Add-on therapy in treatment of ocular hypertension and glaucoma proves vital

Newport Beach, CA-Alpha₂ adrenoceptor agonist therapy using brimonidine tartrate 0.1% with a preservative (Alphagan P 0.1% with Purite, Allergan) has a wide spectrum of uses in the management of ocular hypertension and glaucoma, said Ehsan Sadri, MD.

"Brimonidine provides potent IOP-lowering efficacy, shows promising neuroprotective activity, and the formulation containing 0.1% of active ingredient preserved with Purite is very safe, well-tolerated, and priced the same as the 0.15% generic formulation preserved with Polyquad," said Dr. Sadri, a glaucoma specialist in private practice, Newport Beach, CA.

"For these reasons, [brimonidine 0.1% with a preservative] is a valuable option for add-on therapy in patients whose disease is not controlled [with] a prostaglandin analogue, but it can also be a useful alternative as monotherapy in a number of situations where a prostaglandin analogue would not be preferred," he said.

"Alpha₂ adrenoceptor agonists both reduce aqueous production and increase uveoscleral outflow and work nicely with a prostaglandin analogue that acts primarily to increase uveoscleral outflow albeit via a different mechanism [from] brimonidine," he said. "Generally, patients have an excellent, robust response with the addition of Alphagan P to existing prostaglandin analogue treatment in terms of IOP reduction and mitigation of progressive optic neuropathy."

Dr. Sadri added that although t.i.d. dosing is recommended in the product information for Alphagan P, he usually prescribes it twice daily with good results. Its favorable safety and tolerability profile also make the medication an excellent choice for adjunctive therapy with a prostaglandin analogue. Its most common side effects include allergic conjunctivitis, oral dryness, conjunctival hyperemia, and somnolence.

However, with the lower concentration of brimonidine in the newest formulation of the medication, drug exposure is reduced and so are adverse event rates. Brimonidine also has a more favorable systemic safety profile compared with timolol, he said.

"When prescribing Alphagan P, it is important to caution patients about the potential for hyperemia although this problem occurs less often with the branded brimonidine formulation than with generics," Dr. Sadri said. "Overall, the majority of patients experience no significant adverse events with brimonidine."

Brimonidine monotherapy

In a variety of clinical situations where inflammation is an issue and a prostaglandin analogue is best avoided, brimonidine is a useful alternative as monotherapy.

One such commonly encountered scenario is represented by the patient who will be undergoing cataract surgery because ongoing prostaglandin analogue treatment can increase the risk of postoperative cystoid macular edema (CME). In these patients, Dr. Sadri switches the IOP-lowering medication to brimonidine twice daily 1 month prior to cataract surgery and continues the alpha₂ adrenoceptor agonist for at least 90 days.

"IOP control is generally well maintained with the switch to brimonidine, and I recently had a patient who achieved an even further IOP lowering of 1 mm Hg in one eye and 2 mm Hg in the fellow eye after [therapy was] switched from latanoprost to brimonidine," Dr. Sadri said.

He added that some clinicians will restart the prostaglandin analogue sooner after cataract surgery. Emerging studies, however, indicate that the risk of postoperative CME is reduced if the prostaglandin analogue is avoided for at least 90 days. Thereafter, brimonidine may be continued if the patient is doing well and appears compliant with the twice-daily dosing regimen.

For some patients, less is more when it comes to dosing frequency so that therapy will be switched back to their prostaglandin treatment. Other conditions where brimonidine is preferred over a prostaglandin analogue include pseudoexfoliation glaucoma, uveitic glaucoma, and neovascular glaucoma.

In addition, for patients with light irides who wish to avoid a risk of permanent prostaglandin-induced iris color change and those who develop intolerable hyperemia with prostaglandin analogue therapy, brimonidine is an excellent, safe, and effective option, Dr. Sadri concluded.