Makindo Medical Notes Comprehensive Medical Encyclopedia | Education for Healthcare Professionals

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Drug Toxicity Assessment and Management

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Many of these agents may also cause coma or delirium and so clinical signs may assist when history is unavailable.

General Measures when there is diagnostic uncertainty
Staff should protect themselves if concerns such as Organophosphates ABC and give Oxygen if O₂ sats < 94%. GCS < 9 get ITU review. Eye or skin contamination needs appropriate washing or irrigation. ED/First responder should check CBG > 4.0 mmol/L. If unsure give glucose. If opiate toxicity possible then consider Naloxone Get IV access and Bloods. Send a paracetamol/salicylate level Activated charcoal (50 g PO) if toxic amount ingested < 1 hr before (Not ethylene glycol, iron, lithium, mercury, methanol) See Assessing Coma and Management if comatose Check COHb levels on ABG. ABC, Recovery position, high flow O₂. IV fluids. Assessment top to toe. Front and back. Check for Opiate/fentanyl patches and remove them. Get CT Head +/- Neck if unclear. Are there any injuries. Is neck stiff. Look at pupils. Single large suggest ipsilateral coning should be seen on CT. Both small pupils: opiates, GHB, Cholinergic syndrome (OP) Both large pupils: cocaine, TCA, Amphetamine +/- resultant ICH/SAH. Rewarm if hypothermia. Is patient acidotic with anion gap ( Na⁺ – (Cl- + HCO₃-) ) normal 4 to 12mmol/L Normal AG High AG: Alcohol, Methanol, Ethylene glycol, CO, Salicylates, Lactic acidosis, DKA Little harm and much good in giving Naloxone and Glucose if unsure. If no alternative diagnosis on CT consider IV Cefotaxime and IV Aciclovir. Consider LP. Treat Cerebral malaria if travel and blood films suggest. EEG if non convulsive status. If no ceiling of care discuss HDU/ITU. If Sepsis then broad-spectrum antibiotics Differential depends on Context

General Measures when there is diagnostic uncertainty

Staff should protect themselves if concerns such as Organophosphates
ABC and give Oxygen if O₂ sats < 94%. GCS < 9 get ITU review.
Eye or skin contamination needs appropriate washing or irrigation.
ED/First responder should check CBG > 4.0 mmol/L. If unsure give glucose.
If opiate toxicity possible then consider Naloxone
Get IV access and Bloods. Send a paracetamol/salicylate level
Activated charcoal (50 g PO) if toxic amount ingested < 1 hr before (Not ethylene glycol, iron, lithium, mercury, methanol)
See Assessing Coma and Management if comatose
Check COHb levels on ABG.
ABC, Recovery position, high flow O₂. IV fluids.
Assessment top to toe. Front and back.
Check for Opiate/fentanyl patches and remove them.
Get CT Head +/- Neck if unclear.
Are there any injuries. Is neck stiff. Look at pupils.
- Single large suggest ipsilateral coning should be seen on CT.
- Both small pupils: opiates, GHB, Cholinergic syndrome (OP)
- Both large pupils: cocaine, TCA, Amphetamine +/- resultant ICH/SAH.
- Rewarm if hypothermia.
Is patient acidotic with anion gap ( Na⁺ – (Cl- + HCO₃-) ) normal 4 to 12mmol/L
- Normal AG
- High AG: Alcohol, Methanol, Ethylene glycol, CO, Salicylates, Lactic acidosis, DKA
Little harm and much good in giving Naloxone and Glucose if unsure.
If no alternative diagnosis on CT consider IV Cefotaxime and IV Aciclovir. Consider LP. Treat Cerebral malaria if travel and blood films suggest.
EEG if non convulsive status.
If no ceiling of care discuss HDU/ITU. If Sepsis then broad-spectrum antibiotics
Differential depends on Context

Risk factors

Psychiatric illness (depression, schizophrenia)
Male sex
Living alone
Recent bereavement, divorce or separation
Suicide note written
Age > 45
Unemployment
Chronic physical ill health
Drug or alcohol misuse
Previous attempts (violent method)

Any patient with sepsis and a lactate > 4 mmol/L should be treated as for septic shock, even if normotensive. This requires immediate IV fluid resuscitation, antibiotics, and inotropes according to the sepsis resuscitation bundle.

