Rhopressa (netarsudil) produces no measurable levels in the bloodstream, even after repeated daily use. In FDA testing, plasma concentrations were undetectable on both Day 1 and Day 8 of dosing, falling below the lowest measurable threshold of 0.100 ng/mL. This means the drug stays almost entirely in your eye and clears from the body rapidly, with virtually zero systemic presence to worry about.
Why Rhopressa Barely Enters Your Bloodstream
Rhopressa is a topical eye drop, and the active ingredient netarsudil is designed to work locally. Once the drop hits your eye, enzymes in the cornea called esterases quickly convert netarsudil into its active form. That active compound then goes to work in the fluid-filled front chamber of the eye, improving drainage and lowering eye pressure.
Because this conversion and activity happen right at the surface and interior of the eye, very little of the drug ever reaches general circulation. The tiny amount that might be absorbed into blood vessels around the eye is rapidly broken down by the liver, and the resulting compound does not undergo any further metabolism. In lab testing, liver enzymes showed no ability to break it down further, suggesting the body handles whatever trace amount reaches the bloodstream very efficiently.
How Long It Works Inside the Eye
While Rhopressa clears your bloodstream almost instantly, it persists long enough inside the eye to lower pressure for a full 24 hours. That is why it is prescribed as a once-daily drop, typically applied in the evening. The corneal metabolism that converts it into its active form creates a local reservoir of the working compound in the eye’s fluid, sustaining the pressure-lowering effect between doses.
If you stop using Rhopressa, the pressure-lowering effect will wear off within roughly a day as the remaining active compound in the eye is cleared. There is no meaningful drug accumulation in the body over time.
What This Means for Drug Interactions and Testing
Because Rhopressa does not produce detectable blood levels, the risk of it interacting with other medications you take by mouth is essentially zero. For the same reason, it would not show up on any standard blood work or drug screening. If you are switching to a different glaucoma medication, the transition is straightforward since there is no systemic “washout” period needed for the drug to leave your body. Your eye pressure will simply begin rising back toward its untreated level within about 24 hours of your last dose.
How Long Side Effects Last After Stopping
The most common side effect of Rhopressa is redness of the eye, which occurs because the drug dilates small blood vessels on the eye’s surface. This redness is a local effect, not a sign of the drug circulating through your body. It typically fades within a day or two after you stop using the drops, since the blood vessels return to their normal size once the drug is no longer being applied.
Other local side effects, like small deposits on the cornea or a feeling of something in the eye, also resolve after discontinuation. Because these are caused by direct contact between the drop and eye tissue rather than systemic drug levels, they clear as the eye’s surface naturally renews itself. Most people find that any irritation or redness is gone within a few days of their last dose.