Emergency Pharmacology

💊 The Emergency Pharmacology Arsenal: Life-Saving Drug Mastery

In the chaos of a crashing patient, your pharmacological decisions can mean the difference between recovery and catastrophe. This lesson equips you with the essential drug arsenal for cardiovascular collapse, respiratory failure, neurological emergencies, and toxicological crises-teaching you not just what to give, but when, why, and how to anticipate each agent's effects. You'll master vasopressors that restore perfusion, antidotes that reverse poisoning, analgesics that enable critical procedures, and sedatives that facilitate life-saving interventions. By integrating mechanism with clinical context, you'll build the confidence to act decisively when seconds matter most.

📌 Remember: CRASH - Cardiac arrest drugs, Respiratory support agents, Analgesics and anesthetics, Sedatives and paralytics, Hemostatic and antidotes

The emergency pharmacology landscape encompasses 8 major drug categories, each with specific indications, mechanisms, and monitoring requirements. Mastering these categories provides the foundation for confident emergency prescribing across all clinical scenarios.

• Cardiovascular Emergency Drugs
  • Vasopressors: Epinephrine (1 mg IV q3-5min), Norepinephrine (0.1-2 mcg/kg/min)
  • Antiarrhythmics: Amiodarone (300 mg IV bolus), Lidocaine (1-1.5 mg/kg)
    • Success rates: Amiodarone 74% vs Lidocaine 47% for VF/VT
    • Onset: Amiodarone 2-3 hours, Lidocaine 1-2 minutes
• Respiratory Support Agents
  • Bronchodilators: Salbutamol (2.5-5 mg nebulized), Ipratropium (500 mcg)
  • RSI medications: Propofol (1-2 mg/kg), Succinylcholine (1-1.5 mg/kg)
• Neurological Emergency Drugs
  • Anticonvulsants: Lorazepam (0.1 mg/kg IV), Phenytoin (20 mg/kg loading)
  • Thrombolytics: Alteplase (0.9 mg/kg, max 90 mg over 60 minutes)

💡 Master This: Every emergency drug decision involves 4 critical calculations: weight-based dosing, renal/hepatic adjustment, drug interactions, and monitoring intervals. Mastering these calculations prevents 78% of medication errors in emergency settings.

Understanding emergency pharmacology mechanisms reveals why specific drugs work in crisis situations. Sympathomimetics dominate cardiovascular emergencies through α1 (vasoconstriction), β1 (inotropy), and β2 (bronchodilation) receptor activation. GABA modulators control seizures and provide sedation through chloride channel enhancement. Sodium channel blockers terminate arrhythmias by prolonging refractory periods.

Connect these foundational drug categories through systematic emergency protocols to understand how pharmacological interventions integrate into comprehensive resuscitation algorithms.

⚡ Cardiovascular Crisis Command: Mastering Hemodynamic Rescue

📌 Remember: SHOCK - Septic (norepinephrine), Hypovolemic (fluids first), Obstructive (treat cause), Cardiogenic (dobutamine), Keep monitoring MAP >65 mmHg

Vasopressor Mechanisms and Clinical Applications:

• Epinephrine (Non-selective α/β agonist)
  • Cardiac arrest: 1 mg IV every 3-5 minutes (Class I recommendation)
  • Anaphylaxis: 0.3-0.5 mg IM (anterolateral thigh)
    • Bioavailability: IM 34% vs IV 100% but safer in anaphylaxis
    • Repeat dosing: Every 5-15 minutes if no improvement
• Norepinephrine (α1 > β1 agonist)
  • Septic shock: 0.1-2 mcg/kg/min (first-line vasopressor)
  • Cardiogenic shock: 0.05-0.5 mcg/kg/min (combined with inotropes)
    • MAP target: 65-70 mmHg (optimal organ perfusion)
    • Mortality benefit: 15% reduction vs dopamine in cardiogenic shock

Antiarrhythmic Emergency Protocols:

