Emergency & Toxicology

Beta-blocker and calcium channel blocker overdose

Clinical Overview and When to Suspect Beta-blocker/CCB Overdose

— BBs antagonize β1/β2 receptors → ↓cAMP → ↓inotropy, ↓chronotropy, ↓AV conduction; lipophilic agents (propranolol) add Na-channel blockade and CNS toxicity; sotalol adds K-channel blockade (QT prolongation, torsades).

— Non-dihydropyridine CCBs (verapamil, diltiazem) block L-type Ca channels in myocardium and AV node → bradycardia, AV block, negative inotropy. Dihydropyridines (amlodipine, nifedipine) primarily cause vasodilatory shock, with reflex tachycardia early but bradycardia at massive doses.

— CCBs uniquely impair pancreatic β-cell Ca-mediated insulin release → hyperglycemia (a useful diagnostic clue distinguishing CCB from BB toxicity).

— Adult or adolescent with unexplained bradycardia + hypotension + AV block, especially with cardiac comorbidity or psychiatric history.

— Hypoglycemia in a child or non-diabetic adult on a BB.

— Hyperglycemia + shock + bradycardia → think CCB until proven otherwise.

— Polypharmacy ingestion (intentional self-harm) — co-ingestion with benzos, opioids, or alcohol is common.

Board pearl: Hyperglycemia + bradycardia + shock → CCB overdose; hypoglycemia + bradycardia + seizures → propranolol overdose. This single lab differentiator is heavily tested.

Beta-blocker (BB) and calcium channel blocker (CCB) overdose are among the deadliest cardiovascular drug poisonings in the US, accounting for a disproportionate share of cardiotoxic fatalities reported to poison control.

Mechanism overview:

When to suspect:

High-risk scenarios: sustained-release (SR) preparations (delayed peak 12–24 h), propranolol (CNS + QRS widening), sotalol (QT/torsades), pediatric exploratory ingestion of grandparent's pills ("one pill can kill" — amlodipine, verapamil, propranolol).

Mortality drivers: refractory shock, asystole, and delayed presentation with SR formulations whose toxicity peaks after the ED "observation window."

Presentation Patterns and Key History

— Immediate-release BB/CCB: peak toxicity within 1–3 hours.

— Sustained-release (SR) diltiazem, verapamil, metoprolol XL, propranolol LA: peak 6–24 hours; deceptively well-appearing on arrival.

— Sotalol: QT prolongation and torsades may appear >12 hours post-ingestion.

— BB toxicity: bradycardia, hypotension, bronchospasm (especially nonselective), hypoglycemia (children, diabetics on insulin), AV block, depressed mental status.

— Propranolol-specific: seizures, coma, QRS widening (Na-channel block), ventricular dysrhythmias — disproportionately lethal.

— Sotalol-specific: QT prolongation, torsades de pointes — needs prolonged telemetry.

— Non-dihydropyridine CCB: profound bradycardia, junctional rhythms, AV block, cardiogenic shock, preserved or altered mentation (patients often lucid until they crash — pathognomonic).

— Dihydropyridine CCB: reflex tachycardia + vasodilatory shock; resembles distributive shock.

— What, how much, when, why — pill bottles, smart-pill packaging, EMS report.

— Identify SR vs IR formulation explicitly (changes disposition).

— Co-ingestants: acetaminophen and salicylate levels mandatory in any intentional overdose; ETOH, benzos, opioids common.

— Underlying cardiac disease, baseline ECG, dialysis status (atenolol, sotalol, nadolol are renally cleared).

— Suicidality assessment, access to firearms, prior attempts.

Step 3 management: Always obtain acetaminophen and salicylate levels plus a pregnancy test in any intentional overdose, even when the toxin seems "obvious" — this is a high-yield safety net the exam expects you to order reflexively.

Symptom onset timeline:

Classic syndromes:

Essential history (collateral often required):

Red flags for severe toxicity: ingestion of SR product, propranolol or sotalol involved, co-ingestion of another cardioactive drug (digoxin, clonidine, TCA), pediatric ingestion >1 tablet, delayed presentation >2 hours after SR ingestion.

Physical Exam Findings and Hemodynamic Assessment

— Bradycardia (HR often <50, can be <30 in severe cases).

— Hypotension (SBP <90, MAP <65) — may be normotensive early then crash.

— Respiratory depression with lipophilic BBs (propranolol) or co-ingested sedatives.

— Temperature usually normal; hypothermia in prolonged shock.

— Weak, thready pulses; cool clammy extremities in BB/non-DHP CCB toxicity (cardiogenic pattern).

— Warm, flushed, bounding pulses in dihydropyridine CCB toxicity (distributive/vasodilatory pattern) — mimics sepsis.

— JVP often normal or low; pulmonary edema if myocardial failure dominates.

— CCB (non-DHP): mentation often preserved despite shock — a deceptive finding; patients chat with you, then arrest.

— Propranolol: seizures, coma, dilated pupils from lipophilic CNS penetration.

— Hypoglycemia symptoms (diaphoresis, tremor) may be masked by BB itself.

— Cold + bradycardic + hypotensive → BB or non-DHP CCB cardiogenic profile.

