Opioids Flashcards
Effects of opioid peptides can be antagonized by __
naloxone
Opioid receptors are ____ and the primary action is __ NT release and neuronal excitability
Gi/o linked
decrease
Mu (morphine) receptors are ____ anaglesia where as kappa receptors are ___ analgesia
spinal/supraspinal
spinal
SE of Mu receptors
- Respiratory depression
- Euphoria
- Decreased GI motility
- Miosis
- PHYSICAL dependence
SE of kappa (dynorphin) receptors
- Dysphoria
- Miosis
- Sedation
opioids elicit analgesia effects by 2 ways:
- elevation of pain threshold by activation of brain stem descending inhibitory CNS pathways in Periaqueductal gray
- Change in subjective response to pain in limbic system via inducement of tranquility, euphoria
Opioids can elevate pain threshold by activation of brain stem descending inhibitory CNS pathways in Periaqueductal gray to:
- presynaptically decrease release of substance P and glutamate (via decrease in Ca2+ influx)
- Postsynaptially decrease response of pain transmission neuron
Compare and contrast Opioids vs non-opioid analgesia
- Op. are more efficacious but more dangerous (resp. depresion)
- Op. are dose dependent whereas NSAIDS have ceiling effect
- analgesia w/o loss of consciousness as seen with general anesthetics
- No antipyretic or anti-inflammatory effects
- Greater potential for tolerance and dependence
- dull, persistent tonic pain [C fibers] relieved better than sharp superficial pain [Adelta] - both
Uses of opioids
- Anaglesics
- Anti-diarrheal
- Cough suppressant (dextromethorphan)
- MI (morphine-fentanyl)
- dyspnea from pulmonary edema associated w/ cardiac dysfunction
Why is morphine good for MIs
- decrease preload
- decrease inotropy
- Decrease chronotropy
- reduce myocardial oxygen consumption
- Relieves anxiety via limbic system
SE of opioids in short term use
- Constipation
- N/V
- Sedation
- Dizziness
- Itching
- Dry mouth
__ and __ is NOT seen with therapeutic doses of nonopioid analgesics
Sedation and CNS depression
Which category of OTC products contains agents that are most likely to result in additive CNS depression if given to a patient who has been prescribed opioid analgesics for pain?
A. Analgesics (e.g., ibuprofen)
B. Antihistamines (e.g., diphenhydramine)
C. Laxatives (e.g., psyllium seed)
D. H2 Blockers (e.g., ranitidine)
E. Antidiarrheal agents (e.g., loperamide)
B. Antihistamines (e.g., diphenhydramine)
1st generation**
Constipation w/ opioids is due to:
- direct– inhibit ENS fxn at myenteric plexus
2. indirect– decrease ACh release (anticholinergic)
How do you manage constipation caused by opioids
- prophylaxis laxative (stimulant (senna) + stool softner (docusate))
- PAMORAs (peripherally acting u-opioid receptor antagonist)- Naloxegol for failed lax. on opioids for chronic pain
*no studies have shown superiority of one laxative over another
Describe the different OTC laxatives
- Stimulants (bisacodyl-senna)- often 1st line
- Osmotic (Miralax- sorbitol- PEG)
- Bulk-forming (psyllium)
- Stool softeners/wetting agents (docusate)- ineffective as monotherapy
Jackson is a 64-year-old male who has been treated for severe pain following a car accident in which he sustained a broken leg and broken arm. He has been converted to oral morphine in anticipation of his discharge. What other medication should he receive with his morphine upon discharge? A. Diphenhydramine B. Methylphenidate C. Docusate sodium with senna D. Docusate sodium E. Polyethylene glycol F. Prednisone
C. Docusate sodium with senna (stimulant + stool softener)
E. Polyethylene glycol (osmotic)
Adverse Reactions of Opioids
- Constipation
- Respiratory depression
- Sedation
- N/V
- Histamine release (itching)
- Flushing
- Urinary retention
- tolerance-dependence
Respiratory depression w/ opioids is the most serious acute SE but rarely a problem if therapy follows dosing guidelines. The primary action is ____ that leads to fall in RR
decrease in sensitivity of respiratory centers to CO2
**prominent sedation generally PRECEDES significant depression
What is the classic triad of sx with opioid overdose?
- Coma
- pinpoint pupils
- respiratory depression
How do you tx resp. depression w/ opioids?
