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Emergency Drugs Every Duty Doctor Must Know

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1. CARDIAC ARREST (ACLS)

Epinephrine (Adrenaline)

• MOA: Alpha + beta adrenergic agonist; increases coronary/cerebral perfusion pressure
• Dose: 1 mg IV (1:10,000) every 3-5 min during CPR
• Pediatric: 0.01 mg/kg IV (1:10,000); max 1 mg
• Indications: VF/pulseless VT (after 2 shocks), PEA, asystole
• Pitfall: Tissue necrosis if extravasates - needs central line for infusion; dysrhythmias

Amiodarone

• MOA: Class III antiarrhythmic - blocks Na/K/Ca channels + beta blockade
• Dose: 300 mg IV bolus for shock-refractory VF/pulseless VT; second dose 150 mg
• Infusion: 1 mg/min x 6 h, then 0.5 mg/min x 18 h
• Indications: Shock-refractory VF/VT, stable VT, AF rate control
• Pitfall: Hypotension, bradycardia, pulmonary toxicity (chronic), thyroid disease

Lidocaine (alternative to amiodarone)

• Dose: 1-1.5 mg/kg IV bolus for VF/pulseless VT
• Maintenance: 1-4 mg/min infusion
• Pitfall: CNS toxicity (seizures, confusion) at toxic levels

Magnesium Sulfate

• Dose: 2 g IV push (pulseless Torsades); 2 g IV over 15 min (Torsades with pulse, status asthmaticus, eclampsia)
• Indications: Torsades de Pointes, eclampsia/pre-eclampsia, status asthmaticus, hypomagnesemia
• Pitfall: Hypotension, respiratory depression, loss of patellar reflex (monitor Mg levels)

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2. BRADYCARDIA / HEART BLOCK

Atropine

• MOA: Muscarinic antagonist - increases SA node rate, AV conduction
• Dose: 0.5 mg IV; repeat every 3-5 min; max 3 mg
• Pediatric: 0.02 mg/kg IV; min dose 0.1 mg; max 0.5 mg (child), 1 mg (adolescent)
• Indications: Symptomatic bradycardia, vagal syncope, organophosphate poisoning
• Pitfall: Paradoxical bradycardia at doses < 0.1 mg (pediatrics); ineffective in heart transplant patients

Dopamine

• Dose: 2-20 mcg/kg/min IV infusion
• Low (2-5 mcg/kg/min): renal/mesenteric vasodilation
• Mid (5-10 mcg/kg/min): beta-1 = inotrope/chronotrope
• High (>10 mcg/kg/min): alpha = vasoconstrictor
• Indications: Symptomatic bradycardia unresponsive to atropine, cardiogenic/distributive shock

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3. TACHYARRHYTHMIAS

Adenosine

• MOA: Blocks AV node conduction transiently (endogenous purinergic agonist)
• Dose: 6 mg rapid IV push + flush; if no response in 1-2 min, 12 mg; may repeat 12 mg once
• Indications: SVT (AVNRT, AVRT) - diagnostic and therapeutic
• Pitfall: Very short half-life (10 s) - must push fast and flush; transient complete heart block; bronchospasm in asthma; do not use in pre-excited AF (WPW) - may precipitate VF

Metoprolol / Esmolol (beta-blockers)

• Esmolol: 500 mcg/kg loading dose, then 50-300 mcg/kg/min infusion
• Indications: AF/flutter rate control, aortic dissection, SVT
• Pitfall: Decompensated CHF, bronchospasm, hypotension

Diltiazem (CCB)

• Dose: 0.25 mg/kg IV over 2 min; repeat 0.35 mg/kg in 15 min if needed
• Indications: AF/flutter rate control, SVT (if beta-blockers contraindicated)
• Pitfall: Hypotension, heart block; contraindicated in WPW with AF

