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Pharm Exam 5 > L 17-18 Opioids and Antagonists > Flashcards

L 17-18 Opioids and Antagonists Flashcards

1
Q

What are the receptors involved in opioid action?

A

Mu: found pre- and post-synaptically. Pre- decreases Ca influx and thereby neurotransmitter release. Post- increases K+ influx to hyperpolarize the cell
Analgesia, euphoria, sedation

Kappa: Presynaptic, analgesia in some, dysphoria in others

Delta: Presynaptic, dysphoria

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2
Q

Opioid action to reduce pain

A

Inhibits pain transmission in the spine
Turns on the descending fibers that release endogenous opioids to inhibit pain transmission by inhibiting the inhibitors of these neurons

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3
Q

Analgesic effects of opioids

A

Opioids are great at decreasing not only the sensation of pain, but also the feeling of suffering because of the pain.
Tolerance develops rapidly

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4
Q

Opioids and sedation

A

Opioids cause sedation, but it is more like a mental clouding and they cannot be used as sleep aids. Can also cause CNS depression in overdose.
Creates a floating, dream-like state
Codeine can cause excitement in overdose.

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5
Q

Euphoria and opioids

A

Most often people respond with a euphoric state of floating and pleasure.
Some people feel dysphoric

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6
Q

Opioids and emesis and cough

A

Nausea and vomiting are common
Opioids are great at reducing cough reflex:
Codeine and dextromethorphan are most commonly used
The effect is not related to analgesic effects because dextromethorphan is not analgesic and meperidine doesn’t suppress cough

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7
Q

Opioids and respiration

A

Opioids cause respiratory depression especially with overdose
Useful for pulmonary edema because decreases response of brain stem to CO2 and makes people less gasping for air.
Can lead to increased CO2 in blood which causes vasodilation and can cause cerebral increased pressure

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8
Q

Opioids and miosis

A

Miosis is pupil constriction

Common effect except for meperidine

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9
Q

Opioids and body temperature

A

Causes dysregulation in hypothalamus and can lead to low body temp

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10
Q

Opioids and trunkal rigidity

A

Cause a supraspinal effect that increases the tone of trunk muscles
Especially seen with Fentanyl

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11
Q

Opioids and GI

A

Decreased GI activity leads to Constipation. Huge side effect!
Be proactive and give laxatives

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12
Q

Opioids and GU

A

Can increase sphincter tone and make harder to urinate or pass a stone

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13
Q

Opioids and Histamine

A

Opioids commonly release histamine => itching, flushing, sweating
Morphine is the worst

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14
Q

Opioids and tolerance

A

Analgesic tolerance is common and can occur quickly
Physical dependence also occurs
Blocking of NMDA receptors can decrease tolerance
Tolerance happens mostly to analgesia, euphoria, sedation but not to miosis, respiratory depression, constipation, seizures

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15
Q

Opioids and hyperalgesia

A

Long-term use can lead to hyperalgesia, perhaps from increase in dynorphin in spinal cord making pain more effective
Blocking NMDA receptors helps prevent this also

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16
Q

Opioid adverse effects

A 
Nausea/Vomiting
Constipation
Urinary retention (worse with BPH)
Itching and hives from histamine
Respiratory depression
Postural hypotension
Restlessness
Dysphoria
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17
Q

Opioids and addiction

A

More common if you under-prescribe because it sets up the reward pathway in the brain. Staying ahead of the pain prevents the reward pathway and prevents addiction. This means taking the pills before you are in agony. Stay ahead of the pain!

18
Q

Opioid withdrawal

A

Withdrawal won’t kill you, but will be very dysphoric, will yawn, can’t sleep, chills and goosebumps (cold turkey!), diarrhea, lots of sympathetic activation–can use clonidine to help or a another opioid that doesn’t cause euphoria–methadone

19
Q

Opioid overdose

A

CNS depression
Respiratory depression
Pin point pupils (may dilate if severely hypoxic)
Can treat with Naloxone (an opioid antagonist) which

20
Q

What was the original use of heroin?

