Pharmacology
1. Pharmacology Overview
Video 1
General Anesthetics Overview
Get a broad overview of general, regional, and local anesthesia, including key drug classes like inhaled agents, IV anesthetics, benzodiazepines, barbiturates, and local anesthetics. A perfect intro to the foundations of anesthesiology.
Video 2
Anesthetic Drugs
This 10-minute video offers a rapid overview of essential anesthesia and ICU drugs. This includes covering induction agents, opioids, anti-emetics, muscle relaxants, local anesthetics, and emergency medications.
Dr. Sandra Lee's comprehensive module reviews key anesthetic agents across all phases of general anesthesia, highlighting their effects, uses, and contraindications.
This U of T resource outlines key anesthetic agents, their mechanisms, dosing, and physiologic effects. A foundational guide to pharmacology for safe & effective anesthesia care.
2. Induction Agents
2.1 Primary Induction Agents
Propofol
Video 1
GABA agonist → ↓cerebral O₂ consumption, ↓ICP, ↓SVR
Dose: 1–2.5 mg/kg IV
Onset: 30 s · Duration: 5–10 min
Pearls:
• Smooth induction, anti-emetic properties
• ↓ BP and CO; titrate slowly in frail patients
⚠️ Apnea, hypotension → pre-oxygenate and prepare fluids
Ketamine
Video 2
NMDA antagonist → dissociative anesthesia, ↑HR, ↑BP
Dose: 1–2 mg/kg IV
Onset: 30–60 s · Duration: 10–20 min
Pearls:
• Preserves airway tone and spontaneous breathing
• Excellent for asthma, shock, or trauma cases
⚠️ Emergence delirium, ↑ secretions → consider midazolam + suction
Dexmedetomidine
Video 3
α2 agonist ↓NE release → sedation & analgesia without apnea
Dose: 0.5–1 mcg/kg IV load → 0.2–0.7 mcg/kg/hr
Onset: 10–15 min · Duration: 1–2 hr
Pearls:
• Ideal for awake intubation or light sedation
• No respiratory depression safe for OSA patients
⚠️ Bradycardia, hypotension → cautious use in volume-depleted pts
Dr. Lee provides a concise, student-focused summary of primary IV induction agents, ideal for quick review during clinical rotations.
This U of T resource reviews commonly used anesthetic agents with detailed coverage of mechanisms, dosing, and physiologic effects.
2.2 Adjuvant Agents
Midazolam
Benzodiazepene
GABA-A agonist → anxiolysis, amnesia, sedation
Dose: 1–2 mg IV (pre-op)
Onset: 2–3 min Duration: 30–60 min
Pearls:
• Reduces anxiety and anterograde memory
• Can smooth induction in anxious patients
⚠️Synergistic respiratory depression with opioids → monitor closely
Fentanyl
Opioid
μ-opioid agonist → analgesia, blunts sympathetic response
Dose: 1–2 mcg/kg IV (pre-induction)
Onset: 1–2 min Duration: 30–60 min
Pearls:
• Reduces pain, HR/BP spikes during intubation
• Combine with propofol for balanced induction
⚠️ Respiratory depression and chest wall rigidity at high doses
Remifentanil
Opioid
μ-opioid agonist → ultra-short analgesia
Dose: 0.5–1 mcg/kg IV bolus → 0.05–2 mcg/kg/min infusion
Onset: 1 min · Duration: 5–10 min
Pearls:
• Ideal for brief, intense stimuli (e.g., laryngoscopy)
• Excellent control with rapid offset
⚠️ Profound bradycardia & apnea → titrate carefully, esp with propofol
Dexamethasone
Glucocorticoid
Corticosteroid → anti-emetic, anti-inflammatory
Dose: 4–8 mg IV (at induction)
Onset: 30 min · Duration: 24–48 hr
Pearls:
• Prevents PONV and reduces airway edema
• Give at induction for max effect
⚠️ Avoid in uncontrolled diabetics → may raise glucose post-op
Dr. Lee explains the role of adjuvant agents like midazolam, opioids, and dexamethasone in enhancing induction, minimizing pain, and blunting stress responses during intubation.
2.3 Neuromuscular Junction Blocking Agents (NMBAs)
Rocuronium
NMJ Blocker
Non-depolarizing NMJ blocker → competitive ACh antagonist
Dose: 0.6–1.2 mg/kg IV
Onset: 45–90 s Duration: 30–60 min
Pearls:
• Reliable paralysis for intubation and maintenance
• Can be reversed with sugammadex (dose-dependent)
⚠️ Prolonged effect in hepatic impairment or high doses
Succinylcholine
NMJ Blocker
Depolarizing NMJ blocker → ACh mimic → sustained depolarization
Dose: 1–1.5 mg/kg IV
Onset: 30–60 s · Duration: 5–10 min
Pearls:
• Fastest onset and offset, ideal for rapid sequence induction
• Avoid if risk of hyperkalemia (burns, neuromuscular disease, crush injuries)
⚠️ Malignant hyperthermia trigger, bradycardia with repeat doses
Dr. Lee provides a quick, student-oriented guide to neuromuscular blockers used during induction, focused on key agents, uses, and clinical pearls.
