Essential Paramedic Pharmacology Revision Guide

Why Pharmacology Matters in Pre-Hospital Care

For student paramedics in the UK, pharmacology is one of the most demanding — and most critical — areas of your degree. Understanding not just what drug to give, but why, how, and when is what separates competent clinical practice from genuinely safe, evidence-based patient care. This guide breaks down the core drug knowledge you need, structured around the JRCALC Clinical Guidelines that underpin UK pre-hospital practice.

Understanding Drug Mechanisms: The Foundation

Before memorising individual drugs, build a solid understanding of how drugs work at a physiological level. The key concepts to master include:

• Agonists and antagonists: Agonists activate receptors (e.g. salbutamol on beta-2 receptors); antagonists block them (e.g. naloxone on opioid receptors).
• Pharmacokinetics (ADME): How the body handles a drug — Absorption, Distribution, Metabolism, and Excretion.
• Pharmacodynamics: What the drug does to the body, including dose-response relationships and therapeutic windows.
• Routes of administration: IV, IM, IN, oral, nebulised, and sublingual routes each affect onset, bioavailability, and clinical decision-making.

Understanding these principles means you can reason through an unfamiliar drug rather than relying purely on rote memorisation — a skill that will serve you both in exams and on the road.

Core Drug Classes for UK Paramedics

Analgesics

Pain management is central to pre-hospital care. The key analgesics within the JRCALC scope of practice include:

• Morphine sulfate: A strong opioid with a well-understood profile. Know its CNS and respiratory depressant effects, onset via IV vs IM, and the importance of titration.
• Methoxyflurane (Penthrox): A self-administered inhaled analgesic useful for moderate acute pain. Understand contraindications including renal impairment and conscious level requirements.
• Paracetamol (IV): Increasingly used in pre-hospital settings for mild-to-moderate pain, particularly in paediatric and elderly patients where opioids carry higher risk.
• Entonox (50% O₂/50% N₂O): Fast-acting and patient-controlled. Key considerations include pneumothorax, bowel obstruction, and head injuries as contraindications.

Cardiovascular Drugs

Cardiac emergencies demand rapid, confident drug administration. Focus on:

• Aspirin 300mg: First-line in suspected ACS. Understand its antiplatelet mechanism and the importance of early administration.
• GTN (glyceryl trinitrate): A vasodilator used in ACS and acute pulmonary oedema. Always check systolic BP before administration and avoid in hypotension or recent PDE5 inhibitor use.
• Adrenaline (epinephrine) 1:10,000 IV: Used in cardiac arrest per the Resuscitation Council UK guidelines. Also available as 1:1,000 IM for anaphylaxis.
• Amiodarone 300mg IV: Given after the third shock in shockable cardiac arrest rhythms. Know the dilution requirements and potential interactions.
• Atropine: While largely phased out of cardiac arrest algorithms, it remains relevant for symptomatic bradycardia in certain clinical contexts.

Respiratory Drugs

Respiratory presentations are among the most common in pre-hospital care. Key drugs include:

• Salbutamol: A selective beta-2 agonist used in bronchospasm. Understand its tachycardia side effects and the difference between nebulised and back-to-back dosing in severe asthma.
• Ipratropium bromide: An anticholinergic bronchodilator used alongside salbutamol in moderate-to-severe asthma and COPD exacerbations.
• Hydrocortisone IV/IM: A corticosteroid used in severe asthma and anaphylaxis to reduce inflammatory response.

Neurological and Sedation Drugs

• Diazepam (rectal/IV) and midazolam (buccal/IN/IV/IM): Benzodiazepines used in seizure management. Midazolam has become the preferred pre-hospital agent due to its versatility of routes and faster onset.
• Glucagon and glucose (oral/IV): Critical in hypoglycaemia management. Know the Hypostop gel, oral glucose, and IV dextrose pathways based on conscious level.
• Naloxone (Narcan): Opioid antagonist used in opioid toxicity. Understand its shorter half-life compared to most opioids and the risk of re-narcotisation requiring repeat dosing or infusion.

Drug Calculations: Non-Negotiable Competency

Drug calculation errors can be fatal. You must be confident in:

• Weight-based dosing (mg/kg), particularly for paediatric patients — use the Broselow tape or APLS formulas
• Concentration calculations (e.g. mg/mL, percentage solutions)
• Drip rates and infusion calculations
• Unit conversions: micrograms, milligrams, grams, and millilitres

Practise calculations regularly under timed conditions. In real emergencies, mental arithmetic under stress is a genuine skill that must be developed intentionally.

Special Populations: Adjusting Your Approach

Pharmacology doesn't exist in a vacuum — patient factors significantly affect drug choice and dosing:

• Paediatrics: Always calculate weight-based doses. Neonates and infants have different pharmacokinetics due to immature hepatic and renal systems.
• Elderly patients: Reduced renal and hepatic function, polypharmacy, and altered drug distribution mean standard adult doses often require modification.
• Pregnancy: Many drugs carry teratogenic risks or affect uterine tone. Always consider gestational age and consult JRCALC guidance for obstetric emergencies.
• Renal and hepatic impairment: Affects drug clearance significantly — relevant when administering renally cleared drugs or hepatically metabolised agents.

Revision Tips for Paramedic Pharmacology Exams

Structured revision is essential when covering a broad and clinically detailed topic. Try these approaches:

1. Build a drug card for each JRCALC medication: indication, dose, route, contraindications, and mechanism.
2. Use active recall — test yourself rather than re-reading notes.
3. Link drugs to clinical scenarios to understand contextual decision-making.
4. Practise OSCE-style drug administration questions with colleagues.
5. Work through mock exam questions under timed conditions to simulate real assessment pressure.

The JRCALC Clinical Guidelines app is an invaluable reference tool, but your revision should focus on developing the underlying understanding that allows you to apply those guidelines safely — not just look them up.