Mechanism of ocular hypotensive action of bimatoprost (Lumigan) in patients with ocular hypertension or glaucoma.
OBJECTIVE
To determine the mechanism of ocular hypotensive action of bimatoprost in patients with ocular hypertension or glaucoma.


METHODS
Double-masked, placebo-controlled, randomized, paired comparison crossover study of the effect of bimatoprost on aqueous humor dynamics.


METHODS
Twenty-nine patients with ocular hypertension or glaucoma.


METHODS
Bimatoprost and a placebo were administered once a day, in the evening, for 7 days before assessment of aqueous dynamics using tonometry, Schiötz tonography, and fluorophotometry. Intraocular pressure (IOP) response to water drinking was measured.


METHODS
Aqueous humor flow rate, outflow facility, and IOP.


RESULTS
Intraocular pressure was lowered 29% in the morning and 33% at noon by bimatoprost. Aqueous humor flow was unchanged. Tonographic facility of outflow was increased 47% by bimatoprost relative to the placebo. Assuming an extraocular pressure of 8 mmHg and that extraocular pressure is not altered by bimatoprost, the calculated rate of pressure-insensitive outflow was increased 95% by bimatoprost. During the first hour after water drinking, bimatoprost dampened the IOP rise.


CONCLUSIONS
As was seen in healthy normal eyes, bimatoprost increased both the pressure-sensitive and the pressure-insensitive outflows of aqueous humor in patients with ocular hypertension or glaucoma. Bimatoprost had no significant effect on aqueous humor formation.
Christiansen
Gregory A
GA
Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, USA.
Nau
Cherie B
CB
McLaren
Jay W
JW
Johnson
Douglas H
DH
D000328:Adult; D000368:Aged; D000577:Amides; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001082:Aqueous Humor / Q000187:drug effects* / Q000378:metabolism; D000069580:Bimatoprost; D003008:Cloprostenol / Q000031:analogs & derivatives; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D015590:Fluorophotometry; D005901:Glaucoma / Q000188:drug therapy* / Q000378:metabolism; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects*; D008055:Lipids / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000188:drug therapy / Q000378:metabolism; D009883:Ophthalmic Solutions / Q000008:administration & dosage / Q000494:pharmacology; D014065:Tonometry, Ocular
D000577:Amides; D000959:Antihypertensive Agents; D008055:Lipids; D009883:Ophthalmic Solutions; D003008:Cloprostenol; D000069580:Bimatoprost