Opioid analgesics & antogonists

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Opioid analgesics & antogonists

  1. 1. Opioid Analgesic Agents
  2. 2. Analgesics <ul><li>Medications that relieve pain without causing loss of consciousness </li></ul><ul><li>Painkillers </li></ul>
  3. 3. Classification of Pain By Onset and Duration <ul><li>Acute pain </li></ul><ul><ul><li>Sudden in onset </li></ul></ul><ul><ul><li>Usually subsides once treated </li></ul></ul><ul><li>Chronic pain </li></ul><ul><ul><li>Persistent or recurring </li></ul></ul><ul><ul><li>Often difficult to treat </li></ul></ul>
  4. 4. Classification of Pain <ul><li>Somatic </li></ul><ul><li>Visceral </li></ul><ul><li>Superficial </li></ul><ul><li>Vascular </li></ul><ul><li>Referred </li></ul><ul><li>Neuropathic </li></ul><ul><li>Phantom </li></ul><ul><li>Cancer </li></ul><ul><li>Psychogenic </li></ul><ul><li>Central </li></ul>
  5. 5. Classification of Pain By Source <ul><li>Vascular pain </li></ul><ul><li>Possibly originates from vascular or perivascular tissues </li></ul><ul><li>Neuropathic pain </li></ul><ul><li>Results from injury to peripheral nerve fibers or damage to the CNS </li></ul><ul><li>Superficial pain </li></ul><ul><li>Originates from skin or mucous membranes </li></ul>
  6. 6. Pain Transmission Gate Theory <ul><li>Most common and well-described </li></ul><ul><li>Uses the analogy of a gate to describe how impulses from damaged tissues are sensed in the brain </li></ul>
  7. 7. Pain Transmission <ul><li>Tissue injury causes the release of: </li></ul><ul><li>Bradykinin </li></ul><ul><li>Histamine </li></ul><ul><li>Potassium </li></ul><ul><li>Prostaglandins </li></ul><ul><li>Serotonin </li></ul><ul><ul><li>These substances stimulate nerve endings, starting the pain process. </li></ul></ul>
  8. 8. Pain Transmission <ul><li>There are two types of nerves stimulated: </li></ul><ul><li>“ A” fibers </li></ul><ul><li>and </li></ul><ul><li>“ C” fibers </li></ul>
  9. 9. Pain Transmission <ul><li>“ A” Fibers “C” Fibers </li></ul><ul><li>Myelin sheath No myelin sheath </li></ul><ul><li>Large fiber size Small fiber size </li></ul><ul><li>Conduct fast Conduct slowly </li></ul><ul><li>Inhibit pain Facilitate pain transmission transmission </li></ul><ul><li>Sharp and Dull and well-localized nonlocalized </li></ul>
  10. 10. Pain Transmission <ul><li>Types of pain related to proportion of “A” to “C” fibers in the damaged areas </li></ul>
  11. 11. Pain Transmission <ul><li>These pain fibers enter the spinal cord and travel up to the brain. </li></ul><ul><li>The point of spinal cord entry is the DORSAL HORN. </li></ul><ul><li>The DORSAL HORN is the location of the “GATE.” </li></ul>
  12. 12. Pain Transmission <ul><li>This gate regulates the flow of sensory impulses to the brain. </li></ul><ul><li>Closing the gate stops the impulses. </li></ul><ul><li>If no impulses are transmitted to higher centers in the brain, there is NO pain perception. </li></ul>
  13. 13. Pain Transmission <ul><li>Activation of large “A” fibers CLOSES gate </li></ul><ul><li>Inhibits transmission to brain </li></ul><ul><ul><li>Limits perception of pain </li></ul></ul>
  14. 14. Pain Transmission <ul><li>Activation of small “B” fibers OPENS gate </li></ul><ul><li>Allows impulse transmission to brain </li></ul><ul><ul><li>Pain perception </li></ul></ul>
  15. 15. Pain Transmission <ul><li>Gate innervated by nerve fibers from brain, allowing the brain some control over gate </li></ul><ul><li>Allows brain to: </li></ul><ul><ul><li>Evaluate, identify, and localize the pain </li></ul></ul><ul><ul><li>Control the gate before the gate is open </li></ul></ul>
