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Pharmacology > Cholinergic Drugs > Flashcards

Cholinergic Drugs Flashcards

1
Q

What are the two cholinergic receptors?

A

Nicotinic and Muscarinic

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2
Q

ACh released from the ___ nerve terminal interacts with subunits of the ___ nicotinic receptor to open it, allowing ___ influx to produce local depolarization and contraction.

A

motor; pentameric; Na+

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3
Q

The nicotinic receptor contains ___ subunits and binds ___ molecules of agonist.

A

five; two

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4
Q

Nicotinic receptors can be homomeric or heteromeric. Describe adult and fetal skeletal muscle

A

Adult: two alpha-1, one each of beta, episilon, and delta
Fetal: two alpha-1, one of each beta, gamma, and delta

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5
Q

Which subunit binds ACh?

A

alpha-1

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6
Q

Why do nicotinic receptors have complex pharmacology?

A

there are many combinations of 5 subunits (a2-a7 subunits and B2-B5 subunits)

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7
Q

In addition to acetylcholine, muscarinic receptors bind ___ and nicotinic receptors bind ___.

A

muscarine; nicotine

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8
Q

How many different muscarinic receptors are there?

A

five, M1-M4 are better appreciated than M5

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9
Q

___ receptors contain seven transmembrane domains whose ___ cytoplasmic loop is coupled to ___ proteins.

A

Muscarinic; third; G

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10
Q

Which muscarinic receptors are linked to G-alpha-q and activate DAG and IP3 signaling and activate phospholipase C to promote Ca2+ release?

A

M1, M3 and M5 (odd)

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11
Q

Which muscarinic receptors are linked to G-alpha-i and inhibit adenylate cyclase?

A

M2 and M4 (even)

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12
Q

How are direct acting cholinergic agonists different from indirect acting?

A

direct: bind to muscarinic or nicotinic ACh receptors or both
indirect: cholinesterase inhibitor

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13
Q

What is the purpose of the quarternary amine on acetylcholine?

A

binding to the receptor

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14
Q

acetylcholine → ___ + ___ by what enzyme?

A

acetate; choline; acetylcholinesterase

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15
Q

Which drug is similar to acetylcholine but is hydrolyzed much slower by esterase?

A

Carbachol (carbamylcholine)

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16
Q

List 4 non-selective cholinergic agonists.

A

acetylcholine, muscarine, nicotine, carbamoylcholine

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17
Q

List two nicotinic and muscarinic cholinergic agonists.

A

Nicotinic: dimethylphenylpiperazinium, succinylcholine
Muscarinic: pilocarpine, cevimeline

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18
Q

What has a profound effect on the duration of cholinergic agonists?

A

hydrolysis by cholinesterase

Acetylcholine hydrolyzed rapidly (short duration of action)
Methacholine hydrolyzed slower (somewhat longer duration of action)
Carbachol, bethanechol, cevimeline, and alkaloids are not hydrolyzed (longer duration of action)

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19
Q

___ muscarinic receptors on the sphincter muscles mediate pupil ___. ___ receptors on ___ muscle also mediate muscle contraction. This increases drainage by the ___ network and reduces ocular pressure.

A

M3; contraction; M3; ciliary; trabecular

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20
Q

What type of muscarinic receptors are found on cardiac muscles? What happens when these receptors are activated?

A

M2

reduce cardiac output

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21
Q

What type of receptors are expressed on vascular endothelial cells? What happens when these receptors are activated?

A

M3

vasodilation

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22
Q

Activation of M3 receptors increase ___ in endothelial cells. The Ca2+/calmodulin complex activates ___ to produce ___, which travels to the smooth muscle cell, enhances ___ production leading to muscle relaxation (enhances myosin light chain phosphatase activity).

A

Ca2+; NOS; NO; cGMP

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23
Q

What type of receptors are on the bronchial muscle and what happens when they are activated?

