Bimatoprost is a prostamide, a synthetic analog of prostaglandin F2α (PGF2α) with potent ocular hypotensive activity. Bimatoprost lowers intraocular pressure (IOP) in patients with glaucoma or ocular hypertension by increasing outflow of aqueous humor through both the trabecular meshwork and uveoscleral routes. Timolol is a non-selective beta-adrenergic receptor blocker and functions by reducing aqueous humor production through blockage of the beta receptors on ciliary epithelium.
Use of preservative containing eye drops has been implicated in the development or worsening of ocular surface disease. Management of open angle glaucoma and ocular hypertension require long term treatment with eye drops containing preservatives. Symptoms and signs of ocular surface disease such as ocular surface breakdown, irritation, burning, foreign body sensation, dryness, inadequate quantity of tears, etc. are prevalent in a large proportion of patients with open angle glaucoma and ocular hypertension.
Compared to eye drops preserved with benzalkonium chloride, preservative-free eye drops induce significantly fewer ocular symptoms and signs of irritation in patients, such as pain or discomfort, foreign body sensation, stinging or burning, and dry eye sensation.
Patients experiencing hypersensitivity reactions with benzalkonium chloride cannot use a commercial bimatoprost product containing benzalkonium chloride which is preserved even with 0.005% w/v benzalkonium chloride. Benzalkonium chloride also may be absorbed by the soft contact lenses therefore patients wearing soft contact lenses are advised to remove lenses prior to administration and wait at least 15 minutes before reinserting them.