  16. 16. Pain Transmission <ul><li>“ T” cells </li></ul><ul><li>Cells that control the gate have a threshold </li></ul><ul><li>Impulses must overcome threshold to be sent to the brain </li></ul>
  17. 17. Pain Transmission <ul><li>Body has endogenous neurotransmitters </li></ul><ul><ul><li>Enkephalins </li></ul></ul><ul><ul><li>Endorphins </li></ul></ul><ul><li>Produced by body to fight pain </li></ul><ul><li>Bind to opioid receptors </li></ul><ul><li>Inhibit transmission of pain by closing gate </li></ul>
  18. 18. Pain Transmission <ul><li>Rubbing a painful area with massage or liniment stimulates large sensory fibers </li></ul><ul><li>Result: </li></ul><ul><ul><li>GATE closed, recognition of pain REDUCED </li></ul></ul><ul><ul><li>Same pathway used by opiates </li></ul></ul>
  19. 19. Opioid Analgesics <ul><li>Pain relievers that contain opium, derived from the opium poppy </li></ul><ul><li>or </li></ul><ul><li>chemically related to opium </li></ul><ul><ul><li>Narcotics: very strong pain relievers </li></ul></ul>
  20. 20. Opioid Analgesics <ul><li>codeine sulfate </li></ul><ul><li>meperidine HCl (Demerol) </li></ul><ul><li>methadone HCl (Dolophine) </li></ul><ul><li>morphine sulfate </li></ul><ul><li>propoxyphene HCl </li></ul>
  21. 21. Opioid Analgesics <ul><li>Three classifications based on their actions: </li></ul><ul><li>Agonist </li></ul><ul><li>Agonist-antagonist </li></ul><ul><li>Partial agonist </li></ul>
  22. 22. Opioid Analgesics: Site of action <ul><li>Large “A” fibers </li></ul><ul><li>Dorsal horn of spinal cord </li></ul>
  23. 23. Opioid Analgesics: Mechanism of Action <ul><li>Bind to receptors on inhibitory fibers, stimulating them </li></ul><ul><li>Prevent stimulation of the GATE </li></ul><ul><li>Prevent pain impulse transmission to the brain </li></ul>
  24. 24. Opioid Analgesics: Mechanism of Action <ul><li>Three types of opioid receptors: </li></ul><ul><li>Mu </li></ul><ul><li>Kappa </li></ul><ul><li>Delta </li></ul>
  25. 25. Opioid Analgesics: Therapeutic Uses <ul><li>Main use: to alleviate moderate to severe pain </li></ul><ul><li>Opioids are also used for: </li></ul><ul><ul><li>Cough center suppression </li></ul></ul><ul><ul><li>Treatment of constipation </li></ul></ul>
  26. 26. Opioid Analgesics: Side Effects <ul><li>Euphoria </li></ul><ul><li>Nausea and vomiting </li></ul><ul><li>Respiratory depression </li></ul><ul><li>Urinary retention </li></ul><ul><li>Diaphoresis and flushing </li></ul><ul><li>Pupil constriction (miosis) </li></ul><ul><li>Constipation </li></ul>
  27. 27. Opiate Antagonists <ul><li>naloxone (Narcan) </li></ul><ul><li>naltrexone (Revia) </li></ul><ul><li>Opiate antagonists </li></ul><ul><li>Bind to opiate receptors and prevent a response </li></ul><ul><ul><li>Used for complete or partial reversal of opioid-induced respiratory depression </li></ul></ul>
  28. 28. Opiates: Opioid Tolerance <ul><li>A common physiologic result of chronic opioid treatment </li></ul><ul><li>Result: larger dose of opioids are required to maintain the same level of analgesia </li></ul>
  29. 29. Opiates: Physical Dependence <ul><li>The physiologic adaptation of the body to the presence of an opioid </li></ul>
  30. 30. Opiates: Psychological Dependence (addiction) <ul><li>A pattern of compulsive drug use characterized by a continued craving for an opioid and the need to use the opioid for effects other than pain relief </li></ul>
  31. 31. Opiates <ul><li>Opioid tolerance and physical dependence are expected with long-term opioid treatment and should not be confused with psychological dependence (addiction). </li></ul>
  32. 32. Opiates <ul><li>Misunderstanding of these terms leads to ineffective pain management and contributes to the problem of undertreatment. </li></ul>
