Paracetamol
Class: analgesic – non-opioid
Indications: step 1 on the WHO analgesic ladder, co-analgesic, antipyretic – mild to moderate pain; pyrexia with discomfort
Contraindications/cautions: severe hepatic impairment
Adverse reactions: less common: rash, pancreatitis on prolonged use, liver damage in overdose (> 6 g in 24 hours) or in combination with heavy alcohol intake, nephrotoxicity
Metabolism/clearance: metabolised in the liver mainly by glucuronidation
Hepatic impairment: avoid in severe impairment or hepatic failure; in mild to moderate impairment maximum daily dose no more than 60 mg/kg/day (max 2g/day) in people with body weight <50kg or chronic liver disease
Renal impairment: caution in severe impairment if eGFR < 30 mL/min/1.73m^2 – increase dose interval
Interactions:
- increased toxicity of paracetamol may occur with alcohol
- increased anticoagulant effect of warfarin may occur if given with concurrent paracetamol regularly for a long time so monitor INR
- increased absorption of paracetamol may occur with metoclopramide and domperidone
- increased risk of hepatotoxicity may occur with concurrent carbamazepine, phenytoin
| Dosing: | |
|---|---|
| oral: | 500 mg to 1 g 4 to 6 hourly (max. 4 g in 24 hours) |
| subcut: | infusion available but large volume |
| rectal: | as for oral |
Syringe driver: not used subcut due to high volume
Mechanism of action: thought to have a central effect on pain pathways preventing transmission of nociceptive signals from peripheral tissues to the spinal cord; it may reduce prostaglandin production resulting in reduced pain sensation. Anti-pyretic effect but is not anti-inflammatory
Onset: 0.5 hours
Duration: 4 hours
Notes:
- give regularly rather than if required
- available in tablets, oral liquid & suppositories
- combination preparations are not recommended
- liver damage is likely to occur in overdose
- useful analgesic when given regularly in combination with opioids