Pethidine Macure
Synthetic opioid analgesic for short-term moderate to severe pain
Quick Facts About Pethidine Macure
Key Takeaways About Pethidine Macure
- Short-term use only: Pethidine is intended for brief treatment (generally under 48 hours) because its active metabolite norpethidine can build up and cause tremor, confusion, and seizures
- Never combine with MAOIs: Pethidine must not be used together with monoamine oxidase inhibitors, or within 14 days of stopping them – the combination can cause a fatal reaction
- Given by healthcare professionals: As an injection, Pethidine Macure is administered in hospitals, clinics, ambulances, or palliative care settings, not by the patient at home
- Risk of dependence and respiratory depression: Like all strong opioids, pethidine carries risks of addiction, tolerance, and life-threatening slowing of breathing, especially when combined with alcohol or sedatives
- Not a first-line opioid in most guidelines: Modern pain management guidelines (WHO, NICE, major anaesthesia societies) generally favour morphine or other opioids over pethidine for most indications
What Is Pethidine Macure and What Is It Used For?
Pethidine Macure is an injectable form of pethidine (meperidine), a synthetic opioid painkiller used for the short-term relief of moderate to severe pain. It is given by injection into a muscle, under the skin, or into a vein by healthcare professionals. Typical uses include post-operative pain, pain during medical procedures, pain in labour, and certain forms of acute pain such as renal or biliary colic.
Pethidine belongs to a group of medicines known as synthetic opioid analgesics. Chemically it is a phenylpiperidine derivative, unrelated to morphine but acting on the same opioid receptors in the central nervous system. It was introduced into clinical use in 1939 and was for many decades one of the most widely used strong painkillers in hospitals, particularly for acute and obstetric pain.
The active substance in Pethidine Macure is pethidine hydrochloride, at a concentration of 50 mg per millilitre of solution. The medicine works by binding primarily to mu-opioid receptors in the brain and spinal cord, reducing the transmission of pain signals and altering the emotional response to pain. Pethidine also has some anticholinergic (atropine-like) activity and weakly blocks serotonin reuptake – properties that help explain some of its side effects and drug interactions.
Pethidine is approximately one-tenth as potent as morphine on a milligram basis. A 100 mg dose of pethidine provides roughly the same analgesic effect as 10 mg of morphine given by the same route. Onset of action is rapid (5–10 minutes after intravenous injection; 10–15 minutes after intramuscular injection) and the duration of pain relief is relatively short – typically 2 to 4 hours, which is notably shorter than morphine.
Pethidine Macure is prescribed by doctors for a range of acute pain conditions, including:
- Post-operative pain: Pain after surgical procedures, particularly in the early recovery period
- Procedural pain: Painful diagnostic or therapeutic procedures such as endoscopy, cardioversion, or orthopaedic manipulations
- Obstetric pain: Pain during labour and delivery, where its rapid onset has traditionally been valued
- Renal and biliary colic: Severe abdominal pain caused by kidney stones or gallstones – pethidine is sometimes chosen because, unlike morphine, it is thought to have less effect on the sphincter of Oddi, although modern evidence shows this distinction is less important than once believed
- Pain in emergency and palliative settings: Short-term control of severe pain where intravenous access is available and rapid titration is required
- Post-anaesthetic shivering: A specialist use in low doses to treat shivering after general anaesthesia, where pethidine has a specific and well-documented effect
The World Health Organization (WHO) analgesic ladder places strong opioids – including pethidine – at Step 3 for severe pain. However, because of pethidine’s short duration of action, risk of neurotoxic metabolites, and serious drug interactions, most modern national formularies and pain guidelines recommend morphine or other opioids as first-line choices. Pethidine’s role has narrowed over recent decades to specific, short-term situations.
How Pethidine Works in the Body
After injection, pethidine is rapidly distributed throughout the body and easily crosses the blood-brain barrier. In the central nervous system, it binds to mu- and kappa-opioid receptors, reducing the release of pain-signalling neurotransmitters and activating descending pain-inhibitory pathways. The result is a powerful reduction in both the sensation of pain and its emotional unpleasantness, together with sedation and, at higher doses, respiratory depression.