— Warm + tachycardic (early) → bradycardic (late) + hypotensive → DHP CCB vasodilatory profile.

— Point-of-care echo: reduced EF in BB/non-DHP CCB; preserved or hyperdynamic EF with low SVR in DHP CCB — guides vasopressor selection.

Key distinction: Preserved mental status in a profoundly hypotensive bradycardic patient is a CCB toxicity signature — don't be falsely reassured; intubate early if airway protection becomes a concern, as decompensation is abrupt and catastrophic.

Vital signs — the diagnostic backbone:

Cardiovascular exam:

Pulmonary: wheezing (nonselective BB-induced bronchospasm), crackles if cardiogenic pulmonary edema develops.

Neuro:

Skin: flushing (DHP CCBs), diaphoresis (hypoglycemia), no track marks unless co-ingestant.

Hemodynamic phenotyping at bedside:

Reassess vitals every 5–15 minutes; trend is more informative than any single value.

Diagnostic Workup — Initial Labs, ECG, and Bedside Studies

— BB: sinus bradycardia, 1st-degree AV block, junctional escape; propranolol → QRS widening (>100 ms) from Na-channel blockade; sotalol → QT prolongation, U waves, risk of torsades.

— Non-DHP CCB: sinus bradycardia, PR prolongation, 2nd/3rd-degree AV block, junctional rhythm, asystole.

— DHP CCB: sinus tachycardia early, bradycardia late, often unremarkable conduction.

— Compare to prior ECG if available.

— Hyperglycemia (>140–250 mg/dL) → CCB toxicity (impaired insulin release); severity correlates with prognosis.

— Hypoglycemia → BB toxicity, especially propranolol or in children/diabetics.

— BMP (K+, bicarbonate, anion gap, creatinine — renal clearance for atenolol/sotalol/nadolol).

— VBG/ABG with lactate — lactic acidosis signals tissue hypoperfusion; trend it.

— CBC, magnesium, calcium (ionized), phosphate.

— Acetaminophen + salicylate levels, ethanol, urine drug screen, β-hCG in women of reproductive age.

— Troponin (may rise from demand ischemia or direct cardiotoxicity).

— Portable CXR: pulmonary edema, aspiration, ETT placement.

— Bedside echo (POCUS): distinguishes cardiogenic (low EF) from vasodilatory (preserved EF, hyperdynamic, low SVR) shock — directly guides vasopressor + inotrope choice.

CCS pearl: In your CCS case, order "continuous cardiac monitor," "ECG STAT," "fingerstick glucose," "ABG with lactate," "BMP," "acetaminophen level," "salicylate level," "β-hCG," and "bedside echocardiogram" as your opening salvo. These orders cover the diagnostic and risk-stratification needs simultaneously.

ECG — obtain within minutes, repeat serially:

Bedside glucose — single most useful immediate lab:

Core labs:

Imaging:

Continuous telemetry, arterial line for accurate BP, central access anticipated.

Drug levels for BB/CCB are not clinically useful — don't waste time waiting for them; treat the syndrome.

Diagnostic Workup — Advanced and Confirmatory Studies

— BB/CCB quantitative serum levels are send-out, slow, and don't correlate well with clinical severity. Exceptions: digoxin level (if co-ingestion suspected — overlapping bradyarrhythmia syndrome) and acetaminophen/salicylate (mandatory screening).

— Arterial line for beat-to-beat BP, especially during titration of vasopressors and high-dose insulin.

— Central venous access for vasopressors, calcium infusion, and high-dose insulin (peripheral OK temporarily).

— Pulmonary artery catheter rarely used; serial bedside echo + lactate trend + ScvO2 typically sufficient.

— Every 15–30 minutes initially, then hourly. Watch for QRS widening (propranolol — consider sodium bicarbonate), QT prolongation (sotalol — magnesium, overdrive pacing prep), and progressive AV block.

— Pill count from EMS/family/pharmacy.

— Pharmacy database / state PDMP query (PMP/I-STOP) — identifies prescribed agents and quantities.

— Call Poison Control (1-800-222-1222) early — both for guidance and medicolegal documentation; their recommendations carry weight in CCS scoring.

— Immediate-release BB/CCB, asymptomatic: monitor 6–8 hours.

— Sustained-release ingestion: monitor ≥24 hours even if initially well — delayed peaks are notorious for causing post-discharge cardiac arrest.

— Sotalol: at least 12–24 hours for QT/torsades surveillance.

Board pearl: A patient who took a sustained-release verapamil or diltiazem and looks fine at hour 4 is not safe to discharge. The exam loves the vignette where a "stable" patient is sent home and arrests at home — admit all SR ingestions for 24-hour monitored observation regardless of initial appearance.

Why drug levels rarely help:

Advanced hemodynamic assessment:

Repeat ECGs:

Confirmatory contextual studies:

Telemetry duration:

Psychiatric evaluation prior to discharge for all intentional overdoses — required for both safety and disposition.

Risk Stratification and First-Line Management Logic

— Airway: low threshold to intubate if altered mentation, refractory shock, or propranolol with seizures. Ketamine + rocuronium preferred (avoid etomidate's adrenal effect in prolonged shock; avoid propofol's hypotension).

— Breathing: O2 to keep SpO2 >94%; bronchodilators if BB-induced wheeze.

