Drugs For the Control of Pain Chapter 18

1. Drugs For the Control of Pain Chapter 18

2. OVERVIEW: Neuro System escitalopram (Lexapro) Tri-Cyclic Antidepressant Antidepressant / Anxiolytic MAOIs Benzodiazepines lorazepam (Ativan) diazepam (Valium) GABA Antagonist zolpidem (Ambien) A phenytoin (Dilantin) valproic acid (Depakote) Phenytoin-Like Drugs Succinimides ethosuximide (Zarontin) phenobarbital (Luminal) Barbiturates Phenothiazines chlorpromazine (Thorazine) Non-Phenothiazines halperidol (Haldol) Opioids morphine (Infumorph) Atypical Antipsychotics risperidone (Risperdal) aspirin (ASA) Salicylates ibuprofen (Motrin) NSAIDs acetaminophen (Tylenol) Non-Opioid tramadol (Ultram) Central Acting ergotamine (Cafergot) Sumatriptan (Imitrex) Anti-Migraine Opioid Antagonists naloxone (Narcan)

3. Pain Assessment Subjective experience for clients Numerical scales and surveys assist in assessment. Effective pharmacotherapy depends on Assessment of degree of pain Determining underlying disorders

4. Acute Pain Intense Defined period of time

5. Chronic Pain Over six months’ duration Interferes with daily activities

6. Nociceptive Pain Due to injury to tissues Sharp, localized Dull, throbbing, aching

7. Neuropathic Pain Due to injury to nerves Burning, shooting, numbing

8. Pain Transmission Nociceptor stimulation Spinal cord receives pain impulse through ∂ fibers – believed to signal sharp, well-defined pain C fibers – believed to conduct dull, poorly localized pain

9. Endogenous Opioids May modify sensory information, interrupting pain transmission Endorphins, dynorphins, ekaphalins

10. Interruption of Pain Transmission Several target areas Peripheral level CNS level Pharmacological Nonpharmacological

11. Nonpharmacologic Techniques for Pain Management Used alone or in conjunction with pharmacotherapy May allow for lower doses and possibly fewer drug-related adverse effects

12. Nonpharmacological Therapies Acupuncture Biofeedback Massage; therapeutic or physical touch Heat or cold Meditation or prayer Relaxation Art or music therapy Chiropractic manipulation Hypnosis TENS Energy therapies such a Reiki and Qi gong

13. Treatment for Intractable Cancer Pain Radiation or chemotherapy Relieving nerve stimulation Surgery Nerve block

14. Opioids A natural or synthetic morphine-like substance responsible for reducing moderate to severe pain

15. Opioid Receptors • Receptors: mu, kappa, sigma, delta, epsilon • For pain management mu and kappa receptors are most important • Opioid agonist drugs: stimulate receptors • Opioid antagonist drugs: block receptors

17. Figure 18.2 Opioid receptors

18. Opioid Antagonists • Block opioid activity • Compete for opioid receptor • Reverse symptoms of addiction, toxicity, and overdose • Naxalone (Narcan) may be used to reverse respiratory depression and other acute symptoms • Also used to diagnose overdose

19. Opioid Dependence Potential to cause physical and psychologic dependence Patient-controlled analgesia (PCA) Combinations with nonnarcotic analgesics

20. Treatment for Opioid Dependence Switch from IV and inhalation forms to methadone, the oral form Methadone maintenance Does not cure but avoids withdrawal symptoms Treatment may continue for many months and years

21. Newer Treatment Early treatment: buprenorphine (Subutex) Mixed opioid agonist-antagonist Sublingual route Later maintenance: Suboxone

22. Role of Nurse Careful monitoring of client’s condition Providing education Obtaining medical history Obtaining list of allergies Assessing client’s pain level Obtaining history of medications and alcohol and CNS-depressant use

23. Opioid Therapy Assess potential for opioid dependency Have narcotic antagonists available to reverse negative effects Assist with activity Monitor urine output for retention Monitor client’s bowel habits for constipation

24. Opioid Antagonist Therapy Continue careful monitoring of client’s condition Especially respiratory status Have resuscitative equipment available

25. Nonopioid Analgesics Careful monitoring of client’s condition and providing education is necessary Thorough assessment for hypersensitivity, bleeding disorders Through assessment for gastric ulcers, severe renal/hepatic disease, pregnancy

26. Nonopioid Analgesics (continued) Obtain laboratory tests on renal and liver function Pain assessment Monitor for side effects

27. Opioid (Narcotic) Analgesic Prototype drug: Opioid agonists (morphine) Mechanism of action: interacts with mu and kappa receptor sites Primary use: for analgesia and anesthesia Adverse effects: respiratory depression, sedation, nausea, and vomiting

29. Table 18.2 (continued) Opiods for Pain Management

31. Morphine Animation Click here to view an animation on the topic of morphine.

32. Opioid Antagonists Prototype drug: naloxone (Narcan) Mechanism of action: interact with receptors Primary use: to reverse respiratory depression and other acute symptoms of opioid addiction, toxicity, overdose

34. Opioids with Mixed Agonist-Antagonist Activity Example: Talwin Stimulate opioid receptor, thus causing analgesia Withdrawal symptoms and side effects not as intense as those of opioid agonists

35. Salicylates Prototype drug: aspirin (ASA) Mechanism of action: as anticoagulant, antipyretic, anti-inflammatory, and analgesic Adverse effects: with high doses may cause GI distress and bleeding May increase action of oral hypoglycemic agents

37. Nonsteroidal Anti-inflammatory Drugs (NSAIDs) Prototype drug: ibuprofen (Motrin) Mechanism of action: to inhibit cyclooxygenase and prevent formation of prostaglandins Primary use: for mild or moderate pain and to reduce inflammation Adverse effects: GI upset, acute renal failure

38. Selective Cox-2 Inhibitors Prototype drug: celecoxib (Celebrex) Mechanism of action: is similar to the NSAIDs Primary use: to relieve pain, fever, inflammation Adverse effects: mild and related to GI system

39. Nonopioid Analgesics Prototype drug: acetaminophen (Tylenol) Mechanism of action: to treat fever: at the level of the hypothalamus and causes dilation of peripheral blood vessels enabling sweating and dissipation of heat Primary use: treatment of fever and to relieve pain Adverse effects: uncommon with therapeutic doses

40. Acetaminophen Animation Click here to view an animation on the topic of acetaminophen.

42. Table 18.3 (continued) Nonopioid Analgesics

43. Centrally Acting Agents Prototype drug: tramadol (Ultram) Mechanism of action: has weak opioid activity Primary use: as centrally acting analgesic Adverse effects can include: CNS, GI, CV and dermatologic effects

44. Ergot Alkaloids Mechanism of action: to promote vasoconstriction Primary use: to terminate ongoing migraines Adverse effects: GI upset, weakness in the legs, myalgia, numbness and tingling in fingers and toes, angina-like pain, tachycardia

45. Triptans Prototype drug: sumatriptan (Imitrex) Mechanism of action: to act as serotonin agonists, constricting certain intracranial vessels Primary use: to abort migraines with or without auras Adverse effects: GI upset

47. Table 18.4(continued) Antimigraine Drugs

49. Opioid Agonists Mechanism of action: to interact with specific receptors Primary use: to relieve moderate to severe pain; some used for anesthesia Examples: OxyContin, Percocet

50. Opiod Antangonists • Blockers of opioid activity • Used to reverse symptoms of opioid addiction, toxicity, overdose • Examples: Revex, Narcan, Trexan