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4. ANAPHYLAXIS

Epinephrine - FIRST LINE, give immediately

• Adult: 0.3-0.5 mg IM (1:1,000 = 1 mg/mL) in anterolateral thigh; repeat every 5-10 min
• Pediatric: 0.01 mg/kg IM (1:1,000); max 0.5 mg; repeat every 5-10 min
• IV infusion (severe/refractory): Start 1 mcg/min, titrate up
• Simultaneously: oxygen, supine position, large-bore IV, 1-2 L NS bolus

Second-Line (do NOT delay epinephrine for these)

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5. RESPIRATORY EMERGENCIES

Salbutamol (Albuterol)

• MOA: Selective beta-2 agonist - bronchodilation
• Nebulized: 2.5-5 mg q20 min x 3, then q1-4h prn; or 10-15 mg continuous
• IV (severe): 5 mcg/min, titrate to 20 mcg/min
• Indications: Acute asthma, COPD exacerbation, anaphylaxis bronchospasm, hyperkalemia
• Pitfall: Hypokalemia, tachycardia, hyperglycemia

Ipratropium Bromide

• Dose: 0.5 mg nebulized q20 min x 3 (combined with albuterol in first hour)
• Indications: Acute asthma, COPD exacerbation (add to beta-agonist)

Hydrocortisone / Methylprednisolone

• Status asthmaticus: Hydrocortisone 1-2 mg/kg IV q6h; or methylprednisolone 1-2 mg/kg IV
• Reduces airway inflammation, decreases relapse rate

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6. HYPERTENSIVE EMERGENCIES

Labetalol

• Dose: 20 mg IV slowly over 2 min; may repeat 40-80 mg q10 min; max 300 mg total. Infusion: 0.5-2 mg/min
• Indications: Hypertensive emergency, aortic dissection, hypertension in pregnancy (safe in pregnancy)
• Pitfall: Bronchospasm, heart block

Nitroglycerin (GTN)

• Dose: 5-200 mcg/min IV; start low and titrate q3-5 min
• Indications: Acute LVF/pulmonary edema, unstable angina/NSTEMI, hypertensive emergency
• Pitfall: Hypotension (especially with sildenafil/PDE5 inhibitors - absolute contraindication), methemoglobinemia

Sodium Nitroprusside

• Dose: Start 0.3 mcg/kg/min; titrate to effect; max 10 mcg/kg/min
• Indications: Hypertensive emergency with end-organ damage, acute LVF
• Pitfall: Cyanide toxicity (prolonged use or high doses), methemoglobinemia, photosensitive - cover infusion bag

Hydralazine

• Dose: 10-20 mg IV/IM; repeat q4-6h
• Indications: Hypertension in pregnancy/eclampsia (widely used)
• Pitfall: Reflex tachycardia, lupus-like syndrome (chronic)

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7. CHEST PAIN / ACS

Aspirin

• Dose: 300-325 mg PO (chewed) immediately
• Indications: Suspected ACS (STEMI/NSTEMI), stroke prevention
• Pitfall: Active GI bleed, true aspirin allergy

Morphine

• Dose: 1-5 mg IV slow push; titrate q5-15 min
• Indications: Severe pain in ACS, acute pulmonary edema (use cautiously - some evidence of harm in NSTEMI)
• Pitfall: Respiratory depression, hypotension, nausea; may delay absorption of P2Y12 inhibitors

Heparin (Unfractionated)

• STEMI/NSTEMI: 60-70 units/kg IV bolus (max 5000 units), then 12-15 units/kg/h
• Indications: ACS, PE, DVT, AF
• Pitfall: HIT (heparin-induced thrombocytopenia), bleeding

Enoxaparin (LMWH)

• Dose: 1 mg/kg SC q12h; or 1.5 mg/kg SC q24h (PE/DVT)
• Indications: NSTEMI, PE, DVT
• Pitfall: Renally excreted - reduce dose in CKD; avoid with spinal anesthesia; monitor anti-Xa in obesity/renal impairment

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8. SEIZURES / STATUS EPILEPTICUS

Diazepam

• Dose: 5-10 mg IV/IM/PR; repeat q5 min; max 30 mg
• Pediatric: 0.1-0.3 mg/kg IV/PR
• Indications: First-line status epilepticus, alcohol withdrawal seizures, eclamptic seizures
• Pitfall: Respiratory depression, hypotension; has propylen glycol vehicle (irritant IV)