Pethidine is metabolised in the liver, mainly to norpethidine (normeperidine), an active metabolite with weaker analgesic effects but strong central nervous system stimulation. Norpethidine has a half-life of 8–21 hours – much longer than pethidine itself (2.5–4 hours) – and is cleared mainly by the kidneys. Accumulation of norpethidine is responsible for many of the characteristic toxicities of pethidine, including tremor, agitation, myoclonus, and seizures. Patients with kidney impairment, older adults, and those receiving repeated doses are at particular risk.
What Should You Know Before Receiving Pethidine Macure?
Before receiving Pethidine Macure, your healthcare team needs to know about all your medical conditions and medicines – especially breathing problems, kidney or liver disease, head injury, history of seizures, current or recent use of MAO inhibitors or antidepressants, and any history of substance misuse. Pethidine must not be used in several situations and requires caution in many others.
Contraindications
You must not receive Pethidine Macure if any of the following apply:
- Allergy to pethidine hydrochloride or any other ingredient in the solution
- Severe respiratory depression – significantly impaired breathing, especially in the presence of low oxygen levels or high carbon dioxide
- Acute or severe bronchial asthma in an unmonitored setting or without resuscitation equipment
- Use of monoamine oxidase inhibitors (MAOIs) currently or within the past 14 days – this combination can cause a fatal serotonergic reaction
- Known or suspected gastrointestinal obstruction, including paralytic ileus
- Severe liver impairment – pethidine metabolism is heavily impaired, increasing toxicity
- Severe kidney impairment, because the toxic metabolite norpethidine accumulates and can cause seizures
- Epilepsy or a history of seizures not adequately controlled – pethidine and norpethidine can lower the seizure threshold
- Raised intracranial pressure or head injury – opioids can obscure neurological signs and increase intracranial pressure
- Phaeochromocytoma – risk of hypertensive crisis
- Supraventricular tachycardias, because pethidine’s anticholinergic effect can increase heart rate
Pethidine must never be given to a patient who is currently taking a monoamine oxidase inhibitor (MAOI) such as phenelzine, tranylcypromine, isocarboxazid, selegiline, rasagiline, moclobemide, or linezolid, or who has stopped one in the past 14 days. The combination can cause severe serotonin syndrome with high fever, muscle rigidity, seizures, cardiovascular collapse, and death. Always tell your doctor about every medication you take, including those for depression, Parkinson’s disease, or infections.
Warnings and Precautions
Tell your doctor or anaesthetist before receiving pethidine if you have any of the following conditions, as dose adjustments, additional monitoring, or alternative treatments may be required:
- Chronic obstructive pulmonary disease (COPD), asthma, or sleep apnoea – pethidine can worsen breathing difficulties and may trigger respiratory depression
- Moderate kidney or liver impairment – slower clearance of pethidine and norpethidine increases the risk of toxicity
- Hypothyroidism, Addison’s disease, or other endocrine disorders – increased sensitivity to opioid effects
- Prostatic hypertrophy or urethral stricture – pethidine can worsen urinary retention
- Inflammatory or obstructive bowel disorders – opioids reduce gut motility
- Biliary tract disease or pancreatitis – theoretically less spasmogenic than morphine, but caution is still required
- Low blood pressure or blood volume depletion – risk of pronounced drop in blood pressure, especially after intravenous injection
- Older age (65+) – increased sensitivity and higher risk of norpethidine accumulation; many geriatric guidelines specifically advise against pethidine
- History of substance use disorder, including alcohol, prescription, or illicit drug misuse – higher risk of dependence and abuse
- Concurrent depression or mental health conditions – may increase risk of misuse and interact with some psychiatric medicines
Tolerance, Dependence, and Addiction
Pethidine, like all strong opioids, carries a measurable risk of tolerance, physical dependence, and substance use disorder. Tolerance means the same dose produces less effect over time. Physical dependence means the body adapts to the drug and withdrawal symptoms may appear if it is stopped abruptly. Addiction is a behavioural disorder characterised by compulsive drug use despite harmful consequences.
Short courses of pethidine in hospital settings are generally associated with a low risk of long-term dependence in previously opioid-naive patients. However, pethidine has a particular history of misuse among healthcare workers because of its rapid onset and euphoric effect when given intravenously. For this reason, strict record-keeping and security requirements apply to its storage and use in every healthcare institution.
