. A beta-blocker may be used with digoxin to slow the heartbeat in
dogs with atrial fibrillation. A beta-blocker may be useful in cats with
hypertrophic cardiomyopathy as well as animals with certain congenital heart
malformations.
Adverse effects are usually related to excessive beta blockade and
individual animals vary considerably in their response; thus, low doses are
used initially and slowly increased to effect. Dosage and frequency of
administration also depends on the drug used. Adverse effects can include
excessively slow heart rate, worsening of heart failure, low blood pressure,
bronchospasm (more likely with propranolol), depressed attitude, and possibly
masking early signs of low blood sugar (especially in diabetics).
Nitroglycerin (NitroBid®, Nitrol®)
and Isosorbide dinitrate (Isordil®,
Sorbitrate®)
These drugs are prescribed sometimes to dilate veins and help reduce
congestion. Nitroglycerin ointment is applied to the animal’s skin, often in
the groin or armpit area or inside the earflap.
Gloves or an application paper should be used to apply this medicine to
your pet. Do not get this medicine on your skin
because you will absorb it also.
Isosorbide comes in pill form.
Spironolactone (Aldactone®)
Spironolactone is another diuretic that works by a different
mechanism from furosemide. It is sometimes used in addition to furosemide in
the treatment of chronic, refractory congestive heart failure. Adverse effects
relate to excess potassium retention and stomach/intestinal upset. If used
with an ACE inhibitor or oral potassium supplement, blood potassium must be monitored
closely.
Chlorthiazide (Diuril®) or Hydrochlorothiazide (Hydrodiuril®)
These drugs are diuretics that are sometimes used with furosemide
for refractory heart failure. Adverse effects are usually related to excessive
fluid and/or electrolyte losses.
This Pet Health Topic was written by
O. L. Nelson, DVM, MS, Diplomate ACVIM (Cardiology
& Internal Medicine) Washington State University.
Washington State University assumes no liability for injury to
you or your pet incurred by following these descriptions or procedures.
Last Edited: Dec 19, 2007 12:12 PM
