Of the serotonin receptors, it is an especially potent antagonist of the 5-HT2 receptors. This is thought to underlie its effectiveness in the treatment of serotonin syndrome. However, it is possible that blockade of 5-HT1 receptors may also contribute to its effectiveness in serotonin syndrome. Cyproheptadine has been reported to block 85% of 5-HT2 receptors in the human brain at a dose of 4 mg three times per day (12 mg/day total) and to block 95% of 5-HT2 receptors in the human brain at a dose of 6 mg three times per day (18 mg/day total) as measured with positron emission tomography (PET). The dose of cyproheptadine recommended to ensure blockade of the 5-HT2 receptors for serotonin syndrome is 20 to 30 mg. Besides its activity at neurotransmitter targets, cyproheptadine has been reported to possess 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: 1371  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. == References ==