People at higher risk of developing dependence include:
- Those with a personal or family history of alcohol, prescription drug, or illicit drug misuse
- Current smokers
- Those with a history of mood disorders, anxiety, or other mental health conditions
- People previously treated for substance use disorder
If pethidine has been used for more than a few days, abrupt discontinuation can cause an opioid withdrawal syndrome with muscle aches, sweating, runny nose, watery eyes, anxiety, abdominal cramps, diarrhoea, tremor, rapid heartbeat, and dilated pupils. In long-term users, the dose should be reduced gradually under medical supervision.
A unique safety issue with pethidine is accumulation of its active metabolite norpethidine. Norpethidine does not respond to the opioid antidote naloxone and causes central nervous system excitation: agitation, anxiety, tremor, involuntary muscle jerks (myoclonus), and in severe cases seizures. This risk rises sharply with repeated dosing beyond 48 hours, in kidney impairment, at high cumulative doses, and in older adults. For these reasons, most specialist societies recommend restricting pethidine to single doses or short courses (typically no more than 24–48 hours).
Pregnancy and Breastfeeding
If you are pregnant, breastfeeding, think you may be pregnant, or are planning a pregnancy, talk to your doctor before receiving pethidine.
Pregnancy: Pethidine crosses the placenta rapidly and can reach the foetus in appreciable concentrations. Historically, pethidine was one of the most commonly used opioids for pain in labour, but its use has declined in many countries because it can cause respiratory depression, drowsiness, and reduced feeding in the newborn, especially when given within 2–3 hours of delivery. Prolonged use at higher doses during pregnancy may cause neonatal opioid withdrawal syndrome, requiring specialist care after birth. Outside of labour, pethidine should only be used during pregnancy when clearly necessary and at the lowest effective dose for the shortest possible time.
Breastfeeding: Pethidine and its metabolite norpethidine are secreted into breast milk. Infants exposed through milk – especially after multiple maternal doses – can experience sedation, poor feeding, and in rare cases respiratory depression. Short-term single-dose exposure (such as a single injection after caesarean section) is usually considered acceptable, but prolonged or repeated use is generally not recommended during breastfeeding. If pethidine is needed, alternative analgesia, temporary pumping and discarding of milk, or closer monitoring of the infant may be advised.
Driving, Machinery, and Ability to Work
Pethidine causes significant sedation, dizziness, and impaired coordination. After receiving pethidine, you must not drive, operate machinery, or perform any task requiring full mental alertness for at least 24 hours (and often longer, depending on the dose and your individual response). Most hospitals require that patients who have been given pethidine are accompanied home by a responsible adult and are told not to drive or work at height until the effects have fully worn off.
How Does Pethidine Macure Interact with Other Drugs?
Pethidine has numerous clinically important drug interactions. The most dangerous is with monoamine oxidase inhibitors (MAOIs), which is absolutely contraindicated. Other major interactions include other opioids, benzodiazepines, alcohol, and serotonergic drugs such as SSRIs and SNRIs. Always provide your healthcare team with a complete list of medications, supplements, and recreational substances.
The simultaneous use of pethidine with certain other medicines can cause serious, life-threatening effects. The most important interactions involve drugs that affect serotonin signalling (risk of serotonin syndrome) and drugs that depress the central nervous system (risk of respiratory depression and death). Your healthcare team will review all your current medications before giving pethidine.
