Understanding the Timing: Why is Xalatan Given at Bedtime?

October 8, 2025 •

4 min read

According to the medication's prescribing information, the recommended dosage is one drop in the affected eye(s) once daily in the evening. But why is Xalatan given at bedtime? The specific timing is crucial for maximizing its therapeutic benefits and managing a patient's intraocular pressure (IOP) effectively around the clock.

Quick Summary

The specific bedtime application of Xalatan is timed to align with the body's natural circadian rhythm, maximizing the medication's intraocular pressure-lowering effect when pressure can naturally rise overnight. This dosing schedule also helps minimize the impact of common temporary side effects.

Key Points

Peak Effectiveness at Night: The body's intraocular pressure (IOP) naturally rises at night and in the early morning; Xalatan is timed for bedtime use so its peak IOP-reducing effect aligns with this nocturnal peak.
24-Hour Coverage: A single dose of Xalatan at night provides consistent IOP reduction for at least 24 hours, ensuring continuous pressure control.
Minimizes Side Effects: Common temporary side effects like blurred vision or stinging are less disruptive when they occur while the patient is asleep.
Enhances Compliance: The once-daily bedtime schedule simplifies the routine, improving patient adherence to the medication regimen.
Prevents Paradoxical Effects: Using Xalatan more than once a day can decrease its efficacy, so the single bedtime dose prevents this from happening.
Increases Uveoscleral Outflow: The drug's mechanism of action involves increasing the outflow of aqueous humor through the uveoscleral pathway, which is effectively managed by the bedtime dose.

The Circadian Rhythm of Intraocular Pressure

Intraocular pressure (IOP) is not static; it fluctuates throughout a 24-hour period according to the body's natural circadian rhythm. For many people with glaucoma, IOP tends to peak during the night and in the early morning, often while they are sleeping. Elevated IOP is a major risk factor for optic nerve damage and subsequent vision loss associated with glaucoma. Therefore, controlling this nocturnal pressure spike is a critical part of effective glaucoma management.

Xalatan (latanoprost) is a prostaglandin analog designed for once-daily use. It is a prodrug that is converted into its active form in the eye. The medication begins to reduce IOP approximately 3 to 4 hours after administration, with its peak effect occurring about 8 to 12 hours later. A nighttime dose ensures that the drug's maximal IOP-reducing effect coincides with the body's nocturnal pressure peak, providing the most consistent 24-hour control.

Pharmacological Mechanism of Latanoprost

Latanoprost works by increasing the outflow of aqueous humor from the eye through the uveoscleral pathway. This mechanism is distinct from other glaucoma medications and is what makes it so effective at lowering IOP. By enhancing this natural drainage pathway, it helps normalize the fluid balance within the eye, thereby reducing pressure. Administering the medication at night leverages this specific pharmacological profile to address the high-pressure period effectively.

Benefits of Nighttime Dosing

There are several reasons why administering Xalatan at bedtime is the optimal strategy:

Maximizes Therapeutic Efficacy: The drug's peak effectiveness is timed to counteract the natural nighttime elevation of IOP, ensuring consistent pressure control over a 24-hour period.
Minimizes Temporary Side Effects: Xalatan can cause temporary side effects such as blurred vision, stinging, or eye irritation. By taking the drops before sleep, patients can minimize the inconvenience of these effects, as they will be sleeping while the effects occur.
Enhances Patient Compliance: The simple, once-daily nighttime schedule is easier for many patients to remember and adhere to compared to more frequent dosing schedules required by some other glaucoma medications. Better compliance leads to more consistent IOP control and better long-term outcomes.
Reduces Paradoxical Effects: Using prostaglandin analogs like latanoprost more than once a day can paradoxically decrease their IOP-lowering effect. Sticking to the once-daily bedtime schedule avoids this issue and maintains the drug's effectiveness.

Comparison of Glaucoma Eye Drops and Their Dosing

Understanding the different dosing schedules of various glaucoma medications highlights the importance of Xalatan's specific regimen. Below is a comparison of some common drug classes.


Drug Class (Example)	Mechanism of Action	Typical Dosing	Rationale for Timing
Prostaglandin Analog (Xalatan)	Increases uveoscleral outflow.	Once daily, in the evening.	To maximize effect during nocturnal IOP peak and minimize daytime side effects.
Beta-Blocker (Timolol)	Decreases aqueous humor production.	Once or twice daily, often in the morning.	Aqueous humor production is lower at night, so morning dosing is often preferred for 24-hour control.
Alpha-Agonist (Brimonidine)	Decreases aqueous production and increases uveoscleral outflow.	Two or three times daily.	Requires multiple doses throughout the day to maintain adequate IOP reduction.
Carbonic Anhydrase Inhibitor (Dorzolamide)	Decreases aqueous humor production.	Two or three times daily.	Requires multiple doses to maintain continuous IOP control.

Proper Application Technique for Xalatan

To ensure maximum effectiveness and safety, it is essential to follow the correct administration procedure for Xalatan:

Wash your hands thoroughly before applying the drops.
Remove contact lenses before use, and wait at least 15 minutes before reinserting them.
Tilt your head back, pull down the lower eyelid to form a pocket, and squeeze one drop into the pocket.
Close the eye gently and apply light pressure to the inner corner of the eye near the nose for 1-2 minutes. This helps prevent the medication from draining into the bloodstream, where it could cause more systemic side effects, and keeps it concentrated in the eye.
If using other eye drops, wait at least 5 minutes between medications.
Do not use more than one drop per night, as this can reduce effectiveness.

Conclusion

The practice of administering Xalatan at bedtime is a well-researched and established standard of care based on the drug's pharmacology and the body's natural circadian rhythm of intraocular pressure. By applying the eye drops in the evening, patients can achieve the most potent and consistent IOP reduction throughout the entire 24-hour cycle, effectively targeting the crucial nocturnal pressure peak. This strategy not only optimizes therapeutic outcomes but also improves patient tolerance by allowing temporary side effects to occur during sleep. Adherence to this specific once-daily bedtime schedule is the key to successfully managing elevated intraocular pressure with Xalatan.

For more information on the safety and usage of Xalatan, consult the official prescribing information from Pfizer at Xalatan.com.

Frequently Asked Questions

Xalatan (latanoprost) is an eye drop used to reduce elevated intraocular pressure (IOP) in people with open-angle glaucoma or ocular hypertension, which helps prevent vision loss.

No, it is not recommended to use Xalatan in the morning. For optimal effectiveness, it should be applied once daily in the evening to align with the body's natural circadian rhythm and achieve maximum pressure reduction during the nocturnal peak.

If you miss a dose, you should continue with your normal schedule the next evening. Do not double the dose to make up for the missed one, as this can reduce its effectiveness.

Common side effects include stinging, burning, itching, eye redness, irritation, and temporary blurred vision. More long-term side effects can include increased pigmentation of the iris (making eyes browner), darkening of the eyelids, and changes to eyelashes.

Unopened bottles should be stored in the refrigerator. Once opened, the bottle can be kept at room temperature for up to six weeks.

Using Xalatan more than once daily can actually decrease its IOP-lowering effect. Therefore, the dosage should not exceed once per day.

Yes, if using other eye drops, you should administer them at least five minutes apart from Xalatan to avoid dilution and ensure each medication works properly.