What is chlorpromazine?
Chlorpromazine (brand names Thorazine®, Largactil®, Chlorprom®, Chlorpromanyl®) is a phenothiazine sedative and anti-vomiting medication used as a sedative or to treat motion sickness, particularly in cats.
"Many drugs are commonly prescribed for off-label use in veterinary medicine."
Its use in cats and dogs, to treat vomiting or as a sedative is “off label” or “extra label”. Many drugs are commonly prescribed for off-label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.
How is chlorpromazine given?
- Chlorpromazine is given by mouth, in the form of a tablet or liquid. It can also be given by injection in the hospital.
- Measure liquid form medication carefully.
- Do not administer this medication to your pet if the liquid changes to a dark color or if chunks form in the liquid.
- Do not get chlorpromazine on your hands, as skin irritation or a rash may occur.
This medication will take effect quickly, in about 1 to 2 hours, and improvement in clinical signs should follow.
What if I miss giving my pet the medication?
Give the missed dose as soon as you remember, and then wait the recommended amount of time between doses. Never give your pet two doses at once or give extra doses.
Are there any potential side effects?
Side effects may include:
- pink or reddish-brown urine color (temporary)
- tiredness
- low blood pressure
- low heart rate
- a tendency to react or startle to noises
Serious side effects include:
- coma
- agitation
- seizures
- abnormal heart rhythms
- dangerously low blood pressure
In cats, higher doses can cause the following side effects:
- tremors
- shivering
- rigidity
- lethargy
- diarrhea
- loss of anal sphincter tone
- loss of certain reflexes
This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.
Are there any risk factors for this medication?
Chlorpromazine should NOT BE USED in pets that:
- are allergic to it
- have low blood pressure
It should be USED WITH CAUTION in:
- pets that are generally debilitated
- pets with liver disease, heart disease, seizures, or aggressive behavior
- pets that are pregnant or lactating
- dogs with the MDR 1 genetic mutation (consider a lower dose); breeds commonly affected include collies, sheepdogs, and collie- or sheepdog-cross-breeds
Are there any drug interactions I should be aware of?
The following medications should be used with caution when given with chlorpromazine:
- acetaminophen
- amitriptyline
- amlodipine
- antacids
- antidiarrheal mixtures
- central nervous system (CNS) depressant agents
- desmopressin
- laxatives
- loop diuretics
- opiates
Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.
Is any monitoring needed with this medication?
- Heart rate and rhythm, blood pressure, and body temperature should be monitored.
- Monitor your pet to be sure that the medication is working and that the dose is adequate and not excessive.
How do I store chlorpromazine?
- Store at room temperature, protected from light and moisture.
- Do not freeze the liquid solution.
What should I do in case of emergency?
If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.
