Products
Tetryzoline is commercially available in the form of eye drops (Visine Classic, combination products). It has been approved in many countries since 1959. The active ingredient is also known as tetrahydrozoline. Nasal sprays or [nasal drops containing tetryzoline are currently no longer available in many countries.
Structure and properties
Tetryzoline (C13H16N2, Mr = 200.3 g/mol) is present in drugs as tetryzoline hydrochloride, a racemate and a white crystalline powder that is readily soluble in water. Tetryzoline belongs to the imidazolines and is a tetrahydro derivative of naphthalene and a dihydro derivative of imidazole. It is structurally closely related to naphazoline.
Effects
Tetryzoline (ATC S01GA02) has sympathomimetic, vasoconstrictor, and decongestant properties. The effects are due to selective agonism at alpha-adrenoceptors. Effects are immediate and last approximately 4 to 6 (to 8) hours. Tetryzoline has a serum half-life of approximately 6 hours.
Indications
For the temporary symptomatic treatment of noninfectious inflammation and irritation of the conjunctiva of the eye.
Dosage
According to the package insert. Eye drops are usually placed in the affected eyes up to three times daily. The duration of therapy should be kept short and should not exceed about 3 to 5 days. See also under Administering eye drops.
Abuse
After discontinuation of the drops, so-called reactive hyperemia may occur, i.e., increased blood flow, which manifests itself in red eyes, especially if the drops are used for too long or excessively. If the drug is then used on and on, it can lead to habituation and a kind of dependence.
Contraindications
- Hypersensitivity
- Children under 2 years
- Narrow-angle glaucoma
- Bacterial infections or foreign bodies in the eye
For complete precautions, see the drug label.
Interactions
Drug-drug interactions have been described with MAO inhibitors and tricyclic antidepressants.
Adverse effects
Possible adverse effects include local reactions to the eye such as pupil dilation, eye burning, and blurred vision. Side effects may also be caused by the preservative benzalkonium chloride, which is present in some products. Reactive hyperemia may develop with prolonged and excessive use (see above). Despite local application, systemic side effects such as palpitations, tremors, hypertension and headache cannot be excluded. Tetryzoline eye drops should be kept out of the hands of children because ingestion may cause dangerous poisoning.