IDing histamine structures Metcalf

Ethylenediamines

1st gen H1 antihistamines

Ethanolamine ethers

1st gen H1 antihistamines

Alkylamines

1st gen H1 antihistamines

Piperazines

1st gen H1 antihistamines, multiple effects

Tricyclics

1st gen H1 antihistamines, multiple effects

Piperadine

Carbomate

Fexofenadine

2nd Generation, H1, Non-sedating antihistamine

Blockade of hERG K+ channels

LOOK FOR THE BLUE CIRCLED STRUCTURE FOR DRUGS ENDING IN “ine”

Terfenadine, Astemizole

Life threatening hERG K+ ion channel

Not marketed

Loratadine, Desloratadine

2nd Generation, H1, Non-sedating antihistamine

Cetirizine

hydroxyzine oxidized to make this

2nd gen

Acrivastine

Second gen non-sedating antihistamine: notice constrained amine

H2 antagonists (ex: Cimetidine)

Imidazole ring like histamine (causes increases side effects)

4 atom side chain includes sulfur

EWG Substituted guanidine

PPIs (ex: Omeprazole)

Metabolized by CYP 2C19

Isomers metabolized unequally in patient populations — Use of S isomer (Esomeprazole) provides greater bioavailability in extensive metabolizers