There are different poison and antidotes, but the most important aspect in treating poisoning is the identification of the ingested poisonous or corrosive substance.
What is a poison?
A poison is any substance when administered by ways such as mouth, injection, inhalation, skin or mucous membrane, causes ill health, disease, or death. Acute poisoning can be accidental, suicidal, criminal, or occupational.
Posioning can be classified as:
- Intentional: Intentional ingesting of poison, as in assault, suicide.
- Unintentional: Accidentally taking a poisonous substance when ignorant of the adverse effect.
- Undetermined: When the distinction between intentional and unintentional is not clear, as in pesticide/insecticide poisoning.
- Other causes: Heavy metal contamination of food and water sources.
Signs and symptoms of poisoning can either be mild or severe, and include nausea, vomiting, muscle cramps, increased or decreased heart rate, dilation, or shrinking of the pupils, loss of consciousness, respiratory depression and breathlessness, and potentially, death.
Antidotes are substances that react with the overdosed drug, toxic substance or ingested poison, and neutralizes the effect of the poison in the body.
Antidotes can be physiological, chemical, or mechanical.
Physiological antidotes: Also called antagonists. They produce effect by acting in the opposite way to the poison. Examples are sodium nitrite (cyanide poisoning), atropine and physostigmine, two antidotes for each other.
Chemical antidotes: They act by combining with the poison, changes the chemical nature, and converts it into harmless and inactive substance. Examples are EDTA, a chelating agent or heavy metal poisoning, and sodium thiosulphate that converts toxic cyanide to non-toxic thiocyanate.
Mechanical antidote: Prevent absorption of poison into the body. They also expel poison by emesis or through urine. Activated charcoal that absorb poison before they are absorbed by intestinal walls. Copper sulphate, magnesium sulphate inactivate poison, and precipitate and insoluble salt.
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Different Poison and Antidotes
We will classify the poison and antidotes into different classes of poisons. They include:
- Drug or medicines
- Industrial chemicals like lead, mercury.
- Agricultural pesticides like organophosphates, carbamates, organochlorines, rodenticides
- Environmental toxins
- Chemical agents like nerve agents (neurotoxins), blood agents (chemical asphyxiants)
Drug Poisoning and Antidotes
|Acetaminophen||Acetylcysteine ORAL: (diluted to 5% solution): For all ages: Loading dose: 140 mg/kg; Maintenance dose: 70 mg/kg every 4 hrs for 5 doses starting 4 hrs after the loading dose. MAX dose is for ≥ 100 kg patient weight.|
Acetylcysteine (Acetadote): (Note: IV dosing regimens vary), All ages: #1: 150 mg/kg infuse over 1 hr; then #2: 50 mg/kg infuse over 4 hrs; then #3: 100 mg/kg infuse over 16 hrs. MAX dose is for ≥ 100 kg patient weight.
|Anticholinergic delirium||Benzodiazepines: First-line treatment.|
Physostigmine IV/IM: (Note: Use with caution). Adult: 0.5-1 mg over 5-10 min by slow IV push. May repeat dose in 10-15 min if delirium persists and cholinergic excess is not present.The maximum dose is 2 mg total during the first hour.
|Benzodiazepine||Flumazenil IV: Not advisable to use in intentional overdose as it may cause seizures.|
Adult: Initial 0.2 mg over 30 seconds; if needed, give additional 0.3 mg dose over 30 seconds.
Repeat doses: 0.5 mg over 30 seconds at 1 min intervals PRN. The maximum cumulative dose of 3 mg
|Beta Blocker||Glucagon IV: 3-5 mg bolus slow IV push; If no response, repeat in 5-10 min up to total dose 10 mg. Immediately start continuous infusion at an hourly rate equal to effective bolus dose.|
High-Dose Insulin Euglycemic Therapy (HIET): To be used when other therapy are not responding.
|Calcium Channel Blocker||Calcium Chloride 10% IV OR Calcium Gluconate 10%: Initial: 0.2 to 0.6 mEq/kg bolus of Ca2+; Repeat Bolus every 15-20 min as needed, up to 3-4 doses. If needed, follow bolus dosing with a continuous infusion: 0.2 to 0.6 mEq/kg per hour of Ca2+; titrate based on response.|
High-Dose Insulin Euglycemic Therapy (HIET): D50W initial bolus if Blood Glucose < 200 mg/dL; maintain Blood Glucose at 100-200 mg/dL.