• Amiodarone (Class III antiarrhythmic)
  • VF/VT arrest: 300 mg IV bolus, then 150 mg if persistent
  • Stable VT: 150 mg IV over 10 minutes, then 1 mg/min × 6 hours
    • Conversion rate: 74% for VF/VT vs 47% with lidocaine
    • Half-life: 25-60 days (extensive tissue distribution)
• Lidocaine (Class IB antiarrhythmic)
  • VF/VT (amiodarone alternative): 1-1.5 mg/kg IV bolus
  • Maintenance: 1-4 mg/min continuous infusion
    • Onset: 1-2 minutes (faster than amiodarone)
    • Hepatic metabolism: Reduce dose 50% in liver disease

💡 Master This: Cardiovascular emergency drugs follow dose-response relationships where doubling the dose typically increases effect by 30-50% but also doubles adverse effects. Titrate gradually using hemodynamic endpoints rather than arbitrary dose limits.

Understanding cardiovascular pharmacology mechanisms enables prediction of drug interactions and adverse effects. β-blocker therapy requires careful titration when adding vasopressors, as unopposed α-stimulation can cause severe hypertension. Connect these cardiovascular principles through respiratory emergency management to understand multi-system pharmacological support.

🫁 Respiratory Rescue Protocols: Airway and Breathing Pharmacology

Bronchodilator Emergency Protocols:

• Salbutamol (β2-selective agonist)
  • Severe asthma: 2.5-5 mg nebulized every 20 minutes × 3
  • Life-threatening: 10-20 mg continuous nebulization
    • Peak effect: 30-60 minutes after nebulization
    • Duration: 4-6 hours (longer with severe bronchospasm)
    • IV dosing: 250 mcg slowly (only in extremis)
• Ipratropium (Anticholinergic bronchodilator)
  • Combined therapy: 500 mcg nebulized with salbutamol
  • COPD exacerbation: 500 mcg every 6 hours
    • Additive effect: 15-20% additional bronchodilation
    • Onset: 15-30 minutes (slower than β2-agonists)

📌 Remember: ASTHMA - Albuterol nebulized, Steroids IV, Theophylline if severe, High-flow oxygen, Magnesium sulfate, Anticholinergics (ipratropium)

Rapid Sequence Intubation Pharmacology:

• Premedication Phase
  • Fentanyl: 1-3 mcg/kg IV (blunts sympathetic response)
  • Lidocaine: 1.5 mg/kg IV (reduces ICP rise)
    • Timing: 3 minutes before induction for optimal effect
    • Contraindications: Allergy, heart block (relative)
• Induction Agents
  • Propofol: 1-2 mg/kg IV (hemodynamically stable patients)
  • Etomidate: 0.3 mg/kg IV (hemodynamically unstable)
    • Propofol: 30-40 seconds onset, 5-10 minutes duration
    • Etomidate: 15-45 seconds onset, 3-12 minutes duration
    • Ketamine: 1-2 mg/kg IV (bronchospasm, hypotension)

• Succinylcholine (Depolarizing)
  • Standard dose: 1-1.5 mg/kg IV (rapid onset)
  • Contraindications: Hyperkalemia >5.5, burns >24 hours, crush injury >6 hours
    • Onset: 45-60 seconds (fastest available)
    • Duration: 6-10 minutes (pseudocholinesterase metabolism)
    • Potassium rise: 0.5-1 mEq/L (dangerous in susceptible patients)
• Rocuronium (Non-depolarizing)
  • RSI dose: 1.2 mg/kg IV (equipotent to succinylcholine timing)
  • Standard dose: 0.6 mg/kg IV (routine intubation)
    • Onset: 60-90 seconds at high dose
    • Duration: 45-60 minutes (hepatic elimination)
    • Reversal: Sugammadex 16 mg/kg (complete reversal in 3 minutes)

⭐ Clinical Pearl: RSI success rate exceeds 95% when performed by experienced operators using standardized protocols. Failed airway occurs in <2% of emergency department intubations with proper preparation and backup planning.

💡 Master This: Respiratory emergency pharmacology requires weight-based calculations with ideal body weight for lipophilic drugs (propofol, fentanyl) and actual body weight for hydrophilic drugs (succinylcholine, rocuronium). This distinction prevents overdosing in obese patients.

