Prescription Pain Management University of Hawai‘i Hilo Pre - Nursing Program NURS 203 – General Pharmacology Danita Narciso Pharm D 1
2 Objectives Understand how to preform a pain assessment Know which medications fit into which pain management classes Know the general effects and adverse effects of the medications/classes of medications
3 Pain Assessment
4 Pain Assessment Babies Respond to changes Crying Temperature Blood pressure Heart rate Oxygen consumption Activity Scales CRIES, NIPS, FLACC, CHEOPS
5
6 Pain Assessment P Provoke – causes, better, worse? Q Quality – sharp, dull, stabbing, crushing R Radiating – stay in one sport, move to another location S Severity – scale of 1-10 T Time – when start, how long does it last
7 Step treatment strategies - WHO Mild Acetaminophen NSAIDs ASA Celecoxib Moderate Same as “Mild” + a “Moderate” opioid Codeine, hydrocodone, oxycodone Severe Morphine, hydromorphone, fentanyl
8 Step Treatment - WHO STEP 3 High potency opioids STEP 2 Low potency opioids STEP 1 Aspirin Celecoxib Acetaminophen NSAIDs
9 Opioid Receptor Agonists WHO – moderate & severe pain medications Antagonists Naltrexone, naloxone Mixed (agonists & antagonists) Buprenorphine, nalbuphine Other Meperidine, Tramadol, methadone
10 Neuropathic Anticonvulsants Pregabalin, gabapentin, carbamazepine, lamotrigine TCA Amitriptyline, nortriptyline, doxepin etc.
11 Mild pain Celecoxib – Celebrex Selective inhibitor of COX-2 COX-2 Inflammation ARACADONIC ACID Fever CYCLOOXYGENASE Pain 2 PGE2 Fever & Pain
12 Celecoxib - Celebrex Kinetics ADRs Distribution – large Edema, headache, (400 L) dizziness, skin rash, abd pain, diarrhea, cough, Highly protein bound arthralgia, fever – 97% Interactions Metabolized – liver CyP2C9 Other NSAIDs, warfarin, anticoagulants, ACEI, Half life – 11 hrs ARBs, alcohol, ASA Time to peak – 3 hrs products Excretion – feces & Pregnancy urine (metabolites & unchanged drug) C (less than 30 weeks) D
13 Opioid Receptors – Pain Under normal When opioid receptors circumstances are bound - Agonist P P Presynaptic Presynaptic Receptor Receptor C C
14 Opioid Receptors – Pain Decrease in When opioid receptors neurotransmitters are bound - Agonist Glutamate P Acetylcholine NE Presynaptic Serotonin Substance P Receptor C
15 Types of opioid receptors Classic Mu Kappa Delta Non-classic ORL-1
16 Mu Receptors - agonists Endogenous Exogenous Endorphins Morphine Mu receptors are found in: Analgesia Respiratory depression Spinal cord Euphoria Effects Brainstem Sedation Thalamus Decreased GI motility Cortex Miosis Physical dependence
17 Delta Receptors - agonists Endogenous Exogenous Enkephalins DPDE (used in research) Delta receptors are found in: Analgesia (spinal) Olfactory bulb Decreased gastrointestinal Cerebral cortex motility Effects Nucleus accumbens Respiratory depression? Amygdala Pontine nucleus
18 Kappa Receptors - agonists Endogenous Exogenous Dynorphin Ketazocine (research) Kappa receptors are found in: Analgesia – Spinal Limbic system Sedation Effects Hypothalamus Dyspnea Brainstem Physical dependence Spinal cord Dysphoria Inhibit ADH release
19 Mu, delta, & Kappa - antagonist Naloxone Mu – Greatest Blocks the effects of affinity opioids but does NOT Delta – Reduced cause the opposite affinity effects! Kappa – Reduced affinity
20 Opioids - agonists Uses Tolerance Pain Effects Cancer, surgical, Analgesia, sedation, obstetric, trauma, euphoria, nausea, kidney & gall respiratory depression stones, sickle cell Effects IMMUNE to Anesthesia tolerance Adjuvant Miosis & CONSTIPATION Others Dyspnea w/MI Anti-diarrheal Cough suppressant
21 Opioid agonists MOA - Binds to opioid receptors in the CNS, causing inhibition of ascending pain pathways, altering the perception of and response to pain; produces generalized CNS depression Medication in class Codeine < hydrocodone < oxycodone < morphine < hydromorphone < fentanyl