Regular Insulin IV: Initial Loading: 0.5-1 unit/kg; followed immediately by Maintenance continuous infusion at 0.5-1 unit/kg per hour (match loading dose). If no BP response to insulin bolus in 20 min, repeat insulin bolus at a higher dose, and raise the infusion rate to match the re-bolus dose.
Bolus dose and hourly infusion rate may be as high as 10 units/kg and 10 units/kg per hour or even higher in severe poisoning cases. Calcium channel blocker poisoning causes severe insulin resistance.
|High-dose Diazepam for severe cardiotoxicity: All ages: 1-2 mg/kg infused over 30 min, followed by 1 mg/kg total over the next 24 hours by|
continuous infusion or by 0.08 mg bolus every 2 hrs.
|Clonidine||Naloxone IV: All ages: Initial: 5 mg IV. If inadequate response after 2-3 min, repeat 5 mg IV|
|Dabigatran||Idarucizumab IV: Adult: 5 grams (2 x 2.5 g vials) over 15 min; Repeat dose not usually required. OR |
4 Factor Prothrombin Complex Concentrate IV: for partial reversal if Dabigatran is unavailable
|Digoxin or other Cardiac Glycoside drugs||Atropine IV: for bradycardia or AV block: 0.5-1 mg every 3-5 min; MAX total dose: 3 mg.|
Digoxin Immune Fab (DigiFab) IV: Dose (in vials) = Serum Digoxin Level (ng/mL) x Weight (kg) ÷ 100 (Round up to nearest whole vial.)
Use HALF – dose or 2 vials initially in patient who needs therapeutic digoxin effect then reassess.
|Benzodiazepines IV or IM: Adjunct treatment for acute dystonia.|
Diphenhydramine IV or IM or ORAL: All ages: 0.5-1 mg/kg (MAX single dose 50 mg)
|Factor Xa Inhibitors (DOAC) Direct Oral Anticoagulants)||Andexanet alfa IV: To reverse anticoagulation due to apixaban and rivaroxaban, and betrixaban and edoxaban (off label) when there is|
life-threatening bleeding. Dose depends on DOAC dose and recency.
High-Dose Bolus: 800 mg at 30 mg/min; then Continuous Infusion of 8 mg/min for up to 120 min (960 mg) OR
4 Factor Prothrombin Complex Concentrate (Kcentra) IV if Andexanet alfa IV is unavailable.
|Heparin UFH and LMWH||Protamine Sulfate IV: Give by slow IV over 10 min. The maximum single dose is 50 mg:|
1 mg for every 100 units of heparin remaining in the patient; 1 mg for every 1 mg of enoxaparin; 1 mg for every 100 anti-Xa IU of dalteparin or tinzaparin.
|Iron Acute overdose||Deferoxamine IV: for significantly symptomatic acute overdose.|
All ages: Start slowly at 5-10 mg/kg per hour and increase to 15 mg/kg per hour for 8-12 hrs. A maximum of 6 grams daily dosage.
|Isoniazid (INH)||Benzodiazepines IV: Use with Vitamin B6 for management of seizures.|
Pyridoxine (Vitamin B6) IV: All ages: 1 gram for each gram of INH ingested to 5 gram maximum single dose by slow IV push. If INH ingested isunknown, use 5 g pyridoxine. May repeat as needed until seizures controlled.