- Naloxone- reserved for symptomatic resp. depression or progressive obtundation (NOT if somnolent but easily arousable)
* (DOA is shorter than agonists)
Respiration is depressed by an analgesic dose of: A. Morphine B. Naltrexone C. Buprenorphine D. Naproxen E. Hydrocodone F. Methadone G. Meperidine H. Tramadol
A. Morphine C. Buprenorphine (partial agonist) E. Hydrocodone F. Methadone G. Meperidine H. Tramadol (mixed action opioid)
Cause of N/V w/ opioids
Direct stimulaiton of the CTZ in medulla
*MC in ambulatory pts so may have vestibular component
Tx of N/V w/ opioids
- Antagonist of receptors in the periphery and at the CTZ
1. Antihistamine: if N related to ambulation (Diphenhydramine-meclizine)
2. D2 antagonists (1st line- inexpensive): Prochlorperazine, haloperidol
3. 5HT3 antagonists: Ondansteron more expensive)
4. Decrease movement
5. take w/ food and water
Sx of pseudo-allergy w/ opioids
- Itching
- Urticaria
- Flushing/local vasodilation
- Mild hypotension
- Can exacerbate asthma (H-induced bronchospasm)
*due to opioid induced release of HISTAMINE from mast cells NOT IgE mediated anaphylaxis
Tx of pseudo-allergy w/ opioids
- Antihistamines
Tx of true allergy w/ opioids
- Can try switching to different structural class (semisynthetic to synthetic)–> evidence lacking that switching reduces cross-sensitivity
- pretx w/ antihistamine and GC
Tx of opioid OD
- airway
- Ventilate
- Naloxone (see increase in RR in 1-2 min., may precipitate W/D in addicts that are dependent)
Describe the difference btwn Tolerance, Dependence and Withdrawal
Tolerance: need an increase dose to achieve the same effect (>2-3 weeks)
Dependence: chronic dosing alters physiological state so continued administration is required to prevent WD syndrome
Withdrawal: stop abruptly get WD sx
Tolerance less complete to ___ and __ so increasing analgesic dose –> worsens of these SE
-Tolerance is lost in ___ following discontinuation
constipation (and miosis)
1-2 weeks
**No matter how much tolerance develops - a lethal dose will always exist!!
A patient who develops tolerance to a fixed dose of morphine:
A. Will be equally tolerant to all effects of that dose of morphine
B. Probably will be tolerant to the analgesic effect of methadone
C. Probably will be tolerant to the analgesic effect of hydrocodone
D. Often can be relieved of pain if the dose of morphine is increased
E. Will remain tolerant to that dose of morphine for greater than 3 months
B. Probably will be tolerant to the analgesic effect of methadone
C. Probably will be tolerant to the analgesic effect of hydrocodone
D. Often can be relieved of pain if the dose of morphine is increased
How do you tx tolerance/dependence
Taper discontinuation
Sx of Opioid withdrawal
- reverse of opioid agonist action
1. Mydriasis
2. anorexia
3. insomnia
4. yawning
5. sneezing
6. diarrhea
7. lacrimation
8. increase HR
9. increase BP
10. sensitivity to CO2
severity of WD sx depends on
half life
shorter half-life = more severe sx
Tx of opioid WD
- tapering doses
- Methadone
- Clonidine (suppress SNS overactivity)
**rarely life-threatening (resolves 7-10 days), but general CNS depressants (ethanol, benzodiazepines, or barbiturates) may result in death
A young male patient is brought to the ED in an anxious and agitated state. He is subsequently determined to have signs and symptoms of the opioid abstinence syndrome. Which drug will be most effective in alleviating the symptoms experienced by this patient? A. Buprenorphine B. Codeine C. Diazepam - benzodiazepine D. Methadone E. Naltrexone F. Tramadol
D. Methadone
An ED patient with severe pain thought to be of gastrointestinal origin received 80 mg of meperidine. He subsequently developed a severe reaction characterized by tachycardia, hypertension, hyperpyrexia, and seizures. Questioning revealed that the patient had been taking a drug for a psychiatric condition. Which drug is most likely to be responsible for this untoward reaction to meperidine?
A. Alprazolam (Xanax®) - benzodiazepine
B. Bupropion (Wellbutrin®) - NDRI
C. Lithium - mood stabilizer
D. Phenelzine - MAOI
E. Venlafaxine (Effexor®) - SNRI
F. Sertraline (Zoloft®) - SSRI
D. Phenelzine - MAOI
Opioids are relatively contraindicated in who
- Head injury
- Respiratory depression
- Chronic inflammatory pain
- Pregnancy
DDI of opioids
- CNS depressants (additive CNS depression)
- Benzos
- AD/AP
- 1st generation histamines
- Alcohol
MAO inhibitors and SSRIs–> Serotonin syndrome (agitation, hypertension, fever, seizures) - life-threatening
- Especially with meperidine (excitatory metabolite
normeperidine) and tramadol
Phase I oxidation in the liver is activitaing via ____ for:
1.
