How Does Rocklatan Work? Mechanism of Action Explained in Plain English

Rocklatan is a glaucoma eye drop that works unlike any other single medication. Instead of using one approach to lower eye pressure, it combines two medications that work through four distinct mechanisms. To understand why that matters, it helps to first understand what's going wrong in glaucoma.

The Problem: Too Much Pressure Inside the Eye

Your eye constantly produces a clear fluid called aqueous humor. This fluid flows through the eye and drains out through two pathways: the trabecular meshwork (the main drainage canal near the front of the eye) and the uveoscleral pathway (a secondary drainage route through the ciliary body and sclera).

In open-angle glaucoma, the trabecular meshwork — think of it as a drain that gets clogged over time — becomes less efficient. Fluid builds up, pressure rises, and elevated intraocular pressure (IOP) compresses and damages the optic nerve, which connects your eyes to your brain. The damage is permanent.

Think of your eye like a bathtub with the faucet on. Glaucoma happens when the drain gets clogged. The water (IOP) rises. The goal of glaucoma treatment is to unclog the drain, reduce the faucet flow, or both.

How Netarsudil Works: The ROCK Inhibitor Component

Netarsudil (0.02%) is the first component of Rocklatan and belongs to a new class of medications called Rho kinase (ROCK) inhibitors. It was the first new class of glaucoma eye drop approved in over 20 years when it debuted in 2017 as Rhopressa.

Netarsudil lowers IOP through three separate mechanisms:

1. Trabecular meshwork outflow: Rho kinase is an enzyme that controls cellular contraction. In the trabecular meshwork, Rho kinase causes cells to contract and stiffen, reducing drainage. By inhibiting Rho kinase, netarsudil relaxes these cells — unclogging the drain — and restores aqueous outflow through the primary pathway.
2. Reduced aqueous production: Netarsudil also modestly reduces the amount of aqueous humor produced by the ciliary body, turning down the faucet slightly.
3. Reduced episcleral venous pressure: Aqueous humor ultimately drains into veins on the surface of the eye (episcleral veins). Netarsudil dilates these veins, lowering the downstream venous pressure and allowing aqueous to drain more easily. This is a mechanism no other class of glaucoma medication targets.

How Latanoprost Works: The Prostaglandin Component

Latanoprost (0.005%) is the second component of Rocklatan and is the world's most prescribed glaucoma eye drop (sold as Xalatan and available generically). It belongs to the prostaglandin analog class.

Latanoprost works through the uveoscleral pathway — the secondary drainage route through the ciliary body and scleral tissue. By mimicking a naturally occurring prostaglandin (a lipid compound that regulates cell activity), latanoprost relaxes the smooth muscle and connective tissue in this pathway, widening it and allowing more fluid to escape.

Prostaglandins typically reduce IOP by 25–30%. They're highly effective and once-daily dosing improves adherence. Latanoprost is a prodrug — it's absorbed through the cornea and converted to its active form (latanoprost acid) before acting on the eye tissue.

Why the Combination Is More Powerful Than Either Alone

Because netarsudil and latanoprost work through completely different and complementary mechanisms, combining them produces additive IOP lowering. Rocklatan gives patients:

• Increased trabecular meshwork outflow (netarsudil)
• Increased uveoscleral outflow (latanoprost)
• Reduced aqueous production (netarsudil)
• Reduced episcleral venous pressure (netarsudil)

In the MERCURY 1 and MERCURY 2 clinical trials, this combination reduced IOP by 1–3 mmHg more than either netarsudil or latanoprost used alone. More than 60% of Rocklatan patients achieved a ≥30% reduction in IOP. Nearly twice as many patients reached an IOP of ≤16 mmHg compared to latanoprost alone.

When Does Rocklatan Start Working?

Rocklatan begins to lower IOP within hours of the first dose. Peak IOP reduction typically occurs around 8–12 hours after instillation. The full treatment effect builds over the first few weeks of consistent daily use. Your ophthalmologist will check your IOP at a follow-up visit — typically 4–6 weeks after starting — to confirm the medication is working as expected.

Related Reading

For a complete patient overview of Rocklatan, see What Is Rocklatan? Uses, Dosage, and What You Need to Know. For what to expect in terms of side effects, read Rocklatan Side Effects: What to Expect and When to Call Your Doctor.