Trusopt (Dorzolamide) Eye Drops

What Is Trusopt and What Is It Used For?

Trusopt contains dorzolamide, a carbonic anhydrase inhibitor that reduces elevated intraocular pressure (IOP). It is prescribed for the treatment of open-angle glaucoma and ocular hypertension, either as monotherapy or in combination with beta-blocker eye drops.

Trusopt (dorzolamide hydrochloride) belongs to a class of medications known as carbonic anhydrase inhibitors (CAIs). Carbonic anhydrase is an enzyme found throughout the body, including in the ciliary processes of the eye. By selectively inhibiting carbonic anhydrase type II in the eye, dorzolamide reduces the secretion of aqueous humor — the clear fluid that fills the front part of the eye. This reduction in fluid production leads to a measurable decrease in intraocular pressure.

Elevated intraocular pressure is the primary modifiable risk factor for glaucoma, a group of eye diseases that can cause progressive, irreversible damage to the optic nerve. Left untreated, glaucoma can lead to gradual loss of peripheral vision and eventually blindness. According to the World Health Organization (WHO), glaucoma is the second leading cause of blindness worldwide, affecting approximately 80 million people globally as of 2020, with projections estimating 111.8 million by 2040.

Trusopt is indicated for the treatment of elevated intraocular pressure in patients with open-angle glaucoma (the most common form of glaucoma) and ocular hypertension (elevated eye pressure without detectable optic nerve damage). It may be used as a first-line monotherapy when beta-blockers are contraindicated or insufficient, or as an adjunctive (add-on) therapy in combination with topical beta-blocker eye drops when a single agent does not adequately control IOP.

Clinical trials have demonstrated that Trusopt can reduce intraocular pressure by approximately 15–22% from baseline when used as monotherapy. When added to a beta-blocker regimen, it provides an additional 13–21% IOP reduction. This makes it a valuable component in the medical management of glaucoma, where the goal is to lower IOP sufficiently to prevent or slow optic nerve damage.

What Should You Know Before Using Trusopt?

Before using Trusopt, tell your doctor about any kidney problems, history of kidney stones, sulfonamide allergies, or liver disease. Trusopt is not recommended during pregnancy or breastfeeding. Remove contact lenses before application and wait at least 15 minutes before reinserting them.

Contraindications

Trusopt must not be used if you:

• Are allergic to dorzolamide hydrochloride or any of the other ingredients in the formulation (hydroxyethyl cellulose, mannitol, sodium citrate, sodium hydroxide, water for injections, benzalkonium chloride)
• Have severely impaired kidney function or significant kidney disease, as dorzolamide and its metabolite are primarily excreted by the kidneys
• Have a history of kidney stones (nephrolithiasis), since carbonic anhydrase inhibitors can alter urinary composition and potentially promote stone formation

Because dorzolamide is a sulfonamide derivative, there is a theoretical risk of cross-reactivity in patients with a known allergy to sulfonamides. While topical application results in far lower systemic exposure than oral sulfonamide drugs, physicians should exercise caution and carefully weigh the risks and benefits in patients with a documented sulfonamide allergy history.

Warnings and Precautions

Before using Trusopt, talk to your doctor or pharmacist about any of the following conditions:

• Eye conditions: Inform your doctor about any current or past eye problems, previous eye surgeries (especially filtration surgery), or any history of corneal disease. Dorzolamide has been associated with corneal edema in some patients, particularly those with low endothelial cell counts.
• Allergic reactions: If you develop signs of an allergic reaction such as skin rash, severe skin reactions, or itching, discontinue Trusopt and contact your doctor immediately.
• Eye irritation: If you experience irritation, redness, or swelling of the eyelids after using Trusopt, contact your healthcare provider promptly.
• Liver disease: Tell your doctor if you have or have previously had any liver problems, as hepatic impairment could potentially affect the metabolism of dorzolamide.

Use in Children

Trusopt has been studied in infants and children under 6 years of age who have elevated intraocular pressure or a diagnosis of glaucoma. Pediatric glaucoma, while rare, requires careful management to prevent amblyopia (lazy eye) and irreversible vision loss. The dosing and safety profile in children should be discussed with the treating ophthalmologist, as the developing eye may respond differently to topical medications compared to adults.

