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PAIN MANAGEMENT Opioids, NSAIDs, Migraine drugs

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1 PAIN MANAGEMENT Opioids, NSAIDs, Migraine drugs
NURS 203, Pharmacology I Dr. Nolan

2 PAIN Most common complaint leading people to seek healthcare
Can be acute or chronic Acute – less than ~3 months duration Chronic – 3 months or longer

3 TYPES OF PAIN ACUTE CHRONIC (longer than 3 months) CANCER PAIN
SOMATIC PAIN VISCERAL PAIN NEUROPATHIC PAIN

4 Types of Pain Cancer Somatic Visceral Can be acute or chronic
Localized to a certain area (bone, muscle, skin…) Can be acute (injury) or chronic (arthritis) Visceral Not localized, harder to define Nociceptors in internal organs are stimulated (hepatitis, pancreatitis…) Dull, aching, cramping, deep pain

5 Types of Pain Neuropathic
Perpheral pain receptors or nerves, damaged or dysfunctional Excessive excitability in these areas, leading to exaggerated pain response Diabetic neuropathy, herpes zoster (Shingles, post- herpetic neuralgia) Not as responsive to normal analgesics

6 Pain Physiology Tissue damage stimulates peripheral pain receptors – nociceptors Signal transmitted to spinal cord (ascending pathway) – hypothalamus – cerebral cortex A-delta fibers : acute, “fast” pain C fibers : slow, poorly localized pain Descending pathway – inhibitory pathway, includes endogenous opioids, norepinephrine and serotonin to suppress nociceptive transmission of pain impulse via substance P

7 Neural pathways for pain.
Opioid receptors at spinal cord are stimulated by both endogenous opioids, neurotrans serotonin/norepinephrine, and by exogenous opioids (MS). These then block the ascending pathway to the brain for pain. Also they alter perception of pain in the brain. Substance P is the neurotransmitter that sends on pain messages-opioids inhibit its release

8 Pain Treatment - Analgesics
Opioids Non Opioids NSAIDs Tramadol Acetaminophen Antidepressants, antiepileptics Neuropathic pain CNS vasoconstrictors Migraine pain

9 Review Question Which of the following drugs does not have a “ceiling” dose? A) acetaminophen B) ibuprofen C) aspirin D) morphine E) all of the above have ceiling doses that should not be exceeded

10 Opioid Analgesics – general characteristics
Relieve moderate to severe pain by inhibiting pain signal transmission from periphery to brain. Well absorbed with PO, IM, SQ administration. Metabolized in liver, metabolites excreted in urine. Liver or Renal impairment can interfere with metabolism or excretion.

11 Opioids - widespread pharmacological effects
CNS Analgesia CNS depression Respiratory depression Pupil constriction GI Slows motility Constipation N/V Bowel and Biliary spasm

12 Opioids Potent analgesics for moderate to severe pain
Acute and chronic pain best for nociceptive pain Not generally effective for non-nociceptive pain (neuropathic) Serious side effects No ceiling dose chronic use universally leads to tolerance, physical dependence, may lead to addiction tolerance leads to high doses in patients treated long term with opioids that could kill opioid naïve patients

13 Opioids – Mechanism of Action
Stimulate Mu and Kappa receptors Mu Analgesia, ↓ gastric motility, sedation, respiratory depression, euphoria, physical dependence Kappa Analgesia, ↓ gastric motility, sedation Mixed agonist/antagonists stimulate one, antagonize the other Antagonists antagonize both (block opioids from binding to receptor or displace) naloxone

14 Opioids – Mechanism of Action
Binding to Mu and Kappa receptors slows the transmission of pain impulses between cells in the periphery, spine, and brain Stimulating Mu and Kappa receptors activates the endogenous analgesia system Endorphins, etc. act on receptors same as exogenous (narcotic) agents

15 Mu and Kappa are the primary opioid receptors on cells.
Pure agonists like morphine, oxycodone, hydromorphone stimulate both Mu and Kappa. Mixed agonist/antanonists stimulate one receptor but block the other. This results in somewhat lower efficacy but can reduce dependence and side effects to some degree. Examples: buprenophine, butorphanol, pentazocine Antanonists block or displace opioid from both receptors, used for overdose. Naloxone.

