FRCA Pharmacology – High-Yield Summary
Pharmacology accounts for approximately one-third of the Primary FRCA examination and underpins much of the Final FRCA. The exam focuses not only on individual drugs but also on fundamental principles of how drugs work in the body.
1. General Pharmacological Principles
Pharmacokinetics
"What the body does to the drug"
Absorption
- Movement of drug from administration site into circulation.
- Influenced by:
- Blood flow
- Surface area
- Lipid solubility
- Ionisation
Distribution
- Movement from blood to tissues.
- Depends on:
- Protein binding
- Cardiac output
- Tissue perfusion
- Lipid solubility
Metabolism
- Usually occurs in the liver.
- Phase I:
- Oxidation
- Reduction
- Hydrolysis
- Phase II:
Elimination
- Mainly renal.
- Also hepatic, pulmonary and biliary.
Half-life
Time required for plasma concentration to fall by 50%.
Pharmacodynamics
"What the drug does to the body"
- Drug-receptor interaction
- Potency
- Efficacy
- Therapeutic index
- Dose-response relationships
2. Receptors
Ion Channel Receptors
Fast acting (milliseconds)
Examples:
- Nicotinic acetylcholine receptors
- GABA-A receptors
G-Protein Coupled Receptors (GPCRs)
Examples:
- Adrenoceptors
- Muscarinic receptors
- Opioid receptors
Enzyme-Linked Receptors
Examples:
Intracellular Receptors
Examples:
3. Intravenous Anaesthetic Agents
Propofol
Most important FRCA drug.
Mechanism
- Enhances GABA-A activity.
Effects
- Hypnosis
- Amnesia
- Antiemetic
Side Effects
- Hypotension
- Respiratory depression
- Pain on injection
Key FRCA Point
Rapid redistribution explains quick recovery after bolus administration.
Thiopentone
Mechanism
- Barbiturate acting at GABA-A receptors.
Uses
- Neuroanaesthesia
- Status epilepticus
Side Effects
- Cardiovascular depression
- Porphyria trigger
Ketamine
Mechanism
- NMDA receptor antagonist.
Effects
- Dissociative anaesthesia
- Analgesia
Advantages
- Maintains airway reflexes
- Sympathomimetic
Side Effects
- Hallucinations
- Increased secretions
Etomidate
Advantages
Disadvantage
4. Volatile Anaesthetic Agents
Sevoflurane
- Pleasant smell
- Rapid induction
- Paediatric favourite
Desflurane
- Very low blood-gas solubility
- Fastest recovery
Isoflurane
- Stable and inexpensive
- Slower recovery
MAC (Minimum Alveolar Concentration)
Definition:
Alveolar concentration preventing movement in 50% of patients.
Factors Decreasing MAC
- Increasing age
- Hypothermia
- Opioids
- Pregnancy
Factors Increasing MAC
- Hyperthermia
- Chronic alcohol use
5. Opioids
Mechanism
μ (mu) receptor agonists.
Effects:
- Analgesia
- Sedation
- Respiratory depression
Morphine
Metabolites
Problem
Accumulation in renal failure.
Fentanyl
- 100 times more potent than morphine.
- Highly lipid soluble.
Remifentanil
Unique Feature
Metabolised by plasma esterases.
Key FRCA Fact
Context-sensitive half-time approximately 3–5 minutes regardless of infusion duration.
6. Neuromuscular Blocking Drugs
Depolarising
Succinylcholine
Mechanism:
Persistent depolarisation of motor endplate.
Advantages:
- Rapid onset
- Short duration
Complications:
- Hyperkalaemia
- Malignant hyperthermia
- Bradycardia
Non-Depolarising
Examples:
- Rocuronium
- Atracurium
- Cisatracurium
Mechanism:
Competitive antagonism at nicotinic receptors.
Atracurium
Important FRCA topic.
Metabolism:
- Hofmann elimination
- Ester hydrolysis
Useful in:
- Renal failure
- Hepatic failure
7. Reversal Agents
Neostigmine
Mechanism:
Acetylcholinesterase inhibition.
Effects:
- Increased acetylcholine
- Reversal of non-depolarising blockade
Side effects:
Given with:
Sugammadex
Mechanism:
Encapsulates rocuronium and vecuronium molecules.
Advantages:
- Rapid reversal
- Predictable effect
8. Local Anaesthetics
Mechanism
Block voltage-gated sodium channels.
Order of Block
- Pain
- Temperature
- Touch
- Motor
Lidocaine
- Rapid onset
- Intermediate duration
Bupivacaine
- Long duration
- Cardiotoxicity risk
Levobupivacaine
Ropivacaine
Local Anaesthetic Toxicity (LAST)
Features:
- Circumoral tingling
- Tinnitus
- Seizures
- Arrhythmias
Treatment:
9. Cardiovascular Drugs
Vasopressors
Phenylephrine
Metaraminol
Noradrenaline
First-line vasopressor in septic shock.
Inotropes
Dobutamine
Adrenaline
10. Autonomic Pharmacology
Sympathetic Receptors
α1
α2
- Reduced sympathetic outflow
β1
- Increased heart rate
- Increased contractility
β2
Parasympathetic
Muscarinic Receptors
M2:
M3:
11. Non-Opioid Analgesics
Paracetamol
- Central COX inhibition
- Analgesic
- Antipyretic
NSAIDs
Mechanism:
COX inhibition
Effects:
Complications:
- GI bleeding
- Renal impairment
- Bronchospasm
FRCA Pharmacology Topics Most Frequently Examined
- Propofol
- Ketamine
- Volatile agents and MAC
- Opioids (especially remifentanil)
- Neuromuscular blockers
- Sugammadex vs neostigmine
- Local anaesthetics and LAST
- Pharmacokinetics (volumes, clearance, half-life)
- Receptor pharmacology
- Vasopressors and inotropes
Core FRCA Mnemonic
"PK-PD GVOKL VAN"
- PK = Pharmacokinetics
- PD = Pharmacodynamics
- G = GABA drugs (propofol, thiopentone)
- V = Volatiles
- O = Opioids
- K = Ketamine
- L = Local anaesthetics
- V = Vasopressors
- A = Autonomic pharmacology
- N = Neuromuscular blockers
If you master these ten areas, you will cover the majority of examinable pharmacology in the Primary FRCA.