Mar26 M3-Antihistamines

Question 1

autacoid definition

Answer 1

hormones but for paracrine and autocrine signaling only (used a lot by immune system)

Question 2

examples of autacoids

Answer 2

• histamine
• serotonin
• endogenous peptides
• PGs
• leukotriens

Question 3

most important mechanism of histamine release in the body

Answer 3

• response to immuno stimulus by mast cells that are sensitized with a surface IgE
• mast cell degranulates and liberates contents like histamine
• degranulation = type 1 allergic reaction*

Question 4

4 classes of histamine receptors

Answer 4

H1 to H4
(H3 and H4 involved in long term allergic response and mast cell recruitment + H3 = ntr role in CNS and peripheral sites)

Question 5

H1 location and fct

Answer 5

location = SM, endothelium, CNS
function = bronchoconstriction, vasodilation, separation of endothelial cells, pain and itching, allergic rhinitis, motion sickness

Question 6

H2 location and fct

Answer 6

location = gastric parietal cells, vascular SM, basophils
function = INCREASES gastric acid secretion, vasodilation, inhibition of IgE dependent degranulation

Question 7

diseases histamines are involved in

Answer 7

• immediate hypersensitivty rxs and acute inflam response (is a cellular mediator for that)
• anaphylaxis
• seasonal allergies and asthma
• duodenal ulcers
• systemic mastocytosis
• gastrino (ZE syndrome)

Question 8

substances mast cells release other than histamine

Answer 8

• PGs
• LTs
• proteases
• PAF (platelet activating factor)
• TNF
• ILs

Question 9

how we may inhibit release of substances by mast cells

Answer 9

1. albuterol = B2 agonist

2. cromolyn = IN ASTHMA

Question 10

mild, moderate and severe symptoms related to histamine release

Answer 10

mild = erythema, urticaria (hives), itching
moderate = skin rxs, tachycardia, hypotn, resp distress
severe anaphylactic = severe hypotn, vfib, cardiac arrest

Question 11

therapeutic uses of antihistamines

Answer 11

1. allergic rxs (allergic rhinitis, atopic dermatitis, hay fever, urticaria)
2. motion sickness
3. sedation and hypnotics

Question 12

antihistamines that CAN’T be used to sedate and as hypnotics

Answer 12

H1 selective antihistamines (2nd generation ones)

Question 13

4 first generation anti-histamines

Answer 13

1. diphenhydramine (Benadryl)
2. chlorpheniramine
3. promethazine
4. cyclizine

Question 14

1st generation anti-histamines used for what

Answer 14

• sleep aids
• anti motion sickness
• antiallergy

Question 15

side effects of 1st generation anti-histamines associated with off-target anti-muscarinic (Rs) (anti-cholinergic) effect in CNS

Answer 15

1. sedation
2. dizziness
3. fatigue

Question 16

gravol content

Answer 16

dimenhydrinate, a combination of 2 drugs: dipenhydramine (Benadryl) and 8-chlorotheophylline

Question 17

second generation anti-histamines (H1 selective) difference with first generation + some names

Answer 17

• less side effects associated with anti-cholinergic activity
• cetirizine
• fexofenadine (allegra)
• loratadine (claritin)

Question 18

when to think of drug interaction and interference

Answer 18

if diff drugs metabolized by the same hepatic isoenzyme and if one inhibits this isoenzymes (like grapefruit juice) or enhances it

Question 19

fexofenadine in allegra comes from what

Answer 19

is the active metabolite that is derived from the ‘‘prometabolite’ terfenadine

Question 20

important thing all drugs are tested for today

Answer 20

always check if they block HERG (a K channel in the heart)

Question 21

things that slow down the metabolism of fexofenadine (allegra) and loratadine (claritin)

Answer 21

1. erythromycin
2. grapefruit juice
3. ketoconazole

Question 22

cetirizine to avoid in who

Answer 22

pilots. has more sedative (CNS actions) effect than the other drugs (so use fexofenadine or loratadine instead)

Question 23

2 H2 receptor antagonists

Answer 23

ranitidine, cimetidine