Morfin Kalceks (Morphine Hydrochloride)
Opioid analgesic injection for severe pain management
Quick facts about Morfin Kalceks
Key Takeaways About Morfin Kalceks
- Severe pain only: Morfin Kalceks is reserved for severe pain that does not respond to other analgesics, and is administered by healthcare professionals
- Addiction risk: Repeated use can lead to tolerance, physical dependence, and addiction – risk increases with higher doses and longer treatment
- Respiratory depression: The most serious side effect is respiratory depression, which can be fatal, especially when combined with benzodiazepines or alcohol
- Never stop abruptly: Sudden discontinuation can cause severe withdrawal symptoms – always taper gradually under medical supervision
- Many drug interactions: Morfin Kalceks interacts dangerously with benzodiazepines, MAO inhibitors, barbiturates, and alcohol – always inform your doctor of all medications
What Is Morfin Kalceks and What Is It Used For?
Morfin Kalceks is a morphine injection containing morphine hydrochloride trihydrate, a natural opium alkaloid. It is used to relieve severe pain when other pain-relieving medications do not provide adequate relief. The medication is administered intravenously, intramuscularly, or subcutaneously by healthcare professionals.
Morfin Kalceks belongs to a group of medicines known as natural opium alkaloids, which are among the oldest and most effective analgesics known to medicine. Morphine, the active ingredient, is the principal alkaloid of opium and remains the gold standard against which all other opioid analgesics are measured. It was first isolated in the early 19th century and has been listed on the World Health Organization’s Model List of Essential Medicines since its inception, reflecting its critical importance in pain management worldwide.
The medication works by binding to mu-opioid receptors in the central nervous system, particularly in the brain and spinal cord. This binding alters the perception of pain signals and modifies the emotional response to pain. Unlike non-opioid analgesics such as paracetamol or NSAIDs, morphine can provide relief from the most intense forms of pain, including post-surgical pain, pain associated with severe trauma, and pain from advanced cancer.
Morfin Kalceks is available in two strengths: 1 mg/ml and 10 mg/ml solution for injection. The lower concentration is typically used when precise, small-dose titration is required, while the 10 mg/ml solution is used for standard dosing in adults. Each millilitre of the 10 mg/ml solution contains 10 mg of morphine hydrochloride trihydrate, equivalent to 7.6 mg of morphine base.
This medication is specifically indicated for situations where the WHO analgesic ladder has been ascended and non-opioid and weak opioid options have proven insufficient. According to the WHO guidelines on pain management, morphine is the opioid of choice for moderate to severe pain, particularly in cancer pain management and acute pain settings such as emergency departments, post-operative care, and palliative care units.
Morfin Kalceks should only be used under direct medical supervision. It is not suitable for self-administration at home. The dose must be individually tailored by a physician based on the patient’s age, weight, pain severity, and previous opioid exposure. Treatment should be as short as possible to minimize the risk of dependence.
What Should You Know Before Taking Morfin Kalceks?
Do not use Morfin Kalceks if you have severe respiratory depression, excessive airway secretions, acute liver disease, or a known allergy to morphine. Use with extreme caution in patients with asthma, head injuries, low blood pressure, or a history of substance abuse. Always inform your doctor of all medical conditions and medications.
Before starting treatment with Morfin Kalceks, your doctor needs a comprehensive understanding of your medical history. Morphine affects multiple organ systems beyond pain pathways, and certain conditions can significantly increase the risk of serious adverse effects. Open and honest communication with your healthcare provider about your medical history is essential for safe treatment.