A detailed, interactive U of T resource covering depolarizing and non-depolarizing agents, their mechanisms, dosing, and side effects in anesthesia practice.
3. Maintenance Agents
Sevoflurane
Video 1
Volatile anesthetic → GABA-A modulation
MAC: ~2% · Dose: 0.5–3% inhaled
Onset: 1–2 min · Duration: titratable
Pearls:
• Smooth, well-tolerated induction and emergence
• Excellent for pediatrics and inhalational induction
⚠️ Can cause hypotension via vasodilation; rare nephrotoxicity at low flows
Desflurane
Video 2
Volatile anesthetic → GABA-A modulation
MAC: ~6% · Dose: 2.5–8.5% inhaled
Onset: <1 min Duration: rapid offset
Pearls:
• Fast wake-up; useful for short cases and patients BMI ≥ 30
• Very low solubility, precise titration possible
⚠️ Pungent smell → avoid for inhalational induction; may trigger airway irritation
Nitrous Oxide
Video 3
Inhaled anesthetic → NMDA inhibition
MAC: 105% · Dose: 50–70% inhaled
Onset: <1 min Duration: rapid offset
Pearls:
• Potentiates other agents → reduces MAC of volatiles
• Analgesic and anxiolytic properties
⚠️ Contraindicated in pneumothorax, bowel obstruction, or air embolism risk
Dr. Sandra Lee created a high-yield summary of anesthesia maintenance strategies, highlighting drug choices, monitoring goals, and practical considerations for clerkship learners.
A comprehensive, interactive U of T guide to anesthetic agents used across all phases, detailing mechanisms, effects, and dosing for safe anesthesia care.
4. Rescue Agents
4.1 Pharmacologic Reversal
Naloxone
Opioid Antagonist
μ-opioid antagonist → reverses opioid effects
Dose: 0.04–0.4 mg IV q2–3 min PRN
Onset: 1–2 min · Duration: 30–60 min (may need redosing)
Pearls:
• Reverses respiratory depression while preserving some analgesia at low doses
• Can be given IM, SC, or intranasally
⚠️ Reversal may trigger pain, agitation, or withdrawal in opioid-tolerant patients
Sugammadex
NMBA Antidote
Binds steroidal NMBDs (rocuronium, vecuronium) → rapid reversal
Dose: 2–4 mg/kg IV (depends on depth of block)
Onset: 1–3 min · Duration: 30–60 min
Pearls:
• Fast, complete reversal of rocuronium—even from deep block
• No need for anticholinergic co-administration
⚠️ Avoid in severe renal impairment; rare anaphylaxis reported
Neostigmine
Cholinesterase inhibitor
Acetylcholinesterase inhibitor → ↑ACh at NMJ → reverses non-depolarizing blockade
Dose: 0.04–0.07 mg/kg IV (max 5 mg)
Onset: 5–10 min · Duration: 30–60 min
Pearls:
• Use only when spontaneous recovery has begun (TOF ≥ 2 twitches)
• Always pair with anticholinergic to block muscarinic side effects
⚠️ Bradycardia, bronchospasm, ↑ secretions if unopposed
4.2 Cardiovascular Rescue
Ephedrine
Sympathomimetic
Mixed α/β agonist → ↑HR, ↑CO, ↑SVR
Dose: 5–10 mg IV bolus
Onset: <1 min · Duration: 10–15 min
Pearls:
• Great for bradycardic hypotension during induction
• Increases BP by boosting both rate and contractility
⚠️ Tachyphylaxis with repeated doses → switch to phenylephrine if ineffective
Phenylephrine
Sympathomimetic
α1 agonist → ↑SVR, ↑MAP
Dose: 40–100 µg IV bolus
Onset: 30 s · Duration: 5–10 min
Pearls:
• First-line for pure vasodilatory hypotension (e.g. spinal or propofol)
• No effect on HR or contractility
⚠️ Reflex bradycardia → have atropine ready if HR drops
Atropine
Anticholinergic
Muscarinic antagonist → ↑HR, blocks vagal tone
Dose: 0.5–1 mg IV (bradycardia)
Onset: 1–2 min · Duration: 30–60 min
Pearls:
• First-line for bradycardia, especially vagally mediated
• Often given with neostigmine during NMBD reversal
⚠️ Anticholinergic effects: dry mouth, blurry vision, delirium (esp. in elderly)
Glycopyrrolate
Anticholinergic
Muscarinic antagonist → counters neostigmine's parasympathetic effects
Dose: 0.01–0.02 mg/kg IV (or ~0.2 mg per 1 mg neostigmine)
Onset: 2–3 min · Duration: 2–4 hr
Pearls:
• Prevents bradycardia, bronchial secretions, & GI upset during reversal
• Does not cross the blood-brain barrier → no central effects
⚠️ Anticholinergic effects: dry mouth, blurry vision, mild tachycardia
This U of T resource covers depolarizing and non-depolarizing neuromuscular blockers, explaining their mechanisms, clinical use, and adverse effects in anesthesia.
