Analgesia (2)

Question 1

What are the major opiate antagonists?

Answer 1

Naloxone, naltrexone, and methylnaltrexone

Question 2

What receptors do Naloxone, naltrexone, and methylnaltrexone work at?

Answer 2

all 3- mu, kappa, and delta (they precipitate withdrawal syndrome in dependent pts., except methylnaltrexone b/c it does not easily pass the BBB(mitigates AEs without impacting (central) analgesia))

Question 3

What drug is most often used to tx acute opiod OD and to mitigate opiate AEs?

Answer 3

Naloxone IV (may be co-formulated with agonist to prevent drug abuse) (note there is no effect if taken orally, and antagonist action if injected)

Question 4

What is the main use of maltrexone?

Answer 4

used in maintenance programs for addicts (as a single PO dose on alternative days to decrease alcohol craving, and decrease baseline B-endorphin release)

Question 5

How would phsyical exam of someone experiencing withdrawal appear?

Answer 5

agitation, diaphoresis, increased lacrimation, piloerection, and dilated pupils

Question 6

Question 7

How might alcohol and sedative-hypnotic withdrawal appear?

Answer 7

seizures, hyperthermia, HTN, or tachycardia

Question 8

How might opiate withdrawal appear?

Answer 8

pulse and BP WNL (usually)

slight tachycardia reflects agitation, discomfort, or hypovolemia

Question 9

How might sympathomimetic intoxication present?

Answer 9

mydriasis, agitation, tachycardia, and HTN, but usually much more severe than occurs in opiod withdrawal

Question 10

How might cholinergic agent intoxication present?

Answer 10

diarrhea and vomiting

distinguished from opiod withdrawal syndrome by salivation, bradycardia, and altered level of consciousness

Question 11

How should shor-term tx of opiate withdrawal be handled?

Answer 11

Question 12

How addictive are opiates?

Answer 12

as addictive as nicotine, but less than cocaine or amphetamines.

Question 13

What is thought to underlie addiction/dependence for most drugs?

Answer 13

increase in dopamine levels. For ex., activation of opiate receptors in the ventral tegmental neurons leads to increased dopaminergic activation within the nucleus accumbens

Question 14

Question 15

How should opiod dependence be tx?

Answer 15

1) Use of an opiate antagonist such as naltrexone
2) or pts receive a long-acting opiod whose pharmacokinetic properites give rise to only a gradual decline in serum and therefore drug levels, such as buprenorphine

Question 16

Answer 16

Question 17

What is the tx of choice for opiod-dependent pregnant women?

Answer 17

Methadone (dose requirements may increase during the 3rd trimester due to larger plasma volume, reduced protein binding, increased tissue binding, and increased metabolism)

Question 18

What are the AEs of Methadone?

Answer 18

constipation, mild drowsiness, excess sweating, peripheral edema

reduced testosterone leading to reduced libido and sexual performance, and erectile dysfunction

prolonged QT and arrhythmia

Question 19

What are some main features of buprenorphine?

Answer 19

• very tight binding to opiod receptors (displaces other opiods and triggers withdrawal in pts psychically dependent on opiods; blocks the analgesic action of other opiods)
• slow dissociation from opiod receptors (long DOA and relieves withdrawal and cravings for 24+hr)
• no bioaccumulation (allows quick titration to effective dose)
• partial agonist with ceiling effect (very low risk of OD, might be less effective than higher doses of methadone)
• SL and IV absorption; poor PO absorption (can be abused IV)

Question 20

In the ED, suspiciion that a pt in toxicated with an opiate (morphine, heroin, codeine, and hydrocodone- wont work for synthetic opiates like fentanyl, meperidine, and methadone) can be rapidly confirmed by what?

Answer 20

antibody-based enzymatic immunoassay (however, the precise conc and pattern of opiate metabolites requires the use of GC-mass spec)

Question 21

What drug can cause a false positive EIA for opiates?

Answer 21

ciprofloxacin

Question 22

What drugs are most likely to be effective in the setting of nociceptive or inflammatory pain?

Answer 22

NSAIDs

Question 23

What drugs are most likely to be effective in the setting of neuropathic pain or pain from central sensitization?

Answer 23

antidepressants and anticonvulsants

Question 24

How do Gabapentin and Pregabalin work?

Answer 24

Question 25

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Question 27

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Question 28

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Question 29

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Question 30

Answer 30