Latanoprost free acid

What it isThe free acid of latanoprost — the active prostaglandin-F2alpha analog after corneal esterases cleave the ester.

Why it mattersThe ester exists to cross the cornea; the acid is what raises uveoscleral outflow and lowers intraocular pressure.

What it changesIts local action and negligible systemic exposure are why prostaglandin drops dose once daily with so few systemic effects.