This U of T resource focuses on fast-acting drugs used to manage perioperative crises, like hypotension, bradycardia, and anaphylaxis, with dosing and practical tips.
5. Local Anesthetics
Lidocaine
Video 1
Blocks voltage-gated Na⁺ channels → prevents nerve depolarization
Dose: Max 5 mg/kg (7 mg/kg with epi)
Onset: 2–5 min · Duration: 1–2 hr
Pearls:
• Fast onset, versatile: local infiltration, nerve blocks, IV (blunts airway reflexes)
• Can be mixed with epi to prolong effect and reduce bleeding
⚠️ CNS toxicity: tinnitus, perioral numbness, seizures → treat with lipid emulsion
Bupivacaine
Video 2
Blocks voltage-gated Na⁺ channels → long-acting nerve block
Dose: Max 2.5 mg/kg (3 mg/kg with epi)
Onset: 5–10 min · Duration: 3–10 hr
Pearls:
• Preferred for epidurals and long blocks
• Differential motor/sensory block → good for labor analgesia
⚠️ Highest cardiotoxicity risk → ventricular arrhythmias, cardiac arrest → lipid rescue if toxicity suspected
An interactive U of T guide to regional anesthesia techniques, pharmacology, and safety considerations, designed for anesthesia learners building core clinical skills.
Medscape's comprehensive clinical review of regional anesthesia, including anatomy, indications, complications, and evidence-based practice recommendations.
6. Anti-emetics
Ondansetron
Serotonin 5-HT3 Antagonist
5-HT₃ antagonist → blocks vagal serotonin receptors
Dose: 4 mg IV
Onset: 30 min · Duration: 4–6 hr
Pearls:
• First-line for PONV prophylaxis and treatment
• Best when given near end of surgery
⚠️ QT prolongation → avoid in patients with known QT issues
Dimenhydrinate
Antihistamine
H₁ antagonist → antihistamine with anti-emetic effects
Dose: 25–50 mg IV
Onset: 20–30 min · Duration: 4–6 hr
Pearls:
• Good adjunct for motion-sensitive patients
• Often used as part of multi-drug PONV strategy
⚠️ Sedation, dry mouth, dizziness common side effects
Metoclopramide
Dopamine D2 Agonist
D₂ antagonist + 5-HT₄ agonist → anti-emetic & prokinetic
Dose: 10 mg IV
Onset: 1–3 min · Duration: 1–2 hr
Pearls:
• Increases gastric emptying—useful for RSI or full stomach
• Weak anti-emetic effect; often combined with other agents
⚠️ Extrapyramidal symptoms, QT prolongation → avoid in Parkinson’s or seizure disorders
Dexamethasone
Glucocorticoid
Corticosteroid → anti-emetic, anti-inflammatory
Dose: 4–8 mg IV (at induction)
Onset: 30 min · Duration: 24–48 hr
Pearls:
• Prevents PONV and reduces airway edema
• Give at induction for max effect
⚠️ Avoid in uncontrolled diabetics → may raise glucose post-op
PONV: Post-operative nausea and vomitting
This U of T resource provides an anesthesia-focused overview of anti-emetic agents, covering perioperative use, mechanisms, dosing, and adverse effects.
Osmosis brings a simplified, visual summary of antiemetic classes and how they work, ideal for early learners and board prep.
The information provided on this page is for educational purposes only and is not intended to replace clinical judgment or institutional protocols. Drug summaries and pharmacologic content are adapted from UpToDate and other reputable sources. While efforts have been made to ensure accuracy and currency, no guarantee is made that all information is complete or up to date.
This content is not a substitute for professional medical advice, diagnosis, or treatment. Always verify drug doses and indications with official guidelines and consult your supervising clinician before applying information in clinical settings.
The creators of this curriculum and affiliated institutions disclaim any liability for injury or damages resulting from the use of this content.
In: UpToDate, Connor RF (Ed), Wolters Kluwer. (Accessed on Jun 13, 2025.)