Fentanyl
Also known as: Sublimaze, Duragesic, Actiq, Fentora, Ionsys, Fentadon, Durogesic
**Important Safety Information for Pet Owners:** * **Extreme Caution with Children and Pets:** Fentanyl is a highly potent narcotic. If a patch falls off or is removed by the pet, it can be **fatal** if chewed or swallowed by a child or another animal. Dispose of used patches securely (e.g., folding the sticky sides together and flushing down the toilet or returning to the clinic). * **Accidental Human Contact:** If you accidentally touch the sticky side of the patch or the gel, **wash your hands immediately with plain water ONLY**. Do NOT use soap, alcohol, or hand sanitizers, as these can increase the absorption of the drug through your skin. * **NO Heat Sources:** Never allow your pet to lie on a heating pad, heated blanket, or in direct intense sunlight while wearing the patch. Heat causes the drug to be released rapidly, which can cause a fatal overdose. * **Delayed Effect:** The patch takes time to start working (12-24 hours in dogs, 6-12 hours in cats). Your veterinarian may prescribe other pain medications to bridge this gap. * **Monitoring:** Watch your pet closely for extreme lethargy, severe changes in breathing (very slow or shallow), or unusual agitation. Contact your veterinarian immediately if these occur.
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
- Perioperative pain
- Pain management
- Surgical analgesia
- Analgesia
- Induction
- MAC reduction during general anesthesia
- Severe to excruciating pain in the emergent patient
- Epidural for pain control
- Maintenance analgesia/heavy sedation in critically ill hypotensive animals
- Transdermal Analgesia
- Intraoperative analgesia
- Postoperative analgesia
- Postoperative or chronic pain
- Transdermal Analgesia (17-25 kg)
How it is given
Possible side effects
- Dose-related respiratory depression
- CNS depression (sedation)
- Circulatory depression (bradycardia)
- Dysphoria or agitation (especially in cats)
- Urine retention
- Constipation
- Contact dermatitis/rash at patch site
- Altered thermoregulation (hypothermia or hyperthermia)
- Respiratory depression
- Severe bradycardia
- Asystole (with rapid IV injection)
- Reduction in heart rate
Cautions & contraindications
- Known hypersensitivity to fentanyl or patch adhesive
- Conditions where additional respiratory or CNS depression would be deleterious
- No specific contraindications available in the monograph (use with caution in patients with respiratory compromise)
- **Patient Selection:** Use with extreme caution in geriatric, severely ill, or debilitated patients, and those with preexisting respiratory compromise. **Transdermal Patch Warnings:** * **Heat Exposure:** Do NOT allow the applied patch to be exposed to exogenous heat sources (e.g., heating pads, heated cages, direct sunlight). Heat significantly increases drug release and absorption, which has resulted in fatal overdoses. * **Fever:** Febrile patients may have increased absorption of fentanyl and require intense monitoring. Consider removing the patch if a fever develops. * **Patch Integrity:** Do NOT cut patches unless specifically advised by a pharmacist (cutting alters the drug-releasing membrane of gel-reservoir patches, leading to rapid, uncontrolled drug release). * **Variable Absorption:** Absorption is highly variable. Always have injectable rescue analgesia available. **Feline Specifics:** Opioids may cause mydriasis (dilated pupils) in cats. Approach slowly to avoid startling them, and keep them out of bright light. **Laboratory Alterations:** Opiates can increase biliary tract pressure, potentially elevating plasma amylase and lipase values for up to 24 hours post-administration.
Drug interactions
- Azole Antifungals (ketoconazole, itraconazole, fluconazole): May inhibit fentanyl metabolism, increasing risk of toxicity
- CNS Depressants (other): Additive CNS and respiratory depressant effects
- Diuretics: Opiates may decrease diuretic efficacy in congestive heart failure patients
- Macrolide Antibiotics (erythromycin, clarithromycin): May inhibit fentanyl metabolism
- Monoamine Oxidase Inhibitors (amitraz, selegiline): Severe and unpredictable opiate potentiation; generally not recommended within 14 days of MAOI use
- Skeletal Muscle Relaxants: Fentanyl may enhance neuromuscular blockade
- Nitrous Oxide: High fentanyl doses combined with nitrous oxide may cause cardiovascular depression
- Phenobarbital, Phenytoin: May increase the metabolism of fentanyl, reducing its efficacy
- Rifampin: May increase the metabolism of fentanyl
- Tricyclic Antidepressants (clomipramine, amitriptyline): Fentanyl may exacerbate the effects of tricyclic antidepressants
Frequently asked questions
What is Fentanyl used for in pets?
**Important Safety Information for Pet Owners:** * **Extreme Caution with Children and Pets:** Fentanyl is a highly potent narcotic. If a patch falls off or is removed by the pet, it can be **fatal** if chewed or swallowed by a child or another animal. Dispose of used patches securely (e.g., folding the sticky sides together and flushing down the toilet or returning to the clinic). * **Accidental Human Contact:** If you accidentally touch the sticky side of the patch or the gel, **wash your hands immediately with plain water ONLY**. Do NOT use soap, alcohol, or hand sanitizers, as these can increase the absorption of the drug through your skin. * **NO Heat Sources:** Never allow your pet to lie on a heating pad, heated blanket, or in direct intense sunlight while wearing the patch. Heat causes the drug to be released rapidly, which can cause a fatal overdose. * **Delayed Effect:** The patch takes time to start working (12-24 hours in dogs, 6-12 hours in cats). Your veterinarian may prescribe other pain medications to bridge this gap. * **Monitoring:** Watch your pet closely for extreme lethargy, severe changes in breathing (very slow or shallow), or unusual agitation. Contact your veterinarian immediately if these occur.
Is Fentanyl 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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