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65 Cards in this Set

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Describe where synthesis, packaging, and transport of peptides occurs within neurons
Synthesis occurs in the cell bodies
Prepropeptides are packaged into large dense core vesicles in the Gogli apparatus.
They are transported down the axon to the nerve terminals, and they mature along the way.
How is the elimination and metabolism of neuropeptides different from that of other neurotransmitters?
1. Elimination from synapse is SLOWER, and effects are LONGER
2. Neuropeptides are eliminated from synapse by diffusion and metabolism by proteolytic enzymes

*They are NOT taken up by either the presynaptic nerve terminal or glia, like other classical NTs
Which opiates are from the brain?
Enkephalins
List 3 groups of opiates
1. Enkephalins
2. B-endorphin
3. Dynorphin
Which opiate has the partial sequence "Tyr-Gly-Gly-Phe-Met"?
B-Endorphin
Which opiate has the partial sequence "Tyr-Gly-Gly-Phe-Leu"?
Dynorphins
Which opiate peptides are mostly secreted by interneurons in local CNS circuits?
Enkephalins
List 5 areas that enkephalins modulate
1. Nociception (lamina I,II of spinal cord, spinal trigeminal nucleus, periaqueductal gray)
2. Affective behaviors (limbic system)
3. Motor control (caudate nucleus?, globus pallidus)
4. Autonomic function (medulla)
5. Neuroendocrine function (hypothalamus)
Cells containing B-endorphin are localized to which areas?
1. Hypothalamus
2. Medulla (nucleus solitarius)
Where are dynorphin cells found and what are its various functions?
Found throughout CNS

(Functions are similar to enkephalins)
Nociceptive, motor, affective behavior, endocrine functions
List 2 types of enkephalins
1. Methionine enkephalin (Met-ENK)
2. Leucine enkephalin (Leu-ENK)
Which enkephalins make up proenkephalin?
5 Met-ENK + 1 Leu-ENK
Prodynorphin consists of which dynorphins?
1 Dynorphin A + 1 Dynorphin B
Which receptor is a u-opiate receptor (MOR)?
B-endorphin receptor
Which receptor is a delta-opiate receptor (DOR)?
Enkephalin receptor
Which receptor is a k-opiate receptor (KOR)?
dynorphin receptor
Does activation of opiate receptors produce excitation or inhibition of the target cell?
INHIBITION

*Inhibits Ca2+ conduction into presynaptic nerve terminals --> PRESYNAPTIC INHIBITION
*Stimulates K+ conduction on postsynaptic neurons --> HYPERPOLARIZATION
What kind of pain are opioids most effective for treating?
Constant dull pain
(not very effective for intermittent sharp pain)
What is the primary site for opioid's analgesic actions?
GABAergic neurons in the periaquaductal gray region of the midbrain
*GABAergic neurons normally inhibit descending inhibitory neurons that modulate nociceptive inputs in the spinal cord-- so they increase pain perception
*Opiates block the GABAergic neurons, thereby allow inhibition of nociception via descending inhibitory pathways
Where are opiate receptors located in the spinal cord?
What is the result?
1. Presynaptic nerve terminal of the primary afferent neuron
2. Cell body of the second order neuron

RESULT:
1. Inhibit release of GLUTAMATE from primary afferent neurons by blocking Ca2+ channels
2. Hyperpolarize second order neurons by activating K+ channels
What is the effect of opioids on GI motility?
Can this effect eventually be tolerated after long-term use?
Decreases GI motility
(can be used to treat diarrhea)

*Patients who must be on opioids long-term (cancer) must be given stool softeners or laxatives because only mild tolerance develops
How do opioids decrease the cough reflex?
Inhibition of the cough reflex center in the medulla
List 3 therapeutic effects of opioids
1. Analgesia
2. Decreased GI motility
3. Cough suppression
What is a significant and life threatening side effect of opioids?
Respiratory depression
(direct inhibition of respiratory control centers in the medulla)

*Overdose of opioids can result in death due to respiratory depression
Tolerance to opioids affects certain actions of the drugs and not others. Describe the effects of tolerance.
Tolerance affects the following actions:
1. Analgesic
2. Sedation
3. Respiratory inhibition

