Drugs Used to Treat Toxicoses

Sharon M. Gwaltney-Brant, Mahomet, Illinois

Paracelsus, who some consider the “Father of Toxicology,” declared in the sixteenth century, “All substances are poisons; there is none which is not a poison. The right dose differentiates a poison from a remedy.” Given the large number of potential poisons (toxicants) in the world and the wide variety of clinical effects these toxicants have on biological systems, it is not surprising that a vast range of compounds have been used in attempting to treat the effects of these toxicants on the body.

Antidotes

In the broadest definition, any compound that is used to counteract the effects of a toxicant is an antidote. The compound can interfere with the absorption, distribution, metabolism, or elimination of a toxicant; reduce or eliminate the adverse effects of that toxicant; or perform any combination of these biological effects. As our understanding of the mechanisms of action of various compounds increases, so does our ability to choose the most appropriate drugs to counter the adverse effects of toxicoses. This knowledge puts to rest the legend of the “universal antidote,” that mythical compound that can counter the effects of any poison. Table 23-1 lists drugs commonly used in the management of toxicoses.

Table 23-1

Drugs Used in Toxicology *

Drug	Indication
Acepromazine	Sedation for agitation caused by psychotropic drugs (e.g., amphetamines, phenylpropanolamine, pseudoephedrine)
N-acetylcysteine (Mucomyst, Acetadote)	Management of acetaminophen toxicosis Hepatoprotectant
Activated charcoal	Adsorption of ingested toxicants (poor adsorption of many metals and minerals, small molecules [e.g., alcohols]) Multidose protocols: monitor for hypernatremia
Aluminum hydroxide	Antacid; use for ingestion of corrosives or ulcerogenic drugs (e.g., NSAIDs)
Anti-digoxin Fab fragments, ovine origin (Digibind, DigiFab)	Management of cardiac glycoside toxicosis (drugs, plants, toads) in which life-threatening arrhythmias have not resolved with symptomatic therapy or serum potassium levels > 5 mmol/L
Antitoxin, botulinum, equine origin	Management of clinical signs of botulism
Antitoxin, tetanus, equine origin	Management of clinical signs of tetanus
Antivenin Crotalidae polyvalent, equine origin Polyvalent, immune Fab, ovine origin (Cro Fab)	Management of North American crotalid envenomation (rattlesnake, copperhead, water moccasin)
Antivenin Micrurus (Wyeth)	Management of North American elapid envenomation (coral snake)
Antivenin Latrodectus (Merck)	Management of envenomation by black widow spider
Antivenom, Centruroides immune F(ab′)₂, equine origin (Anascorp)	Treatment of clinical signs of North American scorpion envenomation
Apomorphine	Induction of emesis; may not be effective in cats because they have few dopaminergic receptors in their CNS emetic center
Ascorbic acid	Antioxidant Urinary acidifier
Atipamezole hydrochloride (Antisedan)	Reversal of bradycardia, hypotension, and sedation from α-agonists (e.g., amitraz, xylazine, imidazole decongestants)
Atropine	Test dose for suspected organophosphorus (OP) or carbamate toxicosis Management of bradycardia or excessive bronchial secretions from OP or carbamate toxicosis Treatment of bradycardia from cardiac depressant drugs (e.g., digoxin)
Bicarbonate, sodium	Management of acidosis (e.g., ethylene glycol)
Blood, whole	Replacement therapy for anemia (e.g., anticoagulant rodenticides)
Buprenorphine	Management of pain
Calcitonin, salmon	Treatment of hypercalcemia (e.g., vitamin D or analogs)
Calcium EDTA	Heavy metal chelator (lead)
Calcium gluconate, calcium chloride	Management of fluoride or calcium channel blocker toxicosis Management of hypocalcemia
Cholestyramine resin polystyrene	Ion-binding resin; may help remove agents that undergo extensive enterohepatic recirculation Hepatotoxic mushroom ingestion
Chlorpromazine	Antiemetic Sedation for agitation caused by psychotropic drugs (e.g., amphetamines, pseudoephedrine)
Cyproheptadine	Assist in management of serotonin syndrome and serotonergic effects of psychotropic drugs (e.g., SSRI)
Dantrolene	Management of Latrodectus (black widow spider) bites; management of malignant hyperthermia from hops
Dapsone	Management of dermal necrosis from Loxosceles (recluse spider) bites
Deferoxamine mesylate (Desferal, Novartis)	Heavy metal chelator (iron)
Dextrose	Treatment of hypoglycemia due to xylitol, α-lipoic acid, or antidiabetic drug (e.g., sulfonylurea) toxicosis
Diazepam	Sedation for CNS stimulation or seizures; use with caution with sympathomimetic (e.g., amphetamine) intoxication because paradoxical excitation may occur
Dimercaprol (BAL)	Heavy metal chelator (arsenic, lead, mercury)
Diphenhydramine	Management of acute allergic reactions; antiemetic