A

M3

contraction

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24
Q

T/F. Most GI effects are contractile except for sphincter muscles which relax when M2 receptors are activated.

A

True.

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25
Q

What type of receptor is found in secretory (salivary) glands? What happens when the receptor is activated?

A

M3 receptor

Ca2+ stimulates release of glandular contents

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26
Q

___ muscarinic receptors mediate ___ muscle contraction which aids in the voiding of the bladder.

A

M3; detrusor

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27
Q

Why are tertiary amines better absorbed than quaternary amines?

A

Tertiary amines can be charged or uncharged but quarternary amines have a permanent charge. Therefore, they must be inside the cell to work and charged from works on Na+ channel

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28
Q

___ and ___ are well absorbed after oral, subcutaneous or topical administration because they are not charged.

A

Pilocarpine; cevimeline

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29
Q

What patients taking muscarinic agonists are at an increased risk of having adverse responses?

A

patients with asthma (bronchoconstriction), cardiovascular disease (vasodilation, reduced cardiac output), ulcer (lacrimation).

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30
Q

What is the SLUD response to muscarinic agonists?

A

Salivation, Lacrimation, Urination, Defecation/Digestion

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31
Q

What is the hypertensive response to parenteral injections of large doses of pilocarpine or cevimeline?

A

CNS effects, activation of sympathetic postganglionic neurons

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32
Q

Why are intravenous and intramuscular routes generally avoided when administering muscarinic agonists?

A

because of cardiopulmonary effects

topical routes favored, if possible

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33
Q

Anticholinesterase which work by inhibiting the enzyme ___, which prevents hydrolysis of ___ thus increasing their concentration in the synapse and promoting more ___ action.

A

Acetylcholinesterase; ACh; ACh

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34
Q

T/F. Since anticholinesterases promote ACh activity without binding to any receptor they are called indirectly acting cholinergic agonists.

A

True.

35
Q

How is the synapse organized to get rid of as much ACh as quickly as possible?

A

There is enough Acetylcholinesterase in the synapse to hydrolyze 3 X 10^8 molecules of ACh in 1 millisecond (10-3). Normally only 3 X 10^6 ACh are released into synapse.

36
Q

___ is a tertiary amine and ___ is a quarternary amine. Both are ___ reversible anticholinesterases.

A

Physostigmine; neostigmine; slowly

37
Q

T/F. Some reversible anticholinesterases are slowly hydrolyzed by cholinesterase.

A

True

38
Q

___ ___ is an example of an anticholinesterase that acts in a rapidly reversible manner and is not hydrolyzed at all.

A

Ambenonium chloride

39
Q

Sarin and Malathon are reversible acting organophosphates. Which one is an insectiside and which is a nerve gas?

A 
Malathion = insectiside
Sarin = nerve gas
40
Q

Organophosphate anticholinesterases act in completely ___ manner. They covalently react with the enzyme and are not ___ (unless treated with antidote). They are ___ to insects and to people and are only used to kill things.

A

irreversible; hydrolyze; poisonous

41
Q

T/F. In general, anticholinesterases produces effects that are similar to the direct acting cholinergic agonists.

A

True. In effect, increase the concentration of acetylcholine at effector site.

42
Q

T/F. The greater the cholinergic stimulation at the site, the greater the effect.

A

True. ACh must be supplied, if not present, then no effect. Smooth muscle of ocular system, GI tract, urinary bladder are major sites.

43
Q

T/F. Anticholinesterases produce muscarinic receptor mediated vasodilation.

A

False, anticholinesterases DO NOT produce muscarinic receptor mediated vasodilation because there is no parasympathetic innervation to vascular endothelium.

44
Q

Anticholinesterases can produce vasodilatory effects through autonomic ___.

A

ganglia

45
Q

___ (tertiary amine) can produce vasodilatory effects through action in the CNS. It is readily ___ after oral, subcutaneous, and topical administration. It is inactivated by plasma ___.

