Derm IE #2 - Medchem

Ethylenediamines

Also affect other receptors such as cholinergic, adrenergic, dopaminergic, & serotonergic

Diphenhydramine (Benadryl)

Short half-life (so can be used as OTC sleep aid)

Alkylamines

-Longer duration (t1/2 up to 24 hrs)

-Decreased sedation compared to Ethylenediamines & ethanolamine ethers

Alkamine Metabolism

N-dealkylation to corresponding secondary & primary amines

Acid metabolite of hydroxyzine

Cetirizine

Cetirizine

Usually classified w/ 2nd generation non-sedating antihistamines

Desloratadine

-More potent H1 antagonist than loratadine

-Rapid onset of action

Pharmacore for a-adrenergic agonists

-Substituted benzene

-Aliphatic amine separated from benzene by 2 carbons

-(R)-Hydroxyl at C1 carbon

Phenylethanolamines w/ longer duration of action

Metaraminol

Methoxamine

(b/c not a substate for COMT or MAO)

2nd generation H1 antihistamines

-Improved H1 selectivity

-Little or no sedative qualities

-Vary widely in structure

-Less anticholinergic activity

-Long t1/2 (extended duration of action)