Advanced Respiratory Support:

• Magnesium Sulfate
  • Severe asthma: 2 g IV over 20 minutes (smooth muscle relaxation)
  • Mechanism: Calcium channel antagonism + histamine release inhibition
    • Efficacy: 30% reduction in hospitalization for severe asthma
    • Monitoring: Deep tendon reflexes (disappear at 10-12 mg/dL)

Connect respiratory pharmacology principles through pain management protocols to understand how analgesic and sedative agents integrate into comprehensive emergency care algorithms.

🎯 Pain Control Command Center: Emergency Analgesic Mastery

Opioid Analgesic Protocols:

• Morphine (Gold standard μ-opioid agonist)
  • Severe pain: 0.1 mg/kg IV (typical 5-10 mg adult dose)
  • Titration: 2-4 mg IV every 5-10 minutes to effect
    • Onset: 5-10 minutes IV, 15-30 minutes IM
    • Duration: 3-4 hours (hepatic glucuronidation)
    • Renal adjustment: 50% dose reduction if CrCl <30
• Fentanyl (Synthetic μ-opioid agonist)
  • Rapid analgesia: 1-2 mcg/kg IV (50-100 mcg typical adult)
  • Hemodynamic instability: 25-50 mcg IV (minimal hypotension)
    • Onset: 1-2 minutes (highly lipophilic)
    • Duration: 30-60 minutes (rapid redistribution)
    • Potency: 80-100× morphine (careful dosing essential)

📌 Remember: PAIN - Potent opioids (morphine/fentanyl), Adjuvants (ketamine/lidocaine), Infiltration (local blocks), NSAIDs (ketorolac)

Non-Opioid Analgesic Strategies:

• Ketorolac (NSAID)
  • Moderate-severe pain: 30 mg IV/IM (≤65 years), 15 mg (>65 years)
  • Maximum duration: 5 days (renal/GI toxicity)
    • Analgesic equivalence: 30 mg ketorolac = 10 mg morphine
    • Contraindications: CrCl <30, active bleeding, peptic ulcer disease
    • Platelet effect: Reversible inhibition (vs aspirin irreversible)
• Acetaminophen (Paracetamol)
  • IV formulation: 15 mg/kg (max 1 g) every 6 hours
  • Oral dosing: 1 g every 6 hours (max 4 g/day)
    • Hepatotoxicity: Risk increases at >4 g/day or >150 mg/kg
    • Mechanism: COX-3 inhibition + central serotonergic effects

• Ketamine (NMDA receptor antagonist)
  • Sub-anesthetic dose: 0.3-0.5 mg/kg IV (analgesic effect)
  • Continuous infusion: 0.1-0.5 mg/kg/hr (opioid-sparing)
    • Mechanism: NMDA blockade prevents central sensitization
    • Opioid reduction: 25-50% morphine requirement decrease
    • Side effects: Emergence phenomena in 10-15% (reduce with benzodiazepines)
• Lidocaine (Sodium channel blocker)
  • Systemic analgesia: 1-2 mg/kg IV bolus, then 1-3 mg/kg/hr
  • Local infiltration: 1-2% solution (max 4.5 mg/kg without epinephrine)
    • Onset: 2-5 minutes (local), 15-30 minutes (systemic)
    • Duration: 1-2 hours (local), variable (systemic)

Regional Anesthetic Techniques:

• Femoral Nerve Block
  • Hip fracture: 20-30 mL of 0.25% bupivacaine
  • Ultrasound guidance: Success rate >95% vs 70% landmark technique
    • Duration: 8-12 hours with bupivacaine
    • Complications: <1% with ultrasound guidance
• Intercostal Nerve Blocks
  • Rib fractures: 3-5 mL per level of 0.25% bupivacaine
  • Multiple levels: Maximum 2.5 mg/kg total bupivacaine dose
    • Pain reduction: 60-80% improvement in VAS scores
    • Respiratory improvement: 25% increase in tidal volume

⭐ Clinical Pearl: Multimodal analgesia reduces opioid requirements by 30-50% while improving pain scores and reducing side effects. Combine acetaminophen + NSAID + regional block for optimal outcomes.

💡 Master This: Emergency pain management follows pharmacokinetic principles where onset time correlates with lipophilicity (fentanyl fastest), duration correlates with protein binding (bupivacaine longest), and potency correlates with receptor affinity (fentanyl strongest).

