What is diltiazem?
Diltiazem (brand names: Cardizem®, Dilacor XR®, Tiazac®, Diltia XT®, Taztia XT®, Dilt-XR®) is a calcium-channel blocker anti-arrhythmic used in cats, dogs, and ferrets to treat certain heart and vascular conditions such as supraventricular tachycardias due to atrial fibrillation, pulmonary hypertension, systemic hypertension, or hypertrophic cardiomyopathy.
Its use in cats, dogs, and ferrets to treat heart conditions is “off label” or “extra label”. Many drugs are commonly prescribed for off-label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.
How is diltiazem given?
This medication is given by mouth, in the form of a tablet or capsule. Some tablets and capsules must be given whole to work properly, follow directions carefully.- Some forms of diltiazem come as a capsule with four small tablets inside. Your veterinarian may direct you to open the capsule and administer a certain number of the tablets inside. Follow the directions on the label carefully.
- Diltiazem may also be compounded into a liquid to be given by mouth. Follow the directions on the label and measure doses carefully.
- Diltiazem can also be given by injection into the vein in hospital.
- It can be given with or without food, but if your pet vomits after receiving the medication on an empty stomach, try giving future doses with a meal or a treat.
This medication should take effect within 1 to 2 hours; however, effects may not be visible, so laboratory tests may be required to evaluate this medication’s effectiveness.
What if I miss giving my pet the medication?
Give the missed dose as soon as you remember, and then wait the recommended amount of time between doses. Never give your pet two doses at once or give extra doses.
Are there any potential side effects?
In dogs, the most common side effect a slow heart rate. In cats, the most common side effect is vomiting.
Side effects that may occur in cats or dogs include:
- lethargy
- decreased appetite
- weight loss
- general stomach upset
More severe side effects may occur. If any of the following signs develop, stop giving this medication and contact your veterinarian immediately:
- low blood pressure, causing collapse and/or severe weakness
- abnormal heart rhythms, causing collapse and/or weakness
- neurological effects
- elevated liver enzymes, potentially causing yellowing of the skin, eyes and gums
- skin rashes
This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.
Are there any risk factors for this medication?
Diltiazem should NOT BE USED in pets that:
- are allergic to it
- have severely low blood pressure,
- have abnormal heart rhythms such as sick sinus syndrome or AV block,
- have acute myocardial infarction
- have X-ray evidence of lung congestion
Diltiazem should be USED WITH EXTREME CAUTION in pregnant or lactating animals (the benefits of using this medication should outweigh the risks).
It should be USED WITH CAUTION in pets that:
- are geriatric
- have heart failure
- have liver or kidney disease
- are receiving beta blockers
Are there any drug interactions I should be aware of?
The following medications should be used with caution when given with diltiazem:
- amiodarone
- benzodiazepines
- beta-blockers
- clopidogrel
- cyclosporine
- digoxin
- macrolide antibiotics
- fluconazole/ketoconazole
- hydrocodone
- methylprednisolone
- theophylline
Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.
Is any monitoring needed with this medication?
Monitoring will be done while your pet is using this medication, including:
- electrocardiogram (ECG)
- heart rate
- blood pressure
Your veterinarian will schedule these appointments at the appropriate intervals for your pet. Your veterinarian will also monitor your pet to be sure that the medication is working.
Monitor your pet at home for severe side effects.
How do I store diltiazem?
- Store tablets and capsules at room temperature, in a tight container, protected from light.
- For liquid compounded forms, follow the directions on the label.
What should I do in case of emergency?
If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility and contact an animal poison control center.
