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PHARMACOLOGY > CHAPTER 4: CHOLINGERGIC AGONISTS/ DIRECT ACTING > Flashcards

CHAPTER 4: CHOLINGERGIC AGONISTS/ DIRECT ACTING Flashcards

1
Q

Stimulation of the parasympathetic nervous system (PSNS)

A
  • inc motility of GI tract
  • dec heart rate and contractility
  • constrict bronchi, inc gland secretion, bronchospasm
  • relax GI and urinary bladder sphincter
  • inc urination, inc pooping
  • pupillary constriction (miosis)
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2
Q

4 basic cholinergic nerves

A

preganglionic in the ANS, postganglionic in the PSNS AND SNS, motor nerves in skeletal muscles and cholinergic in CNS

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3
Q

what happens if the drug is able to pass the blood brain barrier?

A

it will bind to cholinergic receptors causing therapeutic AND adverse effects

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4
Q

process of neurotransmission at cholinergic neurons (release of Ach steps)

A

1- choline is a cotransporter that goes into the cell also bringing in Na+. bind with the acetyl group from AcCoA to make acetylcholine
2- Ach goes into storage vesicles so it is stored and preserved
3- Action potential reached, depolarization of membrane induces influx of Ca2+ and fusion of synaptic vesicle to the membrane causing synaptic cleft
4- release Ach into presynpatic receptor for negative feedback and binds to receptor
5- degrade acetylcholine using acetylcholinesterase (AchE) into choline and acetate (waste)
6- choline is regenerated and used again

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5
Q

different ways to alter neurotransmission

A

bind and activate receptors, inc Ca concentration to stimulate more vesicle fusion and more Ach binding, block the enzyme so Ach conc increases, or use a drug that acts on choline

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6
Q

cholinergic receptors/cholinoceptors: 2 kinds

A

muscaranic receptors vs. nicotinic receptors

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7
Q

muscarinic receptors

A
  • M1 to M5, 1-3 are most commonly known
  • HIGH affinity for muscarine, LOW affinity for nicotine
  • found on autonomic effector organs (we cant control)
    -metabotropic
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8
Q

metabotropic

A

g protein coupled

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9
Q

nicotinic receptors

A

-NM (muscle) and NN (neurons)
- HIGH affinity for nicotine, LOW affinity for muscarine
-NN in the CNS, adrenal medulla, and autonomic ganglia
-NM in the neuromuscular junction in skeletal muscle
ionotropic

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10
Q

ionotropic

A

ligand-gated ion channel

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11
Q

which substrate is universal for both muscarinic and nicotinic receptors?

A

Ach

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12
Q

mechanism of Ach signal transduction
- muscarinic receptor activation

A

M1 and M3: Gq protein activation results in inc of IP3 and inc DAG
- IP3 increases Ca2+–> inc contractility
-DAG activates protein kinase C–> phosphorylation

M2: Gi protein, inhibit adenylyl cyclase, dec cAMP

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13
Q

mechanism of Ach signal transduction
- nicotinic receptor activation

A

-receptor is composed of 5 subunits that span the membrane and form a CHANNEL
- activated by Ach binding to receptor on ALPHA SUBUNIT–> CONFORMATIONAL CHANGE opens channel and allow flow of CHARGED MOLECULES (Na+ , K+) causing depolarization

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14
Q

how many binding sites on the nicotinic Ach receptors

A

2 binding sites, indicate you need 2 Ach for it to function/activate

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15
Q

A patient develops urinary retention after an abdominal surgery, urinary obstruction was ruled out in this patient. Which strategy would be helpful in PROMOTING urination?

A

you need stimulate the parasympathetic NS and RELAX the sphincters so….
you inhibit AchE (enzyme) from breaking down Ach.
Inc in Ach stimulates PSNS

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16
Q

Cholinergic Agonists- 2 types

A

direct acting and indirect acting (reversible and irreversible)

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17
Q

direct acting cholinergic agonists

A

mimic the effects of Ach by DIRECTLY binding to cholinoceptors, and prefer MUSCARINIC receptors w little specificity

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18
Q

effect of directing acting choli agonists

A

increases stimulation of cholinergic receptor

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19
Q

indirect acting cholinergic agonists

A

react with AChE and prevent it breaking down ACh released from the nerve

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20
Q

effect of indirect acting cholinergic agonists

A

increases stimulation of ACh receptor sites

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21
Q

pk of drug is the

A

plasma concentration of the drug in your system

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22
Q

common direct acting cholinergic agonists

A

acetycholine, bethanechol, carbachol, cevimeline, pilocarpine

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23
Q

different chemical structure of direct acting causes

A

different PK of the drug in your system.