Connect pain management principles through neurological emergency protocols to understand how anticonvulsants and neuroprotective agents integrate into comprehensive emergency neurological care.

🧠 Neurological Emergency Command: Brain-Saving Pharmacology

Status Epilepticus Management Protocols:

• First-Line: Benzodiazepines
  • Lorazepam: 0.1 mg/kg IV (max 4 mg per dose)
  • Diazepam: 0.15 mg/kg IV (alternative if lorazepam unavailable)
    • Seizure termination: 65% success rate with lorazepam
    • Onset: 2-3 minutes (crosses blood-brain barrier rapidly)
    • Duration: 6-8 hours (longer than diazepam's 2-4 hours)
• Second-Line: Antiepileptic Drugs
  • Phenytoin: 20 mg/kg IV loading dose (max 50 mg/min)
  • Levetiracetam: 60 mg/kg IV (max 4500 mg) over 15 minutes
    • Phenytoin efficacy: 58% seizure control vs 47% for fosphenytoin
    • Levetiracetam advantages: No cardiac monitoring, fewer interactions

📌 Remember: SEIZE - Stop with benzos, EEG monitoring, IV antiepileptics, Zero delays, Emergent intubation if refractory

Acute Stroke Thrombolytic Therapy:

• Alteplase (tPA) Protocol
  • Dose: 0.9 mg/kg (maximum 90 mg) over 60 minutes
  • Administration: 10% bolus over 1 minute, 90% infusion over 59 minutes
    • Time window: 4.5 hours from symptom onset (selected patients)
    • NIHSS improvement: 31% achieve mRS 0-1** vs 21% placebo
    • Hemorrhage risk: 6.4% symptomatic ICH vs 0.6% placebo
• Mechanical Thrombectomy
  • Time window: 24 hours (with perfusion imaging selection)
  • Combined therapy: tPA + thrombectomy superior to either alone
    • Recanalization: 85-90% with modern devices
    • Good outcome: 46% vs 17% medical therapy alone

• Osmotic Therapy
  • Mannitol: 0.25-1 g/kg IV over 15-30 minutes
  • Hypertonic saline: 23.4% solution, 30 mL over 10-20 minutes
    • ICP reduction: 25-30% decrease within 15-30 minutes
    • Duration: 1-6 hours (mannitol), 2-4 hours (hypertonic saline)
    • Monitoring: Serum osmolality <320 mOsm/kg (mannitol toxicity threshold)
• Neuroprotective Agents
  • Propofol: 1-3 mg/kg/hr (ICP control + neuroprotection)
  • Barbiturates: Pentobarbital 10-15 mg/kg loading (refractory ICP)
    • Cerebral metabolic rate: 50% reduction with propofol
    • Burst suppression: Target 2-5 second intervals with barbiturates

Hemorrhagic Stroke Management:

• Blood Pressure Control
  • Target: SBP 140-180 mmHg (avoid aggressive reduction)
  • Nicardipine: 5-15 mg/hr continuous infusion
    • Hematoma expansion: 38% risk if SBP >180 mmHg
    • Neurological deterioration: 15% with aggressive BP reduction
• Reversal Agents
  • Warfarin reversal: 4-factor PCC 25-50 units/kg + Vitamin K 10 mg IV
  • DOAC reversal: Idarucizumab 5 g IV (dabigatran), Andexanet alfa (Xa inhibitors)
    • Reversal time: <30 minutes with specific antidotes
    • Bleeding cessation: 68% effective hemostasis with PCC

⭐ Clinical Pearl: Time is brain - every 15-minute delay in stroke treatment reduces good outcomes by 4%. Door-to-needle time <60 minutes and door-to-groin time <90 minutes optimize neurological recovery.

💡 Master This: Neurological emergency pharmacology requires precise timing where therapeutic windows determine efficacy. Seizures require treatment within 5 minutes, strokes within 4.5 hours, and elevated ICP within minutes to prevent irreversible brain damage.

Connect neurological emergency principles through toxicological antidote protocols to understand how specific antagonists and chelating agents reverse life-threatening poisonings.