A

Physostigmine; absorbed; cholinesterases

46
Q

Which type of amine anticholinesterases pass through biological membranes with difficulty and are inactivated by plasma cholinesterases and/or through liver metabolism?

A

Quaternary

47
Q

What condition is atropy of the optic nerve and loss of vision due to elevation in intraocular pressure? What does therapy attempt to do?

A

Glaucoma

Therapy aimed at stimulating musculature of the iris and ciliary body, increasing outflow or decreasing formation of vitreous humor.

48
Q

Muscarinic agonist decrease resistance to vitreous outflow through ciliary muscle contraction. What drugs are used? How are they applied? What is the adverse effect?

A

Pilocarpine, Physostigmine, and demecarium or echothiophate

applied topically

development of cataracts

49
Q

What drugs are frequently used to treat dry mouth (xerostomia)? What must be functional in these patients?

A

Pilocarpine and cevimeline (muscarinic agonists)

functional salivary gland

50
Q

How is pilocarpine and cevimeline administered?

A

Pilocarpine: 5-10mg oral 3X day to increase parotid, submandibular and sublingual secretion. Max flow is produced within 30 mins, return to basal flow within 3 hrs. No significant affect on cardiac function or BP. SE: sweating, chills, nausea, and dizziness

Cevimeline: 30mg, 3X day fewer side effects

51
Q

What type of drug is used to terminate the neuromuscular block of curare-like agents in general anesthesia?

A

Anticholinesterases

52
Q

Anticholinesterases are used to treat Myasthenia Gravis and can cross the blood brain barrier to improve cognitive function in Alzheimer’s patients. What drugs treat each?

A

MG: autoimmune disease with antibodies directed against nicotinic ACh receptors

A: donepezil, rivastigmine, galantamine

53
Q

___ and ___ are teritary anti-muscarinic natural products that will be absorbed and able to cross the ___ ___ ___

A

Atropine; Scopolamine; blood brain barrier

54
Q

___ is a quarternary amine derived from Scopolamine that is poorly absorbed and cannot cross the BBB.

A

Methscopolamine

55
Q

___ (tertiary amine) and ___ (quarternary amine) are synthetic anti-muscarinics.

A

Benztropine; Propanthaline

56
Q

In general, treatment with an anti-muscarinic drug places the target under control by the sympathetic nervous system. What is the exception?

A

Sweat gland, where signals from sympathetic and parasympathetic systems act upon muscarinic receptors at the target and are both blocked by the anti-muscarinic.

57
Q

Anti-muscarinics will cause pupil ___ and paralysis of ___. Intraocular pressure is not significantly affected except in the case of ___ ___ ___, in which they can cause a serious rise in pressure.

A

dilation; accomodation; narrow angle glaucoma

58
Q

How do anti-muscarinics treat COPD? Body temperature?

A

produce bronchodilation and diminish mucus production

inhibit sweating and can elevate body temperature

59
Q

What is the pharmacologic effect of anti-muscarinics on the GI tract?

A

generally inhibit motility and only inhibit secretions at very high concentrations

60
Q

In the secretory glands (___ receptors), anti-muscarinics block ___ mediated secretion.

A

M3; parasympathetic

61
Q

___ anti-muscarinics cause mild bradycardia when given to limit salivation due to selective inhibition of prejunctional ___ receptors that limit ACh release. At ___ doses, the opposite effect is seen due to the direct action at the heart.

A

Oral; M2; higher

62
Q

How does atropine cause changes in urinary retention?

A

Detrusor muscles are relaxed by atropine and sphincter and trigone muscles are contracted.

63
Q

Give 5 therapeutic uses for anti-muscarinics.

A
  1. dilate pupils for opthalmologic procedures
  2. treatment of COPD (quarternary amines administered by inhalation)
  3. Diminish salivary secretions before oral procedures
  4. Anti-spasmodics, and anti-ulcer agents (not useful because of SE)
  5. antidote to anti-cholinesterases
64
Q

Relate oral doses to the effects of antimuscarinics.

