Meclastin
Meclastin - General Information
A histamine H1 antagonist used as the hydrogen fumarate in hay fever, rhinitis, allergic skin conditions, and pruritus. It causes drowsiness. [PubChem]
Pharmacology of Meclastin
Meclastin is an antihistamine with anticholinergic (drying) and sedative side effects. Antihistamines competitively antagonize various physiological effects of histamine including increased capillary permeability and dilatation, the formation of edema, the "flare" and "itch" response, and gastrointestinal and respiratory smooth muscle constriction. Within the vascular tree, H1- receptor antagonists inhibit both the vasoconstrictor and vasodilator effects of histamine. Depending on the dose, H1- receptor antagonists can produce CNS stimulation or depression. Most antihistamines exhibit central and/or peripheral anticholinergic activity. Antihistamines act by competitively blocking H1- receptor sites. Antihistamines do not pharmacologically antagonize or chemically inactivate histamine, nor do they prevent the release of histamine.
Meclastin for patients
Patients taking antihistamines should receive the following information and instructions:
1. Antihistamines are prescribed to reduce allergic symptoms.
2. Patients should be questioned regarding a history of glaucoma, peptic ulcer, urinary retention, or pregnancy before starting antihistamine therapy.
3. Patients should be told not to take alcohol, sleeping pills, sedatives, or tranquilizers while taking antihistamines.
4. Antihistamines may cause drowsiness, dizziness, dry mouth, blurred vision, weakness, nausea, headache, or nervousness in some patients.
5. Patients should avoid driving a car or working with hazardous machinery until they assess the effects of this medicine.
6. Patients should be told to store this medicine in a tightly closed container in a dry, cool place away from heat or direct sunlight and out of the reach of children.
Meclastin Interactions
Additive CNS depression may occur when antihistamines are administered concomitantly with other CNS depressants including barbiturates, tranquilizers, and alcohol. Patients receiving antihistamines should be advised against the concurrent use of other CNS depressant drugs.
Monoamine oxidase (MAO) inhibitors prolong and intensify the anticholinergic effects of antihistamines.
Meclastin Contraindications
Antihistamines are contraindicated in patients hypersensitive to the drug or to other antihistamines of similar chemical structure. Antihistamines should not be used in newborn or premature infants. Because of the higher risk of antihistamines for infants generally and for newborns and prematures in particular, antihistamine therapy is contraindicated in nursing mothers.
Additional information about Meclastin
Meclastin Indication: For the relief of symptoms associated with allergic rhinitis such as sneezing, rhinorrhea, pruritus and acrimation.
Mechanism Of Action: Meclastin is a selective histamine H1 antagonist and binds to the histamine H1 receptor. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine.
Drug Interactions: Donepezil Possible antagonism of action
Galantamine Possible antagonism of action
Rivastigmine Possible antagonism of action
Food Interactions: Take with food.
Avoid alcohol.
Generic Name: Clemastine
Synonyms: Clemastina [INN-Spanish]; Clemastinum [INN-Latin]; Clemastine Fumarate
Drug Category: Anti-Allergic Agents; Antipruritics; Histamine H1 Antagonists
Drug Type: Small Molecule; Approved
Other Brand Names containing Clemastine: Meclastin; Mecloprodin; Tavist; Tavist-1;
Absorption: Rapidly absorbed from the gastrointestinal tract.
Toxicity (Overdose): Oral LD50 in rat and mouse is 3550 mg/kg and 730 mg/kg, respectively. Antihistamine overdosage reactions may vary from central nervous system depression to stimulation. In children, stimulation predominates initially in a syndrome which may include excitement, hallucinations, ataxia, incoordination, muscle twitching, athetosis, hyperthermia, cyanosis convulsions, tremors, and hyperreflexia followed by postictal depression and cardio-respiratory arrest. Convulsions in children may be preceded by mild depression. Dry mouth, fixed dilated pupils, flushing of the face, and fever are common. In adults, CNS depression, ranging from drowsiness to coma, is more common.
Protein Binding: Not Available
Biotransformation: Antihistamines appear to be metabolized in the liver chiefly via mono- and didemethylation and glucuronide conjugation.
Half Life: Not Available
Dosage Forms of Meclastin: Tablet Oral
Chemical IUPAC Name: (2R)-2-[2-[(1R)-1-(4-chlorophenyl)-1-phenylethoxy]ethyl]-1-methylpyrrolidine
Chemical Formula: C21H26ClNO
Clemastine on Wikipedia: https://en.wikipedia.org/wiki/Clemastine
Organisms Affected: Humans and other mammals