🛡️ Antidote Arsenal: Toxicological Rescue Pharmacology

Acetaminophen Poisoning Management:

• N-Acetylcysteine (NAC) Protocol
  • Loading dose: 150 mg/kg IV over 1 hour
  • Second dose: 50 mg/kg IV over 4 hours
  • Third dose: 100 mg/kg IV over 16 hours
    • Hepatotoxicity prevention: >95% if started within 8 hours
    • Efficacy decline: 43% protection if started 15-24 hours
    • Mechanism: Glutathione replenishment + free radical scavenging

📌 Remember: ANTIDOTES - Acetaminophen (NAC), Naloxone (opioids), Thiamine (ethanol), Insulin (CCB/BB), Digoxin Fab, Organophosphates (atropine), Toxic alcohols (fomepizole), Ethylene glycol (antidote), Snake bites (antivenin)

Opioid Overdose Reversal:

• Naloxone (Opioid Antagonist)
  • Initial dose: 0.4-2 mg IV/IM/IN (titrate to respiratory drive)
  • High-potency opioids: 4-10 mg may be required (fentanyl analogs)
    • Onset: 1-2 minutes IV, 2-5 minutes IM, 5-10 minutes IN
    • Duration: 30-90 minutes (shorter than most opioids)
    • Repeat dosing: 20-60 minutes intervals (half-life 60-90 minutes)
• Withdrawal precipitation: Risk with chronic opioid users
  • Start low: 0.04 mg IV and titrate (avoid precipitated withdrawal)
  • Target: Respiratory rate >12/min (not full consciousness)

• Atropine (Muscarinic Antagonist)
  • Initial: 2-5 mg IV (double dose every 5 minutes until atropinization)
  • Maintenance: 0.5-2 mg/hr continuous infusion
    • Endpoint: Dry secretions, pupils >2 mm, HR >80 bpm
    • Total dose: 100-1000 mg may be required in severe cases
• Pralidoxime (2-PAM)
  • Loading: 30 mg/kg IV over 15-30 minutes
  • Maintenance: 8-10 mg/kg/hr continuous infusion
    • Time window: <24-48 hours (before aging occurs)
    • Mechanism: Reactivates acetylcholinesterase

Calcium Channel Blocker/Beta-Blocker Overdose:

• High-Dose Insulin Euglycemic Therapy
  • Insulin: 1 unit/kg IV bolus, then 1-10 units/kg/hr
  • Dextrose: 25-50 g IV to maintain glucose 100-200 mg/dL
    • Mechanism: Improved cardiac metabolism + positive inotropy
    • Success rate: 60-70% in severe CCB/BB poisoning
    • Monitoring: Glucose q30min, potassium q2hr

Toxic Alcohol Management:

• Fomepizole (Alcohol Dehydrogenase Inhibitor)
  • Loading: 15 mg/kg IV over 30 minutes
  • Maintenance: 10 mg/kg q12hr × 4 doses, then 15 mg/kg q12hr
    • Methanol/ethylene glycol: Prevents toxic metabolite formation
    • Advantage: No CNS depression (vs ethanol antidote)
    • Cost: $1000-4000 per treatment course
• Hemodialysis Indications
  • Methanol: >50 mg/dL or visual symptoms
  • Ethylene glycol: >50 mg/dL or renal dysfunction
    • Clearance: 120-180 mL/min (vs 15-20 mL/min endogenous)
    • Duration: 4-6 hours typically required

⭐ Clinical Pearl: Antidote timing determines efficacy - NAC within 8 hours prevents 95% of hepatotoxicity, fomepizole before metabolite formation prevents organ damage, and digoxin Fab reverses toxicity within 30-60 minutes.

💡 Master This: Toxicological pharmacology follows competitive inhibition principles where antidote affinity must exceed toxin affinity for target receptors. Higher antidote concentrations overcome competitive binding and reverse toxic effects.

Connect antidote principles through emergency sedation protocols to understand how rapid sequence medications and procedural sedation agents enable safe emergency interventions.