— Circulation: 2 large-bore IVs, crystalloid bolus 10–20 mL/kg (cautious — avoid pulmonary edema in cardiogenic shock); arterial line and central line.

— Activated charcoal 1 g/kg if presenting within 1–2 hours of ingestion AND airway protected (intubated or fully alert). Avoid in altered mentation without intubation (aspiration risk).

— Whole bowel irrigation with PEG-ELS for sustained-release preparations — give until rectal effluent clear; particularly useful for SR verapamil/diltiazem.

— Gastric lavage rarely indicated; ipecac contraindicated.

— Tier 1: IV fluids, atropine 0.5–1 mg (often ineffective in true overdose but try first).

— Tier 2: IV calcium (gluconate 3 g or chloride 1 g via central line) — first-line for CCB, also helps BB.

— Tier 2: Glucagon 3–10 mg IV bolus, then 1–5 mg/hr infusion — bypasses β-receptor via direct ↑cAMP. Pretreat with antiemetic (vomiting common).

— Tier 3: High-dose insulin euglycemia (HIE) — 1 U/kg bolus, then 1 U/kg/hr (titrate up to 10 U/kg/hr) with D10 infusion to maintain glucose 100–250.

— Tier 4: Vasopressors — norepinephrine for cardiogenic profile, add epinephrine for refractory bradycardia/hypotension.

— Tier 5: IV lipid emulsion (Intralipid 20%) 1.5 mL/kg bolus then 0.25 mL/kg/min for lipophilic agents (propranolol, verapamil).

— Tier 6: VA-ECMO for refractory shock — early consult to cardiothoracic surgery / shock team.

Step 3 management: Don't wait for vasopressors to fail before starting high-dose insulin — it has the best evidence for severe BB/CCB cardiogenic shock and should be initiated early, alongside (not after) calcium and glucagon.

Resuscitation priorities (ABCs first):

GI decontamination:

Tiered pharmacotherapy ladder (escalate as needed):

Pharmacotherapy — First-Line Drug Regimen Deep Dive

— Calcium gluconate 3 g (30 mL of 10%) IV over 10 min — peripheral OK.

— Calcium chloride 1 g (10 mL of 10%) IV — central line preferred (extravasation causes necrosis). 3× more elemental Ca than gluconate.

— Repeat every 10–20 min × 3–4 doses; then infusion 0.5 g/hr CaCl₂ titrated to ionized Ca ~2× normal.

— Monitor ionized calcium every 30 min — avoid hypercalcemia >2× normal.

— Bolus 3–10 mg IV (some sources up to 50 mcg/kg); if responds, infusion at the dose that worked, per hour.

— Mechanism: activates Gs protein directly → ↑cAMP → inotropy/chronotropy, bypassing blocked β-receptors.

— Side effects: vomiting (pretreat with ondansetron, ensure airway), hyperglycemia, hypokalemia.

— Supply limitation — many EDs only stock a few mg; call pharmacy early.

— Regular insulin 1 U/kg IV bolus, then 1 U/kg/hr infusion; titrate up to 10 U/kg/hr for refractory shock.

— Concurrent D10W or D25W infusion — only start dextrose if glucose <250 (CCB patients often hyperglycemic initially).

— Check glucose every 15–30 min initially, then hourly.

— Replete potassium if K+ <2.8 mEq/L (insulin drives K+ intracellularly); mild hypokalemia (3.0–3.4) often tolerated.

— Continue 12–24 h after hemodynamic improvement, then wean.

— Norepinephrine 0.05–2 mcg/kg/min — first choice for combined inotropy + vasoconstriction.

— Epinephrine added for chronotropy/inotropy if HR persistently low.

— Phenylephrine reserved for pure vasodilatory DHP CCB toxicity with preserved cardiac output.

Board pearl: Hyperinsulinemia-euglycemia outperforms glucagon and vasopressors alone for myocardial recovery in severe BB/CCB toxicity. Memorize the dosing: 1 U/kg bolus, 1 U/kg/hr infusion, escalate to 10 U/kg/hr.

Atropine 0.5–1 mg IV (max 3 mg): often ineffective in severe BB/CCB toxicity because bradycardia is not vagally mediated, but always try first per ACLS.

IV Calcium:

Glucagon:

High-Dose Insulin Euglycemia (HIE) — the cornerstone:

Vasopressors:

Adjunctive and Rescue Therapies

— Indications: refractory cardiovascular collapse from lipophilic toxins — propranolol, verapamil, occasionally amlodipine.

— Dosing: Intralipid 20% — 1.5 mL/kg bolus over 1 min, then 0.25 mL/kg/min infusion × 30–60 min; may repeat bolus × 2 if asystole persists.

— Mechanism: "lipid sink" sequesters lipophilic drug; also augments fatty acid metabolism for myocardial energy.

— Adverse effects: pancreatitis, ARDS, fat overload syndrome, interference with lab assays — use as rescue, not routine.

— For propranolol (Na-channel block) with QRS >100 ms → 1–2 mEq/kg IV bolus, repeat to narrow QRS, then infusion (150 mEq NaHCO₃ in 1 L D5W at 250 mL/hr).

— Also for severe metabolic acidosis.