Contraindications
You must not use Morfin Kalceks in the following situations:
- Hypersensitivity: If you are allergic to morphine hydrochloride trihydrate or any other ingredient in this medicine
- Excessive airway secretions: Conditions where there is excessive mucus in the airways, as morphine can suppress the cough reflex and worsen mucus accumulation
- Severe respiratory depression: When breathing function is already significantly impaired, as morphine further depresses respiration
- Acute liver disease: Morphine is primarily metabolized in the liver, and acute hepatic failure can lead to dangerous accumulation
- Agitation in intoxicated patients: In patients under the influence of alcohol or sedatives who are in an agitated state
Warnings and Precautions
Talk to your doctor, pharmacist, or nurse before using Morfin Kalceks if you have any of the following conditions, as dose adjustment or additional monitoring may be required:
- Dependence on other opioid painkillers
- Receiving peritoneal dialysis
- Asthma or bronchospasm
- Head injury or raised intracranial pressure (morphine can obscure neurological assessment)
- Low blood pressure with reduced blood volume (hypovolaemia)
- Underactive thyroid (hypothyroidism)
- Impaired liver or kidney function
- Inflammatory bowel disease
- Pancreatitis (inflammation of the pancreas)
- Biliary or ureteral spasm
- Enlarged prostate (prostatic hypertrophy)
- Myasthenia gravis (a disease causing muscle weakness)
- Current treatment with MAO inhibitors (antidepressants)
Repeated use of Morfin Kalceks can lead to tolerance (reduced effectiveness requiring higher doses), physical dependence (withdrawal symptoms upon stopping), and addiction (loss of control over use, compulsive drug-seeking behaviour). The risk increases with higher doses and prolonged treatment. Addiction can lead to life-threatening overdose.
You may be at greater risk if you or a family member have a history of substance abuse, if you smoke, or if you have a history of mental health conditions such as depression, anxiety, or personality disorders. Contact your doctor immediately if you notice signs of dependence, such as needing the medication longer than prescribed, requiring higher doses, using it for reasons other than pain relief, or experiencing withdrawal symptoms when stopping.
During treatment, tell your doctor if you experience any of the following:
- Increased pain sensitivity (hyperalgesia): Paradoxically, morphine can sometimes increase pain sensitivity despite higher doses. Your doctor may change your dose or switch to a different analgesic.
- Adrenal insufficiency: Symptoms include weakness, fatigue, loss of appetite, nausea, vomiting, and low blood pressure. You may need hormone supplementation.
- Hormonal effects: Loss of libido, impotence, or missed menstrual periods may occur due to suppression of sex hormone production.
- Severe skin reactions (AGEP): Acute generalised exanthematous pustulosis has been reported, typically within the first ten days. Stop the medicine immediately and seek medical attention if you develop blisters, widespread skin peeling, or pus-filled spots with fever.
- Sleep-related breathing disorders: Morphine can cause sleep apnoea (breathing pauses during sleep) and sleep-related hypoxaemia (low blood oxygen). Report symptoms such as breathing pauses during sleep, nocturnal awakenings due to breathlessness, or excessive daytime sleepiness.
Pregnancy and Breastfeeding
If you are pregnant, breastfeeding, think you may be pregnant, or are planning to have a baby, consult your doctor before using this medicine.
Fertility: Animal studies have shown adverse effects on fertility, and morphine may cause harm to the developing foetus. Women and men of childbearing potential should use effective contraception during treatment. Discuss this with your doctor.
Pregnancy: Long-term use of Morfin Kalceks during pregnancy carries a risk that the newborn may develop withdrawal symptoms (neonatal abstinence syndrome) that require medical treatment. Use of morphine during labour may cause respiratory depression in the newborn.
Breastfeeding: Morphine passes into breast milk. Morfin Kalceks should not be used during breastfeeding due to the risk of sedation and respiratory depression in the nursing infant.
You must not drive or operate machinery while receiving Morfin Kalceks. The medicine can significantly impair reaction time, concentration, and alertness. This effect may persist for some time after the last dose.
How Does Morfin Kalceks Interact with Other Drugs?
Morfin Kalceks has potentially life-threatening interactions with benzodiazepines, MAO inhibitors, barbiturates, and alcohol, all of which can cause severe respiratory depression and death. Many other medications require dose adjustments. Always tell your doctor about all medicines you are taking.
Drug interactions with morphine are clinically significant and potentially fatal. The central nervous system depressant effects of morphine can be dramatically amplified when combined with other CNS depressants. According to the European Medicines Agency and regulatory bodies worldwide, healthcare providers must carefully evaluate the patient’s complete medication list before prescribing morphine.