About Lactate and Lactic Acidosis

Normal lactate: < 1 mmol/L
Raised lactate: > 2 mmol/L
Lactic acidosis: Lactate > 4 mmol/L with reduced serum pH < 7.35

Aetiology

Increased lactate production: Due to tissue hypoxia, intense exercise, or metabolic disruptions
Reduced lactate clearance: Often due to liver dysfunction or impaired lactate metabolism

Classification of Lactic Acidosis

Type A (Hypoxia-driven): Due to tissue hypoxia
- Causes include shock, anaemia, hypoxia, bowel ischaemia
- Severe exercise, seizures, cholera
- Phaeochromocytoma, tumour lysis syndrome
Type B (Non-hypoxia related): Excess lactate production or impaired clearance
- Severe liver disease, diabetic ketoacidosis (DKA), chronic ethanol abuse
- Drug-induced: Metformin, methanol, ethanol, ethylene glycol, salicylates, cyanide

Clinical Presentation

Shock symptoms: hypotension, peri-arrest, or moribund appearance
Respiratory: Kussmaul respirations, tachypnoea
Organ failure signs: Possible cardiac, liver, or renal failure

Clinical Clues

Clinical assessment	Possible cause
Pink rosy colour	Cyanide, carbon monoxide
Cyanosis	Methaemoglobinaemia, e.g., dapsone, amyl nitrite
Nausea, vomiting	Paracetamol, opiates, NSAIDs, Iron toxicity, Salicylates
Small pupils	Opiates, Gamma hydroxybutyrate, Cholinergic agents (e.g., insecticides)
Large pupils	Cocaine, Tricyclic antidepressants, Anticholinergics (e.g., atropine)
Severe hypertension	Cocaine, amphetamines
Severe hypotension	Tricyclic antidepressants, Haloperidol
Bradycardia	Digoxin, Beta-blockers, Calcium channel blockers
Tachycardia	Tricyclics, Theophylline, Digoxin
Hypoglycaemia	Insulin, Sulphonylureas, Alcohol
Hyperglycaemia	Organophosphates, Theophyllines
Hyperventilation	Salicylates
Renal failure	Salicylates, Paraquat, Ethylene glycol
Hyperthermia	Serotonin syndrome, Cocaine, Ecstasy
Hypothermia	CNS depressants, Opioids, Phenothiazines
RUQ pain/Jaundice	Paracetamol, Organic solvents
Abdominal pain	Iron, Lead, NSAIDs
Seizures	Mefenamic acid, TCAs, Opioids, Cocaine
Rhabdomyolysis	Amphetamines
Myoclonic jerks	Gamma-hydroxybutyrate
Chest pain	Cocaine, Carbon monoxide
Oral ulcers	Corrosives, Paraquat
Elevated osmolar gap	Acetone, Mannitol, Methanol
Anion gap metabolic acidosis	Methanol, Metformin, Iron, Isoniazid

Specific Antidotes

Always consult local or national poison control guidance and involve senior support as needed.

Drug	Antidote
Digoxin	Digoxin-specific Fab antibodies (Digibind)
Iron	Desferrioxamine 15 mg/kg/hr IV
Opioids	Naloxone 0.4-2.0 mg IV; may require repeat doses
Paracetamol	Oral Methionine or IV N-acetylcysteine
Phenothiazines (dystonic reactions)	Benztropine 1-2 mg IV
Warfarin	Vitamin K 5 mg IV, Prothrombin complex, or FFP
Heparin	Protamine
Ethylene glycol, Methanol	Fomepizole or ethanol
Benzodiazepines	Flumazenil (caution with seizure risk)
Beta-blockers	Atropine or Glucagon 2-10 mg IV
Tricyclics	Sodium bicarbonate IV
Salicylates	Sodium bicarbonate IV
Sulphonylureas	Glucose, Octreotide
Organophosphates	Atropine, Pralidoxime
Methotrexate	Folinic acid (Leucovorin)
Carbon monoxide	100% oxygen or hyperbaric oxygen
Methaemoglobinaemia	Methylene blue
Cyanide	Cyanide kit: Amyl nitrite, Sodium thiosulphate
Arsenic	Succimer or Dimercaprol
Salicylates, Theophylline	Haemodialysis

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