Tolerance only slowly develops to constipation, and has very little effect on miosis
Opioid withdrawal syndrome can occur as a result of which 2 scenarios?
1. Dependent patient discontinues drug use
2. Opioid antagonist is administered to dependent patient
What is the result of a partial agonist administered along with a full agonist?
The partial agonist will reduce the response of the full agonist and act similar to an antagonist
Where are most opioids metabolized?
Liver
*Extensive first pass metabolism

*Adjustments must be made for oral doses to achieve adequate pain relief
Morphine and morphine analogs have a high affinity for which receptor?
u-opioid receptor (MOR)
(lower affinity for KOR and DOR)
Give an example of a morphine analog
Levorphanol
What is Levorphanol?
Morphine analog
What is the drug of choice for severe pain?
Morphine
What is an advantage of Levorphanol over morphine?
Less nausea and vomiting
List 2 meperidine analogs
1. Diphenoxylate
2. Loperamide
Which opioid drug is used only to treat diarrhea?
Which other drug is also used for treating diarrhea?
Diphenoxylate
(inhibits GI motility)

Loperamide
Which opioid has a short half life due to the redistribution into fat?
Fentanyl
List 2 fentanyl analogs
1. Sufentanil
2. Remifentanil
What is loperamide?
Mepiridine analog
What is diphenoxylate?
Mepiridine analog
Which drug is used as a continuous infusion for SHORT surgical procedures, but is a not a drug of choice if post-operative analgesia is needed?
Remifentanil
What is the half life of Remifentanil?
15 minutes
(short)
Which drug can be used to prevent heroine withdrawal?
Methadone
*Sufficient to prevent withdrawal, but will not produce euphoria and reinforcing effects of opioids
Which drug is widely used to treat opioid abuse as a substitute due to the pharmacokinetic profile?
Methadone
What is the half-life of methadone?
15-40 hours
(long)
Which partial MOR agonists are used for mild to moderate pain and cough?
1. Codeine
2. Hydrocodone
Which partial MOR agonist is used for moderate to severe pain?
Oxycodone
List 3 partial MOR agonists
1. Codeine
2. Oxycodone
3. Hydrocodone
Which drug is a partial MOR agonist and KOR antagonist?
Buprenorphine
List 4 agonist-antagonist opioid drugs
1. Buprenorphine
2. Pentazocine
3. Nalbuphine
4. Butorphanol
Which drug is a KOR agonist and a weak MOR antanogist or partial agonist?
Pentazocine
Which agonist-antagonist can produce dysphoria and psychomimetic effects if given in high doses?
Pentazocine
Which drug is a strong KOR agonist and MOR antagonist?
Nalbuphine
Butorphanol produces agonist/antagonist effects on which receptors?
Primarily a KOR agonist
Weak MOR antagonist or partial agonist activity
Nalbuphine produces agonist/antagonist effects on which receptors?
Strong KOR agonist and MOR antagonist
Pentazocine produces agonist/antagonist effects on which receptors?
KOR agonist and MOR antagonist/partial agonist
Buprenorphine produces agonist/antagonist effects on which receptors?
Partial MOR agonist and KOR antagonist
Which drug is a weak MOR agonist and norepinephrine and serotonin reuptake blocker?
Tramadol
What level of pain is Tramadol effective for treating?
Mild to moderate pain
Which opioid treatment may produce seizures or exacerbate seizures in patients with epilepsy?
Tramadol
Tramadol is contraindicated in which patients?
Patients taking SSRIs or MAOIs or other drugs which may lower the seizure threshold
Dextromethorphan is only used for what purpose?
Cough suppression
List 3 non-selective opiate receptor antagonist?
1. Naloxone
2. Naltrexone
3. Methylnatrexone
What is the primary use of Naloxone?
Reverse the effects of an opioid overdose
What is the duration of action of Naloxone?
1-2 hours

*Used to reverse effects of opioid overdose
What group of opiates are "endogenous morphine"?
B-Endorphin