Major Interactions (Potentially Life-Threatening)
| Drug / Drug Class | Risk | Clinical Advice |
|---|---|---|
| Monoamine oxidase inhibitors (MAOIs) (phenelzine, tranylcypromine, moclobemide, selegiline, rasagiline, linezolid) | Severe serotonin syndrome with hyperthermia, rigidity, seizures, cardiovascular collapse, and death | Absolute contraindication. Do not use pethidine during or within 14 days of any MAOI therapy |
| Benzodiazepines (diazepam, midazolam, lorazepam, alprazolam) | Profound sedation, respiratory depression, coma, and death | Avoid combination where possible; if essential, use lowest effective doses with continuous monitoring |
| Other opioid analgesics (morphine, oxycodone, fentanyl, tramadol, codeine) | Additive respiratory depression and sedation | Avoid concurrent systemic use; consult pain or anaesthesia specialist |
| Alcohol | Fatal respiratory depression and loss of consciousness | Absolutely contraindicated during and immediately after pethidine therapy |
| SSRIs and SNRIs (fluoxetine, sertraline, paroxetine, venlafaxine, duloxetine) | Increased risk of serotonin syndrome | Avoid where possible; if pethidine is essential, use lowest dose and observe closely for agitation, tremor, sweating, hyperreflexia |
| Other serotonergic drugs (triptans, lithium, tramadol, St John’s wort, MDMA) | Serotonin syndrome | Avoid concurrent use; warn patients about herbal and recreational substances |
| Barbiturates and other sedative-hypnotics | Profound sedation, respiratory depression | Avoid combination; monitor closely if unavoidable |
| Gabapentinoids (gabapentin, pregabalin) | Increased sedation and respiratory depression | Reduce doses; monitor respiratory function and level of consciousness |
Other Significant Interactions
| Drug / Drug Class | Effect | Clinical Advice |
|---|---|---|
| Cimetidine | Reduces pethidine clearance, increasing blood levels and risk of side effects | Consider dose reduction of pethidine; prefer alternative H2-blockers (ranitidine, famotidine) if possible |
| Ritonavir and other strong CYP3A4 inhibitors | Can increase pethidine levels while reducing norpethidine formation | Monitor for increased opioid effects; dose adjustment may be needed |
| Phenobarbital, phenytoin, carbamazepine (enzyme inducers) | Increase norpethidine formation; higher risk of neurotoxicity | Avoid long-term combination; limit total pethidine dose and duration |
| Tricyclic antidepressants (amitriptyline, nortriptyline, clomipramine) | Increased sedation, anticholinergic effects, and possible serotonergic effects | Monitor for excessive drowsiness and confusion; consider dose adjustment |
| Antipsychotics (chlorpromazine, haloperidol) | Additive hypotension, sedation, and anticholinergic effects | Use with caution; monitor blood pressure and conscious level |
| Muscle relaxants (baclofen, tizanidine) | Increased sedation and respiratory depression | Use lower doses and monitor closely |
| Anticholinergic drugs (atropine, hyoscine, some antihistamines) | Additive anticholinergic side effects (dry mouth, urinary retention, tachycardia, confusion) | Use minimum effective doses; watch for urinary retention and delirium, especially in older adults |
| Partial opioid agonists / antagonists (buprenorphine, nalbuphine, pentazocine, naltrexone) | May reduce pethidine analgesia and precipitate withdrawal | Avoid concurrent use; consult specialist for patients on opioid substitution therapy |
What Is the Correct Dosage of Pethidine Macure?
Pethidine Macure is administered only by healthcare professionals. The dose is individually determined based on the severity of pain, the patient’s age, weight, organ function, and prior opioid exposure. The typical adult dose is 25–100 mg by intramuscular or subcutaneous injection, or 25–50 mg slowly intravenously, repeated every 3–4 hours if required. Total daily doses above approximately 600 mg and continued use beyond 48 hours should generally be avoided because of the risk of norpethidine toxicity.
Pethidine is never self-administered. The medicine is given by a doctor, nurse, or paramedic in a setting where breathing, blood pressure, pulse, and level of consciousness can be monitored. The correct dose is always the lowest dose that adequately controls pain for the shortest period necessary. Dosage depends on whether the patient is opioid-naive (has not recently taken strong opioids) or already opioid-tolerant.
Adults
Intramuscular or Subcutaneous Injection
Typical adult dose: 25–100 mg (0.5–2 ml of Pethidine Macure 50 mg/ml) by deep intramuscular or subcutaneous injection. The dose may be repeated every 3–4 hours according to pain response and sedation. In hospital practice, a starting dose of 50–75 mg is commonly used for moderate to severe acute pain in adults of average build.
Slow Intravenous Injection
Typical adult dose: 25–50 mg given slowly over at least 1–2 minutes, ideally diluted in 10 ml of sodium chloride 0.9%. The dose may be titrated in small increments (for example 10–25 mg every few minutes) to the lowest dose that controls pain. Continuous monitoring of breathing, oxygen saturation, heart rate, and blood pressure is required during and after administration.
Obstetric Pain
For pain in labour, pethidine has traditionally been given as 50–100 mg intramuscularly, repeated every 3–4 hours if needed. Because pethidine crosses the placenta and can cause neonatal respiratory depression, many obstetric units prefer to administer pethidine only in the early stages of labour and to avoid doses within 2–3 hours of anticipated delivery, or to use alternative analgesia. Naloxone must be immediately available for the newborn.
Post-anaesthetic Shivering (specialist indication)
Low-dose pethidine is highly effective for treating shivering after general or regional anaesthesia. Typical doses are 12.5–25 mg intravenously as a single dose, which usually stops shivering within minutes.