A

Lowest → highest

  1. secretion (saliva, sweat, mucus)
  2. mydriasis (pupil dilation) loss of accomodation and tachycardia
  3. loss of parasympathetic control of bladder and GI smooth muscel
  4. gastric secretion
65
Q

T/F. Unlike atropine, the quaternary amines anti-cholinergics are poorly absorbed, have a wide therapeutic margin, and are well tolerated.

A

True.

66
Q

What are the adverse effects of atropine?

A

Hot as a hare, blind as a bat, dry as a bone, red as a beet, and mad as a wet hen.

increased intraocular pressure, ventricular fibrillation, tachycardia, dizziness, nausea, dry mouth, blurred vision, extreme confusion, hallucinations

67
Q

What are the common symptoms known as anti-cholinergic toxidrome?

A

warm, dry skin from decreased sweating, blurry vision, decreased sweating/lacrimation, vasodilation, and effects on the CNS.

68
Q

When nicotine acts on the CNS it will penetrate the ___ and produce CNS effects, feelings of ___ being and ___ irritability.

A

BBB; well; decreased

69
Q

T/F. Ganglionic blockers are rarely used because they block sympathetic and parasympathetic ganglion and their lack of selectivity confers such a broad range of undesirable effects.

A

True

70
Q

Post-synaptic transmission of nerve impulses at skeletal muscle is mediated by ___ ACh receptors.

A

nicotinic

71
Q

Explain receptor desensitization.

A

Although cholinergic agonist biding to ACh receptor initially opens the ion gate (letting Na+ in), continued activity produces desensitization, a refractory state where the ion gate remains closed despite the continued presence of agonist.

72
Q

Drugs now used as ganglion blockers are classified as non-depolarizing competitive antagonists. List some examples of the drugs? What do they competitive antagonist against?

A

d-tubocurarine, pancuronium (bromide salt), atracurium

acetylcholine

73
Q

___ is a depolarizing agent that has a more rapid ___ of action and a shorter ___ of action than non-depolarizing blocking agents.

A

Succinylcholine; onset; duration

Because it is subject to hydrolysis by plasma and liver cholinesterases it has a shorter duration of action.

74
Q

Initially, succinylcholine activates ACh receptors but the chronic ___ at the muscle end-plate leads to ___ of voltage-gated Na+ channels and ___ ___. This is the ___ acting phase one block.

A

depolarization; inactivation; flaccid paralysis; shorter

75
Q

After a while, chronic exposure to succinylcholine leads to ___ of ACh receptors. This is the ___ acting phase II block.

A

desensitization; longer

76
Q

Neuromuscular blocking agents can be given ___ or ___ but it induces ___ ___. ___ infusion is the usual administration pre-surgery.

A

IV; IM; flaccid paralysis; Fast

77
Q

T/F. Neuromuscular blocking agents have side effects in CNS and on autonomics.

A

False, they do not get in CNS and have no particular effect on ganglia

78
Q

Neuromuscular blocking agents can promote ___ release from ___ cells.

A

histamine; mast

79
Q

What two drugs are used in endotracheal intubation?

A
  1. succinylcholine (most rapid) - drug of choice

2. rocuronium (non-depolarizing) - second place

80
Q

In adjunct to general anesthesia during surgery when a doc wants to block neuromuscular transmission what medium speed blocker is favored?

A

d-tubocurarine

81
Q

What is the most significant adverse effect when administering neuromuscular blockers?

A

respiratory failure but arrhythimas (ganglionic activities, pancurium worst) and bradycardia (succinylcholine worst) can also occur.

82
Q

T/F. Neuromuscular blocking agents can have drug interactions with anticholinesterases and general anesthetics.

A

True.

83
Q

T/F. Dentist may occasionally need to produce muscle relaxation when performing surgery (treating jaw fracture) and endotracheal intubation.

A

True

Pharmacology (13 decks)

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