|Chemical and physical data|
|Molar mass||g·mol−1 200.285|
|3D model (JSmol)|
|Melting point||117–119 °C (243–246 °F)  256-257°C for HCl-salt|
|Solubility in water||Very soluble in water and ethanol, slightly soluble in chloroform and insoluble in diethylether mg/mL (20 °C)|
|(what is this?)|
Tetryzoline is an alpha agonist for alpha-2 receptor and imidazoline receptor I-1 agonist. Mainly due to its alpha-2 agonism it can constrict conjuctival blood vessels of the eye when taken in the form of eye drops. This relieves the redness of the eye caused by minor ocular irritants. To treat allergic conjunctivitis, tetryzoline can be combined in a solution with antazoline.
Tetryzoline eye drops may cause blurred vision, eye irritation and dilated pupils. Tetryzoline is not suitable for prolonged use as its vasoconstrictive effects within the eye eventually decrease or stop. When body is accustomed to tetryzoline, ceasing its use may cause redness of the eyes.
Intranasal use of tetryzoline may cause transient burning, stinging, or dryness of the mucosa and sneezing. Prolonged intranasal use often causes opposite effects in the form of rebound congestion with effects such as chronic redness, swelling and rhinitis. Prolonged use thus may result in overuse of the drug.
Overdose most often causes slow heart rate. Respiratory depression, low blood pressure, constricted pupils, hypothermia, brief episodes of high blood pressure, drowsiness, headaches and vomiting may also occur. In serious cases some of these effects may result in circulatory shock. Most often overdoses occur in children who have ingested the drug.
There is no antidote for tetryzoline or other similar imidazoline analogue poisoning, but the symptoms can be alleviated and with treatment, death is rare.
Half-life of tetryzoline in healthy people is about 6 hours and it is excreted unchanged in urine, at least in part. In one study 10 people were given 2 drops of 0.5 mg/ml tetryzoline eye drops (0.025–0.05 mg) at 0, 4, 8 and 12 h. Within 24 h time window since the last dose, tetryzoline blood serum concentration of the subjects was 13.0–210.0 ng/ml and urine concentration was 11–400 ng/ml. Both reached their maximum about 9 h post last dose. These levels correspond to normal ocular use of tetryzoline. Higher concentrations may indicate misuse of the drug or poisoning.
An urban legend suggests that tetryzoline can cause violent diarrhea if given orally, such as by putting a few drops of Visine in an unsuspecting person's beverage. However, the actual results of the prank may be worse, varying from severe nausea and vomiting to seizures or a coma. Diarrhea is not a side effect.
In late August 2018, a South Carolina woman, was charged with murdering her husband by putting eye drops containing tetryzoline in his drinking water. An autopsy found high concentrations of tetryzoline in his body.
In popular culture
Tetryzoline was used as a plot device in the 1990 film The Spirit of '76. Time travelers from the year 2176, where tetryzoline is a rare commodity, have traveled back to 1976 and have to use tetryzoline eye drops, a common item in 1976, as part of a battery in a time machine in order to return to the future.
The 2005 film Wedding Crashers includes the use of eye drops containing tetryzoline to poison a person's drink.
In season 4, episode 4 ("Doctor Psycho") of Netflix's Orange Is the New Black, the character Galina "Red" Reznikov is alleged to have contaminated another inmate's food with an eye-drop topical solution containing tetryzoline. This results in that inmate almost immediately running to a porta-potty toilet and enduring violent diarrhea due to the poisoning.
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