Elderly Patients
Dose Adjustments for Older Adults
Older adults are more sensitive to all opioid effects and are particularly vulnerable to norpethidine accumulation because of age-related declines in kidney function. International geriatric prescribing guidelines (such as the American Geriatrics Society Beers Criteria) strongly discourage pethidine use in people aged 65 and over, and recommend alternative opioids. If pethidine is unavoidable, starting doses should be reduced by 25–50% compared to younger adults, dosing intervals extended, and the total duration of treatment kept as short as possible.
Children
Paediatric Dosing
Pethidine may occasionally be used in hospital settings for children with severe pain under the care of specialists experienced in paediatric analgesia. Typical doses are 0.5–2 mg/kg by intramuscular, subcutaneous, or slow intravenous injection, repeated every 3–4 hours if required, up to a maximum single dose equivalent to the adult dose. Many paediatric units now prefer alternative opioids such as morphine because of pethidine’s neurotoxicity profile in young patients, especially neonates and infants. Pethidine Macure is not generally recommended for children below the age specified by the prescribing physician and is used only when benefits clearly outweigh risks.
Patients with Kidney or Liver Impairment
Kidney and Liver Disease
In kidney impairment, norpethidine accumulates rapidly and greatly increases the risk of tremor, agitation, and seizures. Pethidine should generally be avoided in patients with significant renal dysfunction; alternative opioids are preferred. If used, doses must be reduced, dosing intervals extended, and treatment limited to the shortest possible duration.
In liver impairment, pethidine metabolism is slowed and blood levels increase. Doses should be reduced and intervals extended; in severe hepatic failure, pethidine is contraindicated.
Duration of Treatment
Pethidine is a short-term analgesic. Most specialist bodies recommend limiting its use to 24–48 hours or a small number of doses. If pain persists beyond this period, a switch to a longer-acting opioid (such as morphine or oxycodone) or a multimodal analgesic plan is almost always appropriate. Prolonged use dramatically increases the risk of norpethidine toxicity, dependence, and tolerance without providing better pain control than alternatives.
Missed Dose
Because Pethidine Macure is given by a healthcare professional, usually on an as-needed basis, patients do not self-manage doses. If you feel your pain is not being controlled between scheduled injections, tell your nursing team – do not wait until the pain becomes severe.
Overdose
An overdose of pethidine is a medical emergency. Contact emergency services immediately if overdose is suspected. Signs of overdose include:
- Very slow, shallow, or stopped breathing
- Extreme drowsiness, unresponsiveness, or coma
- Pinpoint pupils (though pupils may dilate terminally as oxygen levels fall)
- Blue or grey discoloration of the lips, fingernails, or skin
- Cold and clammy skin
- Very low blood pressure
- Seizures (especially at very high doses or in renal impairment, caused by norpethidine)
- Agitation, tremor, or confusion before loss of consciousness
The opioid antidote naloxone rapidly reverses the respiratory and sedative effects of pethidine. However, naloxone does not reverse norpethidine-induced seizures; these must be treated with benzodiazepines (such as diazepam or lorazepam) and airway support. In hospital overdoses, repeated doses of naloxone or an infusion may be needed because naloxone wears off faster than pethidine.
What Are the Side Effects of Pethidine Macure?
Like all opioids, pethidine can cause side effects. The most common are nausea, vomiting, dizziness, drowsiness, sweating, and dry mouth. Less common but important side effects include low blood pressure, urinary retention, confusion, tremor, and respiratory depression. Rare but serious reactions include seizures (from norpethidine), severe allergic reactions, and serotonin syndrome.
Not all patients experience side effects, and many unwanted effects are short-lived, lasting only a few hours after an injection. However, some reactions are serious and require immediate medical attention. The list below describes reported side effects organised by frequency. Frequency categories follow the conventions used by the European Medicines Agency: very common (more than 1 in 10), common (up to 1 in 10), uncommon (up to 1 in 100), rare (up to 1 in 1000), very rare (less than 1 in 10 000), and frequency not known (cannot be estimated from available data).