Lorazepam

• Dose: 4 mg IV over 2 min; repeat once after 5-10 min if needed
• Indications: Status epilepticus (preferred by many guidelines over diazepam IV)
• Pitfall: Respiratory depression; requires refrigeration

Midazolam (IM preferred if no IV access)

• Dose: 10 mg IM (>40 kg); 5 mg IM (13-40 kg); buccal/intranasal: 0.2 mg/kg
• Indications: Status epilepticus, procedural sedation, RSI (as induction adjunct)

Phenytoin / Fosphenytoin

• Load: Phenytoin 15-20 mg/kg IV at max 50 mg/min (fosphenytoin 150 mg PE/min, faster)
• Second-line after benzodiazepines fail
• Pitfall: Cardiac arrhythmias during IV load, hypotension, Purple Glove Syndrome (phenytoin extravasation), zero-order kinetics

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9. HYPOGLYCEMIA

Dextrose (Glucose)

• D50%: 25-50 mL (12.5-25 g) IV bolus - adults
• D10%: Preferred in many settings to avoid hyperglycemia rebound
• Pediatric: D10% 2-5 mL/kg IV, or D25% 1-2 mL/kg
• Pitfall: Do not give dextrose to Wernicke's-risk patients without thiamine first

Glucagon

• Dose: 1 mg IV/IM/SC (adult); 0.5 mg (child <25 kg)
• Indications: Hypoglycemia (no IV access), beta-blocker/CCB overdose (3-10 mg IV load)
• Pitfall: Vomiting (aspiration risk), ineffective in starvation/liver disease (depleted glycogen)

Thiamine (Vitamin B1) - give BEFORE dextrose in at-risk patients

• Dose: 100 mg IV/IM
• Indications: Wernicke's encephalopathy risk (alcohol use disorder, malnutrition, prolonged vomiting)

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10. OVERDOSE / POISONING

Naloxone (Narcan)

• Dose: 0.4-2 mg IV/IM/IN; repeat q2-3 min; titrate to respiratory rate
• Indications: Opioid overdose (respiratory depression, coma)
• Pitfall: Short half-life (30-90 min) - opioid may outlast it; may precipitate acute withdrawal; may require infusion for long-acting opioids

Flumazenil

• Dose: 0.2 mg IV over 30 s; repeat 0.1 mg q1 min; max 1 mg
• Indications: Benzodiazepine reversal (diagnostic/therapeutic)
• Pitfall: Precipitates seizures in benzo-dependent patients or those with mixed TCA overdose; do not use routinely in undifferentiated coma

Activated Charcoal

• Dose: 1 g/kg PO (max 50 g); ideally within 1 hour of ingestion
• Indications: Most oral overdoses (effective for salicylates, TCAs, anticonvulsants)
• Pitfall: Contraindicated if airway not protected, caustic ingestion, hydrocarbons, or absent bowel sounds

Atropine (Organophosphate poisoning)

• Dose: 2-4 mg IV every 5-15 min until secretions dry; no ceiling dose
• Indications: Organophosphate/carbamate poisoning, nerve agent exposure
• Mnemonic for OP toxidrome: SLUDGE (Salivation, Lacrimation, Urination, Defecation, GI cramps, Emesis) + DUMBELS

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11. SHOCK / HEMODYNAMIC SUPPORT

Norepinephrine (Noradrenaline)

• Dose: 0.01-3 mcg/kg/min IV infusion; titrate to MAP >65
• Indications: First-choice vasopressor in septic shock, distributive shock
• Pitfall: Tissue necrosis with extravasation; needs central line

Adrenaline (Epinephrine) infusion

• Dose: 1-10 mcg/min (or 0.01-0.5 mcg/kg/min)
• Indications: Anaphylactic shock, cardiogenic shock (add-on), anesthesia-induced hypotension

Dobutamine

• Dose: 2-20 mcg/kg/min IV infusion
• Indications: Decompensated heart failure, cardiogenic shock with low CO
• Pitfall: Tachycardia, hypotension if not euvolemic, proarrhythmic; PVCs

