(For veterinary information only)
WARNING
The size of the tablet/medication is NOT an indication of a proper dose. Never administer any drug without your veterinarian's input. Serious side effects or death can occur if you give medications to your pet without your veterinarian's advice.
It is our policy not to give dosing information over the internet.
Brand Name: Several brand names are available and vary by region.
Available in various strengths (mg). Consult your veterinarian with any questions.
Background
Research into the human experience of pain and its relief has yielded some important information:
- Recovery from illness is faster if pain is alleviated.
- It is more effective to prevent pain than to alleviate existing pain (i.e., using pain medications in anticipation of pain is more effective than waiting until the pain already exists).
- Continuous delivery of pain relief is more effective than periodic administration of pain relief.
Animals need pain relievers in the same situations that humans do. Clearly, relieving animal pain is important and must be done effectively and with neither struggling with the sick patient nor with being bitten while giving medications. Transdermal (through the skin) drug delivery has been very popular for several human medications. It turns out many of these can be adapted to pets. This allows not only for continuous pain relief delivery but also allows for medication to be administered without manipulating the patient's mouth.
How this Medication Works
Fentanyl is a narcotic, a member of the same group of drugs to which opium and morphine belong.
Some of the opiate effects include: pain relief, drowsiness, euphoria, addictiveness, diarrhea control, respiratory depression, and hallucinations.
Fentanyl is approximately 75 to 100 times stronger than morphine, making it an excellent choice for pain relief. It reaches its peak blood level in 3 to 6 hours in cats but may require a full 12 hours in dogs to reach its full effect. After removal, fentanyl blood levels drop to zero within 24 hours. Patches last at least three to four days for dogs and five days or so for cats, though in very painful situations (such as orthopedic surgery), additional pain medicines will likely be necessary.
Side Effects
The most serious potential side effect is respiratory depression (i.e., not breathing adequately). This is a rare problem, but if unusual weakness or drowsiness is observed, the drug may be having a stronger effect than expected. A fentanyl patch may be removed if there is any concern.
Consult your veterinarian or a veterinary emergency clinic IMMEDIATELY if your pet chews on or eats part of a patch, is unresponsive, can’t walk normally, or shows other concerning signs while on this medication.
- Occasionally, a pet reacts to the adhesive on the back of the patch. Such skin reactions should resolve with patch removal and the use of topical cortisone.
- If residual adhesive remains on the skin after patch removal, do not try to clean it off, as this can cause more irritation. Instead, simply allow it to wear off.
- This medication may cause excessive appetite, although in some animals, nausea results, leading to a reduced appetite.
- Fentanyl is not known to be a sedative in cats, but in dogs, some sedation may be observed.
- A wobbly gait may be a sign of sedation.
- Fentanyl may cause dilated pupils in cats. This could manifest as an aversion to bright light or sunshine.
- Fentanyl can slow your pet's heart rate. This is generally not an issue unless other medications are added (see below).
- There is some variability in the blood levels in different pets. Some pets require additional medication for breakthrough pain.
Interactions with Other Drugs
- Fentanyl should be used with caution in combination with medications that have sedating properties, such as antihistamines or other sedating pain relievers. Over-sedation may result.
- Narcotics, including fentanyl, should not be used in patients using Anipryl/L-Deprenyl for the treatment of Cushing's disease or senility/cognitive dysfunction.
- When fentanyl and diuretics are given together, the effectiveness of the diuretics may be reduced.
- Macrolide antibiotics, such as erythromycin, may slow the removal of fentanyl from the body and create a stronger-than-expected fentanyl effect. Similar issues occur with ketoconazole, itraconazole, fluconazole, and cimetidine.
- Conversely, some medications enhance the clearing of fentanyl for a weaker effect: phenobarbital, mitotane, and griseofulvin.
- Fentanyl should not be combined with tramadol as high blood pressure or seizures could result.
- Medications that reduce blood pressure may compound the slowing of the heart rate that can occur with fentanyl. Blood pressure can drop lower than expected.
Concerns and Cautions
The application of heat to a fentanyl patch can lead to sudden delivery of a large amount of fentanyl.
(Be careful of heating pads or electric blankets.) Human deaths have been reported in patients who slept on heated water beds. If your pet has a fentanyl patch, be sure to avoid situations where the patch could be excessively heated.
Always wear gloves when applying transdermal medications, including patches in this circumstance.
Accidental exposure to fentanyl in children can be deadly. Consult your local poison control immediately in this case.
- Fentanyl is a controlled drug, meaning that specific paperwork is required by certain state and federal government agencies to order it and stock it.
- Your veterinarian may require you to return any used patches for documentation of proper disposal.
- Fentanyl patches may be toxic if swallowed by small children. Be alert to any children curious about the patch or attempting to manipulate it.
- Keep new patches in a secure place where pets and children cannot access them.
In the United States, the FDA recommends the following for fentanyl home disposal:
• Folded the used patch in half and flush down the toilet.
• Do not throw in the trash.
Be sure to ask your vet if you have any questions or concerns about this medication.