Very Common
- Nausea and vomiting
- Drowsiness and sedation
- Dizziness, especially on standing
- Sweating (hyperhidrosis)
- Dry mouth
Common
- Low blood pressure, particularly after intravenous injection
- Rapid heart rate (tachycardia) from anticholinergic effect
- Constipation
- Urinary retention or hesitancy
- Headache
- Pupil constriction (miosis)
- Flushing and warmth
- Mild itching at the injection site or generalised pruritus
Uncommon
- Respiratory depression (slow or shallow breathing)
- Confusion or disorientation
- Euphoria or dysphoria (feelings of elation or unease)
- Mood changes, agitation, restlessness
- Muscle twitching (myoclonus)
- Hallucinations
- Bronchospasm
- Biliary spasm
- Skin rash or urticaria (hives)
- Orthostatic hypotension
Rare
- Seizures (particularly with high doses, repeated dosing, or kidney impairment)
- Severe hypotension or cardiovascular collapse after rapid IV injection
- Severe allergic reactions (anaphylaxis) with rash, swelling, and breathing difficulty
- Serotonin syndrome, especially in combination with serotonergic drugs
- Palpitations or arrhythmias
- Hypothermia
- Severe bronchospasm in susceptible patients
Frequency Not Known
- Neonatal respiratory depression when given close to delivery
- Neonatal opioid withdrawal syndrome with prolonged prenatal exposure
- Tolerance, physical dependence, and substance use disorder
- Opioid-induced hyperalgesia (increased pain sensitivity with prolonged use)
- Reduced libido, erectile dysfunction, menstrual irregularities (long-term use)
- Adrenal insufficiency with prolonged use
- Secondary immune suppression
- Pain, redness, or local tissue irritation at injection site
- Breathing becomes very slow or shallow, or the patient cannot be roused
- There are signs of a severe allergic reaction: facial swelling, difficulty breathing, widespread rash, or collapse
- There is unusual tremor, muscle twitching, agitation, or confusion – these can be early signs of norpethidine neurotoxicity and, if not addressed, can progress to seizures
- There are signs of serotonin syndrome: high fever, rigid muscles, rapid heart rate, sweating, tremor, severe agitation, or altered consciousness
- Seizures occur
Long-Term Side Effects
Pethidine is not intended for long-term use, but in rare cases of prolonged administration, additional effects may appear:
- Hormonal changes: Chronic opioid therapy can reduce sex hormones, causing loss of libido, erectile dysfunction, and menstrual irregularities
- Adrenal insufficiency: Symptoms include fatigue, weakness, low blood pressure, nausea, and loss of appetite
- Opioid-induced hyperalgesia: Paradoxical increase in pain sensitivity with prolonged use, which may require dose reduction or a switch to a different opioid
- Immune effects: Opioids can modulate immune function; the clinical impact is usually modest but can be relevant in vulnerable patients
- Cognitive effects: Persistent attention and memory problems in some long-term users
How Should Pethidine Macure Be Stored?
Pethidine Macure is a controlled substance that must be stored securely in a locked medicine cabinet or drug safe within healthcare facilities. It should be kept below 25°C, protected from light, and out of reach of children. Unused or expired ampoules must not be discarded in household waste or sewage – they must be returned to pharmacy services for regulated destruction.
Because Pethidine Macure is an injectable controlled substance, proper storage is a legal requirement in every jurisdiction where the medicine is used. Typical storage and handling requirements include:
- Locked storage in a dedicated controlled-drugs cabinet or safe, with restricted access
- Continuous record-keeping (controlled drug register) of all stock received, dispensed, wasted, and remaining
- Two-person verification for administration and disposal in many healthcare systems
- Temperature control: store below 25°C; do not freeze
- Light protection: keep ampoules in the outer carton until immediately before use
- Expiry date: do not use after the expiry date printed on the label; the date refers to the last day of that month
- Disposal: unused or expired ampoules must be returned to the pharmacy or destroyed under witnessed conditions according to national controlled-substance regulations
Pethidine Macure is not intended for home use. In the rare situations where pethidine is provided for outpatient use (for example in specialist palliative care), strict storage instructions must be followed, and the medicine must be kept securely out of reach of children, adolescents, and unauthorised adults. Accidental ingestion, even of a small amount, can be fatal for a child.
What Does Pethidine Macure Contain?
The active substance in Pethidine Macure is pethidine hydrochloride. Each millilitre of the solution for injection contains 50 mg of pethidine hydrochloride. Typical excipients include sodium chloride for isotonicity, dilute hydrochloric acid and sodium hydroxide for pH adjustment, and water for injections. The solution is a clear, colourless liquid packaged in glass ampoules for single use.
