Glaucoma: Prostaglandin Analogues

• Topical medications are commonly the first line of treatment for glaucoma and likely to remain so.

Prostaglandin Analogues

• Considered first-line pharmaceuticals for glaucoma treatment due to their significant effectiveness.
• Typically administered once daily, offering high efficacy and a minimal systemic side effect profile.
• Work by reducing intraocular pressure (IOP) through increased outflow facility.
• Contraindications include pregnancy, inflammatory conditions, and post-cataract surgery.
• Latanoprost (Xalatan) 0.005% was the first prostaglandin analogue available.
• Latonoprostene bunod (Vyzulta) 0.024%, a nitric oxide-donating prostaglandin analogue, was approved in 2017, combining latanoprost with butanediol mononitrate.
• Bimatoprost (Lumigan) 0.01% is effective for patients not responding to Latanoprost treatment, with a slightly different prostamide structure that impacts the trabecular meshwork (TM) more than uveoscleral outflow.
• Travoprost (Travatan) 0.004% and BAK-Free Travoprost (Travatan Z) are also available.
• Tafluprost (Zioptan) is available in a 0.0015% concentration.

Beta-Blockers

• Decrease aqueous humor (AH) formation by blocking beta-2 receptors in the ciliary epithelium.
• Beta-1 receptors are primarily in the heart, not the lungs, thus these medications do not typically cause pulmonary side effects.
• Beta-1 selective blockers (e.g., betaxolol) do not act as effectively on ciliary processes, resulting in less IOP reduction.
• Can be used as first-line therapy, but usually administered twice daily (BID).
• Timolol (Timoptic) 0.5% is a mainstay medication in this category and can be used once daily in the morning.
• Levobunolol (Betagan) is available in 0.25% and 0.5% concentrations.
• Betaxolol (Betopic-S) is a beta-1 selective blocker.
• Carteolol (Ocupress) is available in a 1% concentration.
• Contraindications include sinus bradycardia, asthma, congestive heart failure (CHF), bronchial spasm, and chronic obstructive pulmonary disease (COPD).

Alpha-2 Adrenergic Agonists

• Act on alpha-2 receptors in the non-pigmented ciliary epithelium (CB NPE), reducing active secretion in AH formation.
• May also act on CB vasculature, causing localized constriction and limiting plasma diffusion and ultra-filtration for AH formation.
• Typically administered BID or TID.
• Offer a dual mechanism by reducing AH production and increasing aqueous outflow.
• Contraindications include MAOI therapy due to risk of hypertensive crisis.
• Not recommended for pediatric or pregnant patients due to potential lethargy and risk of mortality.
• Apraclonidine (Iopidine) 0.5% is used for short-term adjunctive therapy.
• Brimonidine (Alphagan) is available in 0.2% and Alphagan-P in 0.15% concentrations; can be used as a first-line treatment, reducing IOP by 22-24%.

Carbonic Anhydrase Inhibitors

• Inhibit the formation of H2CO3, thus reducing AH production.
• Used as adjunctive therapy, administered BID or TID.
• Dorzolamide (Trusopt) is available in a 2% concentration, and Brinzolamide (Azopt) in a 1% concentration.
• Oral options include Acetazolamide.

Rho Kinase (ROCK) Inhibitors

• Allow for once-daily dosing (QD).
• Offers triple action by decreasing actin-myosin contraction in the TM cytoskeleton, reducing episcleral venous pressure (increasing trabecular outflow), and decreasing aqueous humor production.
• Rhopressa (Netarsudil) 0.02% decreases IOP within 2 hours of instillation and sustains this decrease for 24 hours.

Prostaglandin analogues are first-line pharmaceuticals for glaucoma treatment. Administered once daily, they reduce intraocular pressure (IOP) through increased outflow. Latanoprost, bimatoprost and travoprost are effective medications, but are contraindicated in pregnancy and inflammatory conditions.