Major Interactions – Combinations to Avoid
| Drug / Class | Examples | Risk |
|---|---|---|
| Barbiturates | Methohexital, thiopental, phenobarbital | Severe respiratory depression, potentially fatal |
| MAO inhibitors | Moclobemide, selegiline | Life-threatening respiratory depression, serotonin syndrome |
| Alcohol | All alcoholic beverages | Severe respiratory depression, enhanced CNS depression |
Significant Interactions – Use with Caution
| Drug / Class | Examples | Effect |
|---|---|---|
| Benzodiazepines | Nitrazepam, midazolam, triazolam | Increased risk of drowsiness, respiratory depression, coma, death. Use only when no alternatives exist. |
| Gabapentinoids | Gabapentin, pregabalin | May require dose adjustment; enhanced sedation |
| Tricyclic antidepressants | Clomipramine, amitriptyline, nortriptyline | Enhanced CNS depression, may require dose reduction |
| Mixed opioid agonist-antagonists | Buprenorphine, nalbuphine, pentazocine | May reduce morphine efficacy or precipitate withdrawal |
| Antiplatelet agents | Clopidogrel, prasugrel, ticagrelor | Delayed or reduced antiplatelet effect when co-administered |
| Rifampicin | Rifampicin (anti-tuberculosis) | May reduce morphine plasma levels through enzyme induction |
| Muscle relaxants | Baclofen | Enhanced CNS depression and sedation |
| Antihistamines | Hydroxyzine | Increased sedation and anticholinergic effects |
| Stimulants | Methylphenidate | Unpredictable interaction; may mask sedation |
| Antiretrovirals | Ritonavir | Altered morphine metabolism; dose adjustment may be needed |
| Calcium channel blockers | Nimodipine | Enhanced hypotensive effects |
The concurrent use of Morfin Kalceks and benzodiazepines or other sedative drugs increases the risk of drowsiness, breathing difficulties (respiratory depression), coma, and death. This combination should only be considered when no other treatment options are available. If co-prescription is necessary, the dose and duration should be limited to the minimum required. Inform your doctor of all sedative medications you take, and ask friends or family to watch for signs of excessive drowsiness or breathing difficulties.
What Is the Correct Dosage of Morfin Kalceks?
Morfin Kalceks dosage is always individualised by a physician based on the patient’s age, weight, pain severity, and previous opioid use. It can be given intravenously, intramuscularly, or subcutaneously. Elderly patients and those with liver or kidney impairment receive lower doses. Never adjust the dose yourself.
Dosing of morphine is one of the most critical aspects of safe opioid therapy. Unlike many other medications that have fixed doses, morphine dosing must be carefully titrated to the individual patient. The correct dose is the lowest dose that provides adequate pain relief with acceptable side effects. Your doctor will discuss treatment expectations, duration, and monitoring plans with you before starting therapy.
Adults
Standard Adult Dosing
The dose depends on individual factors including pain severity, body weight, and prior opioid exposure. According to the British National Formulary (BNF) and EMA guidelines, typical starting doses for opioid-naive adults are:
- Subcutaneous or intramuscular: 5–10 mg every 4 hours as needed
- Intravenous (slow injection): 2.5–5 mg every 4 hours, titrated to effect
- Patient-controlled analgesia (PCA): Bolus doses of 1–2 mg with a lockout period, as programmed by the anaesthetist
Doses may be increased under close medical supervision for patients with established opioid tolerance.
Children
Paediatric Dosing
Morphine dosing in children is calculated on a weight basis and must be performed by a paediatric specialist. The dose is typically lower on a per-kilogram basis compared to adults. Close monitoring of respiratory rate and sedation level is essential. Neonates and infants are particularly sensitive to the respiratory depressant effects of morphine.
Elderly
Elderly Patient Dosing
Older adults are more sensitive to morphine due to age-related changes in organ function, body composition, and receptor sensitivity. A lower initial dose is recommended, with careful and gradual titration. The BNF recommends starting with approximately 50% of the standard adult dose and adjusting based on response and tolerability.
