Histamine + Anti-histamine

Question 1

When is histamine released

Answer 1

response to cold, bacterial toxins, bee sting venom or trauma

Histamine is secreted when C3a and C5a interact with membrane receptors or when an antigen interacts with IgE

Allergies and anaphylaxis can also trigger histamine release

Question 2

Types of histamine receptor

Answer 2

All G-protein coupled

H1 receptor (Gq) :
-Contraction of most smooth muscle, except blood vessels
-Vasodilation
-Increased vascular permeability
-Gives the flare and wheel response in the skin

H2 receptor (Gs) :
-Cardiac stimulation increases rate and output
-Gastric secretion

Question 3

Types of hypersensitivity reactions

Answer 3

Type I
IgE – mediated; quick onset after exposure
Allergic

Type II
Cytotoxic/antibody mediated
Cytotoxic

Type III
Immune complex IgG/IgM mediated
Immune complex disposition

Type IV
Delayed or cell mediated
Delayed

Allergic
Cytotoxic
Immune complex
Delayed

Question 4

2 types of antihistamine

Answer 4

1st genertaion
Sedating - crossing the blood brain barrier (BBB)
-Chlorphenamine maleate
-Promethazine hydrochloride
-Cyclizine

2nd generation
Non-sedating - No CNS activity
-cetirizine hydrochloride
-loratidine

Question 5

Treatment of severe hypersensitivity reactions and anaphylaxis

Answer 5

Adrenaline

Question 6

What is given for antiemetics (preventing Nausea/vomiting)

Answer 6

Cyclizine

Question 7

During sedation which histamine h1 receptor antagonist is given

Answer 7

Promethazine