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Cyproheptadine (Molecule of the Month for May 2021)

Periactin, Apetamin

Cyproheptadine 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.

Cyproheptadine is used to treat allergic reactions (specifically hay fever).The evidence for its use for this purpose indicates its effectiveness but second generation antihistamines such as ketotifen and loratadine have shown equal results with fewer side effects. It is also used as a preventive treatment against migraine. In a 2013 study the frequency of migraine was dramatically reduced in patients within 7 to 10 days after starting treatment. The average frequency of migraine attacks in these patients before administration was 8.7 times per month, this was decreased to 3.1 times per month at 3 months after the start of treatment. This use is on the label in the UK and some other countries. It used off-label to treat various dermatological conditions, including psychogenic itch[ drug-induced hyperhidrosis (excessive sweating), and prevention of blister formation for some people with epidermolysis bullosa simplex.

One of the effects of the drug is increased appetite and weight gain, which has led to its use (off-label in the USA) for this purpose in children who are wasting as well as people with cystic fibrosis.

Recently it has been sold under the name Apetamin as an appetite stimulating weight-gain supplement manufactured and sold by the Indian pharmaceutical company. It is a syrup containing cyproheptadine (a hepatotoxin), lysine and some vitamins. It has not been approved by the US Food and Drug Administration or the UK Medicines and Healthcare products Regulatory Agency. It is illegal to sell apetamin in most countries, including the United States and the UK. Sadly it is heavily promoted and illegally sold on social media as a way of achieving the curvy body shape currently fashionable in some communities.

In May 2021, the BBC reported that NHS England has urged Instagram to clamp down on accounts selling an unlicensed, "dangerous" drug mainly targeted at younger women and girls.

Formal Chemical Name (IUPAC)




Picture of Cyproheptadine 3D model

click on the picture of  Cyproheptadine above to interact
with the 3D model of the
Cyproheptadine structure
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Picture of Cyproheptadine

C21 H21 N

Update by Karl Harrison
(Molecule of the Month for May 2021 )

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