THERAPEUTIC FOCUS

Prostaglandin Analog 2.0

Prostaglandin provides IOP reduction with less drug exposure than original.

L. Jay Katz, M.D.

Since intraocular pressure (IOP) is the only known modifiable risk factor for glaucoma, managing and reducing IOP is an obvious, yet pertinent step in slowing and preventing this blinding disease. In order to reduce and stabilize IOP in my patients, one of the drugs I use is bimatoprost ophthalmic solution 0.03%, (Lumigan), from Allergan, Inc. And, based on the results of the 0.01% formulation, I know I'll be offering this drug to patients as well.

Here, I provide an overview of the new formulation, how it works and its proven efficacy.

Overview

Lumigan 0.01% received Food and Drug Adminstration approval as a first line therapy for ocular hypertension and open angle glaucoma patients in late August. The drug is a clear, isotonic, sterile ophthalmic solution that has an osmolarity of 290mOsmol/kg.¹ It comes in an opaque white low-density polyethylene ophthalmic dispenser bottle and has a tip with a turquoise polystyrene cap. In addition, the drug is available in 2.5mL, 5mL and 7.5 mL.

Aside from its active ingredient (i.e. bimatoprost 0.01 mg/mL), Lumigan 0.01% is comprised of the inactive ingredients citric acid, dibasic, purified water, sodium chloride and sodium phosphate.¹

How it works

The revised formulation demonstrates the same ability to reduce IOP as the original formulation. Specifically, it lowers IOP by enhancing the outflow of aqueous humor via both the trabecular meshwork and uveoscleral pathways.¹ It differs from the original formulation, however, in that it accomplishes this with one-third the drug concentration of the original. The lower the amount of drug delivered, the less likelihood for side effects or toxicity — a big plus for patients.

Lumigan 0.01% reduces IOP with one-third the drug concentration of the original formulation. The lower the amount of drug delivered, the less likelihood for side effects or toxicity — a big plus for patients.

Lumigan 0.01% also shares the same dosing schedule as the original. Specifically, the recommended dosage is one drop in the affected eye(s) q.d. at night (meaning any time after dinner until bedtime).¹ The drug reaches its maximum IOP-lowering effect, eight-to-12 hours postinstillation.

The most common ocular adverse event (side effect) seen in Lumigan 0.01% clinical trials was conjunctival hyperemia (25% to 45%), followed by eyelash growth and ocular pruritus (more than 10%). Meanwhile 1% to 10% of patients reported ocular dryness, visual disturbance, ocular burning, foreign body sensation, eye pain, pigmentation of the periocular skin and blepharitis. One percent to 10% also experienced cataract, superficial punctate keratitis, eyelid erythema, ocular irritation, eyelash darkening, eye discharge, tearing, photophobia, allergic conjunctivitis, asthenopia, increases in iris pigmentation, conjunctival edema, conjunctival hemorrhage and abnormal hair growth.¹ Less than 1% of patients reported iritis.

(As a brief aside, be sure to educate patients about the potential for increased brown pigmentation of the iris with this drug, as it could be a permanent side effect. Also, alert the patient to the probability for eyelash changes, such as a disparity in length between the eyes. The eyelash changes, however, are usually reversible upon drug discontinuation.¹)

Efficacy

In one Food and Drug Administration-sanctioned three-month clinical trial of ocular hypertension patients and open angle glaucoma patients who had an average baseline IOP of 23.5 mm Hg, Lumigan 0.01% reduced IOP a mean, or average, of up to 7 mm Hg from baseline.

My professional experience with the drug's older sibling supports these findings. For instance, a 75 year-old gentleman who had primary open angle glaucoma presented with an IOP of 25 mm Hg OD and 21 mm Hg OS. He had difficulty using drops, and I was hoping to have his wife place a single medication once a day for him that could control his IOP. I prescribed Lumigan 0.03%, and this gentleman surpassed his target IOP of 18 mm Hg for both eyes. Specifically, his IOP was 16 mm Hg OD and 14 mm Hg OS after taking the drug for six weeks, and he has remained stable at this level for the past two years. Initially, the patient experienced red eyes, which he said didn't bother him, and this became less noticeable with time.

Because Lumigan 0.01% provides a decrease in IOP with a reduced concentration than the original, though maintains the original's patient compliancefriendly dosing and its track record for proven efficacy and safety, it's become an attractive new option for the treatment of glaucoma. OM

1. Highlights of Prescribing Information: Lumigan 0.01% and Lumigan 0.03% (bimatoprost ophthalmic solution) www.allergan.com/assets/pdf/lumigan_pi.pdf (Accessed September 21, 2010.)

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Dr. L. Jay Katz is the director of the Glaucoma Service at Wills Eye Hospital in Philadelphia and professor of ophthalmology at Jefferson Medical College. He is a paid consultant to Allergan. You can e-mail him at LJKatz@willseye.org.