16 Opioids –Effects Analgesia Sedation, CNS depression (life threatening)
Respiratory depression (life threatening) Constipation Euphoria Nausea/vomiting Dependence Tolerance Miosis

17 Opioids - widespread pharmacological effects
CNS Analgesia CNS depression Respiratory depression miosis GI Slows motility Constipation N/V Bowel and Biliary spasm

18 Opioids - Pharmacokinetics
Well absorbed orally, and via SQ, IM, and IV Metabolized hepatically Excreted via urine Liver or renal disease can inhibit clearance or efficacy T1/2 can range from minutes (IV) to days (fentanyl patch)

19 Opioids – indications Before, during, after surgery
To provide pain relief, sedation, ↓anxiety Acute and chronic pain control, outpatient there is limited data on the safety and efficacy of treating chronic pain with opioids significant safety concerns Pain/anxiety reduction for various procedures

20 Opioids – contraindications/cautions
Respiratory depression, lung disease Hepatic/renal dysfunction Increased intracranial pressure Allergy (true allergy)

21 Morphine Opioid agonist (primarily acts on Mu receptor)
Named after the Greek God of dreams, Morpheus Prototype opioid analgesic DEA Schedule II (DEA CII) Given PO, SL, PR, TD, SC, IM, IV, IT, PCA pump

22 Morphine Maximal analgesia and resp depression within:
10-20 min IV 30 min IM 60-90 min SC 60 min orally (IR). ER forms are QD or BID Duration is 5-7 hours (PO ER ~ hours)

23 Morphine - Pharmacokinetics
T1/2 is about 7 hours Metabolites accumulate in pts with renal/hepatic dysfunction, must reduce dose 30% bound to plasma proteins, extensive first pass metabolism So PO doses considerably higher than Inj doses

24 Morphine – Some specific uses
moderate to severe pain procedure related anxiety/pain MI related pain Pulmonary edema why? Morphine is sometimes used in the setting of pulmonary edema to relieve anxiety and aid in breathing, and is also a non-specific vasodilator (related to it’s pro-histamine effects). Some practitioners question the risk/benefit of this use, given safer alternatives and risk of respiratory depression exacerbating the condition

25 Morphine – Some cautions
head trauma – increased intracranial pressure long acting agents with short acting procedures respiratory depression can manifest after procedure

26 Morphine – Side Effects
Profound sedation/CNS depression Constipation, N/V at least 41% incidence of constipation with chronic opioids in 2000 study, 95% of patients interviewed by nurses in a hospital oncology unit reported constipation as the major side effect of their pain therapy Resp depression, decreased breath sounds Encourage deep breathing, coughing Hypotension Physical dependence Paradoxical CMS stimulation and insomnia

27 Morphine – availability
24 hour controlled release Kadian, Avinza BID-TID controlled release MS Contin, Oramorph Q4-6h immediate release MSIR Liquid MS oral solution, 10mg/5ml, 20mg/5ml, 100mg/5ml (concentrated) Embeda (morphine/naltrexone) naltrexone inactive unless crushed

28 Morphine administration
Embeda, Kadian, Avinza caps can be opened and sprinkled immed. prior to oral admin. DON’T chew the pellets! IM vs. SQ for repeated doses to reduce tissue irritation Don’t administer IV too quickly to avoid excessive sedation and RR depression 2.5mg to 15mg over 5 minutes PO vs parenteral doses TYPICAL DOSE: ORAL 30mg Q4h IV/IM 5-10mg q4h

29 Morphine important points
Breakthrough pain Continuous infusion or SR forms will need short acting bolus or tablets for breakthrough pain HIGH ALERT periodically monitor RR, BP caution if RR<10 Placebo effect Explain the therapeutic effect to the patient Suggestions of efficacy are often very effective in increasing analgesia Don’t let pain get severe opioids are more effective in maintaining analgesia if pain doesn’t become severe

30 Morphine important points
Watch the concentration DON’T confuse 20mg/5mL with 20mg/mL 20mg/mL liquid should be given via oral syringe Bowel function Bowel habits should be documented before beginning opioid therapy assess periodically, daily if constipation. Administer docusate and stimulant laxatives (senna, bisacodyl) on a regular basis if tx exceeds a few days bulk forming may lead to impaction, especially in palliative care watch for confounding drugs (anticholinergics) and dehydration

31 Morphine important points
Don’t crush, break, chew, or dissolve sustained release (SR), controlled release (CR), or extended release (ER) dosage forms! rapid release of entire day’s dose an result in opioid overdose

32 Fentanyl CII, Potent opioid agonist
Available as IV, patch, SL tablet & film IM/IV Used pre, during, post surgery analgesic supplement for general anesthesia Same cautions apply as for morphine head trauma profound sedation, RR depression… Dosed in micrograms (mcg), caution!