🎛️ Emergency Sedation Mastery: Procedural Control Pharmacology

Procedural Sedation Protocols:

• Propofol (GABA-A Agonist)
  • Induction: 1-2 mg/kg IV over 30-60 seconds
  • Maintenance: 25-100 mcg/kg/min continuous infusion
    • Onset: 30-40 seconds (highly lipophilic)
    • Duration: 5-10 minutes (rapid redistribution)
    • Advantages: Rapid recovery, antiemetic properties
    • Disadvantages: Hypotension, respiratory depression
• Ketamine (NMDA Antagonist)
  • Dissociative dose: 1-2 mg/kg IV or 4-5 mg/kg IM
  • Sub-dissociative: 0.3-0.5 mg/kg IV (analgesia + mild sedation)
    • Onset: 1-2 minutes IV, 5-10 minutes IM
    • Duration: 15-30 minutes (active metabolites extend effect)
    • Advantages: Maintains airway reflexes, bronchodilation
    • Contraindications: Age <3 months, psychosis history

📌 Remember: SEDATION - Safety monitoring, Equipment ready, Dose titration, Airway assessment, Time-based checks, Informed consent, Oxygen/suction, Nilsson reversal agents

Benzodiazepine Sedation:

• Midazolam (Short-acting Benzodiazepine)
  • IV dose: 0.02-0.1 mg/kg (typical 1-5 mg adult)
  • Intranasal: 0.2-0.5 mg/kg (pediatric preference)
    • Onset: 2-5 minutes IV, 10-15 minutes IN
    • Duration: 30-60 minutes (hepatic metabolism)
    • Amnesia: Anterograde effect lasting 2-6 hours
    • Reversal: Flumazenil 0.2 mg IV (repeat every 1 minute)
• Lorazepam (Intermediate-acting)
  • Anxiolysis: 0.5-2 mg IV/PO (longer procedures)
  • Duration: 6-8 hours (longer than midazolam)
    • Metabolism: Glucuronidation (safer in liver disease)
    • Elimination: Not affected by CYP450 interactions

• Fentanyl + Midazolam
  • Fentanyl: 1-2 mcg/kg IV (analgesia)
  • Midazolam: 0.02-0.05 mg/kg IV (anxiolysis)
    • Synergistic effect: 50% dose reduction of each agent
    • Respiratory depression: Additive risk requires careful monitoring
• Ketofol (Ketamine + Propofol)
  • Mixture: 1:1 ratio in same syringe (50 mg/mL each)
  • Dose: 0.5-1 mg/kg of mixture
    • Advantages: Hemodynamic stability, reduced emergence reactions
    • Success rate: >95% adequate sedation with <5% adverse events

Pediatric Sedation Considerations:

• Weight-based Dosing
  • Ketamine: 1-2 mg/kg IV (same as adults)
  • Propofol: 2-3 mg/kg IV (higher dose needed)
    • Age-related differences: Faster metabolism in children
    • Volume of distribution: Higher in pediatric patients
• Route Preferences
  • Intranasal midazolam: 0.2-0.5 mg/kg (needle-phobic children)
  • Oral ketamine: 6-10 mg/kg (uncooperative patients)
    • Bioavailability: IN 50%, PO 20% (vs 100% IV)

Monitoring and Safety Protocols:

• Continuous Monitoring Requirements
  • Pulse oximetry: Continuous (target SpO2 >95%)
  • Capnography: Continuous (early respiratory depression detection)
  • Blood pressure: Every 5 minutes minimum
  • ECG: Continuous for cardiac risk patients
    • Capnography sensitivity: >95% for respiratory depression
    • Response time: 45-90 seconds faster than pulse oximetry
• Recovery Criteria
  • Aldrete score: ≥9/10 (activity, respiration, circulation, consciousness, oxygen)
  • Discharge: Stable vitals for 30 minutes post-procedure
    • Time to discharge: Propofol 15-30 min, ketamine 60-90 min

⭐ Clinical Pearl: Procedural sedation success rate exceeds 95% with standardized protocols and continuous monitoring. Adverse events occur in <5% of cases, with respiratory depression being most common (2-3% incidence).

💡 Master This: Emergency sedation pharmacology requires understanding pharmacokinetic interactions where synergistic effects allow dose reduction but increase monitoring requirements. Combination therapy reduces individual drug toxicity while maintaining procedural efficacy.

This comprehensive emergency pharmacology mastery provides the foundation for confident medication management across all critical care scenarios, enabling rapid therapeutic decision-making that saves lives through precise pharmacological intervention.