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Pharmacology and Medical Chemistry I > Exam 3 - Lecture 30, Opioids > Flashcards

Exam 3 - Lecture 30, Opioids Flashcards

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1
Q

Opiate

A

defines drugs derived from opium, including semi-synthetic derivatives of morphine

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2
Q

Opioid

A

term for all agents, natural and synthetic, with morphine or opium-like actions

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3
Q

Endogenous opioid peptides are

A

the group of endogenous peptides with opioid actions; natural ligands for opioid receptors

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4
Q

Narcotic

A

Legal designation for opioid drugs and other drug of abuse that produce stupor and insensibility

medically defined as drugs with sedative/hypnotic and analgesic properties

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5
Q

How do opioid drugs produce their effects?

A

Stereospecificity - Levo isomers are active form

Saturability - finite number of sites; receptor occupancy determines magnitude of agonist effect

Competitive inhibition of binding by antagonists inhibits opioid effects

Affinity of receptor for opioid drugs correlates with their analogies potencies clinically

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6
Q

Four opioid classes

A

Enkephalins
Endorphins
Endomorphins
Nociception/ Orphanin FQ

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7
Q

Enkephalins derived from

A

proenkephalin

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8
Q

Forms of Enkephalin

A

Methionine - enkephalin (H-tyr-gly-gly-phe-met-OH)

Leucine - enkephalin (H-tyr-gly-gly-phe-leu-OH)

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9
Q

Endorphins

A

larger polypeptides than enkephalins but contain in their sequence met-enkephalin

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10
Q

Prodynorphin yields

A

dynorphin A, B, and a-neoendorphin

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11
Q

Pro-opiomelanocortin yields

A

B- endorphin

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12
Q

Endomorphins derived from

A

unknown source currently

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13
Q

Form of Endomorphins

A

Endomorphin 1 = Tyr-Pro-Trp-Phe-NH2

Endomorphin 2 = Tyr-Pro-Phe-Phe-NH2

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14
Q

Nociceptin/Orphanin FQ

A

17 amino acid peptide derived from pronociceptin

Considered the natural ligand for the ORL1 (OP4) opioid receptor

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15
Q

Opioid analgesia mediated in (Descending inhibitory pathway)

A

Mediated in dorsal columns of spinal cord, periaqueductal gray, raphe nucleus (5HT containing neurons)

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16
Q

Opioids produce analgesia by

A

Inhibiting release of substance P (Pain transmitter) from primary afferent pain fibers in spinal cord (Spinal level)

Altering subjective response to pain sensation, probably mediated at higher (supra spinal) centers in brain

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17
Q

Opioids effect on GI and motility

A

Mediated by stimulation of opioid receptors in nerve plexes and glands of stomach and intestine

Can be used as an anti-diarrheal

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18
Q

Four opioid receptor subtypes

A

Mu
Kappa
Delta
ORL1

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19
Q

Mu receptors and binding affinity

A

Morphine, prototype agonist

Endorphins>enkephalins>dynorphins

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20
Q

Kappa receptors and binding affinity

A

Ketocyclazocine, prototype agonist

Dynorphins>endorphins and enkephalins

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21
Q

Delta receptors and binding affinity

A

D-ala, D-leu enkephalin, prototype agonist

Enkephalins > endorphins> and dynorphins

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22
Q

ORL1 (opioid-receptor-like receptor)

A

Named after discovery of nociceptin/orpganin FQ, the endogenous ligand for this receptor

23
Q

Neurons Expressing D2 show

A

enkephalins

24
Q

Neurons Expressing D1 show

A

Dynorphins

25
Q

Mu receptor physiological effect

A

analgesia, euphoria, respiratory depression, dependence, decrease GI motility

26
Q

Kappa receptor physiological effect

A

Analgesia, dysphoria, diuresis

27
Q

Delta receptor physiological effect

A

analgesia, decreased GI motility, immunity

28
Q

ORL1 receptor physiological effect

A

Complex effects on pain, drug reward, feeding, learning and memory

29
Q

Classical opioid receptors

A

Mu, Kappa, Delta

Found in brain, spinal cord and peripheral tissues

30
Q

Opioid receptor structure + biology

A

7 Transmembrane receptors

G protein coupled

Activate Gi/Go to inhibit Adenylate cyclase, activate inward rectifying K+ channels, and or inhibit Ca++ current

31
Q

CNS effects: analgesia

A

Analgesia without loss of consciousness

Distinction between pain sensation and pain as suffering (emotional)

Opioids both elevate pain threshold and increase the capacity to tolerate pain (ie subjective, emotional response to pain)

