Page 40 - 21st Century Perspective - Glaucoma Supplement

Adjunctive Therapies: Alpha-2 Adrenergic Receptor Agonists,
Carbonic Anhydrase Inhibitors, Rho-Kinase Inhibitors

Alpha-2 adrenergic receptor agonists

Brimonidine is the only alpha-2 selective adrenergic receptor agonist available. It is FDA-approved
for three-times-daily administration. Brimonidine is rarely used three times daily because of expense
and clinical need. It is well established that brimonidine works for about 8 hours, and that its effect is
minimal during the sleep cycle. This is why we instruct our patients to instill the drop first thing in the
morning (within 10 to 15 minutes of waking), and then to instill the second drop about 8 hours later
(generally 4:00 p.m. to 5:00 p.m.), to harness the medicine’s greatest therapeutic action. We further

instruct our patients to use a timer or recurring reminder on their cell phone to enhance compliance
with the afternoon drop.

For the treatment of patients with glaucoma, brimonidine is available in four ways:

● The original 0.2% concentration (to which a sizable minority of patients ultimately develop an
allergic response ​[Figure 23]​);
● A 0.15% concentration, which has less potential for allergy but is more expensive compared
with the 0.2%, even though both are available generically;
● A 0.1% concentration, which remains brand name-protected as Alphagan-P (Allergan); it

performs equally as well as the 0.2% and 0.15% counterparts but is more expensive.
Because the odds for successful therapy are with us from both an efficacy and tolerability
perspective, we always prescribe the 0.2% concentration because of cost, and we typically
only default to a topical carbonic anhydrase inhibitor if allergy develops. As always,
marketing and pharmacy expense force all of us to try to balance cost, tolerance and efficacy
— it’s an ever-dynamic game.
● A combination of 0.2% brimonidine and 0.5% timolol (Combigan, Allergan).

40