Short answer: Latanoprost has a half-life of about 17 minutes (in blood). Levels peak about 2 hours (in the eye) after a dose. People vary, so treat these as estimates.
Latanoprost is a prostaglandin analog eye drop that lowers pressure inside the eye by helping fluid drain out. It is sold as Xalatan and as generic 0.005% drops for open-angle glaucoma and high eye pressure. A known side effect is longer, thicker, darker eyelashes; use for lash or scalp hair growth is off-label.
Also known as: Xalatan.
Xalatan is a 0.005% solution (50 mcg/mL) in a 2.5 mL bottle. The label says to keep unopened bottles in the refrigerator and protect them from light.
The FDA Xalatan label approves latanoprost to lower eye pressure in open-angle glaucoma or ocular hypertension. The label dose is one drop in the affected eye or eyes once a day in the evening; using it more than once a day may lower its effect. Contact lenses come out before the drop and can go back in 15 minutes later. If a dose is missed, the next one is taken as normal.
The label warns that it can darken the iris (likely permanent), the eyelid skin and the lashes, and that it can gradually make lashes and fine hair near the treated eye longer, thicker, darker and more numerous; lash changes usually reverse after stopping. It also warns about eye inflammation, swelling of the macula, and use in people with a history of herpes eye infection.
Use on the scalp is off-label. In a 24-week pilot trial in 16 men with mild male-pattern hair loss (Blume-Peytavi, 2012), latanoprost 0.1% applied to a small scalp area raised hair density compared with a placebo area. A 2023 meta-analysis of 6 placebo-controlled trials of prostaglandin analogs for hair loss (Jiang) found better hair length and density, and said the best dose and frequency still need study. These are study protocols, not personalized advice; confirm any dosing with your prescriber.
Latanoprost is turned into its active acid form in the cornea. The Xalatan label says that acid peaks in the fluid inside the eye about 2 hours after a drop and leaves the blood quickly, with a half-life of 17 minutes. Eye pressure starts to fall 3 to 4 hours after a dose, is lowest at 8 to 12 hours, and stays lower for at least 24 hours, which is why it is dosed once a day.
Numbers shown are taken from the source above. Half-life varies from person to person.
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