By Rania Gollakner, BS, DVM, MPH

What is clonazepam?

Clonazepam (brand names: Klonopin®, Antelepsin®, Clonagin®, Clonapam®, CLonax®, Clonex®, Diocam®, Epitril®, Iktorivil®, Kenoket®, Kriadex®, Neuryl®, Paxam®, Rivatril®, Rivotril®, or Solfidin®) is a benzodiazepine antiseizure medication used as a supplemental medication to treat seizures in dogs and cats. It can also be used to treat anxiety or as a muscle relaxant.

Its use in cats and dogs to treat seizures and behavior problems 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 very carefully as their directions may be significantly different from those on the label.

How is clonazepam given?

Clonazepam is given by mouth in the form of a tablet or dissolving tablet. It can be given with or without food; however, if vomiting occurs after dosing on an empty stomach, give future doses with a meal or a treat. Give the first dose under direct supervision to monitor for serious side effects. For anxiety and behavior problems, give this medication an hour before the event or trigger. If dosed regularly, do not stop giving this medication abruptly. 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 sleepiness, incoordination, drooling, or excitement. In cats, increased appetite may occur. There is limited information regarding side effects of this medication in animals, but in humans, increased salivation, vomiting, diarrhea, constipation, blood effects, and liver effects have occurred. In cats, sudden liver damage is possible, and may appear as vomiting, diarrhea, lack of appetite, and yellowing of the skin, eyes, or gums.

This moderate-acting medication should stop working in a few days, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

Clonazepam should not be used in pets that are allergic to it or other benzodiazepines or in pets with significant liver disease. It should be used very cautiously in pets with glaucoma, liver or kidney disease, or myasthenia gravis and in sick or debilitated pets, geriatric pets, pregnant or lactating pets, aggressive pets, or working animals. Do not use the clonazepam dissolving tablets that contain xylitol in dogs as xylitol is toxic to dogs. Do not stop this medication abruptly; this medication should be tapered off to avoid seizures.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with clonazepam: azole antifungals, antihypertensive agents, anticholinergic agents, carbamazepine, carbonic anhydrase inhibitors, cimetidine, central nervous system (CNS) depressant drugs, danazol, digoxin, diltiazem, erythromycin, phenobarbital, phenytoin, propantheline, or rifampin.

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

Liver function tests should be checked regularly in cats. Blood levels of the medication may be monitored. Your veterinarian may monitor your pet to be sure that the medication is working. Monitor your pet at home for signs of serious side effects.

How do I store clonazepam?

Store at room temperature (77°F or 25°C)  with excursions between 59°F and 86°F (15°C and 30°C) allowed. Protect from light and moisture.

Clonazepam is a controlled substance, which means that it has been designated by the Drug Enforcement Administration (DEA) as having a potential for diversion to people other than the patient it was prescribed for. Use of a controlled substance in any person or animal other than that for which it is prescribed is illegal. Therefore, this medication should be stored in a locked cabinet or safe that cannot be easily moved, with access limited to only those that need to administer the medication. Monitor the amount of medication remaining to ensure the expected amount is present.

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.

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