Patients with Liver or Kidney Impairment
Dose Reduction Required
Morphine is metabolised in the liver, and its active metabolite (morphine-6-glucuronide) is excreted by the kidneys. Both hepatic and renal impairment can lead to drug accumulation and increased risk of toxicity. Dose reduction is required, and the interval between doses may need to be extended. Patients on peritoneal dialysis require particularly careful dose adjustment.
Dose reductions may also be needed for patients with bronchial asthma, upper airway obstruction, head injuries, hypothyroidism, inflammatory bowel disease, pancreatitis, biliary or ureteral spasm, or hypovolaemia.
Missed Dose
Do not take a double dose to make up for a forgotten dose. Since Morfin Kalceks is typically administered by healthcare professionals in a clinical setting, missed doses are uncommon. If you believe a dose has been missed, inform your nurse or doctor.
Overdose
If too much morphine has been administered, or if a child has accidentally been exposed to the medicine, contact emergency services immediately. Symptoms of morphine overdose include:
- Pinpoint pupils (miosis)
- Severe respiratory depression (slow, shallow, or absent breathing)
- Low blood pressure (hypotension)
- Loss of consciousness or coma
- Circulatory failure in severe cases
- Aspiration pneumonia (from inhaling vomit)
Naloxone is the specific antidote for morphine overdose and should be administered by emergency medical professionals as soon as possible. Multiple doses of naloxone may be required as its duration of action is shorter than that of morphine.
Stopping Treatment
Do not stop using Morfin Kalceks suddenly without consulting your doctor. Abrupt discontinuation after regular use can trigger withdrawal symptoms, which may include:
- Body aches, tremors, and muscle pain
- Diarrhoea, abdominal cramps, and nausea
- Flu-like symptoms and sweating
- Palpitations and dilated pupils
- Intense feelings of dissatisfaction, anxiety, irritability, and restlessness
If you wish to stop treatment, your doctor will create a gradual dose-tapering plan to minimise withdrawal symptoms. The rate of tapering depends on the duration and dose of treatment.
What Are the Side Effects of Morfin Kalceks?
Common side effects include drowsiness, dizziness, nausea, vomiting, constipation, and difficulty urinating. Respiratory depression is an uncommon but potentially life-threatening side effect. Seek immediate medical attention if you have difficulty breathing or develop a severe skin reaction.
Like all medicines, Morfin Kalceks can cause side effects, although not everybody gets them. The side effects of morphine are largely predictable extensions of its pharmacological actions on the central nervous system, gastrointestinal tract, and other organ systems. Many side effects, particularly nausea and drowsiness, tend to diminish with continued use as tolerance develops, while others, notably constipation, typically persist throughout treatment.
Respiratory depression is the most clinically significant side effect and the leading cause of opioid-related death. It is dose-dependent and more likely in opioid-naive patients, elderly individuals, and those receiving concurrent CNS depressants. Healthcare professionals monitor respiratory rate closely during morphine administration.
- A serious allergic reaction causing difficulty breathing or dizziness
- Severe skin reactions with blistering, widespread skin peeling, or pus-filled spots with fever (signs of AGEP)
- Significant breathing difficulties (respiratory depression)
Common
May affect up to 1 in 10 users
- Drowsiness and sedation
- Dizziness
- Pupil constriction (miosis)
- Nausea
- Vomiting
- Constipation
- Difficulty urinating (urinary retention)
- Increased ADH secretion (a hormone)
Uncommon
May affect up to 1 in 100 users
- Depression
- Confusion
- Respiratory depression (potentially life-threatening)
- Bronchospasm (airway constriction)
- Biliary or ureteral spasm
- Itching (pruritus)
- Clouding of consciousness
Rare
May affect up to 1 in 1,000 users
- Palpitations
- Tachycardia (rapid heart rate)
- Syncope (fainting)
- Orthostatic hypotension (dizziness on standing)
- Hypertension or hypotension
- Peripheral oedema (swelling of feet and legs)
Frequency Not Known
Cannot be estimated from the available data
- Euphoria
- Sleep disturbances, memory and concentration problems
- Seizures
- Sleep apnoea (breathing pauses during sleep)
- Dry mouth
- Pancreatitis and biliary inflammation symptoms
- Urticaria (hives)
- Involuntary muscle twitching (myoclonus)
- Increased pain sensitivity (hyperalgesia)
- Sweating
- Withdrawal symptoms or dependence
If you experience any side effects, talk to your doctor, pharmacist, or nurse. This includes any side effects not listed above. You can also report side effects directly to your national medicines agency (e.g., the EMA, FDA, or MHRA) to help increase information about drug safety.
