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Pharmacy School 2015-16 > PHAR 736 Exam 3 > Flashcards

PHAR 736 Exam 3 Flashcards

1
Q

Effects of muscarinic receptor agonists (SLUDS)

A

Salivation, Lacrimation, Urination, Defecation, Sweating

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2
Q

Effect of muscarinic receptor agonist on eye

A

Miosis through contraction of iris sphincter may help dislodge an adherent iris in acute (closed angle) glaucoma

Nearsightedness: contraction of ciliary muscle may improve aqueous humor flow in chronic glaucoma

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3
Q

Effect of muscarinic agonist on GI tract

A

Contraction of longitudinal muscles and relaxation of sphincters for increased motility

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4
Q

Effect of muscarinic agonist on urinary tract

A

Contraction of detrusor muscle and relaxation of sphincter for increased urinary output

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5
Q

Effect of muscarinic agonist on heart

A

Decrease heart rate at sino-atrial node, and conductivity through AV node

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6
Q

Effect of mucarinic agonist on lungs

A

Bronchoconstriction

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7
Q

Effect of muscarinic agonist on glands

A

Increased salivation, lacrimation and sweating

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8
Q

Describe ACh synthesis

A

Choline acetyltransferase synthesizes ACh from choline and acetate

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9
Q

Inhibition of ACh release

A

Inhibited by M2 muscarinic receptors on presynaptic neurons (AKA acetylcholine autoreceptors)

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10
Q

Nicotinic receptors

A

Ligand-gated ion channels

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11
Q

Muscarinic receptors

A

Located on parasympathetically innervated organs

G-protein coupled receptors; 2 pharmacologic sub-classes (M1 and M2) from five gene products (m1, m2, m3, m4, m5)

*few agonists are capable of distinguishing among the receptor sub-types

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12
Q

Describe M1 type

A

Consists of m1, m3, and m5 gene products

Coupled to Gq/11 family of G proteins and activate phospholipase C-beta enzymes | increases IP3, DAG, intracellular Ca2+ levels | protein kinase C activation

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13
Q

M1 locations and effects at parasympathetically innervated organs

A

*predominately m3 receptors

Glands (pulmonary, GI, sweat, lacrimal, nasopharyngeal) increasing secretions

Longitudinal GI smooth muscle, increasing motility and tone

Bladder smooth muscle, increasing tone and emptying

Bronchiol smooth muscle, increasing bronchoconstriction

Iris sphincter, producing miosis

Ciliary muscle, accommodating for near-sightedness

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14
Q

M1 locations and effects at locations outside of parasympathetic nervous system

A

Brain

Blood vessels (vascular endothelium): 
M1 type (m3) stimulate release of NO | m3 receptors activate PLC-beta to cause NO (endothelium-derived relaxing factor) release | NO stimulates increases in cAMP in smooth muscle which is relaxing
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15
Q

What is the catch with m3 receptors?

A

There are no PNS nerves and no ACh at vascular endothelium so these m3 receptors are not ever naturally activated

Only exogenous substances can activate them

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16
Q

Describe M2 type

A

Consist of m2 and m4 gene products

Coupled to Gi/o family of G proteins | Inhibit adenyly cyclase | inhibit Ca2+ channel opening

Couple to release of G-beta-Y proteins | activate K+ channels causing cell hyperpolarization | hyperpolarization inhibits neurotransmitter release

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17
Q

Locations of M2 receptors

A

Heart (decreasing rate and force of contraction)

Preganglionic cholinergic nerve terminals (inhibiting ACh release)

Brain

Presynaptic on SNS adrenergic neurons

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18
Q

Describe cAMP and its effects on heart

A

Increases cAMP leads to increased rate and contractility (opposite of smooth muscle)

Decrease in cAMP leads to hyperpolarization by opening K+ channels, and inhibition of Ca2+ channels and other effects leading to decreased heart rate and contractility

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19
Q

Describe M2 receptor function on presynaptic SNS adrenergic neurons

A

Heteroreceptors on presynaptic sympathetic neurons, causing inhibition of neurotransmitter release

Further decrease in HR by inhibiting NE release

Further bronchoconstriction by inhibiting NE release onto pulmonary smooth muscle

Relax GI and bladder sphincters by inhibiting NE release (parasympathetic nerves only synapse on sympathetic nerve)

Promote vasorelaxation by inhibiting NE release onto vascular smooth muscle (no parasympathetic nerves)

20
Q

Muscarinic agonists and BPH

A

Not indicated in BPH and be careful when using post trauma (e.g. postpartum) | painful swelling and pressure may ensue if urinary retention is due to blockage of urethra or ureter

21
Q

Muscarinic agonists and Sjogren’s syndrome

A

Anti-m3 muscarinic receptor antibodies are produced and destroy the receptors, leading to eventual destruction of secretory glands

Primary symptoms are dry eyes, severely dry mouth, and anhidrosis

May also include bladder irritability, constipation, fluctuating blood pressure, dilated pupils, and blurred vision.