Use in Elderly Patients

In clinical studies, the efficacy and safety of Trusopt were comparable between elderly and younger patients. No dose adjustment is required based on age alone. However, since older patients may have reduced kidney function, renal status should be assessed before initiating therapy, and periodic monitoring may be advisable.

Pregnancy and Breastfeeding

Trusopt should not be used during pregnancy unless the potential benefit to the mother clearly outweighs the potential risk to the fetus. Animal studies have shown adverse reproductive effects at high systemic doses, although the systemic absorption from topical eye drops is relatively low. Women who are pregnant, planning to become pregnant, or breastfeeding should inform their doctor before starting treatment.

If treatment with Trusopt is considered medically necessary, breastfeeding is not recommended. It is not known whether dorzolamide is excreted in human breast milk, but given its sulfonamide structure and potential for adverse effects in the nursing infant, caution is warranted.

Driving and Operating Machinery

Trusopt may cause side effects such as dizziness and blurred vision, which could impair your ability to drive or operate machinery safely. Do not drive or use machines until these effects have resolved and your vision is clear. If you experience persistent visual disturbance, consult your doctor.

How Does Trusopt Interact with Other Drugs?

Trusopt may interact with other carbonic anhydrase inhibitors (such as acetazolamide) and sulfonamide-containing medications. Combining topical and systemic carbonic anhydrase inhibitors is not recommended due to the risk of additive systemic effects. Always tell your doctor about all medications you use, including other eye drops.

Drug interactions with Trusopt are primarily related to its mechanism as a carbonic anhydrase inhibitor and its sulfonamide chemical structure. While the topical route of administration limits systemic absorption, clinically relevant interactions can still occur, particularly when multiple medications affecting the same enzyme systems are used concurrently.

Major Interactions

The combination of topical dorzolamide with oral carbonic anhydrase inhibitors (such as acetazolamide or methazolamide) is not recommended. Both medications inhibit the same enzyme, and concurrent use may lead to additive suppression of carbonic anhydrase activity throughout the body. This can increase the risk of systemic side effects including metabolic acidosis, electrolyte imbalances, tingling in the extremities, and kidney stone formation.

Minor Interactions

Dorzolamide is a sulfonamide derivative. While the systemic exposure from eye drops is low, patients using other sulfonamide-containing medications should inform their doctor, as there may be an increased potential for hypersensitivity reactions or additive effects.

What Is the Correct Dosage of Trusopt?

When used alone, Trusopt is applied as one drop in the affected eye(s) three times daily (morning, afternoon, and evening). When combined with a beta-blocker eye drop, the dose is one drop in the affected eye(s) twice daily (morning and evening). Always follow your doctor's instructions.

The dosage of Trusopt should always be determined by your prescribing physician based on your specific condition, the severity of intraocular pressure elevation, and whether you are using other medications. It is essential to adhere strictly to the prescribed regimen, as consistent IOP control is critical for preventing progressive optic nerve damage in glaucoma.

Adults

Children

The use of Trusopt in children, including infants, has been studied in clinical trials. The dosing regimen for pediatric patients is typically the same as for adults, although the treating ophthalmologist will determine the most appropriate dose based on the child's age, weight, and clinical response. Parents and caregivers should be trained in proper eye drop administration technique for children to ensure accurate dosing and minimise contamination risk.

Elderly

No specific dose adjustment is required for elderly patients based on age alone. However, given that renal function tends to decline with age, physicians should assess kidney function before prescribing Trusopt and should monitor renal parameters periodically. The standard adult dosing applies unless kidney impairment is identified.

How to Apply Trusopt Eye Drops

Correct application technique is important both for efficacy and for preventing contamination:

1. Wash your hands thoroughly before handling the bottle.
2. Check the seal: Do not use the bottle if the tamper-evident plastic strip around the neck is missing or broken. Remove the strip when opening for the first time.
3. Open the bottle and ensure the dropper tip does not touch your eye, surrounding skin, or fingers.
4. Tilt your head back and hold the bottle upside down above the eye.
5. Pull down the lower eyelid and look upward. Gently squeeze the flat sides of the bottle to release one drop into the pocket formed between the lower eyelid and the eye.
6. Close your eye and press a finger gently against the inner corner of the eye (nasolacrimal occlusion) for approximately two minutes. This minimises systemic absorption and reduces the risk of bitter taste and systemic side effects.
7. If your doctor has prescribed treatment for both eyes, repeat steps 4–6 for the other eye.
8. Replace the cap securely on the bottle.

