CLEMASTINE FUMARATE
Chemistry - Also known as meclastine fumarate or mecloprodin fumarate, clemastine fumarate isan ethanolamine antihistamine. It occurs as an odorless, faintly yellow, crystalline powder. It is veryslightly soluble in water and sparingly soluble in alcohol.
Tavist-D® contains clemastine fumarate in an immediate release outer shell and phenylpropanolamine HCl in a sustained release inner matrix.
Clemastine has been tested in pregnant lab animals in doses up to 312 times labeled without evidence of harm to fetuses. But, because safety has not been established in other species, its useduring pregnancy should be weighed carefully. Clemastine enters maternal milk and may potentially cause adverse effects in offspring.
CNS depressant (sedation) and anticholinergic effects (dryness of mucous membranes, etc.).
Overdosage, Acute Toxicity - There are no specific antidotes available. Significant overdosesshould be handled using standard gut emptying protocols when appropriate, and supportive therapyinitiated when required. The adverse effects seen with overdoses are an extension of the drug's sideeffects; principally CNS depression (although CNS stimulation may be seen), anticholinergiceffects (severe drying of mucous membranes, tachycardia, urinary retention, hyperthermia, etc.) andpossibly hypotension. Physostigmine may be considered to treat serious CNS anticholinergiceffects and diazepam employed to treat seizures, if necessary.
CNS depressant medications, such as barbiturates, tranquilizers, etc. Monoamine oxidase inhibitors (including furazolidone) may intensify the anticholinergic effects of clemastine.
Laboratory Considerations - Because antihistamines can decrease the wheal and flair responseto skin allergen testing, antihistamines should be discontinued 3 -7 days (depending on the antihistamine used and the reference) before intradermal skin tests.
Tavist-D® contains clemastine fumarate in an immediate release outer shell and phenylpropanolamine HCl in a sustained release inner matrix.
Storage, Stability, Compatibility
Oral tablets and solution should be stored in tight, light resistant containers at room temperature.Pharmacology - CLEMASTINE FUMARATE
Like other H1-receptor antihistamines, clemastine acts by competing with histamine for sites on H1-receptor sites on effector cells. They do not block histamine release, but can antagonize its effects. Clemastine has greater anticholinergic activity, but less sedation than average.Uses, Indications
Clemastine may be used for symptomatic relief of histamine1-related al ergicconditions.Pharmacokinetics - CLEMASTINE FUMARATE
In humans, clemastine is almost completely absorbed from the GI tract; itsdistribution is not well characterized, but does distribute into milk. Metabolic fate has not beenclearly determined, but it appears to be extensively metabolized and those metabolites are eliminatedin the urine. In humans, its duration of action is about 12 hours.Contraindications, Precautions, Reproductive Safety
Clemastine is contraindicated in patientshypersensitive to it. It should be used with caution in patients with prostatic hypertrophy, bladderneck obstruction, severe cardiac failure, angle-closure glaucoma, or pyeloduodenal obstruction.Clemastine has been tested in pregnant lab animals in doses up to 312 times labeled without evidence of harm to fetuses. But, because safety has not been established in other species, its useduring pregnancy should be weighed carefully. Clemastine enters maternal milk and may potentially cause adverse effects in offspring.
Adverse Effects, Warnings
The most likely adverse effects seen with clemastine are related to itsCNS depressant (sedation) and anticholinergic effects (dryness of mucous membranes, etc.).
Overdosage, Acute Toxicity - There are no specific antidotes available. Significant overdosesshould be handled using standard gut emptying protocols when appropriate, and supportive therapyinitiated when required. The adverse effects seen with overdoses are an extension of the drug's sideeffects; principally CNS depression (although CNS stimulation may be seen), anticholinergiceffects (severe drying of mucous membranes, tachycardia, urinary retention, hyperthermia, etc.) andpossibly hypotension. Physostigmine may be considered to treat serious CNS anticholinergiceffects and diazepam employed to treat seizures, if necessary.
Drug Interactions
Additive CNS depression may be seen if combining clemastine with otherCNS depressant medications, such as barbiturates, tranquilizers, etc. Monoamine oxidase inhibitors (including furazolidone) may intensify the anticholinergic effects of clemastine.
Laboratory Considerations - Because antihistamines can decrease the wheal and flair responseto skin allergen testing, antihistamines should be discontinued 3 -7 days (depending on the antihistamine used and the reference) before intradermal skin tests.