Morphine is a potent opioid analgesic derived from the opium poppy, used primarily to relieve moderate to severe pain. It acts on opioid receptors in the brain, spinal cord, and peripheral tissues, reducing pain perception and altering the emotional response to it. Morphine is one of the oldest medicines in use and remains a cornerstone of pain management, particularly in palliative care, post-operative care, and acute severe pain.
In critical care following cardiac arrest, opioid analgesics (typically fentanyl or morphine) form part of the sedation and analgesia regimen used to keep mechanically ventilated patients comfortable. In acute chest pain from suspected myocardial infarction, morphine was historically given routinely; however, current guidelines recommend caution, as evidence suggests morphine may slow the absorption and reduce the effectiveness of antiplatelet agents such as aspirin and ticagrelor.
Common side effects include nausea and vomiting, constipation, drowsiness, and respiratory depression (slowed breathing, which can be dangerous at high doses). Respiratory depression is the most serious acute risk and is reversed by the opioid antagonist naloxone, which is available as an emergency treatment. With appropriate dosing and monitoring, these effects are manageable in clinical practice.
Morphine is a controlled drug in the UK, and its prescription, dispensing, and storage are subject to strict regulations to prevent misuse and diversion.
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