Vasopressin

• Dose: 0.03-0.04 units/min IV (fixed dose in septic shock, added to norepinephrine)
• Indications: Adjunct in vasoplegic/septic shock refractory to norepinephrine

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12. PAIN & PROCEDURAL SEDATION

Morphine

• Dose: 2-4 mg IV q4-6h; titrate
• Pediatric: 0.05-0.1 mg/kg IV q2-4h

Fentanyl

• Dose: 25-100 mcg IV q1-2h; recommended 1 mcg/kg
• Procedural sedation: 1-2 mcg/kg IV (fast onset, short duration)
• Pitfall: Respiratory depression, rigid chest syndrome with rapid high-dose infusion, laryngospasm

Ketamine

• Dose (procedural sedation): 1-2 mg/kg IV; or 4-5 mg/kg IM
• Dissociative anesthesia dose (RSI): 1.5-2 mg/kg IV
• Indications: Procedural sedation, RSI induction (bronchospasm, hypotension, trauma), analgesic sub-dissociative (0.1-0.5 mg/kg IV)
• Pitfall: Laryngospasm (rare), emergence reaction (give midazolam 0.05 mg/kg IV to prevent), increased secretions, hypertension/tachycardia

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13. ECLAMPSIA / OBSTETRIC EMERGENCIES

Magnesium Sulfate

• Pre-eclampsia/eclampsia seizure prophylaxis: 4-6 g IV over 15-20 min, then 1-2 g/h infusion
• Monitor: Respiratory rate, patellar reflexes, urine output, Mg level
• Antidote for Mg toxicity: Calcium gluconate 1 g (10 mL of 10%) IV

Labetalol / Hydralazine - for hypertension in pregnancy (see above)

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14. QUICK-REFERENCE DOSE CARD

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Key Principles to Remember

1. Epinephrine is the universal emergency drug - cardiac arrest, anaphylaxis, severe bronchospasm, airway emergencies
2. ABCDE first - drugs support, not replace, basic resuscitation (airway, breathing, circulation)
3. Pre-calculate weight-based doses - especially for pediatric and critically ill patients
4. Know your antidotes: Naloxone (opioids), flumazenil (benzos), atropine/pralidoxime (organophosphates), calcium gluconate (Mg toxicity, CCB OD), N-acetylcysteine (paracetamol), Vitamin K/FFP (warfarin)
5. Dose errors kill - particularly with epinephrine (1:1,000 vs 1:10,000 concentration); always double-check
6. Always have emergency drugs drawn up and labeled before procedures - prefilled syringes with doses written for that patient's weight

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Pain Location as a Diagnostic Guide

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Understanding Pain Types First

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HEAD AND NECK PAIN

Headache Location → Diagnosis

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CHEST PAIN

Key Rule: Radiation Pattern in Cardiac Pain

• Radiates to left arm/shoulder → ischemic heart disease
• Radiates to jaw → MI (often missed, especially in women/diabetics)
• Radiates to back (tearing) → aortic dissection
• Radiates to jaw + back → dissection vs. severe MI

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ABDOMINAL PAIN BY QUADRANT

The Four Quadrant Rule

         RUQ  |  LUQ
        ------+------
         RLQ  |  LLQ

Right Upper Quadrant (RUQ)

Left Upper Quadrant (LUQ)

Right Lower Quadrant (RLQ)

Left Lower Quadrant (LLQ)

Central / Periumbilical Pain

Epigastric Pain

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LOIN / FLANK / BACK PAIN

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PELVIC PAIN

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REFERRED PAIN PATTERNS - IMPORTANT CHART

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THE SOCRATES FRAMEWORK - How Pain Quality Narrows Diagnosis

