Clemastine , also known as meclastin , is an antihistamine and an anticholinergic. Unlike loratadine or fexofenadine, clemastine is a tranquilizing antihistamine; However, it shows fewer side effects than most widely used antihistamines. Clemastine is also classified as antipruritic (ie itching stops).
Video Clemastine
Indication
Clemastine is indicated for use in treating allergic rhinitis, such as sneezing, rhinorrhea, pruritus and lacrimation.
Maps Clemastine
Side effects
Overdose symptoms are paradoxical, ranging from CNS depression to stimulation. Stimulation is most common in children, and is usually followed by excitement, hallucinations, ataxia, loss of coordination, muscle twitching, athetosis, hyperthermia, cyanosis, seizures, tremors, and hyperreflexia. This can be followed by postpeptal depression and heart/respiratory rate. Other common overdose symptoms include dry mouth, dilated pupils fixed, face flushed, and pyrexia. In adults, overdose usually causes CNS depression, ranging from drowsiness to coma.
Pharmacology
Clemastine is an antihistamine with anticholinergic and sedative effects. Competitive antihistamines bind to histamine receptor sites, thereby reducing the effects of neurotransmitters. The effects of histamine (which are resisted by antihistamines) include:
- Increased capillary permeability
- Increased capillary dilatation
- Edema (ie, swelling)
- Pruritus (Itching)
- Gastrointestinal/respiratory smooth muscle digestion
Clemastine inhibits both the effects of vasoconstrictors and histamine vasodilators. Depending on the dose, the drug may produce paradoxical effects, including CNS stimulation or depression.
Most antihistamines show some type of anticholinergic activity. Antihistamines act by binding competitively to H 1 receptor sites, thus blocking endogenous binding histamine. Antihistamines do not chemically disable or prevent the release of normal histamine.
Clemastine also acts as FIASMA (functional inhibitor of sphingomyelinase acid).
Clemastine is rapidly absorbed from the gastrointestinal tract and peak plasma concentrations are achieved within 2-4 hours. Antihistamines are thought to be metabolized in the liver, mostly by conjugating mono-/didemethylation and glucuronide. This is a cytochrome P450 CYP2D6 inhibitor and may interfere with other drugs metabolized by this isozyme.
Action mechanism
Clemastine is a selective histamine H 1 antagonist. This binds to histamine recipes H 1 , thus blocking the action of endogenous histamine, leading to temporary relief of negative symptoms caused by histamine.
Society and culture
Clemastine is a drug free, and is available under many names and forms of dosage around the world. The most common brand names are Tavegyl .
References
External links
- List of Medline Plus NIHs at Clemastine
- Pharmacokinetics and bioavailability of clemastine and phenylpropanolamine in single component formulations and combinations
Source of the article : Wikipedia
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