Ripasudil eye drops are a prescription medication designed to lower intraocular pressure (IOP) in patients requiring treatment. Commercially available as Glanatec in many regions outside the United States, it is classified as the first-in-class Rho Kinase (ROCK) inhibitor eye drop. This designation speaks to its unique method of action compared to older treatments. Ripasudil works by interfering with a specific enzyme pathway within the eye’s natural drainage system.
Understanding Glaucoma and Ocular Hypertension
The need for Ripasudil arises from conditions like glaucoma and ocular hypertension, both linked to high fluid pressure inside the eye. Glaucoma is a progressive disease that damages the optic nerve, often caused by persistently high IOP, and if left unmanaged, can lead to irreversible vision loss. Ocular hypertension is defined as elevated IOP without immediate signs of optic nerve damage. While not glaucoma itself, it significantly increases the risk of developing the nerve damage characteristic of the disease. Therefore, controlling the pressure is a primary goal in managing both conditions.
The pressure within the eye is maintained by a continuous balance between the production and drainage of a clear fluid called aqueous humor. This fluid must exit the eye through the trabecular meshwork, which acts like a microscopic filter. In patients with high IOP, this meshwork can become stiff and compacted, restricting the outflow of aqueous humor and causing pressure to build up. Ripasudil is primarily used to treat open-angle glaucoma and ocular hypertension, often as an add-on therapy.
The Mechanism of Action
Ripasudil’s ability to lower IOP stems from its highly specific role as a Rho-associated coiled-coil containing protein kinase (ROCK) inhibitor. Rho kinase is an enzyme that regulates the contraction and stiffness of cells within the eye’s drainage angle. By inhibiting this enzyme, Ripasudil effectively targets the underlying resistance to fluid outflow within the trabecular meshwork.
The drug promotes the relaxation of the meshwork’s tissue and the cells that line the canal. This relaxation is achieved by disrupting the actin cytoskeleton, the internal scaffolding that gives the cells their structure and contractility. This change reduces the compaction of the trabecular meshwork, which increases its permeability.
By enhancing this outflow facility, Ripasudil effectively reduces the resistance to fluid movement, leading to a sustained reduction in IOP. Clinical data demonstrates that twice-daily use of the 0.4% solution can achieve a mean IOP lowering of approximately 4–6 mmHg. Ripasudil provides an additive effect when combined with other glaucoma medications, as its mechanism is distinct. The peak reduction in IOP typically occurs within one to two hours after the eye drop is administered.
Proper Administration and Usage
Consistent and correct application is important for Ripasudil to achieve its maximum therapeutic effect. The typical prescribed dosage is one drop instilled into the affected eye or eyes twice daily, usually once in the morning and once in the evening. To maintain stable drug levels, it is recommended to space these instillations out, ideally with an interval of ten to twelve hours between doses. If a dose is missed, it should be applied as soon as the patient remembers, but a double dose should never be used to compensate for the skipped one.
To apply the drop correctly, the patient should first wash their hands thoroughly to maintain sterility. While tilting the head back and looking up, the lower eyelid should be gently pulled down to create a small pocket for the medication. The dropper tip must be kept clean and should not touch the eye, eyelid, or any other surface to prevent contamination.
After the drop has been instilled, it is recommended to close the eye and gently press a finger on the inner corner of the eyelid, near the nose, for one to two minutes. This technique, known as nasolacrimal occlusion, reduces the amount of medication absorbed into the bloodstream, thereby minimizing potential systemic side effects.
Patients who use other ophthalmic preparations, such as different eye drops or ointments, must wait at least five to ten minutes between applications. If the patient wears contact lenses, they must be removed before applying Ripasudil and should not be reinserted until at least fifteen minutes after the drug has been instilled, as the preservative in the drops can be absorbed by the lenses. The medication should be stored at a temperature between 15–25°C, protected from light, and discarded one month after the bottle is first opened.
Safety Profile and Adverse Effects
As with any medication, Ripasudil has an associated safety profile, with the majority of adverse effects being local and ocular in nature. The most frequently reported side effect is conjunctival hyperemia, which is a common term for eye redness. This redness can occur in a significant percentage of users, ranging up to 65% in some clinical trials.
The hyperemia is directly linked to the drug’s mechanism of action, as the ROCK inhibition relaxes the smooth muscle of the eye’s blood vessels, causing them to widen and appear more prominent. Patients should be aware that this redness is usually mild to moderate, transient, and often subsides within a few hours of application. Other common local reactions include discomfort, ocular irritation, and conjunctival hemorrhage.
A less common but important adverse effect is blepharitis, an inflammation of the eyelid, which has been reported in post-marketing surveillance and can occasionally lead to discontinuation of the medication. Patients should consult their prescribing physician immediately if they experience severe or persistent symptoms such as allergic reactions, significant pain, or a sudden change in vision. Due to limited data, the drug should be used with caution during pregnancy or breastfeeding, and a physician’s guidance is needed.