Cyproheptadine


Cyproheptadine, sold under the brand name Periactin among others, is a first-generation antihistamine with additional anticholinergic, antiserotonergic, and local anesthetic properties.
It was patented in 1959 and came into medical use in 1961.

Medical uses

Adverse effects include:
Gastric decontamination measures such as activated charcoal are sometimes recommended in cases of overdose. The symptoms are usually indicative of CNS depression and excess anticholinergic side effects. The LD50 in mice is 123 mg/kg and 295 mg/kg in rats.

Pharmacology

Pharmacodynamics

Cyproheptadine is a very potent antihistamine or antagonist of the H1 receptor. At higher concentrations, it also has anticholinergic, antiserotonergic, and antidopaminergic activities. Of the serotonin receptors, it is an especially potent antagonist of the 5-HT2 receptors, and this underlies its effectiveness in the treatment of serotonin syndrome.
Cyproheptadine is known to be an antagonist or inverse agonist of all of the receptors listed in the adjacent table.
Cyproheptadine has weak antiandrogenic activity.

Pharmacokinetics

Cyproheptadine is well-absorbed following oral ingestion, with peak plasma levels occurring after 1 to 3 hours. Its terminal half-life when taken orally is approximately 8 hours.

Chemistry

Cyproheptadine is a tricyclic benzocycloheptene and is closely related to pizotifen and ketotifen as well as to tricyclic antidepressants.

Research

Cyproheptadine was studied in one small trial as an adjunct in people with schizophrenia whose condition was stable and were on other medication; while attention and verbal fluency appeared to be improved, the study was too small to draw generalizations from. It has also been studied as an adjuvant in two other trials in people with schizophrenia, around fifty people overall, and did not appear to have an effect.
There have been some trials to see if cyproheptadine could reduce sexual dysfunction caused by SSRI and antipsychotic medications.
Cyproheptadine has been studied for the treatment of posttraumatic stress disorder.

Veterinary use

Cyproheptadine is used in cats as an appetite stimulant and as an adjunct in the treatment of asthma. Possible adverse effects include excitement and aggressive behavior. The elimination half-life of cyproheptadine in cats is 12 hours.
Cyproheptadine is a second line treatment for pituitary pars intermedia dysfunction in horses.