Agitation, tremors, seizures, opioid exposures – the list of problems patients may present with seems endless. But if you have these 10 drugs on hand you’ll be in a good position to tackle issues that enter your clinic:
Cholestyramine is the chloride salt of a basic anion exchange resin. It binds with bile acids in the intestine, preventing their reabsorption. Since many toxins need to be bound to bile acids for absorption, this stops the cycle and increases fecal excretion of the toxicant. Cholestyramine is useful for several toxins that undergo enterohepatic recirculation: cholecalciferol (vitamin D3), sago palm, cyanobacteria (blue green algae), digitoxin and some NSAID ingestions. Beware, though, since some human formulations contain xylitol and those must not be used for dogs.
Maropitant is a neurokinin-1 receptor antagonist that is very effective at both stopping and preventing vomiting. This drug is most likely already on the shelf of your veterinary clinic because vomiting is so common in dogs and cats. For toxicology cases, it can also be used to prevent vomiting before giving activated charcoal to reduce aspiration risk in recumbent animals or ones who are displaying neurologic signs.
If you have ever treated a dog for an overdose of ADHD medication, or any other amphetamine, you know why this drug is on the list. Acepromazine is a phenothiazine derivative antipsychotic drug used in animals as a sedative; it also has anti-serotonergic properties. Remember that much higher doses than normal sometimes need to be given when dealing with amphetamine toxicity. Acepromazine can also be used to help control hypertension caused by stimulants when nitroprusside is not available – start with small doses and titrate to affect. Always monitor the blood pressure when acepromazine is given.
Cyproheptadine is a 5-HT2 receptor antagonist used to treat serotonin syndrome. It should be used as a second line treatment for overdoses of serotonergic drugs such as SSRIs, amphetamines, tramadol, 5-HTP and marijuana when signs of serotonin syndrome persist despite treatment with first-line drugs like acepromazine or diazepam. Only give cyproheptadine while signs of serotonin syndrome are present, or it can actually cause stimulatory signs – most toxicity cases only require 1-3 doses.
Benzodiazepines are useful for controlling mild agitation, as well as stopping seizures from a variety of toxins. They should not be used for overdoses of amphetamines as they can actually worsen clinical signs. Benzodiazepines are also contraindicated for seizures caused by muscimol (isoxazole) mushroom ingestions as they can cause severe respiratory depression or even respiratory arrest. Levetiracetam loading is a good alternative for these cases and has the added benefit of being water soluble, so it is a good choice in cases where IV lipids are being used.
If you have a patient presenting with tremors instead of seizures, reach for methocarbamol. Though it is expensive, there is nothing that will control tremors as well as injectable methocarbamol. If you find yourself in a jam and only have the tablet form, it can be crushed up and mixed with water and given rectally, though it will take significantly longer to work.
Acetylcysteine works to protect the liver by replenishing glutathione, an antioxidant that prevents damage from reactive oxygen species. It is most commonly used for acetaminophen toxicity but can be given along with SAMe for other hepatotoxins such as xylitol, cyanobacteria, sago palms and amatoxins, among others. Acetylcysteine should be diluted to a 5% solution before administration and can be given orally or intravenously through a filter. If given orally, it should be further diluted with something sweet because it has a very sulfur (rotten egg) smell and taste.
Most veterinarians know that naloxone can be used to reverse opioid exposure but did you know it can be used to reverse severe CNS depression from some other toxins as well? At the Animal Poison Control Center we’ve found that high-dose naloxone (0.1 mg/kg) works well to reverse the coma that can be seen when animals get into large doses of ibuprofen. We have also had success using it for ethanol toxicity and to treat bradycardia due to cyclobenzaprine. If you have an animal who presents with severe CNS depression of unknown cause, try giving a dose of naloxone. If it helps, remember that repeat doses may be needed as signs return.
Propranolol is a non-selective beta blocker that is primarily used to treat sinus tachycardia from chocolate, amphetamines, SSRIs, 5-HTP and other stimulants. If your patient is also hypertensive, a beta 1 specific blocker such as esmolol is preferred – but if you only have propranolol, you can often give a little acepromazine to get the blood pressure down and then give the propranolol. In the case of albuterol toxicity, propranolol is virtually an antidote that will slow heart rate and correct hypokalemia without the need to supplement potassium.
Atipamazole is an alpha 2 blocker, commonly used in vet clinics to reverse dexmedetomidine and xylazine. It can also be used to reverse clinical signs from other alpha agonists such as clonidine, guanfacine, tizanidine, imidazoline and oxymetazoline decongestants and eye drops, and flea collars that contain amitraz.