Strong opioid (synthetic phenylpiperidine)
Pethidine hydrochloride
Adult dose
Dose: PO/IM/SC: 50–150mg every 4h. IV: 25–100mg slowly. Obstetric: 50–100mg IM every 4h
Route: PO/IM/SC/IV
Frequency: q4h
Dose adjustments
Renal
Avoid in renal impairment (norpethidine accumulates — neurotoxic)
Clinical pearls
- Largely superseded; avoid >48h or in renal impairment
- CD2 controlled drug
Contraindications
- Severe renal impairment
- MAOI within 14 days
- Acute respiratory depression
- Raised ICP
- Phaeochromocytoma
Side effects
- Norpethidine-induced seizures
- Sedation
- Respiratory depression
- Constipation
- Confusion
- Tachycardia
Interactions
- MAOIs (severe — fatal)
- SSRIs/SNRIs (serotonin syndrome)
- CNS depressants
Monitoring
- RR
- Sedation
- BP
Reference: BNF; FPM; UK guidelines; https://bnf.nice.org.uk/drugs/pethidine-hydrochloride/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators
- Morphine Milligram Equivalents (MME) Calculator · Pain / Opioids
- Opioid Conversion / Equianalgesic Guide · Pain Management
- Numeric Rating Scale (NRS) Pain Assessment and Management · Pain Management
- Finnegan Neonatal Abstinence Scoring Tool (FNAST) · Neonatal Abstinence Syndrome
- Modified Finnegan Neonatal Abstinence Score (NAS) · Neonatal
- Withdrawal Assessment Tool (WAT-1) for Paediatric Iatrogenic Withdrawal · Critical Care
Pathways
- New-Onset Atrial Fibrillation · ESC 2020 AF Guidelines; NICE NG196
- Hypertensive Emergency · ESC/ESH 2018 Hypertension Guidelines; NICE NG136
- Bradycardia Management · Resuscitation Council UK ABCDE; ESC 2021 Pacing Guidelines
- Ventricular Tachycardia / Fibrillation · Resuscitation Council UK ACLS; ESC 2022 Ventricular Arrhythmia Guidelines
- Syncope Assessment · ESC 2018 Syncope Guidelines; NICE NG109
- Acute Chest Pain · NICE CG95; ESC 2023 ACS Guidelines