|Local Anesthetic (Systemic Toxicity)||Lipid Emulsion 20% IV: All ages: Bolus: 1.5 mL/kg (MAX: 100 mL) 20% lipid emulsion over 1-3 min; may repeat bolus for persistent asystole or pulseless electrical activity. Immediately follow with 0.25 mL/kg per min by continuous infusion to total dose of 8-10 mL/kg (MAX: 1 liter), usually 30-60 min.|
|Opioid/Opiate toxicity||Naloxone IV or IM or Sub-Q: Adult: 0.4 to 2 mg (MAX 10 mg); Repeat every 2-3 min and watch for response. |
For long acting opioid agents, use continuous infusion of 2/3 of total initial bolus per hour if needed.
|Methotrexate||Leucovorin (Folinic Acid) IV or IM or ORAL: for single acute oral overdose or chronic therapeutic overdose.|
Child: 0.25 mg/kg every 6 hrs for 4 doses;
Adult: 15 mg every 6 hrs for 4 doses
|Various Oral ingestion||Activated Charcoal ORAL: Limited indications: If there are significant ingestions within 1–2 hours, and has not developed CNS depression or vomiting, can consider administration of aqueous charcoal suspension. |
Infants: 1 gram/kg; Child: 25 grams;
Teenagers and Adults: 50–100 grams
|Serotonin Toxicity||Benzodiazepines IV: adjunct to manage agitation. If needed, add cyproheptadine.|
Cyproheptadine ORAL: Initial: 4-12 mg, then 4–8 mg every 4–6 hrs if symptoms persist. The maximum dose is 32 mg/day.
Oral Hypoglycemic Drugs
|Dextrose IV: to correct hypoglycemia.|
Octreotide Sub-Q: This is additional therapy for recurrent hypoglycemia after initial dextrose dose.
Adult: 50 mcg Sub-Q; repeat every 6–12 hrs if hypoglycemia recurs; 2–3 doses usually sufficient.
|Tricyclic antidepressant (Imipramine, Amitriptyline, Clomipramine) toxicity||Sodium bicarbonate|
Dosage: 1 to 2mL/kg up to 100mL (1 to 2 mmol/kg up to 100mmol) IV bolus every 3 to 5 minutes. This is titrated to narrow the QRS complex and achieve a pH of 7.50 to 7.55.
Maximum dose 6mL/kg (6mmol/kg)
|Valproic Acid||L-Carnitine IV or ORAL: for management of hyperammonemic encephalopathy from overdose.|
For all ages: 50 mg/kg (MAX: 3 grams) IV bolus over 15-30 min. Maintenance: 50 mg/kg (MAX dose: 3 grams) every 8 hrs for 1–2 days or until ammonia levels decrease and there is a noticeable clinical improvement.
|Vitamin K1 (Phytonadione) IV, Mephyton® ORAL:|
Initial: 2.5-10 mg; Repeat: every 12–24 hrs if needed.
Environmental Toxins and Antidotes
|Black Widow Spider||Benzodiazepines & Opiates|
IV Black Widow Spider (Latrodectus mactans) Antivenin (equine) IV or IM: (For severe envenomation)
All ages: 1 vial, reconstituted, given IM, or diluted and infused IV over 15 min.
|Botulism, Infant||BabyBIG Botulism Immune Globulin IV (Human): 100 ± 20 mg per vial; Dose 50 mg/kg|
|Botulism, Other||Botulism AntiToxin Heptavalent (equine) Types A-G (“BAT”): All ages: 1 vial; weight based dosing.|
|Anticholinergic toxicity of Datura especially Datura stramonium (e.g., jimsonweed)||Physostigmine intravenously to an adult in a dose of 0.5–2.0 mg at a rate of no more than 1 mg/min; second dose if necessary|
Children: 0.02 mg/kg intravenously, at a rate not exceeding 0.5 mg/min
Endogenous Pit Vipers
|CroFab® Antivenin Crotalidae Polyvalent Immune Fab IV: Initial: 4 vials for copperhead; 6 to 12 for rattlesnake, Maximum of 12 vials initially. OR|
ANAVIP®crotalidae immune F(ab’)2 (equine) IV: Initial: 10 vials
|Dog bite||A HRIG is given I.M (20 IU/kg body weight) and |
A 1.0 mL dose of rabies vaccine is given IM in the deltoid area of adults or the anterolateral thigh of young children on Days 0, 3, 7, and 14 of the rabies PEP regimen.
