CYPROHEPTADINE HCL
Chemistry - An antihistamine that also possesses serotonin antagonist properties, cyproheptadine
HCl occurs as a white to slightly yellow crystalline powder. Approximately 3.64 mg are soluble inone ml of water and 28.6 mg in one ml of alcohol.
Uses, Indications - Cyproheptadine may be useful as an antihistamine, and may also be employedin cats as an appetite stimulant. The drug may be useful as adjunctive therapy for Cushing'ssyndrome, probably as a result of its antiserotonin activity. But one study demonstrated efficacy inless than 10% of dogs treated for pituitary dependent adrenocorticism.
Cyproheptadine has been tested in pregnant lab animals in doses up to 32 times labeled dosewithout evidence of harm to fetuses. But, because safety has not been established in other species, its use during pregnancy should be weighed carefully. It is unknown whether cyproheptadine entersmaternal milk or may potentially cause adverse effects in offspring; use with caution.
At higher dosages, cyproheptadine has caused significant polyphagia in dogs.
Overdosage, Acute Toxicity - There are no specific antidotes available. Significant overdosesshould be handled using standard gut emptying protocols when appropriate and supportive therapywhen required. The adverse effects seen with overdoses are an extension of the drug's side effects, principally CNS depression (although CNS stimulation may be seen), anticholinergic effects(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.
Cyproheptadine may increase amylase and prolactin serum levels when administered withthyrotropin-releasing hormone.
Laboratory Considerations - Because antihistamines can decrease the wheal and flair responseto skin allergen testing, antihistamines should be discontinued from 3 -7 days (depending on theantihistamine used and the reference) before intradermal skin tests.
HCl occurs as a white to slightly yellow crystalline powder. Approximately 3.64 mg are soluble inone ml of water and 28.6 mg in one ml of alcohol.
Storage, Stability, Compatibility
Cyproheptadine HCl tablets and oral solution should bestored at room temperature and freezing should be avoided.Pharmacology - CYPROHEPTADINE HCL
Like other H1-receptor antihistamines, cyproheptadine acts by competing withhistamine for sites on H1-receptor sites on effector cells. Antihistamines do not block histaminerelease, but can antagonize its effects. Cyproheptadine also possesses potent antiserotonin activityand reportedly has calcium channel blocking action as well.Uses, Indications - Cyproheptadine may be useful as an antihistamine, and may also be employedin cats as an appetite stimulant. The drug may be useful as adjunctive therapy for Cushing'ssyndrome, probably as a result of its antiserotonin activity. But one study demonstrated efficacy inless than 10% of dogs treated for pituitary dependent adrenocorticism.
Pharmacokinetics - CYPROHEPTADINE HCL
Limited data available. Cyproheptadine is well absorbed after oral administration. Its distribution characteristics are not well described. Cyproheptadine is apparently nearlycompletely metabolized in the liver and these metabolites are then excreted in the urine. Eliminationis reduced in renal failure.Contraindications, Precautions, Reproductive Safety
Cyproheptadine is contraindicated inpatients hypersensitive to it. It should be used with caution in patients with prostatic hypertrophy, bladder neck obstruction, severe cardiac failure, angle-closure glaucoma, or pyeloduodenal obstruction.Cyproheptadine has been tested in pregnant lab animals in doses up to 32 times labeled dosewithout evidence of harm to fetuses. But, because safety has not been established in other species, its use during pregnancy should be weighed carefully. It is unknown whether cyproheptadine entersmaternal milk or may potentially cause adverse effects in offspring; use with caution.
Adverse Effects, Warnings
The most likely adverse effects seen with cyproheptadine are relatedto its CNS depressant (sedation) and anticholinergic (dryness of mucous membranes, etc.) effects.At higher dosages, cyproheptadine has caused significant polyphagia in dogs.
Overdosage, Acute Toxicity - There are no specific antidotes available. Significant overdosesshould be handled using standard gut emptying protocols when appropriate and supportive therapywhen required. The adverse effects seen with overdoses are an extension of the drug's side effects, principally CNS depression (although CNS stimulation may be seen), anticholinergic effects(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 cyproheptadine withother CNS depressant medications, such as barbiturates, tranquilizers, etc. Monoamine oxidaseinhibitors (including furazolidone) may intensify the anticholinergic effects of antihistamines.Cyproheptadine may increase amylase and prolactin serum levels when administered withthyrotropin-releasing hormone.
Laboratory Considerations - Because antihistamines can decrease the wheal and flair responseto skin allergen testing, antihistamines should be discontinued from 3 -7 days (depending on theantihistamine used and the reference) before intradermal skin tests.