33 Fentanyl Patch Duragesic (fentanyl patch) for chronic pain in opioid tolerant pts NOT for post-op pain, intermittent pain, or short term pain 92% absorbed through skin Dosed every 72 hours take about 20 hours for the serum conc to reach one half after removal of patch steady state and maximal analgesia reached by end of second patch application Comes as mcg/hr patches (eg. 50mcg/hr)

34 Fentanyl transmucosal
short acting, for breakthrough cancer pain in opioid tolerant pts (Actiq, Fentora) opioid tolerant means equivalent of 60mg/day morphine Buccal film about half absorbed through muscoa, the other half swallowed swallowed fentanyl is ~20% bioavailable Transmucosal tablets, lozenge (lollipop), and nasal spray also available these products are NOT interchangeable on a per dose basis Exercise extreme caution if children in the household! rapidly fatal watch for partially used discarded “pops”

35 Other opioids Embeda (morphine/naltrexone)
intended use is to prevent abuse combines microencapsulated naltrexone core to morphine sulfate beads inside capsule only crushing, chewing, or dissolving will release the naltrexone to attenuate the euphoric effects of the morphine very expensive compared to morphine sulfate

36 Other opioids Oxycodone (OxyContin) – CII Hydrocodone (Vicodin) – CIII
IR and CR dosage forms “Oxy’s” became a common street drug, selling for over $100 per tablet Can be combined with APAP (Percocet) or ASA (Percodan) Hydrocodone (Vicodin) – CIII Similar to codeine in use and efficacy Combined with APAP

37 Other opioids Hydromorphone (Dilaudid, Exalgo) - CII
PO, PR, SC, IM, IV More potent than morphine, ↑efficacy PO vs morphine Oxymorphone (Opana) Derivative of morphine, similar characteristics Methadone (Dolophine) Synthetic form of morphine longer DOA (T1/2 30h +)

38 Other opioids Propoxyphene (Darvon, Darvocet) - CIV
Least effective opioid out there No more effective than APAP, but causes sedation and resp depression like other opiates Toxic metabolite (norpropoxyphene) can accumulate and cause arrhythmias, pulmonary edema, apnea, and CV events. Often used in suicides Should be avoided in kids, older adults Banned in Britain and many other countries but continues to be prescribed in U.S. UPDATE: FDA just asked for withdrawal of propoxyphene from US market

39 Review question Proper administration of an ordered narcotic
A) can lead to addiction B) should be done promptly to prevent increased pain and the need for larger doses C) would include holding the drug as long as possible until the patient really needs it D) should rely on the patient’s request for medication

40 Other opioids Meperidine (Demerol) - CII
Synthetic derivative of morphine Despite some opinions, meperidine has not shown any benefit beyond other opioids for biliary colic, pancreatitis, labor, or migraine. Does help with drug induced rigors, anesthesia related shivering Toxic metabolite, normeperidine, limits it’s use Accumulates with chronic use (>2 days), renal dysfunction Very long T1/2, not reversible with naloxone Causes seizures, hallucinations, agitation Naloxone will reverse effects of meperidine, leaving normeperidine unopposed – risk of seizures! Use > 2 days not appropriate

41 Other opioids Meperidine (Demerol) - CII Drug interactions
serotonin syndrome increased risk of MAO-I interactions and any serotonergic drug, including triptans serotonin reuptake inhibition

42 Other opioids Nucynta (tapentadol) CII MOA Dosing Monitoring
Opioid agonist (not as potent as morphine) Norepinephrine reuptake inhibitor (NRI) acts on decending pathway Dosing IR and ER forms available 600mg max daily dose. Why? Monitoring CNS/RR depression seizures, tachycardia, BP changes especially in patients taking antidepressants Side effects same as other opioids, but ~20% reduced incidence of GI S/E NOT totally reversed by naloxone

43 Other opioids Tramadol (Ultram, Ultracet, Ryzolt)
Not related to opioids chemically About as effective as Tyl#3 (codeine + APAP) MOA: binds to Mu receptor, SNRI Very little resp. depression, risk of dependence Well tolerated, good for older folks

44 Opioid Morphine (reference) 30mg Codeine 200mg Fentanyl transdermal
MED for Selected Opioids Opioid Approximate Equianalgesic dose (oral & transdermal) * Morphine (reference) 30mg Codeine 200mg Fentanyl transdermal 12.5mcg/hr Hydrocodone Hydromorphone 7.5mg Methadone Chronic: 4mg Oxycodone 20mg Oxymorphone 10mg

45 Opioid antagonists Block binding to opioid receptors, and can displace opioids bound there Used for quick reversal of opioid toxicity/overdose Reverses analgesia and CNS/resp. depression Naloxone (Narcan), naltrexone (ReVia, Vivitrol) Naloxone works within minutes of injection (SC, IM, IV) Short DOA (1-2h), may need to be repeated

46 Naloxone (Narcan) For suspected narcotic OD Give IVP over 10-15 sec
0.4mg – 2mg Repeat q 2-3 min if needed, up to total 10mg If no effect at 10mg, probably not narcotic OD No effect in the absence of opioids in system Caution if suspected chronic opioid user, will precipitate immediate withdrawal