Active Ingredient
Each millilitre of Pethidine Macure solution contains pethidine hydrochloride 50 mg. Pethidine hydrochloride is chemically 1-methyl-4-phenylpiperidine-4-carboxylic acid ethyl ester hydrochloride. It is a white, odourless, crystalline powder that is freely soluble in water and ethanol, producing a clear solution suitable for intramuscular, subcutaneous, or intravenous injection.
Other Ingredients (Excipients)
The solution for injection typically contains:
- Sodium chloride – to make the solution isotonic (similar salt concentration to blood)
- Hydrochloric acid and/or sodium hydroxide – used in small amounts to adjust the pH to a physiologically acceptable range
- Water for injections – as the solvent
Pethidine Macure does not usually contain preservatives and is intended for single use. Any remaining solution in an opened ampoule must be discarded immediately.
Packaging
Pethidine Macure 50 mg/ml is supplied as a clear, colourless solution in glass ampoules, typically containing 1 ml, 2 ml, or 5 ml of solution. Ampoules are packaged in cartons together with a healthcare professional information leaflet. The medicinal product is classified as a controlled drug and is distributed only to licensed healthcare facilities and pharmacies.
Pethidine Macure can be given directly from the ampoule by intramuscular or subcutaneous injection, or slowly intravenously after dilution (commonly to a concentration of 10 mg/ml) using sodium chloride 0.9% or glucose 5%. Do not mix in the same syringe with incompatible drugs such as aminophylline, heparin, phenytoin, or sodium bicarbonate. Always check the appearance of the solution before use – do not administer if particles or discoloration are present.
Frequently Asked Questions About Pethidine Macure
Medical References and Sources
This article is based on current medical research, international guidelines, and approved prescribing information. All claims are supported by scientific evidence from peer-reviewed sources.
- World Health Organization (2018). "WHO Guidelines for the Pharmacological and Radiotherapeutic Management of Cancer Pain in Adults and Adolescents." WHO Guidelines International guideline for cancer pain management including the position of pethidine. Evidence level: 1A
- European Medicines Agency (EMA). "Summary of Product Characteristics: Pethidine hydrochloride solution for injection." EMA European regulatory prescribing information for pethidine injection.
- U.S. Food and Drug Administration (FDA). "Meperidine (Demerol) Prescribing Information." FDA U.S. regulatory prescribing information including boxed warnings for meperidine (pethidine).
- British National Formulary (BNF). "Pethidine hydrochloride." National Institute for Health and Care Excellence (NICE). BNF – Pethidine UK clinical prescribing guidance for pethidine.
- Latta KS, Ginsberg B, Barkin RL. (2002). "Meperidine: a critical review." American Journal of Therapeutics, 9(1):53–68. AJT review Comprehensive clinical review of pethidine pharmacology, toxicology, and modern role.
- American Geriatrics Society Beers Criteria Update Expert Panel (2023). "American Geriatrics Society 2023 Updated AGS Beers Criteria® for Potentially Inappropriate Medication Use in Older Adults." Journal of the American Geriatrics Society. AGS Beers Criteria Identifies pethidine/meperidine as potentially inappropriate in adults aged 65 and older.
- Ullman R, Smith LA, Burns E, Mori R, Dowswell T. (2010). "Parenteral opioids for maternal pain management in labour." Cochrane Database of Systematic Reviews. Cochrane Review Systematic review of parenteral opioids including pethidine in labour. Evidence level: 1A
- World Health Organization (2023). "WHO Model List of Essential Medicines – 23rd List." WHO Essential Medicines Reference list identifying opioid analgesics considered essential for pain management.
Evidence grading: This article uses the GRADE framework (Grading of Recommendations Assessment, Development and Evaluation) for evidence-based medicine. Evidence level 1A represents the highest quality of evidence, based on systematic reviews of randomized controlled trials.
iMedic Editorial Standards
Peer Review Process
All medical content is reviewed by at least two licensed specialist physicians before publication.
Fact-Checking
All medical claims are verified against peer-reviewed sources and international guidelines.
Update Frequency
Content is reviewed and updated at least every 12 months or when new research emerges.
Corrections Policy
Any errors are corrected immediately with transparent changelog.
Medical Editorial Board: iMedic has an independent medical editorial board consisting of specialist physicians in pharmacology, pain medicine, anaesthesiology, and clinical pharmacy.