In people with ocular hypertension including open-angle glaucoma, treatment with latanoprost reduced IOP levels by 22 to 39% over 1 to 12 months’ treatment. Latanoprost was more effective than timolol 0.5% twice daily in 3 of 4 large randomised, double-blind trials. Latanoprost demonstrated a stable long-term IOP-lowering effect in 1- or 2-year continuations of these trials, with no sign of diminishing effect during prolonged treatment. Meta-analysis suggests that latanoprost is more effective than timolol in lowering intraocular pressure. However, it often causes iris pigmentation. While current evidence suggests that this pigmentation is benign, careful lifetime evaluation of patients is still justified.
Closed-angle glaucoma
Patients who had elevated IOP despite iridotomy and/or iridectomy, latanoprost was significantly more effective than timolol in two double-blind, monotherapy trials.
Research suggests that wiping the eye with an absorbent pad after the administration of eye drops can result in shorter eyelashes and a lesser chance of hyperpigmentation in the eyelid, compared to not wiping off excess fluid.
Pregnancy
Use in pregnant women is limited due to high incidence of abortion shown in animal experiments. Because of this, latanoprost is classified as risk factor C according to United States Food and Drug Administration's use-in-pregnancy ratings. Drug excretion in breast milk is unknown.
Like tafluprost and travoprost, latanoprost is an esterprodrug that is activated to the free acid in the cornea. Also like the related drugs, latanoprost acid is an analog of prostaglandin F2α that acts as a selective agonist at the prostaglandin F receptor. Prostaglandins increase the sclera's permeability to aqueous fluid. So, an increase in prostaglandin activity increases outflow of aqueous fluid thus lowering intraocular pressure.
Pharmacokinetics
Latanoprost is absorbed well through the cornea and completely hydrolysed to the active latanoprost acid. Highest concentrations of the acid in the aqueous humour are reached two hours after application, lowering of intraocular pressure starts after 3 to 4 hours, the highest effect is found after 8 to 12 hours, and its action lasts at least 24 hours. When latanoprost acid reaches the circulation, it is quickly metabolised in the liver by beta oxidation to 1,2-dinor- and 1,2,3,4-tetranor-latanoprost acid; blood plasma half life is only 17 minutes. The metabolites are mainly excreted via the kidney. The activation and deactivation pathway is analogous to the one of tafluprost; see Tafluprost#Pharmacokinetics for chemical formulae.
Chemistry
Stability
Latanoprost exhibits thermal and solar instability. The concentration of latanoprost stored at 50 °C will decrease by 10% every 8.25 days. When stored at 70 °C the concentration will decrease by 10% every 1.32 days. Ultraviolet light, for example in sunlight, causes rapid degradation of latanoprost.
