Opioids

Question 1

clonidine and naltrexone

Answer 1

for detox

Question 2

All Opioids

Answer 2

• close voltage gated Ca2+ channels on presynaptic
• inhibit presynaptic neuron (hyperpolarize) by increasing K+ conductance
• inhibits cAMP
• block nociceptors if added to PAG
• disinhibit excitatory PAG neurons that project onto raphe nucleus in medulla to release 5HT and NE on pain fibers

OD: pinpoint pupils, seizures, dry mouth, dysphoria, agitation, constipation, euphoria followed by apathy respiratory depression, coma

withdrawal: rhinorrhea, diarrhea (flulike sx), drowsy, piloerection

OD: coma, respiratory depression

Tx of OD: naloxone

Question 3

Methadone

Answer 3

long term tx

• MOR agonist
• oral, long lasting

Question 4

Buprenorphine

Answer 4

long term tx

• MOR partial agonist and KOR agonist
• less risk for OD and withdrawal
• lower risk for respiratory depression

Pentazocine is another partial agonist that can cause nightmares/hallucinations as SE

Question 5

Naltrexone

Answer 5

long term tx

• oral
• MOR antagonist

Question 6

Naloxone

Answer 6

long term tx, OD tx

• IV
• MOR and KOR antagonist
• shorter acting, withdrawal if on opioids

Question 7

Mixed action opioids

Answer 7

MOR, KOR, DOR

• Pentazocine (partial agonist) (SE: hallucinations) (less respiratory depression)
• Buprenorphine (partial agonist) (less respiratory depression)
• Nalbuphine
• Nalmefene (oral, alcohol dependence)
• Butorphanol

Question 8

Mild/moderate opioid agonists

Answer 8

MOR

• Codeine
• Hydrocodone
• Oxycodone

Question 9

Strong opioid agonists

Answer 9

MOR

• Morphine (middle potency, metabolite of codeine and heroin)
• Hydromorphone
• Oxymorphone
• Methadone
• Meperidine
• Fentanyl (lipophilic, more potent, short acting oral, patch long lasting)
• Sufentanyl (very potent)
• Alfentanil
• Remifentanil
• Levorphanol

SE:
Miosis

Respiratory depression
Analgesia
Truncal Rigidity

Sedation
Cough suppression (codeine)
Euphoria
Nausea
Temperature change

(Also orthostatic hypotension from MVC depression)