What Diquas Treats: Main Uses and Benefits

Diquas is commonly used for the management of Dry Eye Disease (DED), a condition linked to an underlying deficiency in the natural tear film components. The medication is relevant for conditions involving episodic or fluctuating manifestations, specifically addressing subtypes like aqueous-deficient dry eye and those characterized by poor tear film stability. This treatment provides support that helps ease the overall burden of persistent dryness, irritation, and foreign body sensation.

The medication is relevant for supporting the health of the corneal and conjunctival epithelial surface, which is often damaged by chronic desiccation. By promoting the secretion of protective components, Diquas assists with the restoration of the ocular surface and helps maintain a sense of stability when symptoms become more noticeable. It is applied in clinical settings that involve acute or unstable symptom patterns, such as persistent dryness after cataract or refractive surgery. A relevant benefit is found in easing symptoms that interfere with daily functioning, including visual disturbances and associated eye strain.

“The primary goal is to provide symptomatic relief and support the patient's general well-being during difficult episodes.”

Quick Fact: Relief for Chronic Dry Eye Symptoms
Primary Indication	Dry Eye Disease (DED) and associated keratoconjunctival epithelial disorders.
Symptom Focus	Grittiness, foreign body sensation, dryness, and visual fatigue.
Common Contexts	Chronic tear deficiency, post-operative ocular surface stress, and use in older adults.
Main Benefit	Contributes to improved comfort by assisting with ocular surface stability and easing associated symptoms.

Regulatory References

1. Japanese Pharmaceuticals and Medical Devices Agency (PMDA)

Who can and cannot use Diquas?

The use of Diquas Ophthalmic Solution is contraindicated for any individual with a known history of hypersensitivity or allergy to Diquafosol Tetrasodium or to any other inactive ingredient contained in the solution.

The established patient population for use is adults (typically 18 years of age and older) who have been diagnosed with Dry Eye Disease. Regulatory documents indicate that use in pediatric patients (under 18 years) is generally not established due to insufficient clinical data in this age group, though use in older adults is established and acceptable.

Specific eligibility rules apply to certain populations. Women who are pregnant or breastfeeding are categorized as requiring conditional use and careful consultation, as definitive regulatory safety data is limited. Additionally, patients who wear contact lenses must remove their lenses prior to drug instillation and adhere to a waiting period before reinserting them.

Regulatory labeling does not document specific population restrictions related to hepatic (liver) or renal (kidney) impairment, which reflects the medicine's topical administration and negligible systemic absorption. These official statements strictly define who is eligible, who is contraindicated, and who is subject to mandatory conditional use.

Interactions with other medicines and products

Official regulatory information for Diquas (diquafosol ophthalmic solution) indicates that interactions are primarily limited to local, topical considerations due to the drug’s negligible systemic absorption. Systemic drug interactions, including those mediated by metabolic enzymes (CYP) or transporters, are not documented.

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Ophthalmic and Procedural Interactions

Interaction Context	Official Requirement	Mechanistic Basis
Co-administration with other eye drops	Wait a minimum of five minutes between applying Diquas and any other ophthalmic preparation.	Prevents the wash-out or dilution of Diquas, ensuring the correct amount remains on the ocular surface.
Use with Soft Contact Lenses	Remove soft contact lenses before application and wait a specified interval (typically 5 to 10 minutes) before reinserting them.	The preservative in the solution, benzalkonium chloride, can be absorbed by and interact with the soft contact lens material.

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Systemic Interactions

There are no documented interactions between Diquas and systemic medicinal products. Furthermore, official labeling does not contain reported interactions with food, alcohol, or herbal products due to the drug’s minimal systemic bioavailability. No population-specific interaction adjustments (e.g., for patients with kidney or liver impairment) are necessary or documented in the regulatory profile.

Selective P2Y2 Receptor Agonism and Secretory Cascade

Diquafosol acts as a selective agonist of the P2Y2 receptor, a purinergic G protein-coupled receptor located on the epithelial cells of the cornea and conjunctiva, as well as on goblet cells . Binding to this receptor initiates an intracellular calcium signaling cascade. This molecular event triggers a dual-action secretory mechanism localized to the ocular surface.

This cellular signaling cascade simultaneously causes two main physiological consequences. First, the calcium surge induces the active release (exocytosis) of mucin from goblet cells, contributing protective glycoproteins to the tear film. Second, the signaling cascade activates specific chloride ion channels on the epithelial surface. This Cl^- ion efflux establishes an osmotic gradient, which drives the movement of the aqueous fluid component onto the eye's surface. This mechanism results in the generation of both the aqueous and mucin components necessary for tear film structural integrity and volume.

Diquas ophthalmic solution, containing diquafosol sodium, is generally used to treat dry eye by promoting the secretion of water and mucin, which are components of tears.

Administration Guidelines

Follow the specific dosing schedule provided by your healthcare professional. The general dosage for the 3% ophthalmic solution is to instill one drop at a time, six times daily. A long-acting formulation (Diquas LX) may require a reduced frequency, such as three times daily, if prescribed.

