AUG 24, 2010
The authors of this meta-analysis compared the IOP lowering efficacy and safety of a2-adrenergic agonists, b-adrenergic antagonists and topical carbonic anhydrase inhibitors when used in combination with a prostaglandin analog. Studies have shown variable results sometimes with small but statistically significant differences.
The authors identified 10 observer-masked randomized clinical trials that reported baseline IOP while patients received prostaglandin analog monotherapy and follow-up IOP while they received combination therapy. They calculated the pooled IOP-lowering efficacy achieved with each of the three classes of adjunctive agents and the frequency of adverse events.
They found that all three drug classes significantly reduced IOP when used in combination with a prostaglandin analog, and they were all similar in their adjunctive IOP-lowering effects. More specifically, mean diurnal IOP reduction and peak IOP reduction was statistically similar in all three groups. The only difference the authors reported was that alpha agonists demonstrated a statistically smaller IOP-lowering effect at trough.
However, side effects were different between the groups. Xerostomia and eye or eyelid pain, burning or discomfort were significantly more common with alpha agonist use. Fatigue, weakness or dizziness was more common in patients using alpha agonists or beta antagonists compared with those using topical carbonic anhydrase inhibitors. Taste disturbance was significantly more common among those taking topical carbonic anhydrase inhibitors.
Since the adjunctive treatment options have similar levels of effectiveness at reducing IOP, adjunctive agent choice can be customized according to side effect profiles or other considerations of the prescribing clinician and patient.