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Updated 2 Feb 2023 | Opioid analgesics


Solution for injection containing 100mg/ml meptazinol as meptazinol hydrochloride.

Drugs List

  • meptazinol 100mg/1ml injection
  • MEPTID 100mg/1ml injection
  • Therapeutic Indications


    Moderate to severe pain including post-operative pain, obstetric pain and renal colic



    Intramuscular Administration
    75mg to 100mg as a single injection. If necessary, dose may be repeated at intervals of 2 to 4 hours.
    For obstetric pain dose may increased to 100mg to 150mg as a single injection. Dose may be adjusted according to individual bodyweight, which should approximate to 2mg/kg.

    Intravenous Administration
    50mg to 100mg by slow intravenous injection. If necessary, dose may be repeated at intervals of 2 to 4 hours.
    A suitable antiemetic should be administered if vomiting occurs.


    Not recommended in children as safety and efficacy have not been established.

    Patients with Renal Impairment

    UK licensed product information advises that the dose of meptazinol should be reduced in moderate to severe renal impairment.

    Patients with Hepatic Impairment

    Use a reduced dose in patients with hepatic impairment as opioid analgesics may precipitate coma in these patients.


    For intravenous and intramuscular administration


    Acute alcoholism

    Predisposition to paralytic ileus

    Raised intracranial pressure

    Head trauma


    Acute asthma

    Acute respiratory depression

    Myocardial infarction


    Children under 18 years

    Chronic obstructive pulmonary disease

    Within 14 days of discontinuing a MAOI

    Precautions and Warnings

    Use with cautions in the following conditions:

    Hepatic impairment - reduce dose

    Respiratory impairment - reduce dose

    Asthma - avoid using during an attack


    Hypothyroidism - reduce dose

    Benign prostatic hypertrophy


    Urethral stenosis


    Myasthenia gravis

    Obstructive or inflammatory bowel disease

    Adrenocortical insufficiency - reduce dose

    Drug dependence

    Pregnancy ( see Pregnancy)

    Lactation ( see Lactation)

    UK licensed product information advises that the dose of meptazinol should be reduced in patients with moderate to severe renal impairment as patients may experience prolonged and increased effects of the drug. Furthermore, cerebral sensitivity may also be increased (see Dosage - Patients with Renal Impairment ).

    Reduce dose in debilitated patients

    Patients should be advised that meptazinol may cause dizziness and drowsiness and so to use caution when driving and operating machinery.

    Meptazinol is only recommended for short term use; nevertheless, long term therapy may be acceptable if the drug is employed for the management of malignant conditions.

    Tolerance and dependence may develop as a result of long term use. Severe withdrawal symptoms may occur upon abrupt withdrawal; meptazinol should therefore be discontinued gradually.

    The effects of meptazinol are only partially reversed by naloxone.

    Pregnancy and Lactation


    UK licensed product information advises that meptazinol injections should only be given in pregnancy if clearly necessary. The same information nevertheless states that meptazinol may be used during labour.

    Other researchers also note that meptazinol is less tried than other opioid analgesics and they recommend that if an opioid is warranted, other established agents e.g. tramadol or pethidine, are used instead. The use of meptazinol in the first trimester is not seen as a valid reason for the termination of a pregnancy or for the deployment of invasive diagnostic procedures (Schaefer and co-workers, 2007).

    When tested on pregnant animals, meptazinol did not show any evidence of teratogenic effects. Likewise, no congenital anomaly is known from the anecdotal human experience with opioid analgesics, and Lee and co-workers even conclude that opioids are fully compatible with pregnancy as therapeutic doses are unlikely to have any adverse effect on foetal development (Lee and co-workers, 2000). It should be noted, however, that no adequate and well-controlled clinical studies in humans were available for meptazinol at the time of writing.

    Therapy with opioid analgesics during pregnancy is generally associated with the following risks to mother and foetus: pregnant women taking opiates during labour may suffer such adverse reactions as gastric stasis and inhalation pneumonia, while the baby may develop withdrawal symptoms if the mother uses opiates regularly throughout the pregnancy. These withdrawal symptoms will typically include: feeding intolerance, diarrhoea, vomiting, tachypnoea, hypertonia, hyperexcitability, high-pitched cry, tremor and, in severe cases, convulsions (Lee and co-workers, 2000; Schaefer and co-workers, 2007). The newborn may also be exposed to respiratory depression if the mother receives doses within days of delivery.

    Meptazinol crosses the placenta.

    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 ( ).

    Licensed in pregnancy? - No except during obstetric procedures.

    Known human teratogen? - Not known.

    Animal data - No evidence of teratogenic effects.

    Crosses placenta? - Yes.

    Effects on foetus - Withdrawal symptoms (see above for a list of symptoms) after frequent exposure. Respiratory depression if exposure was near term.

    Pregnancy-specific adverse effects on the mother - Gastric stasis and inhalation pneumonia if the drug was taken during labour.


    UK licensed product information recommends that meptazinol should only be administered during lactation if it is clearly necessary. There is effectively very limited information on the use of meptazinol during lactation and other, more established opiates should probably be preferred.

    Opiates may all be excreted into breast milk. No quantitative data are available for meptazinol as of the revision date, however given the slower metabolism of opioids in infants, it is very likely that accumulation will occur if the nursing infant is chronically exposed to even small amounts of drug (Lee and co-workers, 2000).

    Infants exposed to opiates via breast milk may generally experience the following side effects: cyanosis, breathing difficulty, increased sleepiness, limpness, reduced tolerance to breastfeeding (LactMed, 2008).

    Lee and co-workers (2000) advise that mothers on opiate therapy should breastfeed immediately before taking a dose so as to avoid peak concentrations in milk.

    Note that certain opioid agents may increase serum prolactin.

    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

    Drug excreted in breast milk? - Likely. However, No information is currently available for meptazinol.

    Considered suitable or recommended by manufacturer? - No.

    Drug substance licensed in infants? - No.

    Drug known to affect lactation? - No information is currently available for meptazinol. However, certain opioids are known to increase serum prolactin.

    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.


    Patients should be advised that meptazinol may cause dizziness and drowsiness and so to use caution when driving and operating machinery.

    Side Effects

    Abdominal pain
    Respiratory depression
    Muscle rigidity
    Difficulty in micturition
    Ureteric spasm
    Biliary spasm
    Dry mouth
    Facial flushing
    Mood changes
    Reduced libido
    Reduction of male potency
    Withdrawal symptoms
    Postural hypotension
    Sleep disturbances
    Sexual dysfunction
    Urinary retention
    Visual disturbances


    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 ( ) or if this is unavailable at the backup site ( ).

    Shelf Life and Storage

    Do not store above 25 degrees C

    Further Information

    Last Full review Date: February 2012

    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.

    Martindale: The Complete Drug Reference, 37th edition (2011) ed. Sweetman, S. Pharmaceutical Press, London.

    Morphine. Monograph available from LactMed. Revised May 2008.
    Last accessed July 8, 2008

    Summary of Product Characteristics: Meptid injection. Almirall Ltd. Revised March 2011.

    Therapeutics in Pregnancy and Lactation (2000) Lee, A., Inch, S. and Finnigan, D. Radcliffe Medical Press, Abingdon. 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: 04 September 2017

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