| DRUG (UK Name) |
MOA |
DOSE IV |
DOSE PO |
INDICATION |
CONTRAINDICATION / CAUTION |
| Fentanyl |
Opioid agonist providing potent analgesia with some sedation |
25–100 micrograms IV every 1–2 h; ~1 microgram/kg recommended |
N/A |
Severe pain, adjunct sedation |
Respiratory depression, hypotension (vasodilation), potential laryngospasm; caution in pregnancy |
| Hydromorphone |
Opioid agonist providing analgesia and sedation |
1–2 mg IV every 3–6 h |
N/A |
Severe pain |
Respiratory depression, hypotension; approximately 1 mg IV hydromorphone ≈ 7 mg IV morphine; caution in pregnancy |
| Ketamine |
NMDA receptor antagonist producing dissociative anaesthesia and analgesia |
Subdissociative analgesia: 0.1–0.5 mg/kg IV
Procedural sedation: 0.5–1 mg/kg IV
RSI induction: ~2 mg/kg IV
|
N/A |
Analgesia, sedation, induction (RSI) |
Emergence phenomena (may need benzodiazepine), laryngospasm, increased IOP/ICP, tachycardia, hypertension; avoid in certain ocular/head injuries; caution in pregnancy |
| Morphine sulfate |
Opioid agonist providing analgesia with sedative effects |
2–10 mg IV every 2–6 h PRN (~0.1 mg/kg) |
N/A |
Moderate to severe pain |
Respiratory depression, hypotension (vasodilation); caution in pregnancy |
| Codeine |
Weak opioid agonist (metabolised to morphine) |
N/A (commonly oral) |
15–60 mg PO every 4–6 h PRN |
Mild to moderate pain, cough suppression |
Respiratory depression, variable metabolism (CYP2D6), caution in pregnancy and children |
| Paracetamol (Acetaminophen) |
Analgesic and antipyretic, likely via central prostaglandin inhibition |
1 g IV every 6 h (max 4 g/day) |
500–1000 mg PO every 4–6 h PRN (max 3–4 g/day; UK often advises max 4 g/day in adults) |
Mild to moderate pain, fever |
Severe hepatic impairment, overdose risk (hepatotoxicity); generally safe in pregnancy (consult BNF) |
| Dihydrocodeine |
Semi-synthetic opioid agonist |
N/A (primarily oral) |
30 mg PO every 4–6 h PRN |
Moderate pain |
Respiratory depression, caution in opioid-naive, use sparingly in pregnancy |
| Tramadol |
Weak opioid agonist and inhibitor of noradrenaline/serotonin reuptake |
N/A (primarily oral) |
25–100 mg PO every 4–6 h PRN (max ~400 mg/day) |
Moderate pain |
Risk of seizures, serotonin syndrome (if combined with SSRIs), respiratory depression; caution in pregnancy |