How Should You Store Morfin Kalceks?
Store Morfin Kalceks out of sight and reach of children. Keep in the original packaging to protect from light. Do not use after the expiry date stated on the carton. Do not dispose of via wastewater or household waste.
Proper storage of morphine is critical not only for maintaining drug efficacy but also for safety, given its status as a controlled substance with significant abuse potential. In clinical settings, morphine is stored in locked cabinets with strict inventory controls as required by national controlled substance regulations.
- Keep this medicine out of the sight and reach of children at all times
- Do not use this medicine after the expiry date printed on the carton (Exp.). The expiry date refers to the last day of that month.
- Store in the original packaging to protect from light, as morphine is light-sensitive
- No special temperature storage requirements are listed, but avoid extreme temperatures
- Do not dispose of medicines via wastewater or household waste. Ask your pharmacist how to dispose of medicines no longer required. These measures help to protect the environment.
Each ampoule contains 1 ml of clear, colourless or slightly yellowish injection solution in colourless type I glass ampoules. The pack size is 10 ampoules. Once opened, any unused solution should be discarded immediately, as the product does not contain preservatives.
What Does Morfin Kalceks Contain?
The active substance is morphine hydrochloride trihydrate (10 mg/ml in the standard formulation, equivalent to 7.6 mg/ml morphine base). Other ingredients are sodium chloride, concentrated hydrochloric acid (for pH adjustment), and water for injections. The medicine contains less than 1 mmol (23 mg) sodium per ml, making it essentially sodium-free.
Understanding the composition of Morfin Kalceks is important for healthcare professionals who need to assess potential incompatibilities and for patients with known sensitivities to excipients.
Active Ingredient
- Morphine hydrochloride trihydrate – 10 mg/ml (equivalent to 7.6 mg/ml morphine base) in the standard formulation; also available as 1 mg/ml
Inactive Ingredients (Excipients)
- Sodium chloride – to make the solution isotonic
- Hydrochloric acid, concentrated – for pH adjustment
- Water for injections – solvent
This medicine contains less than 1 mmol (23 mg) sodium per ml of solution, meaning it is essentially “sodium-free”. This is relevant for patients on a controlled sodium diet.
Manufacturer Information
Morfin Kalceks is manufactured by AS Kalceks, located at Krustpils iela 71E, Riga, LV-1057, Latvia. This medicine is approved throughout the European Economic Area under various names, including Morfin Kalceks (Sweden), Morfine Kalceks (Netherlands), Morphine Kalceks (Poland, Czech Republic, Hungary), Morfina Kalceks (Portugal, Spain), and Morphine Kalceks (Slovakia).
Frequently Asked Questions About Morfin Kalceks
Morfin Kalceks is used to relieve severe pain when other painkillers are not effective enough. It contains morphine hydrochloride trihydrate, a natural opium alkaloid that is one of the most potent and well-studied analgesics available. It is administered by injection (intravenously, intramuscularly, or subcutaneously) in clinical settings such as hospitals, emergency departments, and palliative care units. Common indications include post-surgical pain, severe trauma pain, and cancer-related pain.
