, also known as meclastin
, is an antihistamine
. Unlike loratadine
, clemastine is a sedating antihistamine, however it exhibits fewer side effects than most of the widely used antihistamines. Clemastine is also classified as an antipruritic
(i.e. it stops itching).
Clemastine is an antihistamine with anticholinergic
effects. Antihistamines competitively bind to histamine
receptor sites, thus reducing the neurotransmitter's effects. Effects of histamine (which are countered by antihistamines) include:
- Increased capillary permeability
- Increased capillary dilatation
- Edema (i.e. swelling)
- Pruritus (Itch)
- Gastrointestinal/respiratory smooth muscle constriction
Clemastine inhibits both the vasoconstrictor
effects of histamine. Depending on the dose, the drug can produce paradoxical effects, including CNS stimulation or depression.
Most antihistamines exhibit some type of anticholinergic
activity. Antihistamines act by competitively binding to H1- receptor sites, thus blocking the binding endogenous histamine. Antihistamines do not chemically inactivate or prevent the normal release of histamine.
Clemastine is rapidly absorbed from the gastrointestinal tract
and peak plasma concentrations are attained in 2-4 hours.
Mechanism of Action
Clemastine is a selective histamine H1 antagonist. It binds to the histamine H1 receptor, thus blocking the action of endogenous
histamine, which leads to... Read More