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SUMMARY QUICK-REFERENCE MAP

LOCATION              THINK OF
─────────────────────────────────────────────────────
Head (thunderclap)  → SAH
Head (unilateral)   → Migraine / Cluster
Temple (elderly)    → GCA
Jaw/arm + chest     → MI/Angina
Tearing chest→back  → Aortic dissection
Sharp chest,posture → Pericarditis
Pleuritic chest     → PE / Pleurisy / Pneumonia
Epigastric (meals)  → PUD (gastric/duodenal ulcer)
Epigastric→back     → Pancreatitis
RUQ + fat meal      → Cholecystitis / Biliary
RUQ + right shoulder→ Liver / Gallbladder / subdiaphragmatic
LUQ + left shoulder → Splenic rupture (Kehr's sign)
Periumbilical→RLQ   → Appendicitis
RLQ (young woman)   → Ovarian torsion / Ectopic
LLQ (elderly)       → Diverticulitis
Loin→groin (colicky)→ Ureteral calculus
Suprapubic + dysuria→ UTI
Shoulder tip        → Diaphragmatic irritation (blood, pus, air)
Low back + legs     → Disc prolapse / Cauda equina

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Critical "Do Not Miss" Pain Presentations

1. Worst headache of life → always rule out SAH (CT + LP)
2. Tearing chest/back pain → aortic dissection until proven otherwise
3. Epigastric pain in elderly/diabetic → may be silent MI - always do ECG
4. Shoulder tip pain → free fluid/air under diaphragm (ruptured ectopic, perforated viscus, splenic rupture)
5. Periumbilical → RLQ migration → appendicitis
6. Pain out of proportion to examination → mesenteric ischemia
7. Sudden severe testicular/scrotal pain → testicular torsion (6-hour window)
8. Saddle anaesthesia + urinary retention + back pain → cauda equina emergency

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Acute Coronary Syndrome (ACS)

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1. DEFINITION & CLASSIFICATION

                    ACS
           ┌────────┴────────┐
     ST-Elevation       No ST-Elevation
       (STEMI)            (NSTE-ACS)
                      ┌────────┴────────┐
                  NSTEMI          Unstable Angina
              (troponin +)        (troponin -)

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2. PATHOPHYSIOLOGY

1. Atherosclerotic plaque builds up in coronary artery wall over years
2. Plaque rupture or erosion - thin fibrous cap tears, exposing lipid-rich core
3. Platelet aggregation - platelets adhere to exposed collagen and lipids
4. Thrombus formation - activation of coagulation cascade
5. Partial occlusion → NSTEMI/UA; Complete occlusion → STEMI
6. Myocardial ischemia → necrosis - begins at subendocardium, progresses outward (wavefront phenomenon)

• Supply reduced: severe hypotension, anemia, hypoxemia, coronary spasm (Prinzmetal angina), dissection
• Demand increased: tachycardia, severe hypertension, thyrotoxicosis

• Thin fibrous cap
• Large lipid core
• Inflammation (macrophage infiltration)
• Low shear stress zones (vessel bifurcations)
• Neovascularization of plaque

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3. CLINICAL PRESENTATION

Typical Symptoms

• Retrosternal pressure, squeezing, or heaviness - often described as "elephant on chest"
• Radiation to left arm, neck, or jaw
• Duration: angina < 20 min; NSTEMI/STEMI ≥ 30 min (or persistent)
• Associated: diaphoresis, nausea, dyspnea, vomiting, syncope

Atypical Presentations (do NOT miss)

• Epigastric pain / indigestion
• Unexplained fatigue or weakness
• Dyspnea alone
• Jaw or arm pain without chest pain
• Sudden-onset dizziness or syncope

"Myocardial ischemia is highly likely if anginal symptoms are accompanied by ECG abnormalities or elevated troponin." - Goldman-Cecil Medicine

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4. DIAGNOSIS

Step 1: ECG (within 10 minutes of presentation)

Step 2: Troponin (High-Sensitivity, hs-cTn)

• Measure at 0 h and 1 h (or 0 h and 3 h)
• Rule-in: hs-cTn very high at 0 h OR significant rise (delta) at 1 h
• Rule-out: hs-cTn very low at 0 h OR low + no delta at 1 h