— For symptomatic bradycardia/AV block refractory to drugs.

— Caveat: electrical capture without mechanical capture is common in severe CCB/BB toxicity — pacing improves HR but not BP/perfusion. Don't rely on pacing alone.

— Indications: refractory cardiogenic shock or cardiac arrest despite maximal medical therapy in a patient with reversible toxicity.

— Outcomes excellent (survival 50–70%) because toxicity is time-limited.

— Early consultation — don't wait for arrest; transfer to ECMO center if not available locally.

— Useful only for water-soluble, renally cleared, low-protein-bound BBs: atenolol, nadolol, sotalol (especially sotalol with renal failure or refractory torsades).

— Not useful for propranolol, metoprolol, or any CCB (highly protein-bound, large Vd).

CCS pearl: In a refractory case, the winning sequence is calcium + glucagon + high-dose insulin + norepinephrine + lipid emulsion, with ECMO consultation placed before arrest occurs — not after.

IV Lipid Emulsion (ILE / "Intralipid"):

Sodium bicarbonate:

Magnesium 2 g IV for sotalol-induced torsades; consider isoproterenol or overdrive transvenous pacing if recurrent.

Transcutaneous → transvenous pacing:

Methylene blue: emerging adjunct for refractory vasoplegic shock (especially amlodipine) at 1–2 mg/kg IV — guanylate cyclase inhibition reduces NO-mediated vasodilation.

VA-ECMO (extracorporeal life support):

Hemodialysis:

Special Populations — Elderly and Renal/Hepatic Impairment

— Highest-risk group for therapeutic misadventure — accidental double-dose, drug-drug interactions, polypharmacy, cognitive impairment.

— Common scenario: elderly patient on diltiazem + metoprolol + amlodipine presents with bradycardia/hypotension after adding clarithromycin (CYP3A4 inhibitor → ↑CCB levels) or after AKI.

— Baseline reduced cardiac reserve → smaller doses cause greater toxicity; may decompensate at "therapeutic" levels.

— Lower threshold for admission, monitored bed, early high-dose insulin.

— Affects atenolol, nadolol, sotalol, acebutolol (renally cleared); accumulation causes prolonged toxicity in CKD/AKI.

— Sotalol + renal failure = prolonged QT and recurrent torsades — hemodialysis is therapeutic.

— CCBs (verapamil, diltiazem, amlodipine) are hepatically metabolized — renal impairment doesn't directly prolong them but coexisting cardiac/hepatic disease worsens outcomes.

— Propranolol, metoprolol, labetalol, carvedilol — extensive first-pass metabolism; cirrhosis or shock liver (from the toxicity itself) prolongs half-life and worsens cardiotoxicity.

— Verapamil and diltiazem hepatically cleared — accumulation in liver dysfunction.

— Diltiazem/verapamil + clarithromycin/erythromycin/azole antifungal → CYP3A4 inhibition → CCB accumulation, profound hypotension.

— BB + verapamil/diltiazem combined therapy → additive AV block, sometimes iatrogenic "overdose" at standard doses.

— Grapefruit juice + felodipine/nifedipine → ↑levels.

Step 3 management: In an elderly patient with new bradycardia/AV block after starting an antibiotic, review the medication list for diltiazem/verapamil + macrolide or azole — this is a classic Step 3 ambulatory-to-ED transition vignette. Discontinue the offending interaction and manage as iatrogenic CCB toxicity.

Elderly patients:

Renal impairment:

Hepatic impairment:

Drug-drug interaction triggers to recognize on exam:

Discharge planning: medication reconciliation, blister-pack dispensing, caregiver education to prevent recurrence.

Special Populations — Pregnancy, Pediatrics, and Other Subgroups

— A single tablet of amlodipine, verapamil, diltiazem, or propranolol can cause lethal toxicity in a toddler (<2 yr, <10 kg).

— Any pediatric ingestion of a CCB or BB → ED evaluation, ECG, glucose; admission for ≥24 hour observation if SR formulation.

— Propranolol in children: profound hypoglycemia and seizures may dominate over cardiotoxicity. Check glucose immediately; treat hypoglycemia with D10W 5 mL/kg (or D25W 2 mL/kg).

— Glucagon dose pediatric: 50 mcg/kg IV bolus, max 5 mg.

— Charcoal if airway protected and within 1 h; whole bowel irrigation for SR products.

— Labetalol commonly used for hypertension/preeclampsia — overdose presentations occur.

— Maternal stabilization is fetal stabilization — give all needed therapies (calcium, insulin, glucagon, vasopressors, lipid emulsion) without modification.

— Continuous fetal monitoring if ≥24 weeks gestation and viable.

— Left lateral decubitus tilt to relieve aortocaval compression and improve venous return.

— Obstetric consult; perimortem C-section within 4 minutes of maternal arrest if ≥20 weeks.

— Most adult BB/CCB overdoses are intentional self-harm; ensure 1:1 safety monitoring, remove access to additional pills, psychiatric consultation prior to medical clearance.

— Discharge requires both medical clearance AND psychiatric disposition — never one without the other.

