- Normeperidine (metabolite) can induce CNS stimulation esp. renal dysfunction pts - Serotonin syndrome with SSRIs - Drug interactions with monamine oxidase inhibitors (MAOIs) - Hyperrexia coma

Pharm (Comp 3) Flashcards by Zai Ganesh

Endogenous opioids

Examples and MOA

Endorphins, Enkephalins, Dynorphins

mu, delta, and kappa reptor agonists

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Effects mediated by mu opioid receptor

Analgesia
euphoria
physical dependence
bradycardia
GI transit slowing
respiratory depression
Modulator of hormone and NT release

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Effects mediated by kappa opioid receptor

spinal analgesia
miosis
sedation, psychomimetic effects
diuresis
slowed GI

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Effects mediated by delta receptor

Dysphoric effects
Analgesia
Modulator of hormone and NT release

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Strong agonist opioids

Morphine, methadone,

heroin, meperidine, fentanyl

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Partial/mixed opioid agonist

Pentazocine, buprenorphine

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Weak opioid agonists

codeine, hydrocodone

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Morphine, Hydromorphone, Oxymorphone

MOA and action/use

Opioid receptor agonist (miu, kappa, and delta)

- Use: Alter mood/anxiolytic, sedation, depress pain reaction

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Morphine, Hydromorphone, Oxymorphone

Toxicity

Respiratory depression, vasodilation
Nausea/vomiting, constipation, Biliary colic
Itching, hypotension, bronchoconstriction (H1)
Miosis
Increased prolactin release, inhibition of LH release
Tolerance, withdrawal, physical dependence, addiction
Increases intracranial pressure
Not in pregnancy. Meperidine preferred in labor.

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Codeine, Hydrocodone

MOA and use

MOA: Weak opioid receptor
agonist; Metabolized to
morphine

Use: Moderate pain treatment, Anti-tussive

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Codeine, Hydrocodone

Toxicity

Nausea, vomiting
drowsiness, dizziness
constipation
Combined with NSAIDs or acetaminophen
Codeine –> CYP2D6 metabolism. Genetic polymorphisms may increase toxic effects.

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Methadone

MOA and Use

Opioid receptor agonist;
antagonism on NMDA receptor
Use: Avoidance of
the withdrawal reaction in opioid dependence patients
Long t1/2 allows a slow taper

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Methadone

toxicity

Accumulates with repeated doses, which can cause respiratory depression.

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Meperidine (Demerol)

MOA and use

Opioid receptor agonist; Antimuscarinic effects; Serotonin effects

Use: Like morphine, but less analgesia

Good in obstetrics: less neonatal respiratory
depression. Inc contractions

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Meperidine

Toxicity

Normeperidine (metabolite) can induce CNS stimulation esp. renal dysfunction pts
Serotonin syndrome with SSRIs
Drug interactions with monamine oxidase inhibitors (MAOIs)
Hyperrexia coma

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Fentanyl, Alfentanil, Sufentanil, Remifentanil

MOA and Use

Opioid receptor agonist
100x more potent than morphine
IV analgesic. Used for extra-anesthetic analgesia.

Fentanyl, Alfentanil, Sufentanil, Remifentanil

Toxicity

Respiratory depression

Available as transdermal (patch) and transmucosal (lozenge) formulations.

Heroin/Diacetylmorphine

MOA and Use

Opioid receptor agonist
Semisynthetic is
metabolized to morphine for action.
Lipid soluble and crosses blood brain barrier quickly

Heroin/Diacetylmorphine

Toxicity

Super CNS action
analgesia
Euphoria
dependence and addiction
Illicit use only

Tramadol

MOA and Use

Mu receptor agonist. NE and 5-HT reuptake inhibitor.
Weak analgesic, neuropathy
Little opioid toxicities.
High bioavailability, active metabolite.

Tramadol

Toxicity

May cause hypertensive crisis with MAOI

- Often combined with acetaminophen (added liver toxicity)

Diphenoxylate, Loperamide

MOA

Weak mu or kappa agonists

- Antidiarrheal

Diphenoxylate, Loperamide

Diphenoxylate –> combined with atropine to reduce abuse potential
Loperamide –> no CNS effects, does not cross BBB (Imodium, OTC use)

Opioid drug interactions

CNS depression with:

ethanol
antipsychotics
tricyclic antidepressants
sedative-hypnotics (eg. benzos)
antihistamines

Opioid OD S&S, Treatment

- Pupillary constriction - Comatose state - Hypotension - Bradycardia - Respiratory depression Administer naloxone and ventilation.

Serotonin Syndrome - Drugs involved - S&S - Treatment

- SSRIs, TCAs, meperidine, dextromethorphan, St. John’s Wort, linezolid, “triptans” (2 of these combined together) Symptoms: rigidity, hyperthermia, myclonus, delirium, hypertension, tachycardia, GI symptoms - within 24 hrs of taking the two drugs Treatment: Benzodiazepines, cyproheptadine, ventilation

Naloxone | MOA and Use

- Antagonist at all opioid receptors. IV use. | - Rapidly antagonizes all opioid effects. Precipitates withdrawal in dependent users.

Naloxone | Toxicity

- Fast onset and short duration of action | - Repeated administration needed until opioid is cleared from the body.

Naltrexone | MOA and Use

- Like Naloxone but 5x more potent; up to 72 hr duration. - Binds all opioid receptors. Oral use. - Maintenance therapy; May reduce alcohol cravings in alcoholics

Naltrexone | Toxicity

Caution in hepatic impaired pts.

Methylnaltrexone | MOA and Use

- μ opioid receptor antagonist | - Treats opioid-induce constipation

Methylnaltrexone | Toxicity

- Does not cross BBB (compound is methylated) | - Targets GI tract

Butorphanol, Buprenorphine, Nalbuphine, Pentazocine | MOA of each

- Butorphanol (κ agonist) - Buprenorphine (partial μ agonist, κ antagonist). Slow dissociation from μ receptor. - Nalbuphine and Pentazocine (κ agonist, μ antagonist)

Butorphanol, Buprenorphine, Nalbuphine, Pentazocine | Use

- Analgesia without euphoria, less chance for dependence. - Buprenorphine used in some rehabilitation programs. Slow dissociation from the mu receptor

Butorphanol, Buprenorphine, Nalbuphine, Pentazocine | Toxicity

- Sim to morphine - Administering these drugs with a pure agonist (eg. morphine) can reduce efficacy of the agonist or precipitate withdrawal. - Pentazocine can increase psychomimetic effects (kappa mediated)

Opioid withdrawal symptoms

- Yawning, hyperventilation - Lacrimation, piloerection, mydriasis - Fever, chills, hyperthermia - muscular aches, vomiting - anxiety and hostility