Isosorbide Dinitrate / Isosorbide Mononitrate
Also known as: Isordil, Ismo, Imdur, Isochron, Dilatrate-SR, Monoket, Titradose
* **Experimental Nature:** There is limited experience using this medication in veterinary medicine; it is typically reserved for advanced or difficult-to-treat heart conditions. * **Administration:** May be given with or without meals. Follow your veterinarian's dosing schedule exactly, as specific timing may be needed to prevent the body from building a tolerance to the drug. * **What to Watch For:** Because this drug lowers blood pressure, watch your pet closely for signs of weakness, lethargy, stumbling, or fainting. If these occur, contact your veterinarian immediately. * **Storage:** Keep the medication tightly closed in its original container, protected from heat and moisture, as these can cause the drug to lose its potency.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
What it is used for
- Adjunctive treatment of heart failure associated with thyroid storm
- Refractory heart failure or in combination with hydralazine or amlodipine in patients unable to tolerate ACE inhibitors
- Refractory heart failure or in combination with hydralazine or amlodipine in patients unable to tolerate ACE inhibitors
How it is given
Possible side effects
- Postural hypotension
- Reflex tachycardia
- Lethargy or weakness (secondary to hypotension)
- Gastrointestinal upset
- Restlessness
- Headache (well-documented in humans, difficult to assess in animals)
- Hypersensitivity reactions (rare)
Cautions & contraindications
- Cardiogenic or hypovolemic shock
- Severe hypotension
- Hypovolemia
- Use as a sole agent for treating heart failure
- Concurrent use with selective phosphodiesterase inhibitors (e.g., sildenafil)
- > **Hemodynamic Warning:** Use with extreme caution in patients with low blood pressure or uncorrected hypovolemia. * **Nitrate Tolerance:** Continuous exposure may lead to tolerance. Consider dosing strategies that allow for a nitrate-free interval if chronic use is intended. * **Laboratory Interference:** Serum cholesterol levels may be falsely decreased by nitrates when using the Zlatkis-Zak color reaction method. * **Pregnancy:** FDA Category C. Use only if the potential benefit justifies the potential risk to the fetus.
Drug interactions
- Antihypertensive Drugs (e.g., ACE inhibitors, amlodipine, beta-blockers): Possible additive hypotensive effects; monitor blood pressure closely.
- Phenothiazines (e.g., acepromazine): Possible additive hypotensive effects due to alpha-adrenergic blockade.
- Selective Phosphodiesterase Inhibitors (e.g., sildenafil, pimobendan): Concurrent use with sildenafil can cause profound, life-threatening hypotension and is strictly contraindicated. Use with pimobendan (a PDE3 inhibitor) is common in vet med but requires monitoring for excessive vasodilation.
Frequently asked questions
What is Isosorbide Dinitrate / Isosorbide Mononitrate used for in pets?
* **Experimental Nature:** There is limited experience using this medication in veterinary medicine; it is typically reserved for advanced or difficult-to-treat heart conditions. * **Administration:** May be given with or without meals. Follow your veterinarian's dosing schedule exactly, as specific timing may be needed to prevent the body from building a tolerance to the drug. * **What to Watch For:** Because this drug lowers blood pressure, watch your pet closely for signs of weakness, lethargy, stumbling, or fainting. If these occur, contact your veterinarian immediately. * **Storage:** Keep the medication tightly closed in its original container, protected from heat and moisture, as these can cause the drug to lose its potency.
Is Isosorbide Dinitrate / Isosorbide Mononitrate safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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