Tetrahydrozoline

Tetrahydrozoline
IUPAC name (RS)-2-(1,2,3,4-tetrahydronaphthalen-1-yl)-4,5-dihydro-1H-imidazole
Identifiers
CAS number	84-22-0 N
PubChem	5419
ChemSpider	5226 Y
UNII	S9U025Y077 Y
KEGG	D08578 Y
ChEBI	CHEBI:28674 Y
ChEMBL	CHEMBL1266 Y
Jmol-3D images	Image 1
SMILES N\1=C(\NCC/1)C3c2ccccc2CCC3
InChI InChI=1S/C13H16N2/c1-2-6-11-10(4-1)5-3-7-12(11)13-14-8-9-15-13/h1-2,4,6,12H,3,5,7-9H2,(H,14,15) Y Key: BYJAVTDNIXVSPW-UHFFFAOYSA-N Y InChI=1/C13H16N2/c1-2-6-11-10(4-1)5-3-7-12(11)13-14-8-9-15-13/h1-2,4,6,12H,3,5,7-9H2,(H,14,15) Key: BYJAVTDNIXVSPW-UHFFFAOYAC
Properties
Molecular formula	C13H16N2
Molar mass	200.28 g/mol
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Tetrahydrozoline, a derivative of imidazoline, is found in over-the-counter eye drops and nasal sprays. Other derivatives include naphazoline, oxymetazoline, and xylometazoline. Poisoning can result from an overdose.

Tetrahydrozoline is an alpha agonist and its main mechanism of action is the constriction of conjunctival blood vessels. This serves to relieve the redness of the eye caused by minor ocular irritants.

When used, “only as directed,” tetrahydrozoline is an effective medication which shrinks blood vessels thus alleviating reddened “bloodshot” eyes. If taken internally, however, this drug acts like a potent high blood pressure medicine. Symptoms reported in both children and adults who have swallowed some of these eye care products either by accident or via malicious activity include marked drowsiness, low blood pressure, slowed heart rate, and possibly even coma and impaired breathing. Quantities as low as ½ to 1½ teaspoonfuls (approximately 1/6 to ½ of a half ounce bottle) have caused pronounced reactions in small children. Toxic effects following tetrahydrozoline ingestion can be serious and at times require close observation and treatment in an intensive care setting. Fortunately, no deaths have been reported.

An urban legend suggests that tetrahydrozoline can cause violent diarrhea if administered orally, such as by putting a few drops of Visine in an unsuspecting person's beverage. However, the actual results of the "Visine Prank" may be worse, varying from severe nausea and vomiting to seizures or a coma. Diarrhea is not a side effect.

Chemistry

Tetrahydrozoline is synthesized in one step by the heterocyclization of 1-cyanotetraline with ethylenediamine.

• M. E. Synerholm, L. H. Jules, M. Sahyun, U.S. Patent 2,731,471 (1956).