Immunocompromised persons receive a fifth vaccination on Day 28.
Patients who have previously received either pre or post-exposure rabies prophylaxis should receive only two rabies vaccine boosters following an exposure, given on Days 0 and 3.
Do not receive HRIG if you have been previously vaccinated.
|Amanita muscaria (fly agaric)||No antidote but supportive care like Gastric lavage, activated charcoal|
Note: Symptoms are both cholinergic and anticholinergic, atropine and physostigmine are contraindicated.
Agricultural Pesticides Poisoning and Antidotes
|Agricultural Pesticides Poisoning||Antidotes|
|Organophosphates and Insecticides like:|
Atropine IV: for muscarinic effects of excessive secretions, bradycardia, diarrhea, etc. Adult: 1-2 mg slow IV push.
Diazepam IV: Adjunct for management of CNS symptoms lik confusion, agitation, seizures.
For adult, At first, 1000 to 2000 mg injected into a vein usually as an infusion in 100 mL of normal saline, over a 15- to 30-minute period
For children: Dose is 20 to 50 mg/kg body weight injected into a vein
The dose may be repeated after one hour, and then every eight to twelve hours if muscle weakness persists.
Brodifacoum, or Diphacinone, pindone
|Start parenteral Vitamin K1 as for warfarin, that is subcutaneous 2.2 mg/kg weight.|
Administer Vitamin K1 at 1.1 mg/kg SC, q 12h to stabilise hematocrit value and reduce active bleeding.
Maintain oral Vitamin K1 at 1.1 mg/kg PO q 12h for a total of 2 weeks.
After every two weeks, taper the maintenance dose by one-half.
Maintain this therapy for 6 weeks to avoid relapse.
Gamma benzene hexachloride
|No specifi antidote but use:|
Oxygen mask for air support
Use benzodiazepines eg diazepam for seizure and convulsion
Adult: 5-10mg repeat after 5 to 10 minutes to a maximum of 30 mg.
Child: 0.2 – 0.5 mg/kg every 5 minutes. Maximum 10 mg in children above 5 years, and maximum 5mg in children under 5 years.
Adult: 4 gram doses, 4 times a day before meal and at bedtime
Child: 240 mg/kg divided every 8 hours in a day (24 hours)
Industrial Chemical Poisoning and Antidotes
This is poisoning due to intake of salts of heavy metals such as lead, arsenic, iron, mercury, cadmium etc. Activated charcoal is initially given in heavy metal poisoning to absorb the metals, before emetics are added.
Inorganic compounds such as activated charcoal, magnesium sulfate, light kaolin helps in precipitating heavy metals to avoid absorption in the stomach.
|Industrial Chemical Poisoning||Antidotes|
|Lead||Succimer ORAL: for BLL > 45 mcg/dL in Child or > 80 mcg/dL in Adult.|
All ages: 10 mg/kg every 8 hrs for 5 days; then 10 mg/kg every 12 hrs for 14 days, in a lead-free environment.
Combination parenteral chelators, reserved for BLL ≥ 70 mcg/dL in patients with lead encephalopathy.
Dimercaprol IM only: 3-4 mg/kg/dose every 4 hrs for 2-7 days. Use in conjunction with Calcium Disodium EDTA.
Calcium Disodium EDTA IV or Deep IM: (Begin treatment with 2nd dose of Dimercaprol.)
25 mg/kg/day IV over 8-12 hrs for 5 days.
