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Pethidine hydrochloride

Updated 2 Feb 2023 | Opioid analgesics


Tablets containing pethidine hydrochloride 50mg

Drugs List

  • pethidine 50mg tablets
  • Therapeutic Indications


    Pre-anaesthetic medication

    Analgesia during anaesthesia

    Obstetric analgesia

    Management of moderate to severe pain


    Treatment should be supervised by a specialist.


    Maintenance dose: 50mg to 150mg.
    This dose should not normally be repeated within 4 hours.


    Initial dose: 50mg.
    Use with caution. Elderly patients are more likely to be susceptible to the central depressant effects of pethidine.


    Maintenance dose: 0.5mg/kg to 2mg/kg.
    This dose should not be repeated within 4 hours.


    Use with caution and reduce dose if necessary in neonates and premature infants.

    Patients with Renal Impairment

    Severe renal impairment
    Not recommended.

    Mild to moderate renal impairment
    A dose reduction may be required.

    There may be increased cerebral sensitivity if used in patients with renal impairment.

    Patients with Hepatic Impairment

    Severe hepatic impairment
    Not recommended.

    Mild to moderate hepatic impairment
    A dose reduction may be required.

    If used in patients with hepatic impairment, pethidine may precipitate coma.


    For oral administration



    Acute respiratory depression

    Obstructive airways disease

    Acute asthma

    Respiratory insufficiency

    Concurrent monoamine oxidase inhibitors (MAOI's)
    Within 2 weeks of discontinuing MAOI's

    Acute alcoholism

    Increased intracranial pressure

    Convulsive disorders

    Paralytic ileus
    Risk of paralytic ileus

    Head injury

    Severe renal impairment

    Severe hepatic impairment


    Acute diarrhoeal conditions associated with antibiotic-induced pseudomembranous colitis or diarrhoea caused by poisoning (until the toxic material has been eliminated)

    Within 7 days of discontinuing safinamide

    Precautions and Warnings

    Treatment should be supervised by a specialist.

    Use with caution and reduce dose if necessary in patients with the following conditions:
    Mild to moderate renal impairment - see Dosage; Renal Impairment
    Mild to moderate hepatic impairment - see Dosage; Hepatic Impairment
    Biliary tract disorders
    Adreno-cortical insufficiency
    Prostatic hypertrophy
    Supraventricular tachycardia
    Inflammatory bowel disorders
    Obstructive bowel disorders
    Myasthenia gravis
    Reduced respiratory reserve
    Urethral stricture
    History of convulsive disorders

    Pethidine neurotoxicity may occur in patients with renal failure, cancer or sickle cell anaemia if concurrent anticholinergics are administered or during prolonged administration of increasing pethidine doses.

    Elderly - see Dosage; Elderly

    Use with caution and reduce dose if necessary in neonates and premature infants.

    Use with caution in debilitated patients. A reduction in dosage may be advisable in these patients.

    Use with caution in patients with drug addiction or a history of drug addiction.

    Pregnancy - see Pregnancy section

    Lactation - see Lactation section

    Repeated use can lead to tolerance and dependence. Withdrawal symptoms may occur on cessation of therapy, therefore abrupt withdrawal should be avoided.

    Pethidine may cause drowsiness. If affected patients should be advised not to drive or operate machinery.

    Pregnancy and Lactation


    The manufacturer advises that pethidine may only be administered during pregnancy if the expected benefits outweigh the potential risks.

    Safety of pethidine administration during pregnancy has not been adequately established. However, this product has been widely used for many years without apparent ill consequence, and epidemiologic studies have not uncovered an association between use during the first trimester and congenital malformations. Animal studies have not shown any hazard associated with pethidine.

    Pethidine crosses the placenta rapidly during pregnancy. It can reach higher foetal concentrations than in maternal serum due to the limited metabolic capacity of the foetus: pethidine is decomposed slowly and has a considerably lengthened half-life of 18 hours, compared to 3-4 hours in adults.

    Administration during labour may cause respiratory depression in the neonate and gastric stasis and inhalation pneumonia in the mother. However, Schaefer states that pethidine is the analgesic of choice during labour as labour is not lengthened, the strength of contractions is not diminished, and neither the severity of bleeding or the involution of the uterus is influenced. Neonates may experience withdrawal symptoms if the mother is dependent on pethidine.

    Schaefer concludes that although use as an analgesic during pregnancy is not recommended, inadvertent use does not require either a termination or additional diagnostic procedures.

    The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14-17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( ) or if this is unavailable at the backup site ( ).


    The manufacturer advises that pethidine may only be administered during breastfeeding if the expected benefits outweigh the potential risks.

    Pethidine is excreted in breast milk. No adverse effects in nursing infants were reported in studies of mothers who had received pethidine during labour. However, the long half-life of pethidine and its metabolite may result in neonatal plasma accumulation, especially in premature infants. Schafer recommends that pethidine is acceptable if necessary, but because of its depressive effect on respiration, particular care should be taken with children with a tendency towards apnoea. A physician should be contacted immediately if the neonate shows signs of increased sleepiness, difficulty breastfeeding, breathing difficulties or limpness.

    Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
    Specialist advice is available from the UK Drugs in Lactation Advisory Service at

    Effects on Ability to Drive and Operate Machinery

    This class of medicine is in the list of drugs included in regulations under 5a of the Road Traffic Act 1988 (England and Wales). When prescribing this medicine: Advise patient the medicine can affect cognitive function and is likely to affect ability to drive. Advise patient not to drive until they know how the medicine affects them.


    Advise patients that their ability to drive and operate machinery may be impaired by treatment

    Side Effects

    Respiratory depression
    Anaphylactic reaction
    Orthostatic hypotension
    Facial flushing
    Loss of mental acuity
    Mood changes
    Blurred vision
    Double vision
    Visual disturbances
    Dry mouth
    Biliary spasm
    Urinary retention
    Difficulty in micturition
    Ureteric spasm
    Anti-diuretic effect
    CNS excitation
    Reduced libido
    Reduction of male potency


    It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

    The following number will direct the caller to the relevant local centre (0844) 892 0111

    Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet (

    Shelf Life and Storage

    Do not store above 25 degrees C
    Store in a dry place

    Reference Sources

    Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 2nd edition (2007) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.

    Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 8th edition (2008) ed. Briggs, G., Freeman, R. and Yaffe, S. Lippincott Williams & Wilkins, Philadelphia.

    Medications and Mothers' Milk, 14th Edition (2010) Hale, T. Hale Publishing, Amarillo, Texas.

    Summary of Product Characteristics for Pethidine Tablets, Martindale Pharmaceuticals Ltd, September 2000 Summary of Product Characteristics for Pethidine Injection, Martindale Pharmaceuticals Ltd, November 1999
    Summary of Product Characteristics for Pethidine Injection, Wockhardt, March 2005

    US National Library of Medicine. Toxicology Data Network. Drugs and Lactation Database (LactMed).
    Available at:
    Meperidine - Record 365. Last revised: July 5, 2011
    Last accessed: July 19, 2011 Government departments. Department for Transport. Publications. Drug driving and medicine: advice for healthcare professionals. Drug driving: Guidance for healthcare professionals on drug driving. Available at: Last accessed: 6 January 2015
    New drug driving offence implications for medicines packaging. Medicines Regulatory News. 10 December 2013. Available at: Last accessed: 6 January 2015

    NICE Evidence Services Available at: Last accessed: 15 September 2017

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