tetrahydrozoline, ophthalmic

Action and Spectrum

Mechanism of action

The mechanism of action of tetrahydrozoline ophthalmic involves the constriction of blood vessels in the eyes, reducing the flow of blood to the affected area. This leads to a reduction in the redness and swelling associated with allergic reactions or other irritants. The drug achieves this effect by binding to alpha-2 adrenergic receptors, which are present in the smooth muscle cells of blood vessels

Spectrum

The spectrum of activity of tetrahydrozoline ophthalmic is limited to the eyes and the surrounding tissues. It is ineffective in treating conditions that affect other body parts

Drug Interaction

Adverse Reaction

Frequency  not defined:

Blurred vision

Tremor

Tachycardia

Burning/Irritation

Headache

Hypertension

Palpitation

Black Box Warning

Contraindication / Caution

Contraindications

Contraindications of tetrahydrozoline ophthalmic include:

• Hypersensitivity: tetrahydrozoline ophthalmic should not be used in individuals who have a known hypersensitivity or allergy to the drug or any of its components
• Angle-closure glaucoma: tetrahydrozoline ophthalmic can increase intraocular pressure, and therefore it should not be used in individuals with narrow-angle glaucoma or a history of angle-closure glaucoma
• Severe cardiovascular disease: tetrahydrozoline ophthalmic can cause systemic absorption, which may lead to adverse effects such as increased blood pressure and heart rate. Therefore, it should be used cautiously in individuals with severe cardiovascular disease, such as uncontrolled hypertension, coronary artery disease, or arrhythmias
• Diabetes: tetrahydrozoline ophthalmic can affect blood sugar levels, so it should be used cautiously in individuals with diabetes
• Pregnancy and breast-feeding: tetrahydrozoline ophthalmic should be used cautiously during pregnancy and breast-feeding, as its safety in these populations has not been established.

Caution

While tetrahydrozoline ophthalmic is generally safe and well-tolerated when used as directed, some cautions should be taken into consideration when using this medication:

• Prolonged use: Long-term use of tetrahydrozoline ophthalmic can cause rebound hyperemia, where the redness and irritation return or worsen after discontinuing the medication. Therefore, tetrahydrozoline ophthalmic should not be used for more than 3-4 days without medical supervision
• Eye infections: tetrahydrozoline ophthalmic should not be used to treat eye infections, as it may mask the symptoms and delay proper diagnosis and treatment
• Contact lenses: tetrahydrozoline ophthalmic should not be used while wearing contact lenses, as it may cause discoloration or damage to the lenses. Contact lenses should be removed before using tetrahydrozoline ophthalmic and can be reinserted 15 minutes after administration
• Children: tetrahydrozoline ophthalmic should be used with caution in children under the age of 6, as their response to the medication may be unpredictable and may cause adverse effects
• Other medications: tetrahydrozoline ophthalmic may interact with other medications, including monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants (TCAs), increasing the risk of side effects

Pregnancy / Lactation

Pregnancy consideration: C

Lactation: Excretion of the drug in human breast milk is unknown

Pregnancy category:

Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester.

Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women.

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.

Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.

Category N: There is no data available for the drug under this category

Pharmacology

Pharmacology

The pharmacology of tetrahydrozoline ophthalmic involves its action as a sympathomimetic drug, specifically an alpha-adrenergic agonist. Alpha-adrenergic receptors are found in various body tissues, including the eyes. When tetrahydrozoline is applied topically to the eyes, it binds to these receptors and causes them to constrict, reducing blood flow to the area

In addition to its vasoconstrictive effects, tetrahydrozoline ophthalmic also has some local anesthetic properties that can help to relieve eye irritation and discomfort

Pharmacodynamics

The pharmacodynamics of tetrahydrozoline ophthalmic involves its interaction with alpha-adrenergic receptors in the eyes. It is a selective alpha-1 adrenergic receptor agonist which binds to and activates alpha-1 receptors in the smooth muscle of the blood vessels in the eyes.

Activation of these receptors causes vasoconstriction or narrowing of the blood vessels, which results in decreased blood flow to the eyes. It reduces redness and swelling of the conjunctiva (the thin layer that covers the white part of the eye). This action also decreases the amount of fluid that leaks out of blood vessels, decreasing edema and irritation

In addition to its alpha-1 adrenergic effects, tetrahydrozoline ophthalmic also has some local anesthetic properties that can relieve eye discomfort and irritation

Pharmacokinetics

Absorption

When applied topically to the eye, tetrahydrozoline ophthalmic is absorbed through the conjunctiva and cornea into the aqueous humor and the bloodstream. The absorption of the medication into the systemic circulation is minimal.

Distribution

tetrahydrozoline ophthalmic has a relatively short half-life of about 2-3 hours and is primarily distributed to the ocular tissues after topical administration. The medication does not appear to accumulate in the body with repeated dosing

Metabolism

tetrahydrozoline ophthalmic is metabolized primarily by hepatic enzymes, specifically by the cytochrome P450 2D6 (CYP2D6) pathway. The major metabolite of tetrahydrozoline ophthalmic is 2-amino-1,2-dihydro naphthalene, which is excreted in the urine

Elimination and Excretion

The elimination of tetrahydrozoline ophthalmic occurs primarily through renal excretion of the metabolites. The medication and its metabolites are excreted rapidly, with up to 90% of the dose being eliminated within 24 hours of administration

Adminstartion

Administration

• tetrahydrozoline ophthalmic is a medication used to relieve eye redness caused by minor eye irritations such as smoke, dust, wind, or pollen. It is a vasoconstrictor that works by narrowing blood vessels in the eye
• Before using tetrahydrozoline ophthalmic, it is essential to wash your hands thoroughly. Tilt your head back and use your index finger to pull down the lower eyelid to create a small pocket. Hold the bottle of eye drops above your eye and squeeze one or two drops into the pocket. Close your eye for a few seconds to allow the medication to spread evenly across the eye
• Do not touch the tip of the eye drop bottle to any surface, including your eye or fingers, as this can contaminate the medication and increase the risk of infection. Replace the cap on the bottle immediately after use

Patient Information Leaflet

Patient information leaflet

Generic Name: tetrahydrozoline, ophthalmic

Pronounced:[ TE-tra-hye-DROZ-oh-leen-off-THAL-mik ]

Why do we use tetrahydrozoline, ophthalmic?

tetrahydrozoline ophthalmic is a medication used to relieve eye redness caused by minor eye irritations, such as smoke, dust, wind, or pollen. It works by narrowing the blood vessels in the eye, which reduces redness and swelling

Here are some common uses of tetrahydrozoline ophthalmic:

• Eye redness relief: tetrahydrozoline ophthalmic is primarily used to relieve eye redness caused by minor irritations, such as allergies or environmental factors
• Eye strain relief: If you have been staring at a computer screen or reading for an extended period, your eyes may become strained and appear red. Tetrahydrozoline ophthalmic can provide temporary relief from eye strain
• Contact lens discomfort relief: Wearing contact lenses for an extended period can cause eye redness and discomfort. tetrahydrozoline ophthalmic can help alleviate these symptoms