  33. 33. Opiates <ul><li>Physical dependence on opioids is seen when the opioid is abruptly discontinued or when an opioid antagonist is administered. </li></ul><ul><ul><li>Narcotic withdrawal </li></ul></ul><ul><ul><li>Opioid abstinence syndrome </li></ul></ul>
  34. 34. Opiates <ul><li>Narcotic Withdrawal Opioid Abstinence Syndrome </li></ul><ul><li>Manifested as: </li></ul><ul><ul><li>anxiety, irritability, chills and hot flashes, joint pain, lacrimation, rhinorrhea, diaphoresis, nausea, vomiting, abdominal cramps, diarrhea </li></ul></ul>
  35. 35. Opioid Analgesics: Nursing Implications <ul><li>Before beginning therapy, perform a thorough history regarding allergies, use of other medications,health history, and medical history. </li></ul><ul><li>Obtain baseline vital signs and I & O. </li></ul><ul><li>Assess for potential contraindications and drug interactions. </li></ul>
  36. 36. Opioid Analgesics: Nursing Implications <ul><li>Perform a thorough pain assessment, including nature and type of pain, precipitating and relieving factors, remedies, and other pain treatments. </li></ul><ul><ul><li>Assessment of pain is now being considered a “fifth vital sign.” </li></ul></ul>
  37. 37. Opioid Analgesics: Nursing Implications <ul><li>Be sure to medicate patients before the pain becomes severe as to provide adequate analgesia and pain control. </li></ul><ul><li>Pain management includes pharmacologic and nonpharmacologic approaches. Be sure to include other interventions as indicated. </li></ul>
  38. 38. Opioid Analgesics: Nursing Implications <ul><li>Oral forms should be taken with food to minimize gastric upset. </li></ul><ul><li>Ensure safety measures, such as keeping side rails up, to prevent injury. </li></ul><ul><li>Withhold dose and contact physician if there is a decline in the patient’s condition or if VS are abnormal—especially if respiratory rate is below 12 breaths/minute. </li></ul>
  39. 39. Opioid Analgesics: Nursing Implications <ul><li>Follow proper administration guidelines for IM injections, including site rotation. </li></ul><ul><li>Follow proper guidelines for IV administration, including dilution, rate of administration, and so forth. </li></ul><ul><ul><li>CHECK DOSAGES CAREFULLY </li></ul></ul>
  40. 40. Opioid Analgesics: Nursing Implications <ul><li>Constipation is a common side effect and may be prevented with adequate fluid and fiber intake. </li></ul><ul><li>Instruct patients to follow directions for administration carefully, and to keep a record of their pain experience and response to treatments. </li></ul><ul><li>Patients should be instructed to change positions slowly to prevent possible orthostatic hypotension. </li></ul>
  41. 41. Opioid Analgesics: Nursing Implications <ul><li>Patients should not take other medications or OTC preparations without checking with their physician. </li></ul><ul><li>Instruct patients to notify physician for signs of allergic reaction or adverse effects. </li></ul>
  42. 42. Opioid Analgesics: Nursing Implications <ul><li>Monitor for side effects: </li></ul><ul><li>Should VS change, patient’s condition decline, or pain continue, contact physician immediately. </li></ul><ul><li>Respiratory depression may be manifested by respiratory rate of less than 12/min, dyspnea, diminished breath sounds, or shallow breathing. </li></ul>
  43. 43. Opioid Analgesics: Nursing Implications <ul><li>Monitor for therapeutic effects: </li></ul><ul><li>Decreased complaints of pain </li></ul><ul><li>Increased periods of comfort </li></ul><ul><li>With improved activities of daily living, appetite, and sense of well-being </li></ul>

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