47 Naloxone vs. Naltrexone
short acting competitive opioid antagonis given parenterally, only 2% bioavailable PO Used exclusively to reverse opioid intoxication Naltrexone given PO (Revia) and IM (Vivitrol) to treat alcohol dependence (main use) and opioid dependence (not very effective) Vivitrol - monthly IM injection Revia – PO QD Experiments in the ’70’s showed that low dose (2mg) but not high dose naloxone had analgesic properties. Probably caused by upregulation of opioid receptors and/or induction of endogenous endorphin production. The low dose antagonist would wear off, allowing for increased endorphins/receptors to reduce pain. Higher dose antagonist would blunt the effects of increased endorphins

48 Opioid withdrawal Withdrawal
unlike withdrawal of benzodiazepines and barbiturates, opioid withdrawal is not life threatening in otherwise neurologically and cardiovascularly healthy patients Stage I – drug craving, anxiety (~5-15 hrs) Stage II – yawning, perspiration, crying, rhinorrhea (~ 18 hrs) Stage III – mydriasis, continuation of Stage II, hyperreflexia, hot/cold flashes, cramping (16-24 hrs) Stage IV – continuation and worsening of Stage III, severe cramping, involuntary leg movements, diarrhea, HBP, ↑ body temp, ↑ RR, tachycardia, nausea (24 – 36hrs)

49 Opioids withdrawal Withdrawal
stage V – ↑ severity of earlier stages, fetal position, diarrhea, nausea, significant weight loss, leukocytosis, profuse sweating stage VI – appetite returns, bowel function normalizes, beginning of psychological withdrawal symptoms, ↑ sensitivity to pain, GI symptoms may see chronic withdrawal symptoms, both psychological and physical, after the post-acute withdrawal symptoms subside

50 Opioids - NURSING CARE Obtain baseline vital signs
Have naloxone available and know how to give it Consider need for fixed schedule for patients experiencing chronic pain Do not crush or break ER capsules/tablets Usually give IV opioids through the maintanance IV line which is usually NS

51 Opioids - NURSING CARE Assess pain relief Document pain relief
Use pain scale Document pain relief Respiratory rate <12 BPM may be sign of overdose Baseline pupil size Miosis may be sign of toxicity Restlessness must be assessed and differentiated Is it hypoxia? Is it a need for more pain control? Is it paradoxical CNS stimulation? (more common in women and older adults)

52 Opioids - NURSING CARE Encourage turning, coughing, and deep breathing at regular intervals Be alert for orthostatic hypotension in ambulatory patients Monitor urine output as morphine may dull the perception of a full bladder Want pain free, but able to ambulate and take care of ADL’s. Too sedated, can’t do that…

53 Opioids – NURSING CARE No person should suffer pain needlessly
Pain occurs when the patient says it does Pain should be relieved by whatever means required Doses of opioids should be titrated to maximal effectiveness Dependence rarely results from medications taken for physical pain

54 Opioids – NURSING CARE Withdrawal
unlike withdrawal of benzodiazepines and barbiturates, opioid withdrawal is not life threatening in otherwise neurologically and cardiovascularly healthy patients Stage I – drug craving, anxiety (~5-15 hrs) Stage II – yawning, perspiration, crying, rhinorrhea (~ 18 hrs) Stage III – mydriasis, continuation of Stage II, hyperreflexia, hot/cold flashes, cramping (16-24 hrs) Stage IV – continuation and worsening of Stage III, severe cramping, involuntary leg movements, diarrhea, HBP, ↑ body temp, ↑ RR, tachycardia, nausea (24 – 36hrs)

55 Opioids – NURSING CARE Withdrawal
stage V – ↑ severity of earlier stages, fetal position, diarrhea, nausea, significant weight loss, leukocytosis, profuse sweating stage VI – appetite returns, bowel function normalizes, beginning of psychological withdrawal symptoms, ↑ sensitivity to pain, GI symptoms may see chronic withdrawal symptoms, both psychological and physical, after the post-acute withdrawal symptoms subside

56 WHO 3-STEP LADDER

57

58 Review Question You administer the third morphine dose of the day to a patient. Shortly thereafter, she’s found to be extremely lethargic with RR of 10. What course of action might be taken? A) None, she’ll probably be fine after the morphine wears off B) 0.4mg of IV naloxone and monitor C) 4mg of oral Narcan and monitor

59 FACTORS TO CONSIDER Type of pain combinations
non-pharmacologic interventions Acute pain: PRN Chronic pain: scheduled Change the opioid if reduced efficacy Ceiling vs. non-ceiling Route Short vs long acting, time release Break through pain PCA USE THE LEAST POTENT DRUG THAT IS EFFECTIVE

60 ROUTE SELECTION NONINVASIVE Oral, rectal, transdermal INVASIVE
Subcutaneous, IM, IV, spinal infusion When the route is changed, the dosage MUST be changed


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