Sympathomimetics Flashcards Preview

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Flashcards in Sympathomimetics Deck (116):
1

 Constitute a group of drugs used for
Cardiovascular
Respiratory
Other conditions

adrenomimetics

2

Type of adrenomimetics based on mode of action
 Bind to and activate the adrenoceptors
 Result to sympathetic stimulation

DIRECT-ACTING SYMPATHOMIMETICS

3

INDIRECT-ACTING SYMPATHOMIMETICS
 Displacement of stored cathecolamines in the synapse

releasers

4

example of releasers

tyramine, amphetamine

5

INDIRECT-ACTING SYMPATHOMIMETICS
Inhibit the reuptake of cathecolamines by nerve terminals

Reuptake inhibitors

6

example of Reuptake inhibitors

Cocaine, tricyclic antidepressants

7


 Constitute a third class of adrenoceptors
 Drugs mentioned have little effect on dopamine receptors
 May act as a potent dopamine receptor agonist itself
 Intermediate doses activate beta receptors
 Large doses activate alpha receptors

DOPAMINE

8

dopamine
Intermediate doses activate -- receptors

beta

9

dopamine
Large doses activate --receptors

dopamine

10



 Drug preferentially binds to one subgroup of receptors at concentrations too low to interact with another receptor

RECEPTOR SELECTIVITY

11

 Parent compound of sympathetic drug

phenylethylamine

12

effect of Increasing the size of alkyl substituents

Enhanced activity for beta 2 receptors
Lowers alpha receptor activity

13

 Methyl substitution on NE yields ----
Effect:
Enhanced activity for beta 2 receptors

epinephrine
Effect: Enhanced activity for beta 2 receptors

14

 Isopropyl substitution on NE yields

isoproterenol

15

 -OH groups at the C? and C? positions yield cathecolamines

c3 and c4

16

effect of  Absence of one or both –OH group

Increases bioavailability after oral administration
 COMT resistant
 Increase distribution to the CNS
 Amphetamine and ephedrine

17

effect of C. Substitution on the alpha carbon
 Add methyl group

MAO resistant
Amphetamine and ephedrine

18

effect of D. Substitution on the beta carbon
 Add OH group

Facilitates activation of adrenoceptors
For storage of cathecolamines
Direct-acting sympathomimetics
Dopamine does not contain beta-OH group

19

does dopamine contain a beta-OH group

Dopamine does not contain beta-OH group

20

comparative competency for alpha receptors

E > NE> isoproterenol

21

receptor responsible for
Increase in phosphatidyl inositol (IP3)
Release of calcium

alpha 1

22

receptor responsible for decrease cAMP

D1 and alpha 2

23

comparative competency BETA RECEPTOR ACTIVATION

Isoproterenol > epinephrine > NE

24

receptors responsible for increase cAMP

B1, B2, B3

25

Penetrates the CNS producing stimulant effects

Amphetamine

26

ORGAN SYSTEM EFFECTS
B. EYE

Pupillary dilator responds with mydriasis
 Accommodation is not significantly affected
 Alpha agonists reduce intraocular pressure by increasing outflow of aqueous humor

27

---- agonists reduce intraocular pressure by increasing outflow of aqueous humor

Alpha

28

ALPHA agonists reduce intraocular pressure by

increasing outflow of aqueous humor

29

EFFECT OF BETA ANTAGONISTS IN AQUEOUS HUMOR

 Beta antagonists decrease production of aqueous humor

30

ORGAN SYSTEM EFFECTS
BRONCHI

C. BRONCHI
 Marked relaxation of the smooth muscles of the bronchi
 Most efficacious and reliable for reversing bronchospasm

31


 Well endowed with both alpha and beta receptors
 Located on the smooth muscles and neurons of the enteric nervous system

GIT

32

WHAT ORGAN
Activation of either receptors leads to the relaxation of the smooth muscles

