Autacoids and Antagonists Flashcards

1
Q

Histamine sources

A
  • plant
  • animal tissues
  • product of venoms
  • neoplasms
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2
Q

H1 receptors location

A

Smooth muscle, endothelium, brain

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3
Q

H2 receptors location

A

Gastric mucosa, cardiac, mast cells, brain

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4
Q

H3 receptors location

A

Brain

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5
Q

H4 receptors location

A

Eosinophil, neutrophil, CD4 T cells

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6
Q

Histamine storage

A

As granules (vesicles) in mast cells and basophils

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7
Q

Physiological funcions of histamine

A
  • Allergic reactions (urticaria)
  • Anaphylactic shock
  • Gastric acid secretion
  • Chemotaxis
  • Neurotransmitter
  • Role in immune function
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8
Q

Allergic reaction (urtacaria)

A
  • Tissue oedama (vasodilation -> transudation of fluid into tissue)
  • Triple response (red spot, edema, flare response)
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9
Q

Anaphylactic shock

A
  • Bronchoconstriction mediated by H1 receptors

* H1 activation -> release of NO -> vasodilation -> decrease in blood pressure

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10
Q

Gastric acid secretion

A
  • Contraction of intestinal smooth muscle

* Stimulate gastric acid secretion (H2)

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11
Q

Neurotransmitter

A
  • Increase in HR (H2)
  • Metabolic effects (increased wakefulness, decreased appetite, body temp ctrl)
  • local stimulation of peripheral nerve endings (H1 and H3)
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12
Q

Histamine receptor antagonists pharmacological actions

A
  • Sedation
  • Anti-nausea
  • Anti-parkinsonism
  • Inhibit release of histamine
  • Inhibit adrenergic receptors
  • Inhibit serotonin receptor
  • Local anaesthetic action
  • Anti-cholinergic action
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13
Q

Histamine therapeutic uses

A
  • Provocative test of bronchial hyperreactivity

* Positive control for allergy skin test

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14
Q

Urticaria medication

A

H1 antagonists

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15
Q

Atopic dermatitis

A

Diphenhydramine

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16
Q

Anaphylactic shock medication

A

Chlorpheniramine IV

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17
Q

Allergic rhinitis and chronic urticaria medication

A

2nd generation agents

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18
Q

Motion sickness medication

A

Scopolamine, cyclizine, meclizine

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19
Q

Vertigo medication

A

Cinnarizine

20
Q

Morning sickness medication

A

Doxylamine

21
Q

Common cold and cough medication

A

Symptomatic relief

22
Q

Drug-induced parkinsonism medication

A

Diphenhydramine (due to anti-dopaminergic action)

23
Q

Appetite stimulant

A

Cyperhepatidine (due to anti serotonin action)

24
Q

Histamine receptor antagonists adverse effects

A
  • Sedation
  • Orthostatic hypotension
  • Urine retention and blurred vision
  • CNS excitation and convulsion in children
  • Allergy to antihistamine
  • Cardiac arrythmia
25
Q

2nd generation antihistamines characteristics

A
  • Do not cross BBB (lesser CNS adverse effects)
  • No anticholinergic effects (higher H1 selectivity)
  • Additional mechanisms of anti allergic action (inhibit release of histamine from mast cells)
  • No psychomotor impairment
26
Q

Drug interactions of H1 antagonists

A

Terfenadine, astemizole + CYP3A4 inhibitors (erythromycin, ketoconazole) -> fatal cardiac arrhythmia

27
Q

Drug interactions of H1 antagonists

A

1st generation agent + other CNS depressants -> additive effects, contraindicated while driving or operating machinery

28
Q

Drug interactions of H1 antagonists

A

Autonomic blocking effects of older (1st generation) antihistamines + other antimuscarinic or a-blockers -> additive effect (orthostatic hypotension or urine retention/blurred vision)

29
Q

Serotonin sources

A
  • EC cells of gut
  • Platelets in blood
  • Nerve endings, CNS
30
Q

Serotonin metabolism

A
  • Stored in vesicles

* Rapidly inactivated by monoamine oxidase (MAO)

31
Q

Serotonin physiological effects (CNS)

A
  • Control of mood, sleep, hallucination, behaviour, appetite
  • Pain perception
  • Precursor of melatonin (biological clock, circadian rhythm)
  • Vomiting centre, activation results in vomiting
32
Q

Serotonin physiological effects (GIT)

A
  • 5HT receptors present, involved in vomiting reflex

* Powerful stimulant of GI smooth muscle, increase tone and facilitate peristalsis

33
Q

Serotonin physiological effects (Resp)

A
  • Stimulate bronchial smooth muscle

* Facilitate acetylcholine release from bronchial vagal nerve endings -> episodes of bronchoconstriction

34
Q

Serotonin physiological effects (CVS)

A

• Powerful vasoconstrictor, causes platelet aggregation

35
Q

Serotonin pharmacological action (CNS)

A
  • Anxiolytic (enhance control of mood, sleep etc)
  • Anti-emetic (block vomiting)
  • Control of appetite (block)
36
Q

Serotonin pharmacological action (GIT)

A
  • Anti-emetic (block vomiting)

* Prokinetic agent (enhance GI smooth muscle tone and peristalsis)

37
Q

Serotonin pharmacological action (CVS)

A

• Vasoconstrictor agent (enhance vasoconstriction)

38
Q

Serotonin agonists (anxiolytic)

A

Buspirone

39
Q

Serotonin agonist (Prokinetic action)

A
  • Cisapride (treat gastro-oesophageal reflux disease and motility disorders)
  • Tegaserod (IBS, constipation)
40
Q

Serotonin agonist (control of appetite)

A

Dexfenfluramine

41
Q

Serotonin agonist (vasoconstrictor action)

A

• Sumatriptan (for migraine)

42
Q

Serotonin antagonist (stimulate appetite)

A

Cyproheptadine (appetite stimulant in cancer)

43
Q

Serotonin antagonist (anti-emetic)

A

Ondansetron (prevention of nausea and vomiting associated with cancer chemotherapy)

44
Q

Serotonin antagonist (antipsychotic)

A

Clozapine

45
Q

Serotonin syndrome

A

Occurs when overdose with single drug, or concurrent use of several drugs -> excess serotonergic activity in CNS