Cyproheptadine

Cyproheptadine
Clinical data
Pronunciation	/ˌsaɪproʊˈhɛptədiːn/
Trade names	Periactin, others
AHFS/Drugs.com	Monograph
MedlinePlus	a682541
License data	US DailyMed: Cyproheptadine;
Pregnancy; category	AU: A; ;
Routes of; administration	Oral
ATC code	R06AX02 (WHO) ;
Legal status
Legal status	AU: S3 (Pharmacist only); CA: OTC; UK: General sales list (GSL, OTC); US: ℞-only; In general: Over-the-counter (OTC);
Pharmacokinetic data
Protein binding	96 to 99%
Metabolism	Liver, including glucuronidation
Onset of action	1–4 hours (peak)
Elimination half-life	8.6 hours
Excretion	Faecal (2–20%; of which, 34% as unchanged drug) and renal (40%; none as unchanged drug)
Identifiers
	IUPAC name 4-(5H-Dibenzo[a,d]cyclohepten-5-ylidene)-1-methylpiperidine;
CAS Number	129-03-3 969-33-5 (hydrochloride);
PubChem CID	2913;
IUPHAR/BPS	277;
DrugBank	DB00434 ;
ChemSpider	2810 ;
UNII	2YHB6175DO;
KEGG	D07765 ;
ChEBI	CHEBI:4046 ;
ChEMBL	ChEMBL516 ;
CompTox Dashboard (EPA)	DTXSID8022872 ;
ECHA InfoCard	100.004.482
Chemical and physical data
Formula	C21H21N
Molar mass	287.406 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES c43\C(=C1/CCN(C)CC1)c2ccccc2\C=C/c3cccc4;
	InChI InChI=1S/C21H21N/c1-22-14-12-18(13-15-22)21-19-8-4-2-6-16(19)10-11-17-7-3-5-9-20(17)21/h2-11H,12-15H2,1H3 ; Key:JJCFRYNCJDLXIK-UHFFFAOYSA-N ;
	(verify)

Cyproheptadine, sold under the brand name Periactin among others, is a first-generation antihistamine which is used to treat allergies. In addition, it has a number of off-label uses, such as treatment of serotonin syndrome and insomnia. As well as being used as an appetite stimulant. The drug is taken orally.

It is an antihistamine and hence acts as a histamine H₁ receptor antagonist. In addition to its antihistamine activity, cyproheptadine has anticholinergic, antiserotonergic, antidopaminergic, and local anesthetic properties. These activities make cyproheptadine useful for various additional uses besides antihistamine indications. As a first-generation antihistamine, cyproheptadine crosses the blood–brain barrier and can produce sedation. The drug can also produce significant central anticholinergic effects at clinically used doses.

Cyproheptadine was patented in 1959 and came into medical use in 1961. In 2023, it was the 234th most commonly prescribed medication in the United States, with more than 1 million prescriptions.