OPTIZOLINE DROPS

Indications

• Ocular redness
• Nasal congestion
• Allergic rhinitis
• Conjunctival irritation

Dosage

Children: Refer to the BNF for Children for specific paediatric dosing recommendations.

Adults: Refer to the BNF for specific adult dosing recommendations.

Mechanism of action

Tetrahydrozoline selectively stimulates alpha-1 adrenergic receptors, which are G-protein-coupled receptors that regulate vascular tone. By activating these receptors, tetrahydrozoline induces vasoconstriction of the blood vessels in the nasal passages and conjunctival tissue, thereby reducing redness and congestion.

Pharmacodynamics

As a sympathomimetic amine, tetrahydrozoline possesses vasoconstricting and decongestant properties. It effectively constricts the smaller arterioles in the nasal and conjunctival blood vessels, alleviating symptoms of allergic rhinitis and ocular irritation. Additionally, tetrahydrozoline can cross the blood-brain barrier, where it may interact with alpha-2 adrenoceptors and imidazole receptors, potentially leading to effects such as hypotension, bradycardia, sedation, and analgesia.

Pharmacokinetics

Tetrahydrozoline is absorbed systemically and can be distributed throughout the body, including crossing the blood-brain barrier. The onset of action is typically rapid, with effects observed shortly after administration. The metabolism and excretion pathways are not extensively detailed in the available literature, hence specific pharmacokinetic parameters such as half-life and elimination pathways should be referenced from additional pharmacological sources.

Adverse effects

• Headache
• Dizziness
• Dry mouth
• Nausea
• Rebound congestion with prolonged use
• Increased intraocular pressure

Precautions

• Use with caution in patients with cardiovascular disease
• Use with caution in patients with hypertension
• Caution in patients with hyperthyroidism
• Caution in pregnant and breastfeeding women

Pregnancy

Tetrahydrozoline should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether tetrahydrozoline is excreted in human milk. Caution should be exercised when administering to nursing mothers.

Storage

Store at room temperature, away from moisture and heat.

Formulations

• Ophthalmic solution
• Nasal spray

Mechanism of action

Adrenergic receptors are G-protein-coupled receptors (GPCR) that regulate vascular tone: stimulation of alpha-1 adrenergic receptors leads to vasoconstriction. Ocular redness and nasal congestion often result from vasodilation of nasal, conjunctival, and corneal capillary blood vessels. Activation of alpha-1 adrenergic receptors have been therefore associated with a reduction of symptoms of ocular irritation and nasal congestion. Tetryzoline is a selective agonist of alpha-1 adrenergic receptors, causing vasoconstriction and alleviating ocular and nasal symptoms.

Pharmacodynamics

Tetryzoline is a sympathomimetic amine and an alpha-adrenergic agonist with vasoconstricting and decongestant properties. It works by constricting the smaller arterioles of the nasal passages and conjunctival blood vessels to ameliorate allergic rhinitis, nasal congestion, and ocular irritation. Tetryzoline is known to cross the blood-brain barrier to work on alpha-2 adrenoceptors and imidazole receptors, causing effects like hypotension, bradycardia, analgesia, hypothermia, sedation, and hypnosis.