Diphenhydramine is an amino alkyl ether analogue
anti-histamine. Commonly used for cough.
IUPAC name : 2-(Benzhydryloxy)-N,N-dimethylethanamine
Brand name : Benadryl (by Johnson
& Johnson)
Synthesis
Step 1 : Diphenylmethane is the starting
compound. (chosen for 2 benzyl group). To this,
bromide (Br) is added in the
presence of light. Result - HBr is removed, another
bromine is substituted in diphenylmethamine.
Step 2 : Now, 2-(dimethylamino)ethan-1-ol
is added in the presence of
Potassium carbonate and Heat.
Diphenhydramine is produced.
Mechanism of Action
Diphenhydramine (H1 antagonist) act by
competitively inhibiting the effects of histamine at H1 receptor.
Anti-cholinergic action : Antagonizes the action of
Acetylcholine.
Uses
Cough
Motion Sickness
Pruritides (itching)
Acute muscle dystonia
Adverse effects
Sedation, diminished
alertness and concentration, motor incoordination
Dryness of mouth, alteration of bowel
movements, blurring of vision - due to anti-cholinergic property.
