Tetrahydrozoline
Encyclopedia
Tetrahydrozoline, a derivative of imidazoline
, is found in over-the-counter eye drop
s and nasal spray
s. Other derivatives include naphazoline
, oxymetazoline
, and xylometazoline
. Poison
ing 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 affects 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.
with ethylenediamine.
Imidazoline
Imidazoline is a nitrogen-containing heterocycle with formula C3H6N2, derived from imidazole. The ring contains an imine bond, and the carbons at the 4 and 5 positions are singly bonded, rather than doubly bonded for the case of imidazole...
, is found in over-the-counter eye drop
Eye drop
Eye drops are saline-containing drops used as a route to administer medication in the eye. Depending on the condition being treated, they may contain steroids, antihistamines, sympathomimetics, beta receptor blockers, parasympathomimetics, parasympatholytics, prostaglandins, non-steroidal...
s and nasal spray
Nasal spray
Nasal sprays come in a variety of forms. Medicated such as Astelin, Afrin and Nasonex and natural such as Sinusoothe and Sterimar. Although delivery methods vary, most nasal sprays function by instilling a fine mist into the nostril by action of a hand-operated pump mechanism.-Antihistamine nasal...
s. Other derivatives include naphazoline
Naphazoline
Naphazoline is the common name for 2--2-imidazoline hydrochloride. It is a sympathomimetic agent with marked alpha adrenergic activity. It is a vasoconstrictor with a rapid action in reducing swelling when applied to mucous membrane...
, oxymetazoline
Oxymetazoline
Oxymetazoline is a selective alpha-1 agonist and partial alpha-2 agonist topical decongestant, used in the form of Oxymetazoline hydrochloride, in products such as Afrin, Dristan, Nasivin, Logicin, Vicks Sinex, Visine L.R., Sudafed OM, and Zicam. It was developed from Xylometazoline at E.Merck...
, and xylometazoline
Xylometazoline
Xylometazoline is a drug which is used as a topical nasal decongestant. It is applied directly into the nose, either as a spray or as drops....
. Poison
Poison
In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....
ing can result from an overdose.
Tetrahydrozoline is an alpha agonist
Alpha-adrenergic agonist
An adrenergic alpha-agonist is a drug that selectively stimulates alpha adrenergic receptors. The alpha-adrenergic receptor has two subclasses α1 and α2.-Classes:...
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 affects 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
Urban legend
An urban legend, urban myth, urban tale, or contemporary legend, is a form of modern folklore consisting of stories that may or may not have been believed by their tellers to be true...
suggests that tetrahydrozoline can cause violent diarrhea if administered orally, such as by putting a few drops of Visine
Visine
Visine is a brand of eye drops produced by Johnson & Johnson. Johnson & Johnson acquired Visine, along with Pfizer's entire consumer healthcare portfolio, in December 2006.-Visine Original:...
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-cyanotetralineTetralin
Tetralin is a hydrocarbon having the chemical formula C10H12. This molecule is similar to the naphthalene chemical structure except that one ring is saturated.The compound can be synthesized in a Bergman cyclization...
with ethylenediamine.
- M. E. Synerholm, L. H. Jules, M. Sahyun, (1956).