Epinephrine	Systemic treatment of acute anaphylaxis
Esmolol	Management of ventricular arrhythmias; ultra–short acting β-blocker
Ethanol	Prevent formation of toxic metabolites in ethylene glycol toxicosis
Etidronate	Treatment of hypercalcemia (e.g., vitamin D or analogs)
Flumazenil	Benzodiazepine antagonist used to aid in severe benzodiazepine overdose
Fomepizole (Antizol-Vet)	Prevent formation of toxic metabolites in ethylene glycol toxicosis
Furosemide	Diuretic for use in management of pulmonary edema secondary to inhaled toxicants Enhance calcium excretion in hypercalcemia (e.g., cholecalciferol toxicosis)
Glucagon	Manage hypotension (e.g., β-adrenergic blocker, calcium channel blocker, tricyclic antidepressant toxicosis); manage hypoglycemia (e.g., antidiabetic drug toxicosis)
H₂-blockers (cimetidine, famotidine, nizatidine, ranitidine)	Reduce gastric acid production Prevention and healing of gastrointestinal ulcers (e.g., NSAIDs)
Hemoglobin glutamer-200, bovine (Oxyglobin)	Replacement therapy for anemia (e.g., anticoagulant rodenticides); does NOT provide clotting factors Improved perfusion of tissues with pressure hypoperfusion (e.g., snakebite swelling)
Hydroxocobalamin (Cyanokit)	Management of cyanide toxicosis
Hydrogen peroxide USP, 3%	Induction of emesis; CAUTION: overuse can result in esophagitis or gastritis
Intravenous lipid solution, intravenous fat emulsion (20%; Liposyn, Intralipid)	Management of intoxication by highly lipid-soluble compounds (e.g., avermectins, baclofen, calcium channel blockers); emerging modality that some consider experimental; should be reserved for severe cases that are poorly responsive to other therapy
Kaolin-pectin	Demulcent and putative adsorbent; CAUTION: many formulations now contain salicylates
Lactulose	Laxative and reduces blood ammonia levels Management of liver insufficiency (e.g., Cycas toxicosis)
Leucovorin calcium	Management of folate antagonist (methotrexate, trimetrexate) overdoses
Lidocaine	Management of ventricular arrhythmias
Magnesium hydroxide	Antacid; use for ingestion of corrosives or ulcerogenic drugs (e.g., NSAIDs)
Magnesium sulfate	Cathartic
Mannitol	Management of oliguric renal failure Treatment of cerebral edema
Maropitant (Cerenia)	Antiemetic
Methocarbamol	Management of muscle tremors, rigidity, convulsive activity (e.g., permethrin toxicosis, metaldehyde toxicosis)
Methylene blue	Treatment of methemoglobinemia; use with extreme caution, especially in cats (many clinicians no longer recommend); DO NOT USE new methylene blue from staining kits
Metoprolol	Management of tachycardia
Milk	Diluent May reduce pain from exposure to insoluble calcium oxalate–containing plants
Misoprostol (Cytotec)	Synthetic prostaglandin; prevention and healing of gastrointestinal ulcers (e.g., NSAIDs)
Naloxone	Opiate antagonist; management of opioid toxicosis
Neostigmine, physostigmine, pyridostigmine	Management of toxicosis from non-depolarizing neuromuscular blocking agents, botulism, atropine, coral snake envenomation, and anticholinergics
Nitroprusside	Treatment of hypertension
Norepinephrine	Treatment of hypotension
Ondansetron (Zofran)	Antiemetic
Pamidronate (Aredia)	Treatment of hypercalcemia (e.g., vitamin D or analogs)
D-Penicillamine	Heavy metal chelator (arsenic, copper, lead)
Pentobarbital	Management of seizures
Phenobarbital	Management of seizures
Plasma, frozen plasma, fresh frozen	Management of coagulopathy from anticoagulant rodenticides; provide clotting factors
Pralidoxime chloride (Protopam)	Treatment of nicotinic signs of OP insecticide intoxication
Prednisone	Adjunct therapy in hypercalcemia (e.g., cholecalciferol)
Propofol	Management of seizures
Propranolol	Management of tachycardia or other cardiac arrhythmias; management of hypokalemia in albuterol toxicosis
Protamine sulfate	Management of heparin overdoses
Proton pump inhibitors (e.g., omeprazole, lansoprazole, pantoprazole)	Reduce gastric acid production Prevention and healing of gastrointestinal ulcers (e.g., NSAIDs)
Prussian blue	Management of thallium toxicosis
Pyridoxine (vitamin B₆)	Management of seizures from penicillamine, Gyromitra mushroom, isoniazid, and hydrazines; adjunct therapy for ethylene glycol toxicosis
SAMe	Hepatoprotectant
Silymarin	Hepatoprotectant
Sodium sulfate	Cathartic
Sorbitol	Cathartic
Succimer (Chemet, Lundbeck)	Heavy metal chelator (arsenic, lead, mercury)
Sucralfate	Management and prevention of esophageal (slurries) and gastrointestinal ulceration
Trientine (Syprine)	Heavy metal chelator (copper)
Vitamin K₁ (phytonadione)	Treatment of anticoagulant rodenticide coagulopathy
Xylazine	Emetic, especially for cats
Yohimbine	Reversal of bradycardia, hypotension, and sedation from α-agonists (e.g., amitraz, xylazine, imidazole decongestants)