LG 7.4 - Pharm - Antihistamines

Question 1

What’s an H-1 receptor? where are they found? what happens when they’re stimulated?

Answer 1

1. Gq receptors located in smooth muscle and endothelial cells. 2. (activation results in increases in PLC, IP3, PKC, Ca. 3. biological response is acute allergic response (vasodilation, increased vascular permeability, contraction of nonvascular smooth muscle) resulting in edema, hypotension, bronchoconstriction, watery eyes

Question 2

Explain the mechanism of action of diphenhydramine, loratadine and fexofenadine?

Answer 2

these meds are antihistamines. They block H-1 receptors. This blocks all the effects of stimulating H-1 receptor.

Question 3

What’s the initial drug of choice for emergency treatment of severe allergic reactions?

Answer 3

epinephrine

Question 4

Explain the clinical advantage that loratadine and fexofenadine have over diphenhydramine - as it relates to drowsiness.

Answer 4

1. loratadine and fexofenadine are non-drowsy. diphenhydramine gets into CNS and causes drowsiness there. The other 2 meds can’t cross into CNS - so no drowsiness.

Question 5

List some biological consequences of choinergic stimulation.

Answer 5

Question 6

Explain the clinical advantage that loratadine and fexofenadine have over diphenhydramine - as it relates to anticholinergic effects.

Answer 6

loratadine and fexofenadine have less anticholinergic SE than diphenhydramine. diphenhydramine causes more ‘OPPOSITE of DUMBBELS’ SE than the other 2 meds. (specifically, constelation of anticholinergic effects are dry mouth, constipation, urinary retention, blurred vision, confusion)