Autacoids: Histamine, Serotonin

Question 1

Histamine receptors and the autoreceptor among them

Answer 1

H1, H2, H3, H4

Auto : H3 located presynaptically

Question 2

Inverse agonists at H3 and their indications

Answer 2

Tiprolisant
Pitolisant

Indication: narcolepsy

Question 3

H4 receptor location and function

Answer 3

L: WBCs
F: thought to promote chemotaxis

Question 4

DOC for narcolepsy

Answer 4

Modafinil

Question 5

Differences between first and second gen anti-histamines

Answer 5

First

• cross BBB (second don’t cross OR cross minimally eg cetrizine in 10% people does cross)
• non specific action e.g. Antimuscarinic

Question 6

Examples of first generation anti-histamines

Answer 6

Promethazine (phenargan)
Diphenhydramine
Dimenhydrinate
Pheneramine
Chlorpheneramine (avil)
Cyclizine
Buclizine

Question 7

Examples of second generation anti-histamines

Answer 7

Fexofenadine
Terfenadine (w/drawn)

Loratidine
Desloratidine

Cetrizine
Levocetrizine

Astemizole (w/drawn)

Olapatadine
Azelastine

Question 8

Indications of first generation anti-histamines

Answer 8

• give children before blood collection

- drug induced Parkinsonism

Question 9

Disadvantages of first gen anti-histamines

Answer 9

ADRs:

• sedation
• anti-muscarinic: DUB FP

Contraindications:

• truck drivers
• pilots people who shouldn’t be sedated on job

Question 10

3rd generation anti-histamines

Answer 10

Isomer or metabolite of 2nd generation

• desloratidine (metabolite)
• fexofenadine (metabolite)
• levocetrizine (isomer of cet that has even less BBB penetration)

Question 11

Uses of anti-histamines

Answer 11

1. Antihistaminic usesMm: HISTAMINEHay fever, ivy poisoning, skin allergies eg urticaria, dermatitis
   Tranfusion rxn, angioedema, Med (drug) allergy
   INsect bite eg bee sting, eye condition eg allergic conjunctivitis
2. Anticholinergic usesMm: Possess Anti Cholinergic PropertiesParkinsonism (drug induced)
   Akathisia, acute muscular dystonia
   Common cold (rhinorrhoea)
   Prophylaxis of motion sickness

Question 12

Cetrizine in common cold

Answer 12

Irrational because being 2nd generation, it lacks anti cholinergic properties of decreasing nasal discharge

Question 13

Drugs increasing QTc

Answer 13

CAT drugs

Cisapride
Astemizole
Terfenadine

Esp when combined with enzyme inhibitors

Question 14

Serotonin autoreceptors

Answer 14

5HT-1A