Lect 7

• DRUGS Acting on the Central Nervous System (CNS) Lecture 13: Analgesics Anait S Levenson, M.D., Ph.D
• The active chemical compound in opium is Morphine and Codeine.
• Somatic pain is musculoskeletal damage.
• The pain processing system consists of four stages: 1) sensory input, 2) transmission, 3) modulation, and 4) perception.
• Phenothiazines, tricyclic antidepressants, cholinesterase inhibitors, and anticonvulsants are used in pharmacological intervention of pain processing.
• Opioids are derivatives of opium, a substance extracted from the white milky sap of unripe bulbs of the poppy plant, which contains morphine and codeine.
• Visceral pain is felt in the abdominal or thoracic cavity.
• Opioids have hypnotic, analgesic, and cough suppressant properties.
• Representatives of opiates include opium, morphine, and heroin, which are three times more potent than morphine.
• Chronic pain is slow in onset and persists for weeks or months, causing altered homeostasis and long-term distress.
• Neuropathic pain is damage affecting the somatosensory nervous system.
• Opioids are fully-synthetic or semi-synthetic narcotic drugs that mimic the natural opiate and are not found in nature.
• Combination of potent analgesics is used to treat chronic pain.
• Opiates are narcotic drugs derived from opium poppy or semi-synthetic derivatives with narcotic properties.
• Pain initiates from a traumatic insult and is well controlled with an analgesic.
• Drugs act like neurotransmitters, transferring electro-chemical messages between neurons in the brain and spinal cord.
• CNS drugs act on specific receptors that modulate synaptic transmission.
• CNS drugs can alter the function of the CNS to provide analgesia (narcotic opioids and non-narcotic NSAIDs & NMDA receptor antagonists), tranquilization (sedation) effects, anticonvulsant effects, antiemetic effects, anxiolytic, sedative, and hypnotic effects, general anesthetic effects, and behavioral effects.
• CNS drugs include analgesics, CNS pharmacology and drug development, CNS drugs: therapeutic importance, drug action in CNS, sites and mechanisms of drug action, agonists and antagonists, the blood-brain barrier (BBB), types of pain and pain processing system, sites of pharmacological intervention, opioids: classification and uses, opioids: mechanisms of action (receptors), opioids: pharmacological effects (agonists and antagonists), opioids: adverse effects, NMDA-receptor antagonists as analgesics, non-opioid analgesic agents.
• Some nonspecific agents like alcohol and anesthetics have non-receptor-mediated actions that result in alterations in synaptic transmission.
• CNS pharmacology is the study of how drugs alter brain activity and offset pathology.
• CNS drugs can speed up the transfer: CNS stimulants and can slow down the transfer: CNS depressants.
• PsychoPharmacology is the study of how drugs modify behavior, perception, affect a thought.
• Neuropharmacology is the study of how drugs act on neurons at the cellular/molecular level.
• Naltrexone is used for wildlife and large animals.
• Analgesic and antitussive (cough suppressant) are therapeutic uses of Nalbuphine.
• Naloxone is used for reversal of sedation and respiratory depression in small animals.
• Carprofen, Deracoxib, Firocoxib, and Meloxicam are MNMDA Receptor Antagonists used for analgesic purposes in dogs, cats, reptiles, and birds.
• Naloxone has no affinity for the opioid receptor.
• Acute pain, antitussive (cough suppressant), and anesthetic are therapeutic uses of Buprenorphine.
• Naloxone is used for small animals.
• Naltrexone is used for reversal of sedation and respiratory depression in wildlife and large animals.
• Naltrexone has no affinity for the opioid receptor.
• Amantadine, Ketamine, Gabapentin, Amitriptyline, and Lidocaine patch are non-opioid analgesic drugs used for analgesic purposes in dogs, cats, and other animals.
• Buprenorphine has a partial degree of affinity for the opioid receptor.
• Buprenorphine is used for acute pain, antitussive (cough suppressant), and anesthetic purposes in small animals.
• Nalbuphine is used for dogs, cats, and other small animals.
• Acetaminophen (Tylenol), Ibuprofen, and Aspirin are non-opioid analgesic drugs used to reduce swelling, stiffness, joint pain caused by inflammation.
• Nalbuphine is more potent than Buprenorphine and has a degree of affinity for the opioid receptor.
• In the respiratory system, opioids can cause decreased respiration and tidal volume (μ-receptor agonists), decreased PaO2 and PaCO2 (partial pressure of O2 and CO2), and a ceiling effect with some agents.