The maximum daily dose: Child: 1,000 mg, Adult: 2,000-3,000 mg
|Mercury||Succimer ORAL: All ages: 10 mg/kg every 8 hrs for 5 days; then 10 mg/kg every 12 hrs for 14 days.|
Dimercaprol Deep IM: Initial dose: 5 mg/kg for 1 dose. Subsequent doses: 2.5 mg/kg, once or twice daily for 10 days OR
Switch to Succimer when tolerated
|Arsenic||Dimercaprol Deep IM Only; for severe acute poisoning: All ages: 2.5-3 mg/kg every 4 hrs on Days 1-2, then a tapering schedule.|
Switch to Succimer as soon as tolerated. OR
Succimer ORAL (Off label, All ages): 10 mg/kg every 8 hrs for 5 days; then 10 mg/kg every 12 hrs for 14 days
|Ethylene Glycol or Methanol||Fomepizole|
15 mg/kg IV x 1 dose, then 10 mg/kg every 12 hours x 4 doses, then 15 mg/kg every 12 hours until ethylene glycol level < 20 mg/dL and/or pH improves. Ethyl Alcohol PO if fomepizole not available
Folinic Acid (Leucovorin): 1 mg/kg (up to 50 mg) every 4 – 6 hours until toxicity resolves
Folic Acid: 50 mg IV every 4 – 6 hours until toxicity resolves
Thiamine to treat the ethylene glycol toxicity, and thiamine deficiency
associated with chronic alcoholism
|Cyanide poisoning||Sodium thiosulfate and amyl nitrite and sodium nitrite (Cyanide antidote kit)|
Give Amyl nitrite in alternate intervals of 15 sec followed by 15 sec rest, using a new ampule every 3 minutes. Reapply until sodium nitrite can be administered with the IV still in place.
Once the IV line is in place, discontinue amyl nitrite. Infuse 10 mL of 3% sodium nitrite (300mg) I.V at a rate of 2.5 – 5.0 mL/min (2-4 mins). A single dose of sodium nitrite is typically enough to raise methemoglobin levels to 20% in an adult. As long as methemoglobin levels are kept below 35-40%, a second dose of up to half the previous dose may be administered.
Give Sodium thiosulfate I.V immediately following sodium nitrite administration at a dose of 12.5 g. A second dose of half the initial dose may be given if necessary.
A 5 g (one vial) I.V infusion over 15 minutes.
A second 5 g dose may be administered if the response is not adequate.
The maximum total dose is 10 g.
|Methemoglobin agents like nitrites, nitrates, anilines, dapsone, chlorates, naphthalene.||Methylene Blue IV: All ages: Initial: 1 mg/kg IV over 5-30 min; Repeat dose: 1 mg/kg after 1 hr if methemoglobin > 30%.|
Other Chemical Poison and Antidotes
Some chemicals such as cyanide, formaldehyde, nerve gas can cause poisoning. In cyanide poisoning, inhalation of fumes of hydrogen cyanide or ingesting cyanide salt, cyanide releasing compounds like silver polishes, peach of apricot, cyanogen chloride, bitter almond, photography chemical could trigger it.
Dosage of 300 mg potassium cyanide in the body may be fatal.
|Organic phosphorus chemical (“nerve gas”) or neurotoxin poisoning like:|
Adults, teenagers, and children with weight 40 kg or above:
Dose: 600mg or 2 mL injection into a muscle. May repeat dose fifteen minutes after the first dose and fifteen minutes after the second dose, if needed.
Children, teenagers 16 years and younger, with weight 40 kg or lower.
Dose: Deepends on weight. The dose is 15mg/kg of body weight injected into the muscles of the thighs. May repeat dose fifteen minutes after the first dose and fifteen minutes after the second dose, if needed.
|Blood agents (Chemical asphyxiants) like|
|Sodium thiosulfate and amyl nitrite and sodium nitrite (Cyanide antidote kit)|
|Thallium or Cesium toxicity||Prusssian blue|
|Hydrofluoric acid, oxalic acid dermal exposure||Calcium Gluconate Gel 2.5%: Apply liberally to burn until pain resolution.|
Alternative: 1 g calcium gluconate mixed with 40 mL water-soluble lubricant.
Alternative: 500-600 mg calcium carbonate tabs crushed & mixed with 20 mL water-soluble lubricant.
|Methylene chloride, carbon tetrachloride, carbon monoxide, hydrogen sulfide||Hyperbaric oxygen|
|Acetonitrile, Acrylonitrile||Dicobalt EDTA,|
Sodium thiosulfate and amyl nitrite and sodium nitrite