Antihistamine Flashcards
Which histamine receptor is targeted in GI conditions?
H2 -> H1 is for allergic response and 3 and 4 have no clinical use.
Name some side effects of first generation antihistamines
Sedation, anti-emetic, dizziness, etc
Which generation of antihistamines have anticholinergic side effects (opposite of sludge-bbb) and 5-HT receptor activity?
1st generation. E.g. promethazine, dexchlorpheniramine, etc
How do glucocorticoids help in allergies?
Extremely effective at reducing inflammation regardless of its cause. Short term use only
Name some ADRs of glucocorticoids
Immunosuppressive Skin fragility Weight gain Growth failure Muscle breakdown Reduced ovulation
Describe MOA of pseudoephedrine
Induces the release of noradrenaline from pre-synaptic storage vesicles
Describe MOA of phenylephrine
Alpha1-adrenoreceptor agonist
Describe mast cell stabilisers and what is the main limitation of their use
These drugs prevent the release of histamine from mast cells in the first place. However, they are only effective if taken prior to exposure to the allergen. Takes 2-4 weeks to take effect
Describe anaphylactic shock. Which 3 molecules are involved?
Involves the sudden onset of allergy symptoms involving 2 or more organ systems. Due to the excessive release of histamine, prostaglandins and leukotrienes.
Name symptoms of anaphylactic shock (both minor and major)
Minor=
Confusion, fainting, hives, swelling, arrthymia, BP drop
Major=
Cardiovascular shock or respiratory arrest
Pseudo and phenylephrine are both xxxx, which relieves congestion
Vasoconstrictors
Compare physiological effects of histamine binding to H1 vs H2
H1 = vasodilation, bronchoconstriction, itching, rhinitis, etc
H2 = gastric acid production, tachycardia, airway mucus secretion
How does adrenaline work in anaphylactic shock?
Causes vasoconstriction, increasing blood pressure. Also causes bronchodilation
