Buprenorphine Buprenex,Available as injectable but usually prescribed as an oral spray or liquid, Opiates have been used since ancient times for their pain relieving and euphoric properties. Neurologic studies have revealed brain receptors that bind opiates, each type of receptor being responsible for different opiate effects. These receptors are named for Greek letters mu, kappa, delta, and sigma. The mu receptor is responsible for the narcotic effects of euphoria, pain relief, addiction, lowering of heart rate, and respiratory depression. Buprenorphine is partially active at the mu receptor.
While buprenorphine is considered approximately 30 times stronger than morphine in many of its effects, morphine is a much a stronger pain reliever because it is more active at the mu receptor. Buprenorphine is best used for mild to moderate pain.
How this Medication Is Used
This drug can be used as an injectable in the hospital but can also be used at home for pain control as an oral drop or spray. While buprenorphine is commonly dispensed for three times daily usage, how long a dose lasts actually depends on the size of the dose because of buprenorphine’s ceiling effect, which means that once a maximum effect has been reached (i.e. all the receptors have been bound with drug) giving more buprenorphine does not create a greater effect. Instead, the higher the dose, the longer the effects last.
In cats (but not dogs), buprenorphine is absorbed into the body directly from the mouth membranes; swallowing is unnecessary. This is called transmucosal administration and is how buprenorphine is almost always used at home.
Approximately 2/3 of people using this medication experienced drowsiness.
Buprenorphine can cause a drop in heart rate as well as in blood pressure.
Because respiratory depression is a possible side effect, buprenorphine should not be used in patients with respiratory compromise, including respiratory compromise from heart failure or head trauma. Respiratory depression from buprenorphine would be unusual in normal patients.
Buprenorphine is removed from the body through the liver. Patients with liver disease will have prolonged effects.
Naloxone can be used to reverse side effects of this or any other narcotic.
Interactions with other Drugs
The sedation side effect is more severe if this medication is used in conjunction with other medications that have a sedating side effect including antihistamines.
Buprenorphine should not be used with selegiline or any other monoamine oxidase inhibitor because a potentially dangerous blood pressure situation called serotonin syndrome can result. A two-week waiting period is recommended if buprenorphine or any other narcotic is to be used in a patient on such a drug (usually a dog with canine cognitive dysfunction taking seligiline). Other compounds that could be problematic in this way include tick control products containing amitraz or the pain reliever tramadol.
Concerns and Cautions
Buprenorphine should be stored at room temperature and protected from light exposure.
Buprenorphine definitely crosses the placenta to unborn young and is secreted in mother’s milk, possibly in a concentrated form. It is thus best not used in pregnancy or lactation.
Opiates should be used with caution in patients with hypothyroidism, hypoadrenocorticism, or who are generally debilitated.
Transmucosal delivery of buprenorphine in cats is as reliable as injection but in dogs only about 50 percent of the buprenorphine is absorbed into the body from the mouth. This route might still be useful if dose adjustments are taken into consideration.
In 2014, a veterinary labelled product called Simbadol® was released. This product is for cats only and is injectable only. The buprenorphine in Simbadol® has been treated so that one dose can be expected to last for 24 hours. This version of buprenorphine cannot be used orally.
If you skip a dose by accident, do not double up on the next dose. Instead, simply pick up at the next dose as normal.
Buprenorphine is a controlled substance. Specific paperwork is necessary for its prescription.
It is our policy not to give dosing information over the Internet.
By Wendy C. Brooks, DVM, DipABVP
Educational Director, VeterinaryPartner.com