Morphine

Drug Information: Morphine

Morphine is a potent opioid analgesic medication used primarily to relieve severe pain. It is derived from opium and acts on the central nervous system to reduce the perception of pain. While highly effective, Morphine carries a risk of dependence and respiratory depression, necessitating careful monitoring and appropriate use. It is available in various formulations, including immediate-release and extended-release tablets, injections, and solutions. Its use is carefully controlled due to its potential for abuse and addiction.

Category

Drugs for ACS

Mechanism of Action

Morphine exerts its analgesic effects primarily by binding to opioid receptors, predominantly the mu (μ) opioid receptors, located in the brain and spinal cord. These receptors are G-protein coupled receptors. When morphine binds to these receptors, it activates the G proteins, which in turn modulate intracellular signaling pathways. This activation leads to a decrease in neuronal excitability and reduced transmission of pain signals. Specifically, morphine:

• Inhibits Adenylyl Cyclase: Activation of the mu receptor inhibits adenylyl cyclase, decreasing the production of cyclic AMP (cAMP). This reduction in cAMP levels hyperpolarizes the neuron, making it less likely to fire.
• Increases Potassium Conductance: Morphine increases potassium (K+) conductance, leading to potassium efflux from the neuron. This further contributes to hyperpolarization and reduced neuronal excitability.
• Reduces Calcium Influx: Morphine decreases calcium (Ca2+) influx into the presynaptic nerve terminals. This reduces the release of excitatory neurotransmitters, such as glutamate and substance P, which are involved in pain transmission.

By modulating these processes, morphine effectively diminishes the perception of pain and produces analgesia. It’s important to note that the effects of morphine extend beyond pain relief; it also affects other areas of the central nervous system, leading to side effects such as respiratory depression, sedation, and euphoria.

Clinical Uses

Morphine is widely used in the management of moderate to severe pain. Its clinical applications include:

• Acute Coronary Syndrome (ACS): Morphine is used in ACS to relieve chest pain associated with myocardial ischemia. It also helps to reduce anxiety and preload, decreasing the workload on the heart.
• Post-operative Pain: It is commonly used to manage pain following surgical procedures.
• Cancer Pain: Morphine is a crucial component of pain management strategies for patients with cancer, particularly for breakthrough pain or chronic pain that is not responsive to other analgesics.
• Trauma: For severe pain associated with traumatic injuries, morphine provides effective relief.
• Palliative Care: In end-of-life care, morphine is often used to alleviate pain and suffering, improving the quality of life for terminally ill patients.

The use of morphine should be carefully considered, balancing the benefits of pain relief with the potential risks of adverse effects and dependence. Alternatives and adjuncts should be considered to minimize morphine dosage and exposure.

Dosage

Dosage varies depending on the route of administration, severity of pain, and patient factors. Here are typical dosage guidelines:

• Adults:
  • IV/IM/SC: 2.5-10 mg every 3-4 hours as needed. Titrate to effect.
  • Oral (Immediate Release): 15-30 mg every 4 hours as needed.
  • Oral (Extended Release): Dosage is individualized; start with a low dose and titrate slowly based on pain control and side effects.
• Pediatrics:
  • IV/IM/SC: 0.05-0.1 mg/kg every 3-4 hours as needed. Maximum single dose is 10 mg.
  • Oral: Not generally recommended for acute pain management in children due to variable absorption.

Important Considerations: Dosage adjustments are necessary in patients with renal or hepatic impairment, and in elderly patients. Always monitor for respiratory depression and other adverse effects. Naloxone should be readily available as an antidote for opioid overdose.

Indications

Common indications for Morphine include:

• Severe acute pain (e.g., post-operative, trauma)
• Chronic pain management (e.g., cancer pain)
• Pain associated with acute myocardial infarction (AMI) or unstable angina (ACS)
• Palliative care and end-of-life pain management

Contraindications

Morphine is contraindicated in the following conditions:

• Significant respiratory depression
• Acute or severe bronchial asthma (in the absence of resuscitative equipment)
• Known hypersensitivity to morphine or other opioid agonists
• Paralytic ileus
• Head injury or increased intracranial pressure (may mask neurological signs)
• Concurrent use with monoamine oxidase inhibitors (MAOIs) or within 14 days of stopping MAOIs

FAQ

• Q: What is Morphine used for?
  
  A: Morphine is a strong pain reliever used to treat severe pain, such as after surgery, due to injury, or from cancer. It is also used to relieve shortness of breath.
• Q: How does Morphine work?
  
  A: Morphine works by binding to opioid receptors in the brain and spinal cord, which reduces the feeling of pain.
• Q: What are the common side effects of Morphine?
  
  A: Common side effects include constipation, nausea, vomiting, drowsiness, confusion, and dizziness.
• Q: Is Morphine addictive?
  
  A: Yes, Morphine can be addictive if used long-term or misused. It’s important to take it exactly as prescribed by your doctor.
• Q: What should I do if I miss a dose of Morphine?
  
  A: If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not double your dose to catch up.
• Q: Can I drink alcohol while taking Morphine?
  
  A: No, you should not drink alcohol while taking Morphine, as it can increase the risk of serious side effects, such as respiratory depression.
• Q: What are the signs of Morphine overdose?
  
  A: Signs of Morphine overdose include slowed or stopped breathing, pinpoint pupils, severe drowsiness or unresponsiveness, and confusion. Call emergency services immediately if you suspect an overdose.
• Q: What should I tell my doctor before taking Morphine?
  
  A: Tell your doctor about any allergies, medical conditions (especially breathing problems, kidney or liver disease), and all other medications you are taking.