32
Q

CNS effects: Drowsiness and euphoria

A

Feeling of warmth over entire body, facial itching, especially of nose (cause of abuse). Some individuals find these effects unpleasant

Muscle tone reduced, ability to concentrate and awareness reduced, apathy and lethargy prominent, “mental clouding”

33
Q

CNS effect: Suppression of cough

A

Known as “anti-tussive” effect

due to a direct action on medullary cough center

34
Q

CNS effect: CNS excitation

A

only at extremely high doses or moderate doses in susceptible individuals

Convulsions may occur, mechanism unkown

35
Q

CNS effect: Emetic effects

A

Nausea and vomiting are frequent side-effects of opioid drugs

Due to stimulation of CTZ in medulla

Apomorphine, DA agonist, potent emetic agent

36
Q

CNS effect: effect on pupil diameter (Miosis)

A

Pin point pupils consistent features of opioid drug use

No tolerance develops to the pupillary constriction caused by opioid drugs

Due to action on oculomotor nucleus in brain

37
Q

CNS effect: effect on respiration (depression)

A

Direct depression of brainstem respiratory center
- Reduced rate, minute volume, tidal exchange

Blunting of normal reflex response to CO2

Deaths from opioid OD almost always due to respiratory arrest

38
Q

Morphine effects on GI

A

Delay gastric emptying

Decrease propulsive movement of small and large intestine, increase in resting ton and periodic intestinal spasms

Failure to perceive sensory stimuli which normally activate defecation reglex

No tolerance develops to the constipating effects of opioid drugs

39
Q

Morphine: Cardiovascular effects

A

Little effect on heart rate, rhythm or blood pressure in supine patient (laying on back)

Postural hypotension due to opioid induced vasodilation prominent in upright position

40
Q

Morphine vasodilation due to

A

release of histamine
Suppression of adrenergic vasoconstrictor tone
Suppression of reflex vasoconstriction due to increased CO2 levels

41
Q

Morphine effects on smooth muscle

A

Urinary bladder reduce capacity, urinary urgency with difficulty in peeing

Uterine contractions no significantly affected, but duration of labor my be prolonged

Bronchial muscle maybe constricted causing narrowing of the airway

42
Q

ADME opioids

A

Well absorbed from GI tract, nasal mucosa, subcutaneous and intramuscular site

Effects of a a given dose are greater after parenteral admin than oral admin due to “first pass” effect

Distribution influenced by plasma protein binding (1/3) of total and accumulation of drug in kidney, lung, liver, Skm

Metabolism of morphine primarily by hepatic conjugation with glucuronic acid; conjugated drug excreted primarily in pee and 7-10% poop

43
Q

Drugs that potentiate opioid effects

A

Phenothiazine antipsych

Tricyclic antidepressants

Monoamine oxidase inhibitors

44
Q

Opioid and amphetamine

A

Amphetamine potentiates euphorigenic effects, “speed-balling”

45
Q

Opioid tolerance develops to

A

Analgesic action
Euphoric effect
Respiratory depressant effects

No tolerance develops to mitosis and constipating effects

46
Q

Tolerance opioids

A

Decreased response to drug after its chronic use

Higher doses needed to achieve original response, cell mechanism unknown

47
Q

Cross-tolerance

A

Tolerance of one drugs invokes tolerance to drugs with similar mechanisms of action

48
Q

Dependence

A

Change resulting from chronic drug exposure such that drug is required for normative response

Only seen in absence of drug (withdrawal) or can be shown with antagonist

Cell mechanism unknown, can be suppressed by re-admin of drug or another drug with similar mechanism of action

49
Q

High Chances of Tolerance Opioids

A 
Analgesia
Euphoria
Mental clouding
Sedation
Respiratory depression
Cough suppression
Nausea and vomiting
50
Q

Minimal to no chances of Tolerance opioids

A

Miosis
Constipation
Convulsions

51
Q

Physical Dependence

A

develops after repeated use

revealed as a withdrawal syndrome when drug is discontinued

Admin of any opioid agonist can abruptly abolish withdrawal symptoms

52
Q

Opioid Addiction

A

Distinct from tolerance and physical dependence

Many addictions start with prescription use of opioids for pain

53
Q

Criteria for Opioid addiction

A 
tolerance
Withdrawal symptoms when stopped
use of large amounts over time
unsuccessful attempt to stop
alot of time spent getting drug
continued use despite negative effects
54
Q

Opioid locations in Afferent pain transmission

A

VPL, Amygdala, Parabrachial nucleus, Dosal Horn

Pharmacology and Medical Chemistry I (30 decks)

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