Beta blockers block beta-1 (and beta-2) receptors → bradycardia, AV block, low contractility, hypotension, hypoglycemia (especially children), bronchospasm. Propranolol also blocks sodium channels (wide QRS, seizures).

Calcium channel blockers (CCBs) block L-type calcium channels in heart and vessels → hypotension, bradycardia and AV block (verapamil, diltiazem), or vasodilation with reflex tachycardia (amlodipine, nifedipine). They also block insulin release → hyperglycemia, a marker of severity.

Digoxin inhibits the Na⁺/K⁺-ATPase pump → more intracellular calcium (stronger contraction) and more vagal tone. In toxicity, the pump failure raises serum potassium (acute) and triggers almost any dysrhythmia.

Organophosphate and carbamate pesticides inhibit acetylcholinesterase → acetylcholine accumulates at muscarinic, nicotinic, and CNS synapses. Organophosphates bind almost permanently; after a period the bond "ages" and the enzyme cannot be reactivated. Carbamates bind reversibly and wear off faster.

Carbon monoxide (CO) binds hemoglobin about 200–250 times more strongly than oxygen and shifts the dissociation curve left → tissue hypoxia; it also injures mitochondria.

Cyanide blocks cytochrome oxidase → cells cannot use oxygen → severe lactic acidosis despite normal oxygen levels.

Toxic alcohols (methanol, ethylene glycol) are harmless until alcohol dehydrogenase converts them to toxic acids (formic acid → blindness; glycolic and oxalic acids → kidney failure). Fomepizole blocks this enzyme.

Digoxin immune Fab indications: life-threatening dysrhythmia or bradycardia; potassium above 5.0 mEq/L (mmol/L) in acute toxicity; high serum level (e.g., 10 ng/mL [12.8 nmol/L] or more at steady state); large ingestion; end-organ hypoperfusion.

High-dose insulin euglycemia therapy (CCB and beta blocker poisoning): regular insulin about 1 unit/kg IV bolus, then an infusion that starts around 0.5–1 unit/kg/h and may be titrated much higher, with dextrose infusion to keep glucose normal. It improves heart muscle energy use; the effect takes 15–60 minutes.

Organophosphate atropine protocol (WHO-style)

1. Atropine 1–3 mg IV bolus
2. Double the dose every 5 minutes until atropinization: chest clear on auscultation (no bronchorrhea or wheeze), heart rate above 80/min, systolic BP above 80 mmHg, dry axillae, pupils no longer pinpoint
3. Continue an infusion (commonly 10–20% of the total loading dose per hour). The main end point is a clear chest (dry secretions, easier breathing); heart rate, BP, and pupils are supporting signs, not targets on their own
4. Pralidoxime as ordered, early (before aging), e.g., 30 mg/kg IV loading dose then 8 mg/kg/h

• Beta blocker and CCB poisoning in older adults and children: even small ingestions of extended-release products can be dangerous; observe for at least 24 hours after extended-release ingestion as directed by the poison center.
• Calcium and digoxin: older teaching forbade IV calcium in digoxin toxicity; current evidence suggests the risk is lower than thought, but Fab is the treatment, and calcium is given only as ordered with monitoring.
• Digoxin toxicity risk rises with hypokalemia, hypomagnesemia, hypercalcemia, kidney impairment, older age, and interacting drugs (amiodarone, verapamil, diltiazem, macrolides, some azole antifungals). After Fab, total digoxin levels are falsely high for days — do not use them to judge toxicity.
• Organophosphates: tachycardia is not a reason to withhold atropine (hypoxia and nicotinic effects cause it); avoid succinylcholine for intubation (prolonged paralysis); avoid morphine-like respiratory depressants and theophylline.
• Sodium nitrite is avoided in smoke inhalation (CO already reduces oxygen delivery) — hydroxocobalamin is preferred.
• Pregnancy: CO crosses the placenta and fetal hemoglobin binds it strongly; the threshold for hyperbaric oxygen is lower. Antidotes are given when indicated.
• Fomepizole: no benefit once the parent alcohol is fully metabolized; dialysis removes it (dose more often).

Listed in priority order.

1. Protect yourself and others — for pesticide exposure, remove and bag the client's clothing, wash skin and hair with soap and water, and wear gloves (nitrile or butyl rubber), gown, and eye protection. Do not let contaminated vomit or clothing contact staff.
2. Airway and breathing — organophosphates: frequent suctioning of secretions, oxygen, early intubation for weakness or bronchorrhea; CO and cyanide: 100% oxygen by non-rebreather mask immediately.
3. Circulation and rhythm — continuous ECG; transcutaneous pacing pads on for bradycardic cardiovascular poisonings; two IV lines; fluids and vasopressors as ordered.
4. Titrate and document antidotes
   • Atropine: auscultate the chest and check HR, BP, axillae, and pupils every 5–15 minutes; watch for atropine toxicity (agitation, fever, absent bowel sounds, urinary retention) → hold and notify
   • High-dose insulin: glucose every 15–30 minutes at first, then hourly; potassium every 1–2 hours
   • Glucagon: side-lying position, antiemetic, suction ready
   • Calcium: ionized calcium, IV site
   • Digoxin Fab: potassium, rhythm, HF signs
5. Organophosphates after the first day — watch for the intermediate syndrome (about 24–96 hours): neck flexion weakness, proximal limb weakness, cranial nerve palsies, and respiratory failure even after cholinergic signs improve. Check neck flexion strength, single-breath count or vital capacity, and SpO₂.
6. Laboratory — glucose, potassium, creatinine, ABG, lactate, anion gap and osmolal gap (toxic alcohols), carboxyhemoglobin by co-oximetry (CO), RBC or plasma cholinesterase (supports organophosphate diagnosis; treatment is clinical), digoxin level (at least 6 hours after the last dose unless acute toxicity).
7. Neurologic and mental health — CO survivors can develop delayed memory and personality changes weeks later; intentional ingestion needs psychiatric assessment once stable.

• Take cardiac medicines exactly as prescribed; use a pill organizer; never double a missed dose; keep them out of children's reach (one tablet can be dangerous to a toddler)
• Digoxin: report nausea, vomiting, loss of appetite, yellow-green or blurred vision, or slow or irregular pulse; tell prescribers before starting new drugs
• Pesticides: store in original labeled containers, locked away from food, never in drink bottles; wear protective clothing; wash after spraying; do not enter treated fields until allowed; dispose of empty containers safely
• CO: install CO alarms; never run generators, charcoal stoves, or engines indoors or in closed garages; get everyone out and call for help if several household members have headache and nausea together
• Buy alcoholic drinks only from registered, labeled sources; unlabeled home-distilled spirits may contain methanol
• Keep antifreeze and windshield fluid locked away

• Beta blocker → glucagon; CCB → calcium; both → high-dose insulin with dextrose
• Beta blocker = hypoglycemia; CCB = hyperglycemia
• Digoxin toxicity: GI symptoms + visual changes + dysrhythmias; hypokalemia worsens it; Fab for life-threatening toxicity or K⁺ > 5.0
• Organophosphates: decontaminate first, protect staff
• Atropine is titrated to dry lung secretions, doubling every 5 minutes; tachycardia does not stop it
• Pralidoxime works only before "aging" — give early
• Watch for the intermediate syndrome (neck and respiratory muscle weakness) 1–4 days later
• CO: pulse oximetry is falsely normal — get COHb; 100% oxygen; hyperbaric oxygen in selected clients
• Cyanide → hydroxocobalamin (red urine and skin, lab interference)
• Methanol → blindness; ethylene glycol → kidney failure; both → fomepizole ± dialysis