22
Q

ACh analogue muscarinic agonists

A

Acetylcholine, Methacholine, Carbachol, Bethanechol

Duration of action limited by acetylcholinesterase | usefulness limited by poor selectivity for muscarinic versus nicotinic receptors

23
Q

Acetylcholine

A

Endogenous neurotransmitter for muscarinic receptors

Rapidly hydrolyzed by AChE (acetylcholinesterase)

Also activates nicotinic receptors which is problematic

Used in the eye to induce miosis, short-term

24
Q

Bethanechol

A

Long duration of action, NOT a substrate for AChE

Reduced activity at nicotinic receptors

Poor absorption from GI

Used to increase GI motility and bladder emptying

25
Q

Plant alkaloids and synthetic muscarinic agonists

A

NOT substrates for AChE, this long duration of action

Muscarine-poison, Pilocarpine, Cevimeline

26
Q

Muscarine-poison

A

Prototype muscarinic agonist derived from poisonous mushrooms

High selectivity for muscarinic receptors over nicotinic receptors

Problematic muscarinic side effects (MUST LIST)

27
Q

Pilocarpine

A

High selectivity for muscarinic over nicotinic receptors

Used topically to treat glaucoma

Used as a sialogogue to treat dry mouth

Associated with excessive diaphoresis (sweating)

28
Q

Cevimeline

A

M1-selective muscarinic agonist

Approved for Sjogren’s syndrome

No M2 activation so less cardiac effects than other drugs.

29
Q

Muscarinic antagonists indications/contraindications or problems for eye

A

Retinal exam requiring mydriasis | rare use in acute glaucoma, alternating with a miotic, to break adhesion between iris and lens

Glaucoma | photophobia | Dry eyes | Blurred vision

30
Q

Muscarinic antagonists indications/contraindications or problems for Heart

A

Cardiac stimulation, concurrent with epinephrine in cardiac failure | reflex sinus bradycardia or atrial fibrillation that may follow cardiac catheterization

Tachycardia by blocking parasympathetic basal cardiac tone

31
Q

Muscarinic antagonists indications/contraindications or problems for Bladder

A

Incontinence, reduced bladder capacity, and irritable bladder syndrome by reducing bladder contractility

Urinary retention | BPH

32
Q

Muscarinic antagonists indications/contraindications or problems for glands

A

Control drooling in children | pre-anesthetic to decrease salivation

Xerostomia | anhidrosis and consequent over-heating

33
Q

Muscarinic antagonists indications/contraindications or problems for lungs

A

Chronic obstructive airway diseases (emphysema), chemically-irritated airway constriction and asthma

Increased susceptibility to infection due to decreased respiratory secretions

34
Q

Muscarinic antagonists indications/contraindications or problems for stomach

A

Peptic ulcer by blocking stomach acid secretions

Nausea, delayed stomach emptying

35
Q

Muscarinic antagonists indications/contraindications or problems for GI tract

A

GI spasms and irritable bowel syndrome by slowing motility

Constipation

36
Q

Muscarinic antagonists indications/contraindications or problems for Blood vessels

A

…

37
Q

Muscarinic antagonists indications/contraindications or problems for CNS

A

Motion sickness by acting on vestibular apparatus | tremors associated with Parkinson’s disease and side effects of anti-psychotics

Hallucinations and drowsiness

38
Q

Efficacy of muscarinic receptor antagonists

A

Antagonists have zero efficacy on their own; they only have an effect when blocking an agonist such as an endogenous neurotransmitter

All are competitive antagonists at the muscarinic receptors

Few distinguish among the five muscarinic receptor subtypes

39
Q

Atropine

A

Historic uses as a cosmetic and poison (Catherine de Medici’s ring)

Hierarchical effects of atropine based on dose

Used as cardiac stimulant | useful in treating mushroom poisoning | combined with an opioid for diarrhea | useful for treating nerve gas poisoning | long duration of action (will dilate pupil for 7-10 days)

40
Q

Atropine Hierarchical dosing

A
  1. 5 mg (dry mouth, dry skin)
  2. 0 mg (increased heart rate, thirst)

2 mg (pupillary dilation, blurred vision, tachycardia)

5 mg (reduced peristalsis, urinary retention, hot dry skin, fatigue, flushing)

10 mg (rapid and weak pulse, ataxia, hallucinations, delirium, coma)

41
Q

Hyoscyamine

A

Natural product | old drug | marketed before FDA approval was required

Used for irritable bowel syndrome, incontinence, hyperhidrosis, peptic ulcers

Sedating | side effects similar to scopolamine

42
Q

Scopolamine

A

Natural derivative of atropine from Datura stramonium “Jimson weed”

Easily crosses BBB

Used for treating motion sickness

Amnesia, sedation, stupor and hallucinations | criminally abused to render victims compliant

43
Q

Muscarinic antagonists used for obstructive pulmonary disease

A

Tiotropium, Ipratopium, Aclidinium bromide, Umeclidinium

Poor systemic penetrance - few side effects when inhaled | fewer effects on pulmonary secretions | Tiotropium and umeclidinium have longest duration of action

Dosed once daily

Aclidinium has widest therapeutic index (bronchorelaxation relative to tachycardia) due to rapid hydrolysis in plasma | dosed bid

44
Q

Muscarinic antagonists for urinary incontinence, urgency and bladder hyper-irritability

A

Fesoterodine, Tolterodine, Oxybutynin, Trospium, Solifenacin succinate, Darifenacin

Primary side effects are xerostomia, dry eyes and constipation

45
Q

Tropicamide

A

Muscarinic receptor antagonist for eye exams

Shorter duration of action than atropine (6 hours)

Useful in eye exams for pupillary dilation and treatment of iritis

46
Q

Glycopyrrolate

A

Muscarinic antagonist for decreased salivation

Old drug with no CNS effects

Used as pre-anesthetic agent to control salivation during intubation | recently approved for severe drooling in children associated with neurologic disorders such as cerebral palsy

Fewer effects on heart rate to which children are particularly susceptible

Recently renamed “Glycopyrronium bromide” in an NDA to the FDA as a long acting muscarinic agonist for bronchodilation

47
Q

Benztropine, Biperiden

A

Muscarinic antagonist

Used as anti-parkinson’s agent | lots of CNS penetrance

Pharmacy School 2015-16 (34 decks)

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