19) Opioids Flashcards
1
Q
Types of opioid receptors
A
- μ [mu]
- δ [delta]
- κ [kappa]
2
Q
On the basis of their interaction with several opioid receptors, individual drugs are classified as
A
- Agonists
- Mixed agonist-antagonists
- Antagonists
3
Q
Opioids classified based on
A
- Spectrum of clinical use
- Strength of analgesia
- Ratio of agonist to antagonist effects
4
Q
Spectrum of clinical uses
A
- Therapeutic uses (eg, analgesics, antitussives, and antidiarrheal drugs)
5
Q
Strength of analgesia is based on
A
- Relative abilities to relieve pain
- May be classified as strong, moderate, and weak agonists
- Classification is independent of potency
6
Q
Ratio of agonist to antagonist effects
A
- Agonists (full or partial receptor activators)
- Antagonists (receptor blockers)
- Mixed agonist-antagonists (activate one opioid receptor subtype and block another subtype)
7
Q
Strong agonists (names)
A
- Morphine
- Methadone
- Meperidine
- Hydromorphone
- Fentanyl
- Sufentanil
8
Q
Moderate agonists (names)
A
- Codeine
- Oxycodone
9
Q
Weak agonists (names)
A
- Propoxyphene
10
Q
Mixed agonist-antagonists (names)
A
- Buprenorphine
- Nalbuphine
11
Q
Antagonists (names)
A
- Naloxone
- Naltrexone
- Nalmefine
12
Q
Most opioids are well absorbed when taken orally, but theseundergo extensive first-pass metabolism
A
- Morphine
- Hydromorphone
- Oxymorphone
13
Q
Opioids are widely distributed to
A
- Body tissues
14
Q
With few exceptions, the opioids are metabolized by
A
- Hepatic enzymes
- Usually to inactive glucuronide conjugates
- Elimination by the kidney
15
Q
Morphine-6-glucuronide
A
- Analgesic activity equivalent to that of morphine
- Morphine-3-glucuronide is its primary metabolite (neuroexcitatory)
16
Q
Codeine, oxycodone, and hydrocodone are metabolized by
A
- Cytochrome CYP2D6 (isozyme exhibiting genotypic variability)
17
Q
For codeine, CYP2D6 may be responsible for variability in analgesic response because
A
- The drug is demethylated by CYP2D6 to form the active metabolite, morphine
18
Q
Meperidine is metabolized to
A
- Normeperidine
- May cause seizures at high plasma levels
19
Q
Receptors for endogenous peptides are located in
A
- CNS and peripheral tissues
- Distributed in the brain & spinal cord
- Also outside the CNS (vascular tissues, cardia, airway/lung, gut and cells of the immune system)
20
Q
Three major opioid receptor subtypes have been extensively characterized pharmacologically
A
- µ (mu)
- δ (delta)
- κ (kappa) receptors
21
Q
All 3 opioid receptor subtypes appear to be involved in
A
- Antinociceptive and analgesic mechanisms at both spinal and supraspinal levels
22
Q
The µ-receptor activation plays a major role in
A
- Respiratory depressant actions of opioids
- With κ-receptor activation slows GI transit
23
Q
κ-receptor activation appears to be involved in
A
- Sedative actions
24
Q
δ-receptor activation may play a role in
A
- Development of tolerance
25
All 3 major opioid receptors are coupled to their effectors by
- G proteins
| - Activate phospholipase C or inhibit adenylyl cyclase
26
Major SE of opioids include
- Analgesia
- Sedation
- Euphoria
- Respiratory depression
- Constipation
- Miosis (pupil constriction)
- Truncal rigidity
- Flushing pruritis (through histamine)
27
Opioids (with the exception of meperidine) cause contraction of biliary tract smooth muscle, which can result in
- Biliary colic or spasm
- Increased bladder sphincter tone
- Reduction in uterine tone
28
When used for a prolonged period, these opioids may exacerbate pain (hyperalgesia)
- Morphine
- Fentanyl
- Remifentanil
29
K agonists, with weak µ-receptor antagonist activity
- Butorphanol
- Nalbuphine
- Pentazocine
30
_____ may act as a partial agonist or antagonist at the µ receptor
- Butorphanol
31
Buprenorphine is a µ-receptor partial agonist with weak antagonist effects at κ and δ receptors. These characteristics can lead to
- Decreased analgesia and precipitate withdrawal symptoms when used in patients taking conventional full µ-receptor agonists
32
The mixed agonist-antagonist drugs often cause
- Sedation at analgesic doses
- Dizziness, sweating, and nausea may also occur
- Anxiety, hallucinations, and nightmares are possible adverse effects
33
Mixed agonist-antagonist drugs respiratory effects
- Respiratory depression may be less intense than with pure agonists
34
Chronic use of mixed agonist-antagonist
- Tolerance develops with chronic use, but is less than the tolerance that develops to the full agonists
35
Pure opioid receptor antagonists that have greater affinity for µ receptors
- Naloxone
- Nalmefene
- Naltrexone
36
A major clinical use of the opioid antagonists
- Management of acute opioid overdose
37
Naloxone and nalmefene are given
- Intravenously
38
Because naloxone has a short duration of action (1–2 h), a _____ preparation of naloxone has recently been made available to treat opioid overdose promptly
- Nasal insufflation
39
Nalmefene has a duration of action of
- 8–12 h
40
Naltrexone has a long elimination half-life, blocking the actions of strong agonists (eg, heroin) for up to
- 48 h after oral use
41
Unlike the older drugs, two new antagonists, _____ and _____ do not cross the blood-brain barrier
- Methylnaltrexone
| - Alvimopan
42
Methylnaltrexone and alvimopan block adverse effects of strong opioids on
- Peripheral µ receptors (including those in the GI tract responsible for constipation)
43
Naloxegol is a pegylated form of
- Naloxone
| - It is also used to reverse opioid constipation
44
Miscellaneous opioids
- Tramadol
| - Tapentadol
45
Tramadol
- Weak µ-receptor agonist
| - Partially antagonized by naloxone
46
Tramadol analgesic activity
- Mainly based on blockade of the reuptake of serotonin
| - Weak norepinephrine reuptake blocker
47
Tramadol is effective in treatment of
- Moderate pain
| - Has been used as an adjunct to opioid analgesics in chronic pain syndromes
48
Tramadol is contraindicated in
- Patients with a history of seizure disorders
| - Risk of the serotonin syndrome if it is co-administered with SSRIs
49
Tapentadol
- Strong norepinephrine reuptake-inhibiting activity
| - Modest µ-opioid receptor affinity
50
Tapentadol treatment effectiveness
- Less effective than oxycodone in the treatment of moderate to severe pain
- Causes less gastrointestinal distress and nausea
51
Tapentadol should be used with caution in
- Seizure disorders
52
Fentanyl brand name
- Duragesic
53
Hydromorphone brand name
- Dilaudid
54
Meperidine brand name
- Demerol
55
Morphine brand name
- MS contin
| - Kadian
56
Methadone brand name
- Methadose
57
Oxymorphone brand name
- Opana
58
Sufentanyl brand name
- Sufenta
59
Tramadol brand name
- Ultram
60
Codeine brand name
- No brand name listed
61
Hydrocodone brand name
- Norco
| - Vicodin
62
Oxycodone brand name
- Percocet
| - Oxycontin
63
Buprenorphine brand name
- Subutex
64
Buprenorphine and naloxone brand name
- Suboxone
65
Nalbuphine brand name
- Nubain
66
Naloxone brand name
- Narcan
67
Naltrexone brand name
- Vivitrol