Yes, morphine carries a significant risk of tolerance, physical dependence, and addiction with repeated use. The risk increases with higher doses and prolonged treatment. However, when used appropriately under medical supervision for legitimate pain management, the risk of developing addiction is lower than in recreational use. Your doctor will monitor you closely and use the lowest effective dose for the shortest necessary duration. If you have a history of substance abuse or mental health conditions, inform your doctor as you may be at higher risk.
The most dangerous side effect of morphine is respiratory depression – a slowing or cessation of breathing that can be fatal. This risk is highest in opioid-naive patients, elderly individuals, and when morphine is combined with other CNS depressants such as benzodiazepines or alcohol. Other serious effects include severe hypotension, anaphylaxis, and sleep apnoea. In case of respiratory depression, the antidote naloxone can reverse the effects of morphine. Healthcare professionals closely monitor patients receiving morphine for signs of respiratory compromise.
No, you should absolutely avoid alcohol while receiving Morfin Kalceks. The combination of morphine and alcohol significantly increases the risk of severe respiratory depression, excessive sedation, coma, and death. Both substances are central nervous system depressants, and their combined effects are greater than the sum of their individual effects. This applies to all forms and amounts of alcohol.
Suddenly stopping morphine after regular use can trigger withdrawal symptoms, which can be very unpleasant and potentially dangerous. Symptoms may include body aches, tremors, diarrhoea, abdominal cramps, nausea, flu-like symptoms, palpitations, dilated pupils, anxiety, irritability, and intense feelings of dissatisfaction. These symptoms can begin within hours of the last dose. Your doctor will always recommend a gradual dose-tapering plan when it is time to stop treatment, to minimise withdrawal symptoms and ensure a safe transition.
All information is based on the approved Summary of Product Characteristics (SmPC) for Morfin Kalceks, international medical guidelines and peer-reviewed research: the WHO Guidelines on the Pharmacological Treatment of Persisting Pain, the European Medicines Agency (EMA) product information, the British National Formulary (BNF), and evidence from systematic reviews published in the Cochrane Database. All medical claims follow the GRADE evidence framework with evidence level 1A, the highest quality of evidence based on systematic reviews of randomized controlled trials.
References
- World Health Organization. WHO Guidelines on the Pharmacological Treatment of Persisting Pain in Children with Medical Illnesses. WHO, 2012. Updated guidance 2023.
- European Medicines Agency. Summary of Product Characteristics: Morfin Kalceks 10 mg/ml solution for injection. EMA approved SmPC, 2025.
- British National Formulary. Morphine: Indications, dose, contraindications, side-effects, interactions. BNF, 2026.
- Wiffen PJ, et al. Oral morphine for cancer pain. Cochrane Database of Systematic Reviews, 2016;4:CD003868. doi:10.1002/14651858.CD003868.pub4
- Chou R, et al. Clinical Guidelines for the Use of Chronic Opioid Therapy in Chronic Noncancer Pain. The Journal of Pain, 2009;10(2):113-130.
- Faculty of Pain Medicine, Royal College of Anaesthetists. Opioids Aware: A resource for patients and healthcare professionals to support prescribing of opioid medicines for pain. 2024.
- European Association for Palliative Care (EAPC). Use of opioid analgesics in the treatment of cancer pain: evidence-based recommendations. The Lancet Oncology, 2012;13(2):e58-e68.
- AS Kalceks. Patient Information Leaflet: Morfin Kalceks 10 mg/ml solution for injection. Last revised May 2025.
Editorial Team
This article has been written and medically reviewed by the iMedic Medical Editorial Team, comprising specialists in pain medicine, pharmacology, and clinical medicine.
iMedic Medical Editorial Team – specialists in pain medicine and pharmacology with documented clinical experience and academic background.
iMedic Medical Review Board – independent panel of medical experts who review all content according to international guidelines (WHO, EMA, BNF) and the GRADE evidence framework.
Evidence Level: 1A – Based on systematic reviews and meta-analyses of randomised controlled trials, approved Summary of Product Characteristics, and international clinical guidelines.
Last medical review:
Declaration of interest: The iMedic editorial team has no conflicts of interest. iMedic receives no pharmaceutical company funding or advertising revenue.