Prostaglandin analogs (
PGA) are powerful topical ocular hypotensive agents available for the treatment of elevated intraocular pressure (IOP).
Latanoprost 0.005% and
travoprost 0.004% are
prodrugs and analogs of
prostaglandin F2alpha.
Bimatoprost 0.03% is regarded as a prostamide, and debate continues as to whether it is a
prodrug. The free
acids of all 3 PGAs reduce IOP by enhancing uveoscleral and trabecular outflow via direct effects on ciliary muscle relaxation and remodeling of extracellular matrix. The vast majority of clinical trials demonstrate IOP-lowering superiority of
latanoprost,
bimatoprost and
travoprost compared with
timolol 0.5%,
brimonidine 0.2%, or
dorzolamide 2% monotherapy.
Bimatoprost appears to be more efficacious in IOP-lowering compared with
latanoprost, with weighted mean difference in IOP reduction documented in one meta-analysis of 2.59% to 5.60% from 1- to 6-months study duration. PGAs reduce IOP further when used as adjunctive
therapy. Fixed combinations of
latanoprost,
bimatoprost or
travoprost formulated with
timolol 0.5% and administered once daily are superior to monotherapy of its constituent parts.
PGA have near absence of systemic side effects, although do have other commonly encountered ocular adverse effects. The adverse effects of
PGA, and also those found more frequently with
bimatoprost use include ocular
hyperemia, eyelash growth, and peri-ocular pigmentary changes. Iris pigmentary change is unique to
PGA treatment. Once daily administration and near absence of systemic side effects enhances tolerance and compliance. PGAs are often prescribed as first-line treatment for
ocular hypertension and
open-angle glaucoma.