Tadalafil
Also known as: Cialis, Adcirca
**What is this medication?** Tadalafil is used to treat high blood pressure in the lungs (pulmonary hypertension), helping your dog breathe easier, improving exercise tolerance, and reducing fainting spells. **How to give:** Can be given with or without food. **Important Warnings:** > **Never give this medication if your pet is taking any nitrate medications (like nitroglycerin), as it can cause a fatal drop in blood pressure.** **Side Effects:** Watch for stomach upset, redness/flushing of the skin (especially on the hairless belly area), or lethargy. Report any unusual signs to your veterinarian. **Cost & Off-label use:** This is a human medication used "off-label" in pets. Because it is a newer, long-acting medication, it can be quite expensive. Discuss any financial concerns with your veterinarian.
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
- Pulmonary arterial hypertension
- Pulmonary arterial hypertension
How it is given
Possible side effects
- Cutaneous flushing of the inguinal region
- Gastrointestinal upset (dyspepsia, nausea)
- Decreased neutrophils and platelets (observed at 4X-18X human equivalent doses; reversible)
- Hypotension (especially if combined with other vasodilators)
- Myalgia or back pain (reported in humans)
- Headache or nasal congestion (reported in humans)
Cautions & contraindications
- Concurrent use of any form of organic nitrates (regularly or intermittently)
- Serious hypersensitivity to tadalafil
- Dosage reductions may be required in patients with severe hepatic or renal impairment. Use with extreme caution in patients on concurrent antihypertensive therapies. The safety profile in dogs is not fully established; monitor closely for adverse effects.
Drug interactions
- Alpha-adrenergic blockers (e.g., phentolamine, phenothiazines, phenoxybenzamine): May increase hypotensive effects
- Amlodipine: Potential to increase hypotensive effects
- Antihypertensive / Hypotensive drugs: Potentially could increase hypotensive effects
- Azole antifungals (ketoconazole, itraconazole): May reduce tadalafil metabolism and increase AUC
- Cimetidine: May reduce tadalafil metabolism and increase AUC
- Erythromycin, Clarithromycin: May reduce tadalafil metabolism and increase AUC
- Nitrates (e.g., Nitroglycerin, Isosorbide): Significant potentiation of vasodilatory effects; life-threatening hypotension possible
- Nitroprusside sodium: Significant potentiation of vasodilatory effects; life-threatening hypotension possible
- Phenobarbital: May decrease tadalafil concentrations
- Rifampin: May decrease tadalafil concentrations
Frequently asked questions
What is Tadalafil used for in pets?
**What is this medication?** Tadalafil is used to treat high blood pressure in the lungs (pulmonary hypertension), helping your dog breathe easier, improving exercise tolerance, and reducing fainting spells. **How to give:** Can be given with or without food. **Important Warnings:** > **Never give this medication if your pet is taking any nitrate medications (like nitroglycerin), as it can cause a fatal drop in blood pressure.** **Side Effects:** Watch for stomach upset, redness/flushing of the skin (especially on the hairless belly area), or lethargy. Report any unusual signs to your veterinarian. **Cost & Off-label use:** This is a human medication used "off-label" in pets. Because it is a newer, long-acting medication, it can be quite expensive. Discuss any financial concerns with your veterinarian.
Is Tadalafil 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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