Diltiazem (Dilacor XR), a calcium channel blocker, is used for supraventricular tachycardia (SVT), or irregularly fast or erratic heartbeat, in a variety of animals, including dogs, cats, and ferrets. It may also be used adjunctively for systemic or pulmonary hypertension or supportively in cats and ferrets for thickened heart muscle, also known as hypertrophic cardiomyopathy (HCM).
Several formulations and strengths are available, so it is important to ensure your prescription clearly indicates the product intended. The client also needs to be appropriately counseled on administration techniques to avoid overdosing the patient.
The most commonly used formulations are Diltiazem 30 mg tablets and Diltiazem Extended-Release 240 mg capsules. The immediate-release 30 mg tablets allow for ease of dosing and can be purchased from MWI Animal Health for less than $10 for a bottle of 100. The 240 mg capsules are an extended-release product, but this formulation is unique as it is a capsule that can be opened to reveal four small tablets inside. The inner tablets allow for dosing of veterinary patients at 60 mg per tablet. Even after the capsule is opened, the 60-mg tablets are still considered to be a sustained-release product.
Another formulation that can be prescribed is Diltiazem HCl Extended-Release 60 mg capsules. However, pricing for a 100-count bottle is ~ $200, whereas a 100-count bottle of the 240 mg capsules (containing four times as many tablets) is ~ $100.
There is also a Diltiazem Extended-Release 180 mg capsule product that contains tablets, but pricing makes it more feasible to purchase the bottle of 240 mg capsules.
It is important to recognize that the formulations are not interchangeable, and dosing is formulation dependent. If you prescribe this medication to an outside pharmacy, providing the product’s listing in the FDA’s National Drug Code (NDC) directory will guarantee your patient receives the expected medication. The table above denotes the wholesaler, brands, NDCs, and manufacturer size of the formulations discussed in this article.
By Alex Gochenauer, PharmD, DICVP, FSVHP