Board pearl: In pregnant overdose patients, all standard antidotes (calcium, glucagon, insulin, lipid emulsion, vasopressors) remain indicated. Do not withhold lifesaving therapy out of fetal concern — the best fetal therapy is a resuscitated mother. Left lateral tilt + continuous fetal monitoring ≥24 weeks.

Pediatrics — "one pill can kill":

Pregnancy:

Intentional/psychiatric overdose:

Body-stuffers/packers: rare with BB/CCB but consider in trafficking contexts; abdominal CT and whole bowel irrigation.

Complications and Adverse Outcomes

— Cardiogenic shock with multi-organ hypoperfusion — leading cause of death.

— Asystole, refractory bradyarrhythmias, complete heart block.

— Torsades de pointes (sotalol) — recurrent until QT normalizes; magnesium, overdrive pacing, dialysis.

— Ventricular dysrhythmias (propranolol with QRS widening).

— Myocardial ischemia/infarction from coronary hypoperfusion, even with normal coronaries.

— Non-cardiogenic pulmonary edema (ARDS) — described particularly with verapamil and large fluid resuscitation; manage with lung-protective ventilation.

— Bronchospasm (nonselective BBs).

— Aspiration pneumonitis from depressed consciousness or charcoal misuse.

— Lactic acidosis from tissue hypoperfusion.

— Hypokalemia (insulin therapy, β-agonist vasopressors).

— Hypoglycemia (BB, especially propranolol) or hyperglycemia (CCB, exacerbated by insulin therapy paradoxically improving outcomes).

— Hypocalcemia from prolonged calcium administration paradoxically rare — usually iatrogenic hypercalcemia.

— Seizures, coma (propranolol — lipophilic CNS penetration).

— Anoxic brain injury after prolonged arrest or refractory shock.

— Delirium during recovery, especially elderly.

— AKI from hypoperfusion; may require CRRT.

— Mesenteric ischemia in prolonged shock.

— Vomiting from glucagon (aspiration risk).

— Pulmonary edema from fluid overload.

— Calcium chloride extravasation → tissue necrosis.

— Hyperglycemia >300 with osmotic diuresis from inadequate dextrose during HIE.

— Pacing without mechanical capture giving false reassurance.

Key distinction: A "normal" heart rate after transcutaneous pacing does not equal hemodynamic improvement — always confirm by palpable pulse, arterial line tracing, and rising MAP/lactate clearance. Mechanical capture is what counts.

Cardiovascular:

Pulmonary:

Metabolic:

Neurologic:

Renal:

GI:

Iatrogenic:

When to Escalate Care — ICU, Consult, and Inpatient Triage

— Hemodynamic instability (HR <50, SBP <90, MAP <65, lactate >2).

— Need for vasopressors, high-dose insulin, glucagon infusion, calcium infusion.

— Sustained-release product ingestion regardless of initial presentation.

— Propranolol or sotalol ingestion (CNS toxicity, QRS/QT issues).

— Significant co-ingestion (TCAs, digoxin, opioids, ethanol with respiratory depression).

— Altered mentation, seizure, intubation.

— Acidosis (pH <7.3), AKI, ECG conduction abnormalities.

— Asymptomatic IR ingestion with stable vitals after 6–8 h observation but still within toxicity window.

— Resolving SR ingestion completing 24-hour monitoring.

— Pediatric exploratory ingestion of small amounts of IR product, asymptomatic at 6–8 hours, normal ECG.

— Accidental IR exposure, asymptomatic at 6–8 hours, normal serial ECGs, normal vitals, no co-ingestion — and psychiatry cleared if any intentionality.

— Medical Toxicology or Poison Control (1-800-222-1222) — for every significant overdose.

— Cardiology for refractory shock, pacing decisions, QT monitoring.

— Cardiothoracic surgery / ECMO team — before maximal therapy fails.

— Psychiatry for intentional ingestion.

— Social work / case management for elderly accidental overdose (assess home safety, pill management).

— Pharmacy — to assist with rapid procurement of large quantities of glucagon, insulin, lipid emulsion.

Step 3 management: Initiate ECMO discussion at the point of starting second vasopressor — not when the patient codes. The earlier transfer is initiated, the better the survival.

ICU admission criteria (any of):

Step-down/telemetry (intermediate care):

General medical floor / observation:

Discharge from ED:

Consultations to obtain early (CCS-style):

Transfer criteria: lack of ECMO capability, lack of toxicology consultation, lack of ICU bed — initiate transfer while continuing resuscitation; do not delay for stability.

Key Differentials — Cardiovascular and Toxicologic Causes of Bradycardia/Shock

— Digoxin toxicity: bradycardia + hyperkalemia + GI symptoms + visual yellow halos + characteristic ECG (scooped ST, atrial tachycardia with AV block). Treatment differs: digoxin Fab fragments. Check digoxin level.

— Clonidine/imidazoline (centrally acting α2-agonist) overdose: bradycardia + hypotension + miosis + CNS depression, often in pediatric ingestion of grandparent's clonidine patch or tizanidine. Naloxone may partially reverse.

— Opioid overdose: bradycardia + hypotension + respiratory depression + pinpoint pupils; reverse with naloxone.

— TCA overdose: wide QRS + hypotension + altered mentation + anticholinergic toxidrome — sodium bicarbonate.