2.
CYP2D6
Codeine–> morphine
Tramadol–> more ative opioid
CYP2D6 enzymes: genetic polymorphisms in activity–> interpatient variations in analgesic response and toxicity:
Poor metabolizers–> __
Ultra metabolizers–> __
PM= reduced anaglestic response
UM= greater risk of toxicitiy
**DONT USE CODEINE IN PEDs
Phase I oxidation in the liver is inactivitaing via ____ for:
1.
2.
3.
CYP3A4
- Oxycodone
- Tramadol
- Methadone
**substantial potential for interactions w/ CYP3A4 substrates, inducers or inhibitiors
Genetic polymorphisms in certain drug metabolizing enzymes are established to be responsible for variations in analgesic response to: A. Buprenorphine B. Tramadol C. Codeine D. Fentanyl E. Hydrocodone F. Methadone
B. Tramadol
C. Codeine**
E. Hydrocodone
Naloxone:
A. Increases the threshold for pain
B. Antagonizes respiratory depression induced by barbiturates
C. Can help manage opioid-induced constipation
D. Antagonizes respiratory depression induced by opioids
E. Has a longer duration of action than morphine
C. Can help manage opioid-induced constipation
D. Antagonizes respiratory depression induced by opioids
What are OPIATES
- natural and semisynthetic (phenanthrenes)
1. Morphine*
2. Codeine*
3. Hydrocodone
4. Hydromorphone*
5. Oxycodone*
6. Oxymorphone
**ALSO AGONISTS
What are OPIOIDS
- synthetic
1. Meperidine (phenylpiperidines): fentanyl
2. Methadone (phenylheptamines)
3. Benzenoid: tramadol
Examples of partial agonists and mixed action
Partial: Buprenorphine
Mixed: Tramdol (opioid agonist + NE/5HT reuptake inhibitior)
Full agonists can be classifed by max clinical efficacy as used in usual dosage range.
Strong:
Moderate:
Low-Very low:
Strong: Morphine, Hydromorphone, methadone, meperidine, fentanyl, and analogs
Moderate: oxycodone, hydrocodone
Low-Very low: codeine
*Opioid analgesics in common use today are equally powerful, differing only in potency (dose)
Benefits of partial agonists
ex. Buprenorphine
1. ceiling effect for: analgesia,
2. Resp. depression,
3. abuse potential, and
4. limited use in ACUTE pain
Compare the onset of action with different routes
IV>IM>SC>PO
*Immediate release products are recommended for initial titration of opioid analgesia
Describe the MOA of opioids
Mu receptor agonist in spinal cord (decrease perception of pain) and in limbic system (modify rxn to pain)
*NOT antipyretic or anti-inflammatory
Describe the use of morphine
- rapid action in post surgical pain and
- acute trauma pain
- relief of anxiety and pain
- MI (decrease preload and anxiety)
Describe the PK of morphine including form and DOA
- Form: PO, IV, PCA
2. DOA: 4hrs, SR 12-24 hrs
adverse reactions w/ morphine
- Caution in severe renal dysfxn (neurotoxic metabolite)
- Agitation
- Confusion
- Delirium
Uses of Fentanyl
- Perioperative-postoperative surgical pain (IV)
- Transdermal patch for chronic pain
- Acute/break through CA pain** (transmucosal formulation)— bypass 1st pass metabolism
*Non-parenteral formulations are not appropriate for opioid-naïve patients
describe the potency of Morphine, fentanyl
fentanyl is 100x more potent than morphine
Which of the following statements about fentanyl is correct?
A. Causes less histamine release than morphine
B. Withdrawal symptoms can be relieved by naloxone
C. Active metabolites can cause seizures
D. 100 times more powerful than morphine
E. 100 times more potent than morphine
F. More effective than hydrocodone by oral route
A. Causes less histamine release than morphine
E. 100 times more potent than morphine
What opioids are most likely to cause a Histamine release?
Morphine
Codeine
meperidine
Uses/forms of methadone
- suppress opioid withdrawal sx
- Tx chronic pain
- PO and IV
SE of methadone
- Long t1/2 predisposes to toxic drug accumulation
- Similar to morphine but
- QT prolongation risk!
