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(for veterinary information only)
AVAILABLE IN
1 MG, 5 MG and 10 MG
TABLETS
The opiate class of medication is complicated to describe. There are several types of receptors in the nervous system that respond to opiates. These receptors are designated by different Greek letters (“mu,” “kappa,” and “sigma”). Opiates work by binding and stimulating some receptors (such opiates are said to be “agonists” of the receptors they stimulate) or they may bind and block receptors (in which case they are “antagonizing” the receptor). What the effects of a given opiate are (euphoria, cough suppression, pain relief, hallucination, addiction etc.) depend on which receptors are stimulated and which are blocked. Some opiates only stimulate receptors. These are called “pure agonists.” Some opiates, like butorphanol, stimulate some receptors and block others. This makes butorphanol what is called an “agonist/antagonist.” It seems to stimulate the kappa and sigma receptors and antagonize mu receptors.
Butorphanol is a controlled substance, which means there are special legal requirements for prescribing and stocking it.
Regardless of which receptors are stimulated and which antagonized, butorphanol ultimately is a cough suppressant as well as a short-acting analgesic. It also has some sedating properties. Many people are familiar with codeine, which has nearly identical uses and is also in the opiate family (though it is not an agonist/antagonist like butorphanol). It may be helpful to think of butorphanol as being similar to codeine: lower doses can be used to suppress cough, higher doses for pain relief.
Most opiates can be used to suppress cough but, unlike other opiates, butorphanol does not suppress the respiratory center in the brain (and does not slow respiration nor make breathing more shallow).
Butorphanol is also sometimes used as a pre-anesthetic tranquilizer though it is very mild in this regard. It may also be used for pain relief following a surgical procedure (it acts rapidly but only for a short time so usually a longer acting pain reliever is used in combination).
Butorphanol has some anti-nausea properties and is commonly used in this way prior to the administration of cisplatin in cancer chemotherapy.
The chief side effect is sedation. Occasionally, it can cause diarrhea or appetite loss. Butorphanol is able to slow the heart rate though this is rarely of meaningful significance to normal patients.
Because butorphanol antagonizes the mu receptor, it will fight against opiates that are mu agonists: morphine, oxymorphone, meperidine, etc.
If butorphanol is used with any other drugs that have sedating properties, these sedating properties will be more blatant.
While butorphanol does not normally cause respiratory suppression, it might if used in conjunction with antihistamines or tranquilizers.
There are several circumstances where butorphanol is considered inappropriate. Butorphanol should be used cautiously or not at all in patients with: liver disease, kidney failure, hypothyroidism, hypoadrenocorticism (Addison's disease), head trauma, hydrocephalus, or in very debilitated patients.
Butorphanol will cross the placenta and will be secreted in milk. It should not be used in pregnancy and lactation.
Butorphanol is removed from the body by the liver. If the liver is diseased, one may see abnormal clearance of the drug.
Butorphanol should not be used in respiratory conditions where cough suppression is not desired (such as pneumonia).
Page last updated: 8/11/09
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