GIT

33

---- agonist causes uterine relaxation in pregnancy

Beta2

34

Responsible for Vasoconstriction

Alpha1 agonists

35

agonists that can reduce PVR and BP

beta2

36

causes vasodilatation in the splanchnic and renal vascular beds

Dopamine

37


 Well supplied with beta1 and beta2 receptors

G. HEART

38

 increases renin release

Beta1

39

increases insulin secretion (gluconeogenesis)

Beta2

40

Stimulate lipolysis

beta3

41


 Drug of choice for the immediate treatment of anaphylactic shock
 Rapid acting
 Pressor agent
 Used for cardiac arrest

EPINEPHRINE

42

 Narcolepsy
 Attention deficit disorder
 With appropriate control, weight reduction

PHENYLISOPROPYLAMINES (AMPHETAMINES)

43

 Used topically to produce mydriasis
 Used to reduce conjunctival itching and congestion caused by irritation
and allergy

PHENYLEPHRINE

44


 Drugs of choice in the treatment of acute asthmatic attacks (3)

TERBUTALINE, ALBUTEROL, METAPROTERENOL

45


 Long-acting
 Recommended for prophylaxis of asthma

SALMETEROL

46

? agonists maybe useful in situations like Acute cardiac failure, Some types of shock

Beta1

47

? agonists are useful in situations in which vasoconstriction is needed

Alpha1

48


 Used to suppress premature labor
 Cardiac stimulant effect may be hazardous to both mother and fetus

RITODRINE, TERBUTALINE

49


 Long-acting oral sympathomimetic usedto improve urinary incontinence in children and the elderly with enuresis
 Mediated by the alpha receptors in the trigone of the bladder

EPHEDRINE

50


 Pressor agent
 Cardiac arrest
 Anaphylactic shock

EPINEPHRINE

51


 Potent vasodilator

ISOPROTERENOL

52


 Congestive heart failure
 Inotropic effect

DOBUTAMINE

53


 Inotropic effect
 Lower doses cause renal vasodilation
 Higher doses cause vasoconstriction

DOPAMINE

54

catecholamines

dopamine, dobutamine, isoproterenol, epinephrine, norepinephrine

55


 Pressor agent
 Mydriatic
 Decongestant

PHENYLEPHRINE

56


 Pressor agent, limited clinical application
 IV form only

METHOXAMINE

57


 Pressor agent
 Orthostatic hypotension

MIDODRINE

58


 DRIXINE (brand name)
 Topical decongestants

OXYMETAZOLINE, XYLOMETAZOLINE

59


 Bronchial asthma

TERBUTALINE

60


 Inhibits premature labor

RITODRINE

61


 Local vasoconstrictive
 Anesthetic effect

COCAINE

62


 Byproduct of tyrosine
 Increase BP
 Found in fermented food
Cheese and wine

TYRAMINE

63

Not advised for patients taking MAO inhibitors

TYRAMINE

64

Toxicity of sympathomimetic drugs speciifically endogenous catecholamines

 Limited penetration to the brain
 Little CNS toxicity when given systemically
 In the periphery

65

Toxicity in the peripheral vasculature

Excessive vasoconstriction
Cardiac arrhythmias
Myocardial infarction
Pulmonary edema or hemorrhage

66

? agonists cause hypertension

Alpha

67

? agonists cause sinus tachycardia
and serious arrhythmia

Beta1

68

? agonists cause skeletal muscle tremor

Beta 2

69

? agonists cause skeletal muscle tremor

Beta 2

70

α1 Most vascular smooth muscle

Contracts (↑ vascular resistance)

71

Pupillary dilator muscle
α1

Contracts (mydriasis)

72

Pilomotor smooth muscle
α1

Contracts (erects hair)