Missed Dose

If you forget to apply a dose, use it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose and continue with your regular dosing schedule. Do not apply a double dose to compensate for a forgotten one, as this may increase the risk of local side effects such as eye irritation.

Overdose

If you accidentally apply too many drops into the eye, or if someone (particularly a child) accidentally swallows the contents of the bottle, contact your doctor, hospital emergency department, or local poison control center immediately. Symptoms of systemic overdose may include electrolyte imbalances, metabolic acidosis, and central nervous system effects. Flush the affected eye(s) with clean water if excessive drops have been applied topically.

What Are the Side Effects of Trusopt?

The most common side effect of Trusopt is a burning or stinging sensation in the eye, affecting more than 1 in 10 users. Other common side effects include tearing, blurred vision, eye irritation, headache, nausea, bitter taste, and fatigue. Seek immediate medical attention if you experience signs of a severe allergic reaction.

Like all medicines, Trusopt can cause side effects, although not everyone will experience them. Most side effects are mild and localised to the eye. However, because dorzolamide is a sulfonamide derivative, there is a small risk of systemic allergic reactions similar to those seen with other sulfonamide drugs.

If you experience any side effects, including those not listed above, talk to your doctor or pharmacist. Reporting suspected adverse effects is important for the ongoing monitoring of the benefit-risk balance of medicines. You can report side effects to your national medicines regulatory authority.

How Should You Store Trusopt?

Store Trusopt out of sight and reach of children. Use within 28 days after opening. Keep the bottle in its outer carton to protect from light. No special temperature requirements.

Proper storage of Trusopt is essential to maintain the medication's stability and sterility:

• Keep out of reach of children: Store in a location where children cannot access it.
• Check the expiry date: Do not use Trusopt after the expiry date printed on the label and carton (EXP). The expiry date refers to the last day of that month.
• 28-day in-use shelf life: Once opened, the bottle must be used within 28 days, regardless of how much solution remains. Mark the opening date on the carton for reference.
• No special temperature requirements: The product can be stored at room temperature.
• Protect from light: Keep the bottle in its outer carton when not in use.
• Disposal: Do not dispose of medicines in wastewater or household waste. Ask your pharmacist about proper disposal methods for medications you no longer use. These measures help protect the environment.

What Does Trusopt Contain?

Each millilitre of Trusopt contains 22.26 mg of dorzolamide hydrochloride, equivalent to 20 mg of dorzolamide. The solution also contains hydroxyethyl cellulose, mannitol, sodium citrate, sodium hydroxide, water for injections, and benzalkonium chloride as a preservative.

Active Ingredient

The active substance is dorzolamide. Each 1 ml of solution contains 22.26 mg of dorzolamide hydrochloride, which is equivalent to 20 mg of dorzolamide free base. Dorzolamide is a potent and selective inhibitor of human carbonic anhydrase isoenzyme II (CA-II), the predominant isoenzyme in the ciliary epithelium of the eye responsible for aqueous humor production.

Inactive Ingredients (Excipients)

• Hydroxyethyl cellulose: Viscosity-enhancing agent that prolongs contact time with the eye surface
• Mannitol: Osmotic agent used for tonicity adjustment
• Sodium citrate: Buffer to maintain the solution's pH stability
• Sodium hydroxide: pH adjuster
• Water for injections: Solvent base
• Benzalkonium chloride: Preservative (approximately 0.075 mg/ml). Important for patients using soft contact lenses — see precautions above

Appearance and Packaging

Trusopt is a clear, colourless to nearly colourless, slightly viscous solution. It is supplied in a white, translucent plastic dropper bottle (Ocumeter) containing 5 ml of solution, sealed with a white screw cap and a tamper-evident plastic strip. Available pack sizes include 1 × 5 ml, 3 × 5 ml, and 6 × 5 ml. Not all pack sizes may be marketed in all countries.

The marketing authorisation holder is Santen Oy, Niittyhaankatu 20, 33720 Tampere, Finland. Trusopt is authorised throughout the European Economic Area under the same brand name in multiple countries including Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, the Netherlands, Portugal, Spain, and Sweden.