22 Opioids - agonists Kinetics Absorption Half life Oral – well ~2 hours absorbed, subject Metabolized to first pass effect Liver SubQ, IM, IV – well Excreted absorbed Urine – mostly Rectal – moderate metabolites absorption Decreased in renal Lipophilic forms – failure, elderly, and nasal, sublingual, & young transdermal
23 Opioids - agonists ADRs Interactions Drugs - Alcohol, CNS Bradycardia, depressants, MAO dysphoria, inhibitors dependence, Conditions (CI) – drowsiness, Asthma, constipation, dry emphysema, cor mouth, urinary pulmonale retention, Pregnancy – C, can tolerance, cross the placenta, can concentrate in breast milk
24 Opioid – antagonists Naloxone/naltrexone MOA Pure opioid antagonist that competes and displaces opioids at opioid receptor sites Naltrexone Competitive antagonist at mu opioid receptor
25 Opioid - antagonists Naloxone Naltrexone Used in opioid Differences overdose Orally bioavailable (respiratory (PO & IM) depression) Higher potency Not orally bioavailable Half life – 3 hours (parenteral Duration – 24-28 administration) hours Half life – 30-90 Active metabolite minutes (13 hours) Duration – 1-2 hours
26 Opioids – mixed agonist/antagonists Benefits Pain relief w/o as many addictive qualities Less respiratory depression & constipation Risks Can cause withdrawal symptoms (not for opioid dependent patients) Types Buprenorphine, nalbuphine, others
27 Others Tramadol MOA – Binds to μ -opiate receptors in the CNS causing inhibition of ascending pain pathways, altering the perception of and response to pain; also inhibits the reuptake of norepinephrine and serotonin, which are neurotransmitters involved in the descending inhibitory pain pathway responsible for pain relief
28 Tramadol Kinetics ADRs – Similar to opioid agonists Onset – 1 hour CNS – dizziness, Duration – 9 hrs stimulation, Absorption – rapid headache, & complete insomnia Metabolism – liver Constipation, N&V Half life Weakness Parent – 6-8 hrs Interactions – MAO Metabolite – 7-9 inhibitors, alcohol, hrs CNS depressants Excretion - urine Pregnancy - C
29 Methadone Used - addiction Others Phenylheptylamines – binds to mu receptor Inhibits NMDA & re-uptake Meperidine of Used - Surgery catecholamines/serotonin Phenylpiperidine – still binds mu receptor Substances added to Not cough tablets to prevent abuse suppressant or Variable kinetics antidiarrheal Bioavailability – 36-100% Can accumulate and cause SEIZURES Half life – 8-59 hrs Interaction – MAO Metabolized by CYP3A4 inhibitors & 2B6 ADRs – hyperthermia, Can prolong QTc interval muscle twitching, (EKG) hallucinations
30 Tricyclic Antidepressants MOA - Increases the synaptic concentration of serotonin and/or norepinephrine in the central nervous system by inhibition of their reuptake by the presynaptic neuronal membrane pump Various types of pain (neuropathic pain) – off label Emotional aspect of pain Amitriptyline, nortriptyline, doxepin, imipramine
31 Tricyclic Antidepressants Kinetics ADRs Onset 4-8 weeks Anticholinergic, decrease blood Absorption – rapid pressure, sedation, Metabolism – liver EPS Half life – 13-36 Interactions hours Anticholinergic Excretion – urine agents, BP agents, Can accumulate CNS depressants in elderly Pregnancy – Risk C
32 Anticonvulsants MOA – Vary with individual agents Generally all have CNS effects involving neurotransmitters Calm the over-activity/excitability of the CNS Types Gabapentin, pregabalin, lamotrigine, carbamazepine….
33 Anticonvulsants Best for neuropathic pain Select based on adverse drug effect profiles Drug-drug interactions Carbamazepine – MAJOR CYP enzyme inducer Select based on ease of treatment Dosing schedule
34 Questions ?????????????????????????????????? ?????????????????????????????????? ?????????????????????????????????? ?????????????????????????????????? ?????????????????????????????????? ?????????????????????????????????? ?????????????????????????????????? ?????????????????????????????????? ??????????????????????????????????
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