• Preparation: Before application, thoroughly wash your hands. Gently pull down the lower eyelid to create a small pocket.
• Application: Tilt your head back and look upward. Instill one drop into the eye pocket. Avoid touching the tip of the dropper to your eye, eyelid, or any other surface to prevent contamination.
• Post-Application: After applying, keep your eyes closed for a few minutes (one to five minutes) and apply gentle pressure to the inner corner of the eye near the nose (tear ducts) to facilitate absorption.
• Contact Lenses: Remove soft contact lenses before applying the solution, as the preservative (benzalkonium chloride) may be absorbed by the lens material. Wait at least five to ten minutes before re-inserting the lenses.
• Co-administration: If you are using other eye drops, wait at least five minutes between applications of different medications to prevent the first drop from being washed away.

Continue to use Diquas as directed, and do not discontinue the medication without consulting your doctor. If you miss a dose, apply it as soon as you remember unless it is nearly time for the next scheduled dose, in which case you should skip the missed dose. Do not apply a double dose to compensate.

Research Evidence / Overview of Studies for Diquas

Research has explored Diquafosol Tetrasodium (Diquas) in multiple clinical situations, including randomized controlled trials (RCTs) and long-term observational research. The research examined patterns related to ocular surface health and patient-reported symptoms associated with Dry Eye Disease (DED). The findings describe group patterns, not personal outcomes, and evidence highlights what is known—and what is still uncertain.

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Evidence for Use in Chronic Dry Eye Disease (DED)

The research base explored the use in people with chronic DED. This evidence includes several multi-center, randomized controlled trials, where patients received Diquafosol, a standard therapy, or an inactive solution. Studies monitored objective indicators of the eye’s surface health, such as corneal and conjunctival staining (a measure of surface damage) and Tear Break-Up Time (TBUT), which indicates tear film stability.

Studies report that administration of Diquafosol was associated with specific patterns of change in both objective measures of epithelial damage and subjective reports of symptoms compared to inactive solutions. However, in some initial trials, the pre-specified targets for all outcomes were not met, leading to findings that were mixed across early study cohorts.

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Comparative Study Landscape and Context

Research has also explored how Diquafosol was observed in comparison to other topical agents used for DED, specifically 0.1% Sodium Hyaluronate. These comparative clinical trials monitored changes in ocular surface measures over short to intermediate follow-up durations. Some studies monitored changes measured during the study period when Diquafosol was observed in combination with Sodium Hyaluronate for symptoms where monotherapy had been insufficient.

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What Research Gaps and Uncertainties Remain

While a substantial research base exists, the scientific literature and regulatory reviews highlight areas where certainty remains low or research is incomplete:

• Long-Term Effects: There is limited information for long-term outcomes significantly beyond the 12-month observational period, meaning the full pattern of change over several years is not fully established.
• Comparative Evidence: Comparative evidence is lacking for Diquafosol against certain potent prescription dry eye treatments, which limits direct comparisons.
• Specialized Cohorts: Research in highly specialized groups often has sample sizes that were modest and follow-up durations that were limited.

Key Studies & References

1. Randomized Controlled Study to Investigate the Effect of Topical Diquafosol on Corneal Sensitivity in Patients with Short Tear Break-Up Time-Type Dry Eye (PubMed)
2. Characteristics of Patients with Dry Eye Who Switched from Diquafosol to other Agents (MDPI)

Common questions about Diquas (FAQ)

Q: How long does Diquas take to start working, and when should I see improvement in my dry eye symptoms?

A: Clinical studies have shown that objective improvements in the eye's surface health, such as corneal staining scores, were observed in study participants starting at two weeks of treatment. These improvements were typically sustained throughout the clinical trial observation periods. Studies also noted that some patients reported improvements in certain dry eye symptoms during the same period.

Q: Can I use Diquas with my daily vitamins or other oral medications like blood pressure pills?

A: Regulatory documents state that systemic drug interactions, which involve oral medications, are not documented for Diquas. This is because the eye drop has minimal systemic absorption, meaning very little of the drug enters the bloodstream. Official labeling does not report interactions with food, alcohol, herbal products, or systemic medicines.

Q: Is Diquas available over-the-counter (OTC) or only by prescription?

A: According to official product information and regulatory status, Diquas ophthalmic solution is a prescription-only medicine. It is not available for purchase over-the-counter.

Q: What should I do if my eye irritation and side effects don't go away after the first month of using Diquas?

A: While common side effects are often transient and tend to resolve within the first few weeks of use, official safety information advises caution if symptoms persist. If any significant or continuing eye irritation develops or if side effects do not subside, it is important to consult a healthcare professional for guidance.

Q: What are the inactive ingredients or preservatives in Diquas?

A: The active ingredient in Diquas is Diquafosol Sodium. The formulation also contains other inactive ingredients, including the preservative benzalkonium chloride. This ingredient is known to be adsorbed by soft contact lens material, which is why regulatory safety information addresses contact lens use.

How to Store and Dispose of Diquas

Official regulatory documents define strict environmental and stability rules for storing Diquas (Diquafosol Tetrasodium Ophthalmic Solution).

Storage Conditions

Condition	Requirement
Temperature	Store below 30 C (Room Temperature); Do not freeze.
Protection	Keep tightly closed, away from direct sunlight and moisture.
Child Safety	Must be stored out of the sight and reach of children.

Stability and Disposal

The medicine has a limited stability period once opened. Multi-dose bottles must be discarded one month after the initial opening. Single-use containers must be discarded immediately after use, even if solution remains. Unused or expired solution must be disposed of according to local regulations and must not be shared with others.