A

Cough suppression

21
Q

Use of opioids

A 
Analgesia
Acute pulmonary edema to relieve dyspnea
Relief of cough
Diarrhea
Anesthesia–to control the pain
22
Q

Opioid drug interactions

A

MAO inhibitors: may lead to serotonin syndrome, Meperidine and dextromethorphan worst

CYP2D6 inhibitors: inhibits metabolism of codeine, oxycodone, hydrocodone to active compounds. Fluoxetine worst for inhibition

23
Q

Opioid contraindications

A

Use of a partial agonist with a full agonist
Patients with head injuries => increased intracranial pressure
Pregnancy–mostly at delivery => infant resp. depression and relaxes the uterus
Impaired pulmonary function
Impaired liver or kidney function

24
Q

Morphine

A

All opioid receptors
Strong agonist
Severe pain
Administered in many ways
High first pass and short half-life
Fast onset, lasts 4-6 hours
Excreted mostly in urine
Dosing used as standard for comparison: 10 mg SC or IM
Metabolized by CYP2D6
Itching and vomiting common when injected
Crosses placenta and can cause fetal dependence when born

25
Q

Hydromorphone (Dilaudid)

A

Very strong analgesic
Often better tolerated, less histamine release
Similar onset and duration to morphine

26
Q

Methadone (Dolophine)

A

Long half-life
Mu receptors
May also block NMDA receptors=> decreased tolerance. Makes it better for long-term pain control.
Not great euphoria
Used to prevent withdrawal and to help reduce cravings for addicts

27
Q

Meperidine (Demerol)

A

The odd duck in the group
Mu agonist
Euphoria
Converted to normeperidine which can cause seizures–so should not use long-term or with poor kidney function
No cough suppression
Some anticholinergic effect: dilates pupils and causes tachycardia
Better for OB: causes less resp depression in neonates
Less constipation and urinary retention than morphine
Do not use with MAOI’s => serotonin syndrome

28
Q

Fentanyl (Sublimaze)

A

Highly potent, very lipid soluble
Used commonly in short surgical procedures because wears off quickly, but good in long surgeries because of good CV profile
May cause truncal rigidity if given rapidly
Metabolized by CYP3A4

Alfentanil, Sulfentanil, Remifantanil similar

29
Q

Heroin

A

Very potent
Injected, snorted, smoked
High euphoria

30
Q

Oxycodone (Oxycontin)

A

Moderate effects
Good for mod pain
Also used for tourette’s and restless leg
Frequently combined with acetaminophen
Metabolized by CYP2D6 to increase analgesic effectiveness
Schedule II, often abused

31
Q

Hydrocodone

A

Moderate to severe pain
Often combined with acetaminophen: problem may arise because acetaminophen is in many drugs and can reach daily limits quickly, may be better to not combine
CYP2D6 conversion needed for analgesia

32
Q

Codeine

A

Moderate to low analgesic
Good for cough suppression
Metabolized by CYP2D6 to work, converted to morphine
Don’t give to small kids

33
Q

Pentazocine (Talwin)

A 
Partial agonist for Mu
Kappa agonist
Moderate pain
Not as likely to cause constipation or resp. depression
Low euphoria from low Mu receptor
34
Q

Buprenorphine

A

Partial agonist on Mu and maybe kappa
Low euphoria, good maintenance for addicts
Combined with naloxone (a blocker) so if the drug is injected or otherwise used in a way unintended it blocks the effects of the drug. If taken sublingually, naloxone is not absorbed and the drug works normally.

35
Q

Nalbuphine/Butorphanol

A

Kappa agonist
Mu antagonist or partial agonist
Analgesia similar to pentazocine

36
Q

Tramadol

A

Mild to mod pain
Weak mu agonist
Inhibits NE/5-HT reuptake
Do not combine with antidepressants => seizures

37
Q

Dextromethorphan

A

Cough suppression, not analgesic, not likely to cause constipation
Blocks NMDA–abuse potential in teens
Decreases 5-HT reuptake=>sreotonin syndrome with MAOI’s

38
Q

Opioid antagonists

A

Block opioid action

Can cause withdrawal

39
Q

Naloxone (Narcan)

A

Opioid antagonist
DOC for opioid overdose
Can reverse resp depression, consciousness, awareness of pain, miosis, constipation
Must be injected, give until pupils dilate
Short duration of action (2 hours) repeated dosing may be needed.

40
Q

Naltrexone (ReVia)

A 
Opioid antagonist
Long acting
Used in treatment of opioid addicts
Will precipitate withdrawal
May decrease cravings in alcoholics
Long term can cause liver toxicity
41
Q

What are some of the adverse effects of chronic opioid use?

A 
Hypogonadism
Immunosuppression
Tolerance
Hyperalgesia
Driving impairment

Pharm Exam 5 (6 decks)

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