— Organophosphate poisoning: bradycardia + SLUDGE/DUMBELS toxidrome — atropine + pralidoxime.

— GHB: bradycardia + profound CNS depression that wakes up suddenly.

— Acute inferior MI — bradycardia + hypotension; ECG shows ST elevation in II, III, aVF; troponin elevated. Treat with PCI, not antidotes.

— Sick sinus syndrome / high-grade AV block from intrinsic conduction disease.

— Tachy-brady syndrome.

— Myxedema coma: bradycardia + hypothermia + hypoglycemia + hyponatremia + altered mentation; check TSH; treat with IV levothyroxine + hydrocortisone.

— Adrenal crisis: hypotension + hyponatremia + hyperkalemia; cortisol stim, hydrocortisone.

Key distinction: Hyperkalemia + bradycardia + GI symptoms + visual disturbance = digoxin, not BB/CCB. Hyperkalemia is not typical of BB/CCB; if present, look elsewhere. Digoxin Fab fragments save lives in dig toxicity.

Other cardiotoxic drug overdoses (must distinguish — same category):

Cardiac:

Endocrine:

Don't forget structural causes: tamponade (Beck's triad, POCUS), tension pneumothorax, PE — fast bedside US rules these in/out.

Key Differentials — Other-Category Causes (Non-Cardiotoxic Mimics)

— Distributive shock with warm extremities, fever, leukocytosis, elevated lactate — mimics DHP CCB vasodilatory picture.

— Key distinguisher: fever, infectious source, ↑procalcitonin; tachycardia is typical (BB can blunt this — be cautious).

— Treat with empiric antibiotics + crystalloid + norepinephrine.

— Hypotension + bronchospasm + urticaria; obtain trigger history; epinephrine IM is first-line.

— Patients on BBs may have refractory anaphylaxis — give glucagon as adjunct (same mechanism as BB toxicity).

— Tachycardia + hypotension + narrow pulse pressure; GI bleed, trauma, ruptured AAA. BB use blunts tachycardia — beware.

— Spinal cord injury → bradycardia + hypotension + flushing below lesion; history of trauma, neuro deficit.

— Hypotension + tachycardia + hypoxia + right heart strain on echo; D-dimer, CTPA.

— Bradycardia + hypotension + Osborn (J) waves on ECG; core temp <35°C.

— Bradycardia + hypertension + irregular respirations; head CT.

— Transient bradycardia/hypotension with rapid recovery; benign history.

— Diaphoresis, altered mentation, tachycardia (or bradycardia if severe); D50, then identify cause (insulinoma, sulfonylurea, sepsis).

Board pearl: In a patient on chronic BBs presenting with shock, the absence of tachycardia does not exclude hypovolemia or sepsis — BBs blunt the compensatory response. Use lactate, base deficit, POCUS, and clinical context to make the diagnosis. This pitfall is heavily tested.

Sepsis / septic shock:

Anaphylaxis:

Hypovolemic/hemorrhagic shock:

Neurogenic shock:

Pulmonary embolism (massive):

Hypothermia:

Increased intracranial pressure (Cushing reflex):

Vasovagal/neurally mediated syncope:

Hypoglycemia (non-drug):

Secondary Prevention, Discharge Medications, and Long-Term Plan

— Psychiatric inpatient admission if active suicidal ideation, plan, or unsafe disposition; involuntary hold per state statute if appropriate.

— Initiate or resume antidepressant therapy in collaboration with psychiatry; bridge appointments within 7 days of discharge ("post-discharge follow-up within 7 days" reduces suicide reattempt — heavily emphasized in Step 3 value-based care).

— Means restriction counseling: dispense limited quantities, blister packs, family-held medications, lockboxes. Especially for those returning home with BB/CCB still prescribed.

— Reassess need for the BB/CCB itself — can it be deprescribed or substituted?

— Provide Suicide & Crisis Lifeline 988 and safety plan.

— Medication reconciliation with primary care prior to discharge — eliminate duplicates and interactions.

— Address CYP3A4 interactions (macrolides, azoles, grapefruit) with diltiazem/verapamil.

— Consider switching SR products to IR formulations if compliance/dosing errors caused toxicity.

— Cognitive assessment (Mini-Cog) if dementia suspected; involve caregivers and home health.

— Pillboxes, blister packs, daily caregiver dose administration.

— Poison-proofing education: medications in original child-resistant containers, on high shelves; remove pills from purses and bedside tables.

— Activate child protective services if neglect suspected (repeated ingestions, gross supervision lapses).

— Avoid resuming the offending agent if alternatives exist; if necessary, restart at lower dose with close follow-up.

— Document overdose history in chart prominently to prevent future re-exposure.

Step 3 management: Schedule psychiatric follow-up within 7 days of any intentional overdose discharge — this is a quality metric (HEDIS) and a Step 3 favorite. Linkage to outpatient care reduces 30-day suicide reattempt rate significantly.

For intentional overdose survivors:

For accidental/iatrogenic overdose (elderly):

For pediatric exploratory ingestion:

General prescribing principles after overdose:

Follow-Up, Monitoring Parameters, and Counseling

— Continuous telemetry until off all antidotes (insulin, glucagon, calcium, vasopressors) and hemodynamically stable for 12–24 hours.

