Drugs Used to Treat Toxicoses
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
| Drug | Indication |
| Acepromazine | Sedation for agitation caused by psychotropic drugs (e.g., amphetamines, phenylpropanolamine, pseudoephedrine) |
| N-acetylcysteine (Mucomyst, Acetadote) | Management of acetaminophen toxicosisHepatoprotectant |
| 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 | AntioxidantUrinary 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 toxicosisManagement of bradycardia or excessive bronchial secretions from OP or carbamate toxicosisTreatment 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 toxicosisManagement of hypocalcemia |
| Cholestyramine resin polystyrene | Ion-binding resin; may help remove agents that undergo extensive enterohepatic recirculationHepatotoxic mushroom ingestion |
| Chlorpromazine | AntiemeticSedation 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 toxicantsEnhance 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 productionPrevention 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 factorsImproved 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 levelsManagement 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 failureTreatment 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 | DiluentMay 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 productionPrevention 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) |
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