Uses/forms of Hydromorphone
- Severe pain
2. Parenterally and PO
SE of Hydromorphone
- higher abuse potential
- higher street resale value
- unfamiliarity w/ dosing (more potent than morphine) can lead to inadvertent OD
**perception of less potential for Nausea or itching
Methoxy substitution protects from rapid 1st-pass metabolism - used in oral dosage form
Oxycodone
Uses of hydrocodone
- suited for relief of moderate pain in ambulatory pt
2. combined w/ ASA or acetaminophen to give additional analgestic or anti-inflammatory effect
The most widely used opioid analgestic
Vicodin
Adverse reactions of codeine
- *use has been declining
1. efficacy is marginal
2. sedation
3. rash
4. miosis
5. vomiting
6. potential for serious toxicities related to genetic variation in metabolism
7. AVOID USE IN PEDs
Uses of Meperidine
- acute dosing/PCA pumps
* limit use to 24-48hrs
- NOT USEFUL FOR COUGH OR DIARRHEA
- Falling into disfavor for use as strong analgesic agent
SE of Meperidine
- Neurotoxic metabolite w/ long t1/2
2. DDI w/ MAOIs
Partial agonist at µ-receptor (antagonism at κ-receptor of less clinical relevance)
Buprenorphine
Duration of analgesic action is longer than morphine due to slow dissociation from receptor
Buprenorphine
Uses of Buprenorphine
- acute pain (IV-IM)
- Persistent moderate-severe pain (patch)
- Opioid detoxification (SL_
buprenorphine can antagonize other systemic opioids which may precipatate __
WD sx
Mixed action opioids act by
- Mu receptor agonist
2. inhibition of NE and serotonin reuptake
Uses of Tramadol
- less effective in severe pain than morphine
2. neuropathic pain
SE of Tramadol
- less potential for resp. depression
- less abuse potential but greater than thought
- Lower seizure threshold (esp. w/ TCADs, SSRIs, MAOIs)
- Reuce dose in renal impairment
- DDI w/ MAOI and SSRIs
Example of a mixed agonist-antagonist agent
Pentazocine
Which drug is a full agonist at opioid receptors with analgesic activity equivalent to morphine, a longer duration of activity, good oral bioavailabilty, and fewer withdrawal signs on abrupt discontinuance than morphine? A. Fentanyl B. Hydromorphone C. Methadone D. Oxycodone E. Codeine
C. Methadone
A 63-year-old man, DK, is undergoing radiation treatment as an outpatient for metastatic bone cancer. His pain has been treated with a fixed combination of oxycodone-acetaminophen taken orally. Despite increasing doses of the analgesic combination, the pain is getting worse. The most appropriate oral medication for his increasing pain is: A. Buprenorphine B. Fentanyl C. Hydromorphone D. Codeine plus acetaminophen E. Tramadol F. Meperidine
C. Hydromorphone
It is possible that patient DK will have to increase the dose of the analgesic as his condition progresses as a result of developing tolerance. However, tolerance will not develop to: A. Emesis B. Sedation C. Constipation D. Respiratory depression E. Euphoric effects F. Pupillary constriction
C. Constipation
F. Pupillary constriction
Which of the following should be tried first for initial treatment of mild to moderate pain? A. Acetaminophen B. Fentanyl C. Ketorolac D. Tramadol
A. Acetaminophen
Strong full opioid agonists are generally used for treatment of: A. Mild pain B. Moderate to severe pain C. Chronic lower back pain D. High fever (> 105º C) E. All of the above
B. Moderate to severe pain
Codeine:
A. Is now contraindicated for use in children undergoing tonsillectomy and/or adenoidectomy
B. Is metabolized to morphine
C. May be less effective if taken with fluoxetine
D. All of the above
D. All of the above
Meperidine:
A. Has a potentially toxic active metabolite
B. Should only be used for short-term treatment of moderate to severe acute pain
C. Should not be taken with a monoamine oxidase inhibitor
D. All of the above
D. All of the above
*do not take meperidine or tramadol w/ MAOI
Tramadol: A. Has a dual mechanism of action B. Needs slow dose titration to improve tolerability C. Can cause seizures D. All of the above
D. All of the above
Tolerance usually develops rapidly to most of the adverse effects of opioids except: A. Respiratory depression B. Sedation C. Constipation D. Nausea
C. Constipation
MOA of Pentazocine
K agonist (spinal analgesia) weak mu antagonist or partial agonist
Compare the potency/efficacy of different opioids
Fentanyl> hydromorphone> oxycodone> hydrocodone=tramadol> codeine
Compare the potential for abuse of different opioids
Hydromorphone> Morphine > Oxycodone > hydrocodone > Tramadol
Morphine > buprenorphine