Opioids and Local Anaesthetics Overview

Opioids

• Opioids are medications that act on opioid receptors in the brain and spinal cord to reduce pain.
• They decrease calcium ion influx at the presynaptic terminal, reducing neurotransmitter release.
• Fentanyl is a potent opioid used for severe pain management in cancer patients.
• Naloxone is an opioid antagonist used to reverse opioid overdose.
• Long-term opioid use can lead to constipation.
• Buprenorphine, a partial opioid agonist, has a ceiling effect on respiratory depression, making it safer than full agonists at higher doses.
• The clinical use of codeine includes mild to moderate pain and cough suppression.
• Tramadol's mechanism of action involves serotonin and noradrenaline reuptake inhibition along with opioid receptor agonism.

Local Anaesthetics

• Local anaesthetics, like lidocaine, block sodium channels to prevent action potential propagation, leading to temporary numbness.
• Lidocaine with adrenaline is often used in dentistry to reduce the risk of systemic toxicity by slowing absorption.
• Local anaesthetics are also useful for minor surgeries and procedures.

Antidepressants

• SSRIs, like sertraline, inhibit serotonin reuptake, leading to increased serotonin levels in the brain.
• SSRIs are used for depression and anxiety disorders.
• SNRIs, like duloxetine, inhibit both serotonin and noradrenaline reuptake.

Other Pain Medications

• Paracetamol (acetaminophen) inhibits COX-3, reducing inflammation and pain.
• Amitriptyline, a tricyclic antidepressant, can be used for neuropathic pain due to its ability to inhibit serotonin and noradrenaline reuptake.

Adverse Effects

• Common adverse effects of opioids include respiratory depression, constipation, and sedation.
• Overdose symptoms include respiratory depression, coma, and death.
• Long-term opioid use can lead to dependence and tolerance.
• Opioid withdrawal symptoms include restlessness, sweating, muscle aches, and nausea.
• NSAIDs can cause renal toxicity if used long-term.
• Tramadol can cause serotonin syndrome when combined with SSRIs.
• Methadone can prolong the QT interval, increasing the risk of arrhythmias.
• Paracetamol can cause hepatotoxicity, especially in patients with liver disease.
• Codeine should be avoided in patients taking MAOIs due to the risk of hypertensive crisis.
• Chronic opioid use can lead to constipation.

Important Considerations

• Opioids are generally contraindicated in patients with respiratory depression.
• Naloxone is the antidote for opioid overdose.
• Methadone is commonly used for opioid replacement therapy.
• Opioids can be used to decrease gastrointestinal motility in diarrhoea.
• Paracetamol is a preferred initial analgesic for mild to moderate pain.

Explore the fundamentals of opioids and local anaesthetics in this quiz. Learn about their mechanisms, clinical uses, and important considerations, such as the effects of long-term opioid use and the role of local anaesthetics in dental procedures. Test your knowledge on these essential topics in pharmacology.