24
Q

ACh vs bethanechol, carbachol, and pilocarpine

A

ACh, bethanechol, and carbachol contain ammonium compound–> N+, makes it more difficult to cross membranes
but, pilocarpine does not contain this compound allowing it to cross the BBB easily and go to the brain/cause unwanted effects

25
Q

ACh- mechanism

A

ACh binds to the nicotinic or muscarinic receptors (its target)

26
Q

ACh- inactivation

A

inactivated by cholinesterases (AChE)

27
Q

ACh- therapeutic actions

A

dec heart rate, dec BP
- vagus nerve controls heart rate, decreases heart rate by dec SA node firing
- musc rec in smooth muscle relaxes vessels and dec BP

28
Q

ACh- therapeutic uses/INDICATIONS

A

optho surgeries needing rapid miosis

29
Q

ACh- Adverse effects (systemically)

A

bradycardia (DEC BPM/HEART RATE), hypotension , flushing, sweating, difficult breathing

30
Q

why do we need to check if the patient is taking blood pressure medication when administering ACh systemically?

A

if the patient is taking medication for hypertension (high BP), their BP is already lowered and the adverse effects of ACh, hypotension, will cause BP to fall too low

31
Q

difficulty breathing term-

A

bronchospasm

32
Q

why does ACh have little therapeutic importance?

A

they act on BOTH nicotinic and muscarinic receptors, multiple actions make it less specific to what effect you are looking for

33
Q

does ACh have adverse effects if administered locally?

A

NO! Only if administered systemically, then it will activate effects of the parasymp NS

34
Q

Bethanechol-structure and mechanism

A

structural derivative of ACh
-strong muscarinic activity, lack of nicotinic action
muscarinic activity: action of SMOOTH MUSCLES BLADDER AND GI

35
Q

bethanechol- duration of action longer or shorter than Ach?

A

longer than Ach, 1 hour, metabolized SLOWLY

36
Q

Bethanechol- therapeutic actions

A

-inc GI intestinal motility/tone
-inc detrusor bladder muscle tone
-relax trigone and sphincter–> STIMULATE URINATION

37
Q

Bethanechol- therapeutic uses/indications

A

urology, stimulate atonic bladder (urecholine)

38
Q

atonic bladder

A

patient unable to urinate bc of insufficient destrusor muscle contraction

39
Q

Bethanechol- adverse effects (systemically)

A

sweat, salvation, flushing, nausea, diarrhea, bronchospasm, hypotension/low BP

40
Q

Carbachol- structure and mechanism

A

structural derivative of ACh, similar
BOTH muscarinic and nicotinic actions

41
Q

Carbachol- inactivation and duration of action?

A

LONG duration of action
- not inactivated by AChE but is by other esterases

42
Q

carbachol activates nicotinic and muscarinic receptors. what does this mean it stimulates?

A

since it activates nicotinic that means it ALSO stimulate the sympathetic NS

43
Q

Carbachol- therapeutic actions

A

-stimulate THEN depress cardiovascular and GI systems
- MIOSIS

44
Q

Carbachol- therapeutic uses/indications

A

optho for treating glaucoma/miostat

45
Q

Carbachol- adverse effects

A

little effects, it doesn’t penetrate

46
Q

Pilocarpine- structure, activity, inactivation

A

less potent that ACh and its derivatives (its a natural product and UNCHARGED)
- not metabolized by AChE, ABLE to penetrate CNS
-muscarinic activity

47
Q

Pilocarpine- therapeutic actions

A

-topically induces miosis and contraction of
the ciliary muscle
-orally stimulates secretions (saliva)

48
Q

Pilocarpine- adverse effects

A

CNS disturbances

49
Q

Pilocarpine- indications

A

-optho for glaucoma
-saliva production stimulator (salagen) in sjorgren syndrome

50
Q

what counteracts pilocarpine CNS disturbances

A

atropine

51
Q

types of glaucoma (2)

A

open-angle and angle-closure

52
Q

Open Angle Glaucoma

A

-most common, no symptoms
-damage optic nerve leading to blindness

53
Q

what kinds of people are prone to OPEN ANGLE glaucoma?

A

ppl with high BP or diabetes are at higher risk

54
Q

angle-closure glaucoma (narrow/acute glaucoma)

A

-considered a medical emergency
-outer edge of the iris blocks fluid from draining out the front of the eye
-if not treated, can cause blindness in days

55
Q

what is Sjogrens Syndrome?

A

immune disease characterized by dry mouth and eyes

56
Q

what is xerostomia?

A

dry MOUTH

57
Q

treatment for sjogrens syndrome (2)

A

pilocarpine and cevimeline (in adults)

PHARMACOLOGY (29 decks)

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