— Serial ECGs every 6–12 h until normal; longer for sotalol (QT surveillance).

— Glucose checks every 1–2 h on HIE; potassium every 4–6 h.

— Wean HIE slowly with concurrent dextrose to avoid rebound hypoglycemia (insulin half-life is short but residual effect lingers).

— Daily renal function (atenolol/sotalol/nadolol clearance), LFTs (hepatically metabolized agents).

— Primary care within 1–2 weeks for medication reconciliation, ECG, vital signs.

— Psychiatry within 7 days for intentional overdoses.

— Cardiology referral if persistent conduction abnormalities, reduced EF, or complex cardiac history.

— Consider stress test or echo if myocardial injury occurred during shock.

— Patient: explain overdose risk, signs of toxicity (dizziness, slow pulse, fainting), interactions to avoid (grapefruit juice, macrolides).

— Family: medication safety, recognition of warning signs, when to call 911 vs. poison control.

— Driving / occupational safety after intentional overdose with anoxic injury or persistent symptoms.

— Document all events as a "critical incident" if iatrogenic; report to hospital safety committee for system learning.

— Pharmacy review of dispensing practices, blister pack feasibility, automated interaction alerts.

— Pediatrician visit within 1 week; in-home safety assessment; child-resistant packaging verification.

CCS pearl: When closing a CCS case, order "psychiatric consultation," "social work," "medication reconciliation," "arrange primary care follow-up within 2 weeks," and (for intentional) "psychiatry follow-up within 7 days" before advancing the clock past discharge. Missing transition-of-care orders costs points.

Inpatient monitoring during recovery:

Post-discharge follow-up:

Counseling points:

Quality and safety:

Pediatric follow-up:

Ethical, Legal, and Patient Safety Considerations

— A suicidal patient who refuses treatment after BB/CCB overdose generally lacks decision-making capacity for that refusal; treat under implied consent / emergency exception and place on psychiatric hold per state law.

— Document the capacity assessment explicitly: understanding, appreciation, reasoning, communicating a choice.

— Child abuse/neglect suspicion (repeated pediatric ingestion, gross supervision failure) → state CPS hotline.

— Elder abuse/neglect (intentional overmedication, caregiver-administered toxicity) → adult protective services.

— Some states require reporting of intentional self-harm to public health registries.

— Suicide attempt history is sensitive; disclose to family/employers only with patient consent except where danger to self/others overrides (Tarasoff-style duties vary by state).

— Document explicitly what was shared and with whom.

— Activated charcoal, intubation, central line, ECMO — when patient is altered or sedated, surrogate decision-maker per state hierarchy; in emergency, implied consent applies. Document attempts to reach family.

— Highest-risk window is the first 30 days post-discharge for re-attempt, medication error, and adverse drug events.

— Use teach-back during discharge counseling; provide a written medication list and post-discharge appointment dates.

— Reconcile medications with both the inpatient list AND the pre-admission list — discrepancies are a common cause of bounce-back overdose.

— Look-alike/sound-alike: metoprolol succinate vs. tartrate dosing errors; report near-misses.

— Pharmacy stock of antidotes (glucagon, lipid emulsion) — institutional stocking minimums per ASHP guidelines.

— Root cause analysis after any iatrogenic toxicity event.

Step 3 management: A patient who attempts suicide and then states "I'm fine, let me leave" should be placed on an emergency psychiatric hold (terminology varies — 5150/2PC/etc.) and treated under emergency doctrine. Documenting capacity assessment is the legally protective step.

Capacity and refusal of care:

Mandatory reporting:

Confidentiality and disclosure:

Informed consent edge cases:

Transition-of-care safety (Step 3 staple):

Patient safety / systems:

High-Yield Associations and Rapid-Fire Clinical Facts

Board pearl: Memorize the glucose differentiator — it's the single most efficient way to answer overdose vignettes that ask "Which drug is responsible?" Hyperglycemia → CCB; hypoglycemia → BB (propranolol).

Hyperglycemia + bradycardia + shock → CCB overdose (impaired pancreatic insulin release).

Hypoglycemia + bradycardia + seizures → propranolol overdose (lipophilic CNS, hepatic glucose impairment).

QRS widening in BB toxicity → propranolol (sodium-channel blockade) → treat with sodium bicarbonate.

QT prolongation + torsades in BB toxicity → sotalol (potassium-channel blockade) → magnesium, overdrive pacing, hemodialysis (sotalol is renally cleared).

Preserved mentation in profound shock → non-DHP CCB (verapamil/diltiazem) hallmark.

Warm shock with reflex tachycardia → dihydropyridine CCB (amlodipine, nifedipine) early phase.

"One pill can kill" in toddlers: amlodipine, verapamil, diltiazem, propranolol, also clonidine, opioids, TCAs, sulfonylureas, camphor.

Best evidence-based therapy for severe BB/CCB shock: high-dose insulin euglycemia (1 U/kg bolus → 1 U/kg/hr, titrate to 10 U/kg/hr).

First-line antidotes: atropine → IV calcium → glucagon → high-dose insulin → vasopressors → lipid emulsion → ECMO.

Hemodialysis-removable BBs: atenolol, nadolol, sotalol, acebutolol ("ANSA"). Not propranolol, metoprolol, or any CCB.