73

Liver (in some species, eg, rat)
α1


Stimulates glycogenolysis

74

Adrenergic and cholinergic nerve terminals




Inhibits transmitter release

75

Platelets α2

Stimulates aggregation

76

Some vascular smooth muscle α2


Contracts

77

Fat cells α2

Inhibits lipolysis

78

α2
Pancreatic β (B) cells


Inhibits insulin release

79

β1 Heart

Stimulates rate and force

80

β1Juxtaglomerular cells of kidney

Stimulates renin release

81

Beta 2 Airways, uterine, and vascular smooth muscle





Relaxes

82

Liver (human) Beta 2

Stimulates glycogenolysis

83

Pancreatic β (B) cells Beta 2



Stimulates insulin release

84

Somatic motor neuron terminals (voluntary muscle) Beta 2

Causes tremor

85

Heart Beta 2


Stimulates rate and force

86

β3 Fat cells

Stimulates lipolysis

87

Dopamine1 (D1) Renal and other splanchnic blood vessels

Dilates (↓ resistance)

88

Dopamine2 (D2) Nerve terminals

Inhibits adenylyl cyclase

89

mechanism of action of E

α1, α2, β1, β2, β3 agonist

90

mechanism of action of NE

α1, α2, β1, agonist

91

mechanism of action of Dopamine

D1, α1, α2, β1, β2, β3 agonist

92

mechanism of action of Isoproterenol:

β1, β2, β3 agonist;

93

mechanism of action of Dobutamine:

β1 agonist

94

mechanism of action of PHENYLEPHRINE

α1, α2 agonist

95

mechanism of action of Albuterol, metaproterenol, terbutaline

β2 agonist

96

Displaces stored
catecholamines from nerve
endings

Amphetamine,
methamphetamine

97

Very high addiction
liability. Hypertension,
arrhythmias, seizures

COCAINE

98

Displaces stored catecholamines
No clinical use but found in fermented foods

TYRAMINE

99

An α-agonist drug that reduces conjunctival, nasal, or oropharyngeal mucosal
vasodilation by constricting blood vessels in the submucosal tissue

decongestant

100

A derivative (eg, norepinephrine, epinephrine), a relatively
polar molecule that is readily metabolized by catechol-O-methyltransferase

Catecholamine

101

catecholamine is derived from

dihydroxyphenylethylamine

102

A derivative of phenylisopropylamine (eg, amphetamine, ephedrine). Unlike
catecholamines, they usually have oral activity, a long half-life,
CNS activity, and cause release of stored catecholamines

Phenylisopropylamine

103

A drug that mimics stimulation of the sympathetic autonomic nervous system

Sympathomimetic

104

An indirect-acting drug that increases the activity of transmitters in the synapse by
inhibiting their reuptake into the presynaptic nerve ending. May act selectively on
noradrenergic, serotonergic, or both types of nerve endings

Reuptake inhibitor

105


 Present in the mitochondria in the adrenergic nerve endings
 Inactivates portion of dopamine and norepinephrine in the cytoplasm

MONOAMINE OXIDASE (MAO)

106


 May increase the stores of these transmitters and other amines in
the nerve endings

MONOAMINE OXIDASE INHIBITORS

107


 Single prototype with effects at all receptors
 Alpha1 and alpha2
 Beta1,beta2 and beta3

EPINEPHRINE

108


 Not a cathecolamine
 Resistant to MAO
 Resistant to COMT
 Orally active
 Enter the CNS
 Longer effects

AMPHETAMINES

109

Signaling mechanism of adrenoceptors


 G-protein coupled
 Need a 2nd messenger to induce
sympathetic effect

110

ALPHA SELECTIVE
alpha1 > alpha2

 PHENYLEPHRINE

111

ALPHA SELECTIVE
alpha2 > alpha1

CLONIDINE

112

MIXED (activates both alpha and beta)
alpha1 = alpha2
beta1> beta2

 NE

113

MIXED (activates both alpha and beta)
alpha1 = alpha2
beta1 = beta2

EPINEPHRINE

114

beta1 > beta2

DOBUTAMINE

115

beta2 > beta1

TERBUTALINE

116

beta1 = beta2

ISOPROTERENOL

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