Prazosin
Also known as: Minipress, Hypovase
* **Purpose:** This medication is most commonly prescribed to help relax the urinary tract, making it easier for your pet to urinate (especially in cats recovering from a urinary blockage). * **Administration:** Give this medication exactly as directed by your veterinarian. If possible, give the medication with food. * **First-Dose Effect:** Prazosin can cause a sudden drop in blood pressure, especially after the first dose. Your pet may appear dizzy, weak, or lethargic. Keep them away from stairs or high places initially to prevent falls. * **When to call the vet:** Notify your veterinarian immediately if your pet's condition deteriorates, if they are unable to urinate, or if they become excessively lethargic or depressed.
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
- Decrease urethral resistance
- Decrease urethral resistance
- Functional urethral obstruction
- Urethral spasm
- Reduce urethral tone
- Adjunctive treatment of heart failure
- Hypertension
- Hypertension in a large dog
- Decrease urethral resistance
- Functional urethral obstruction
- Decrease urethral resistance
- Reduce urethral tone
How it is given
Possible side effects
- Hypotension (including orthostatic hypotension/syncope)
- Lethargy
- Dizziness
- Nausea
- Vomiting
- Diarrhea
- Constipation
- Tachyphylaxis (drug tolerance)
- Hypotension (especially first-dose effect)
- Lethargy / Weakness
- Dizziness / Syncope
- Gastrointestinal upset (vomiting, diarrhea)
- Reflex tachycardia
Cautions & contraindications
- Preexisting hypotensive conditions
- Pre-existing hypotension
- Hypovolemia
- Known hypersensitivity to alpha-blockers
- > **MDR1/ABCB1 Mutation Warning:** Anecdotal reports suggest dogs with the ABCB1 mutation may be overly sensitive to prazosin. Consider alternate drugs or reduce dosage and increase monitoring (especially blood pressure). * Use with caution in patients with **chronic renal failure**. * Use with caution in patients with preexisting hypotensive conditions. * **First-Dose Effect:** Syncope secondary to orthostatic hypotension can occur after the first dose. Monitor closely.
Drug interactions
- Beta-blocking agents (e.g., propranolol): May enhance the postural hypotensive effects seen after the first dose of prazosin
- Clonidine: May decrease prazosin antihypertensive effects
- Sildenafil (and other PDE inhibitors): May increase risk for hypotension
- Verapamil or Nifedipine: May cause synergistic hypotensive effects when used concomitantly with prazosin
- Amlodipine: Additive hypotensive effects
- ACE Inhibitors (e.g., Benazepril, Enalapril): Increased risk of severe hypotension
- Beta-blockers (e.g., Propranolol): Exacerbation of postural hypotension
- Sildenafil: Profound hypotension
Frequently asked questions
What is Prazosin used for in pets?
* **Purpose:** This medication is most commonly prescribed to help relax the urinary tract, making it easier for your pet to urinate (especially in cats recovering from a urinary blockage). * **Administration:** Give this medication exactly as directed by your veterinarian. If possible, give the medication with food. * **First-Dose Effect:** Prazosin can cause a sudden drop in blood pressure, especially after the first dose. Your pet may appear dizzy, weak, or lethargic. Keep them away from stairs or high places initially to prevent falls. * **When to call the vet:** Notify your veterinarian immediately if your pet's condition deteriorates, if they are unable to urinate, or if they become excessively lethargic or depressed.
Is Prazosin 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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