Pacing pitfall: electrical capture without mechanical capture is common — confirm pulse and BP.

Glucagon side effect: vomiting (premedicate with ondansetron).

Drug interaction trigger: diltiazem/verapamil + macrolide/azole → severe bradycardia via CYP3A4 inhibition.

Whole bowel irrigation indicated for SR preparations.

SR ingestion → admit for ≥24 h monitored observation regardless of initial appearance.

Sotalol → prolonged QT, torsades; check for renal failure; dialyze if refractory.

Lipid emulsion for lipophilic drugs (propranolol, verapamil); not standard first-line but rescue.

Methylene blue for refractory amlodipine vasoplegia.

VA-ECMO survival in BB/CCB shock: 50–70% — early activation matters.

Board Question Stem Patterns

— Answer: Verapamil or diltiazem (preserved mentation + hyperglycemia + bradycardia + AV block).

— Answer: Propranolol toxicity. Next step: D25W IV + glucagon + airway management.

— Answer: High-dose insulin euglycemia (1 U/kg bolus, 1 U/kg/hr infusion with dextrose).

— Answer: CYP3A4 inhibition → diltiazem accumulation → iatrogenic CCB toxicity. Stop both; supportive care.

— Answer: Hemodialysis (sotalol is renally cleared, dialyzable, and torsades is refractory).

— Answer: Admit to monitored bed for ≥24 hours — SR peak is delayed; do not discharge.

— Answer: Whole bowel irrigation with polyethylene glycol until effluent clear.

— Answer: IV lipid emulsion (Intralipid) 1.5 mL/kg bolus + infusion, and activate ECMO.

— Answer: Emergency psychiatric hold; suicidality negates capacity for refusal in this context.

CCS pearl: Practice typing the antidote sequence quickly: "calcium gluconate IV, glucagon IV, insulin drip with D10W, norepinephrine, lipid emulsion" — having the orders ready saves time and earns points.

Stem 1 (CCB identification): "A 45-year-old woman is brought to the ED after being found unresponsive. HR 38, BP 70/40. Glucose 280. ECG shows complete heart block. She is alert and speaking. What is the most likely ingestion?"

Stem 2 (BB identification): "A 4-year-old is found with an open bottle of his grandfather's propranolol. He is now seizing. Glucose 35. HR 50."

Stem 3 (HIE indication): "Patient with verapamil overdose remains hypotensive despite calcium gluconate, glucagon, and norepinephrine. What is the next best step?"

Stem 4 (drug interaction): "An elderly patient on diltiazem develops bradycardia and shock 3 days after starting clarithromycin for sinusitis."

Stem 5 (sotalol): "A patient with sotalol overdose develops recurrent torsades. Cr 3.5. Magnesium given × 2."

Stem 6 (disposition): "Patient took 20 tablets of extended-release diltiazem 4 hours ago. Currently asymptomatic, normal ECG, normal vitals. Disposition?"

Stem 7 (decontamination): "Patient with SR verapamil overdose 2 hours ago, intubated and stable. Best decontamination?"

Stem 8 (lipid emulsion): "Refractory cardiac arrest after massive propranolol ingestion despite maximal medical therapy."

Stem 9 (ethics): "Patient who took 30 metoprolol tablets in suicide attempt now wants to leave AMA. He is alert."

One-Line Recap

Beta-blocker and calcium channel blocker overdose cause bradycardia, hypotension, and cardiogenic shock that are best managed with a tiered antidote ladder of calcium, glucagon, high-dose insulin euglycemia, vasopressors, and lipid emulsion — with early ECMO consultation for refractory cases and ≥24-hour monitored observation for any sustained-release ingestion.

Board pearl: When in doubt, start high-dose insulin early — it has the strongest evidence base for myocardial recovery in severe BB/CCB toxicity and should be initiated alongside, not after, vasopressors and glucagon. Time-to-HIE is the modifiable variable that most influences survival.

Differentiation pearl: Hyperglycemia + preserved mentation + bradycardia = CCB (verapamil/diltiazem); hypoglycemia + seizures + QRS widening = propranolol; QT prolongation + torsades = sotalol (dialyze if refractory or renal failure).

Antidote ladder (memorize cold): atropine → IV calcium (gluconate 3 g or chloride 1 g) → glucagon (3–10 mg bolus, infusion) → high-dose insulin euglycemia (1 U/kg bolus, 1 U/kg/hr → up to 10 U/kg/hr with D10W) → norepinephrine ± epinephrine → IV lipid emulsion (lipophilic agents) → VA-ECMO (refractory).

Disposition rule: All sustained-release ingestions get ≥24 hours of monitored observation regardless of initial appearance — delayed peak toxicity at 12–24 hours has killed "stable-looking" patients sent home. Pair every discharge with psychiatry follow-up within 7 days for intentional overdoses, full medication reconciliation for accidental ones, and poison-proofing education for pediatric exposures.

Step 3 transition-of-care: Document capacity, place psychiatric hold when needed, reconcile all home medications, identify CYP3A4 interactions (macrolides/azoles + diltiazem/verapamil), arrange primary care within 1–2 weeks, and counsel on means restriction with limited dispensing and lockboxes to prevent recurrence.