Chapter 6 Drugs for Pain Control

6 Drugs for Pain Control Educational Objectives After reading this chapter, the reader should be able to: 1. Discuss the concepts of dental pain. 2. Discuss the commonly used pharmacological agents used for the treatment of orofacial pain. 3. Identify drugdrug interactions that pertain to dental treatment. 4. Describe the classification of narcotic analgesics. 5. Discuss when a narcotic versus a nonnarcotic analgesic is indicated for dental patients. 6. Discuss screening methods to detect potential patients with a chemical dependency. Lecture Outline I. Assessment and Classification of Pain A. Pain. 1. Definition. 2. Components. a. Sensory. b. Reaction. B. Classifications. 1. Nociceptive pain. a. Acute. b. Types. i. Pulpitis. ii. Abscess. iii. Pericoronitis. iv. Postsurgery. (a) Extractions. (b) Periodontal surgery. (c) Surgery for orthodontics. c. Nociceptors. d. Noxious stimuli. e. Tissue damage. f. Normal pain in response to injury. g. Blocking nociceptors. h. Management. i. NSAIDs. ii. Narcotics. 2. Neuropathic pain. a. Chronic. b. Features. i. No biological function. ii. Leads to depression. iii. No specific receptors. c. Types: i. Orofacial neuralgias: Trigeminal neuralgia, tic douloureux. ii. Postherpetic neuralgia. iii. Diabetic peripheral neuropathy. iv. Carpal tunnel syndrome. v. Oral dysesthesia (burning mouth), problem for diabetics. d. Management. i. Antidepressants. II. Nonnarcotic Analgesics, mild-to-moderate pain A. Action. 1. Nociceptor level. 2. COX-1 and COX-2 enzymes. 3. Prostaglandins. 4. Thromboxane A2. B. Aspirin. 1. Ceiling effect. 2. Low dose. a. Antiplatelet effect, thromboxane A2. b. Stroke prevention. c. More effective in inhibiting cox-1 than cox-2. 3. Reye’s syndrome. 4. Indications. 5. Adverse reactions (e.g., drug interactions). 6. Contraindications. C. Other nonnarcotic analgesics, acetaminophen. 1. Liver toxicity. 2. Alcohol. 3. Antidote for overdose, acetylcysteine (Mucomyst). III. Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) A. Used for pain associated with inflammation. B. Selective COX-2 inhibitors. C. Adverse effects. 1. GI bleeding. 2. Drugdrug interactions (e.g., antihypertensive agents [e.g., ACE inhibitors]). 3. Drugherbal interactions (e.g., increased bleeding). IV. Narcotic Analgesics (Opioids) A. Analgesics used for severe pain. B. Classification of Opioids 1. Natural substance. 2. Synthetic morphine-like substance. 3. Opioid agonist. a. Stimulates mu and kappa receptors. b. Morphine. 4. Opioid agonistantagonist. a. Stimulates kappa receptors. b. Block mu receptors. c. Pentazocine (Talwin). 5. Opioid antagonist. a. Blocks mu and kappa receptors. b. Naloxone (Narcan). 6. Adverse effects. 7. Avoid dependence. V. Substance Abuse and Dependence A. Definitions. B. Treatments. VI. Management of Orofacial Pain A. Antidepressants. 1. Amitriptyline. B. Anti-epileptic. 1. Carbamazepine. 2. Gabapentin (Neurontin). 3. Pregablin (Lyrica). C. Lidocaine patch. D. Calcium channel blockers. Teaching Tips 1. Impress upon the students that patients may abuse many narcotic analgesics. 2. Explain the importance of knowing about the cyclooxygenase enzymes and their relationship to homeostasis and inflammation. 3. Stress the importance of learning the concepts of dental pain. 4. Stress the importance of learning common drug interactions that occur with NSAIDs, especially with antihypertensive medications. 5. Explain the importance of learning about the different analgesics used for pain management. Factoids 1. Sears Roebuck & Company started the first prescription mail-order service in the early 1900s. Alcoholism was treated with the “white secret cure,” a mixture that contained opium. The “opium habit” was cured with a cordial that was 40 proof! The mail-order business ended by 1907. The first “Coke-cola” also had a secret white ingredient. 2. The leading cause of acute liver failure in the United States is acetaminophen overdose. Discussion Questions 1. Discuss the important adverse side effects that can occur with analgesics. 2. Discuss pain concepts. 3. Discuss the classification of orofacial pain. 4. Review the various drugs used to manage orofacial pain. 5. Discuss the prostaglandin synthesis pathway and the development of pain. Classroom Activities 1. Divide the class into small groups. Assign each group to research the pharmacology of an analgesic drug. Allow time to present in class. 2. Have students write patient instruction sheets for some of the common narcotic and nonnarcotic analgesics (e.g., codeine, hydrocodone/acetaminophen, ibuprofen, aspirin). Include indication, adverse effects, drugdrug interactions, and how to take the medicine (e.g., take with food and a full glass of water to avoid GI upset and complications). 3. Make a list of analgesics and have students classify each drug as a nonnarcotic or narcotic. 4. Have students draw the prostaglandin/leukotriene synthesis pathway and indicate where NSAIDs and narcotic analgesics work. 5. Have the students discuss drugs that are used in the management of patients with orofacial pain (e.g., antiseizure drugs, antidepressants). Multimedia Found in the PowerPoint Lecture OutlineAnimations 1. Morphine mechanism of action. 2. Naproxen mechanism of action. 3. Acetaminophen mechanism of action. 4. Oxycodone mechanism of action. © 2013 by Education, Inc. Weinberg, Instructor’s Resource Manual for Oral Pharmacology for the Dental Hygienist, 2nd Edition