Cimetidine

Cimetidine

Clinical data
Pronunciation	/sᵻˈmɛtᵻdiːn/ or /saɪˈmɛtᵻdiːn/
Trade names	Tagamet
AHFS/Drugs.com	Monograph
MedlinePlus	a682256
License data	US FDA: Cimetidine
Pregnancy category	AU: B1 US: B (No risk in non-human studies)
Routes of administration	Oral, parenteral
ATC code	A02BA01 (WHO)
Legal status
Legal status	AU: S4 (Prescription only) UK: POM (Prescription only) US: Rx (although 200 mg is OTC)
Pharmacokinetic data
Bioavailability	60–70%
Protein binding	15–20%
Metabolism	Hepatic
Onset of action	30 minutes
Biological half-life	2 hours
Duration of action	4–5 hours
Excretion	Renal
Identifiers
IUPAC name 1-cyano-2-methyl-3-[2-[(5-methyl-1H-imidazol-4-yl)methylsulfanyl]ethyl]guanidine
Synonyms	cimetidine hydrochloride SKF-92334
CAS Number	51481-61-9 Y
PubChem (CID)	2756
IUPHAR/BPS	1231
DrugBank	DB00501 Y
ChemSpider	2654 Y
UNII	80061L1WGD Y
KEGG	D00295 Y
ChEBI	CHEBI:3699 Y
ChEMBL	CHEMBL30 Y
ECHA InfoCard	100.052.012
Chemical and physical data
Formula	C10H16N6S
Molar mass	252.34 g/mol
3D model (Jmol)	Interactive image
SMILES N#CN\C(=N/C)NCCSCc1nc[nH]c1C
InChI InChI=1S/C10H16N6S/c1-8-9(16-7-15-8)5-17-4-3-13-10(12-2)14-6-11/h7H,3-5H2,1-2H3,(H,15,16)(H2,12,13,14) Y Key:AQIXAKUUQRKLND-UHFFFAOYSA-N Y

Cimetidine, sold under the brand name Tagamet among others, is a histamine H₂ receptor antagonist that inhibits stomach acid production. It is available over-the-counter and is mainly used in the treatment of heartburn and peptic ulcers.

The development of longer-acting H₂ receptor antagonists with fewer drug interactions and adverse effects, such as ranitidine and famotidine, decreased the use of cimetidine, and though it is still used, cimetidine is no longer among the more widely used of the H₂-receptor antagonists.

Cimetidine was discovered in 1971 and came into commercial use in 1977. Cimetidine was approved in the United Kingdom in 1976, and was approved in the United States by the Food and Drug Administration for prescriptions in 1979.

Some evidence suggests cimetidine could be effective in the treatment of common warts, but more rigorous double-blind clinical trials found it to be no more effective than a placebo.

Another study used cimetidine for the treatment of chronic calcific tendinitis of the shoulder. The small-scale study took 16 individuals with calcific tendinitis in one shoulder, all of which had previously attempted other forms of therapy, including steroid injection and arthroscopic lavage. During the course of the study, 10 patients reported an elimination of pain and nine displayed a complete disappearance of calcium deposits. With results being on a small scale, cimetidine, for the treatment of chronic calcific tendinitis of the shoulder, has been recommended to be opened to large-scale clinical trials.

Tentative evidence supports a beneficial role as add on therapy in colorectal cancer.

Reported side effects of cimetidine include diarrhea, rashes, dizziness, fatigue, constipation, and muscle pain, all of which are usually mild and transient. It has been reported that mental confusion may occur in the elderly. Because of its hormonal effects, cimetidine rarely may cause sexual dysfunction including loss of libido and erectile dysfunction and gynecomastia (0.1–0.2%) in males during long-term treatment. Rarely, interstitial nephritis, urticaria, and angioedema have been reported with cimetidine treatment. Cimetidine is also commonly associated with transient raised aminotransferase activity; hepatotoxicity is rare.