Step 3: Diagnostic Pathway - HEART Score

• H - History (typical/atypical/non-cardiac features)
• E - ECG (normal / non-specific changes / ST deviation)
• A - Age (< 45 / 45-65 / > 65)
• R - Risk factors (none / 1-2 / ≥3 or known atherosclerosis)
• T - Troponin (normal / 1-3x / >3x ULN)

Additional Tests

• Echo: Wall motion abnormalities, LV function, rule out pericarditis/PE
• CXR: Pulmonary congestion, widened mediastinum (dissection)
• Coronary CTA: In low-intermediate risk, no clear ECG changes
• Stress test: After ruling out ACS in intermediate-risk patients

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5. RISK STRATIFICATION

TIMI Score for NSTE-ACS (0-7 points)

1. Age ≥ 65 years
2. ≥ 3 CAD risk factors (HTN, DM, hyperlipidaemia, smoking, family history)
3. Known CAD (prior stenosis ≥ 50%)
4. ST deviation > 0.5 mm on presenting ECG
5. ≥ 2 anginal events in prior 24 hours
6. Aspirin use in prior 7 days (suggests aspirin-resistant/refractory disease)
7. Elevated cardiac markers (troponin or CK-MB)

GRACE Score Variables

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6. MANAGEMENT

A. IMMEDIATE GENERAL MEASURES (ALL ACS)

• M - Morphine: 2-4 mg IV for severe unrelieved pain (use cautiously in NSTEMI - may delay P2Y12 absorption)
• O - Oxygen: Only if SpO2 < 90% or signs of heart failure; do NOT give routinely
• N - Nitrates: SL/buccal 0.3-0.6 mg q5 min x3, then IV if persistent (avoid if: hypotension, RV infarct, PDE5 inhibitor use)
• A - Aspirin: 300-325 mg chewed immediately (loading dose), then 75-100 mg/day

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B. ANTI-ISCHEMIC THERAPY

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C. ANTIPLATELET THERAPY

• ACS + PCI: minimum 12 months (can extend to 30 months in selected patients with low bleed risk)
• After 12 months, consider P2Y12 monotherapy (ticagrelor 60 mg BID) as per 2025 ACC/AHA guidelines

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D. ANTICOAGULATION

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E. REPERFUSION STRATEGY

STEMI - TIME IS MUSCLE

• Door-to-balloon time: < 90 minutes (if PCI-capable center)
• Door-to-balloon time: < 120 minutes (if transfer needed)
• Preferred over thrombolysis in all settings where achievable within timeframes

• Give within 12 hours of symptom onset (best results < 3 hours)
• Preferred agents: Tenecteplase (weight-based single IV bolus), Alteplase, Streptokinase
• Contraindications to thrombolysis:

NSTEMI - Timing of Invasive Strategy

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F. ADDITIONAL MEDICAL THERAPY

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7. COMPLICATIONS OF ACS

Mechanical

Electrical

• VF/VT: Most common cause of death in first hours (pre-hospital)
• Complete heart block: Inferior STEMI (RCA) - may need temporary pacing
• RBBB / LBBB: Anterior STEMI (LAD); new LBBB = poor prognosis

Haemodynamic

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8. SECONDARY PREVENTION (POST-ACS)

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9. QUICK CLINICAL SUMMARY

STEMI → ECG in <10 min → Activate cath lab → PCI < 90 min
                                  ↓ (if PCI unavailable)
                          Thrombolysis < 12 h of onset

NSTEMI/UA → Risk stratify (TIMI/GRACE/HEART)
                  ↓
         Low risk → Serial troponin + stress test
         High risk → PCI < 24-72 hours
                  ↓
ALL ACS: Aspirin + P2Y12 + anticoagulation + beta-blocker + statin + ACEi

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2025 Update: The landmark 2025 ACC/AHA/ACEP/NAEMSP/SCAI Guideline (Rao SV et al., Circulation 2025 - PMID: 40014670) replaces all prior separate STEMI and NSTEMI guidelines into a single unified document, incorporating new evidence on colchicine, de-escalation strategies for DAPT, and P2Y12 monotherapy post-PCI.