Choose preservative-free options for benzalkonium chloride-sensitive options

July 1, 2010

The use of a preservative-free glaucoma medication is advisable when there is concern about preservatives such as BAK.

Patients may be sensitive to BAK, an ingredient used as a preservative in multi-dose timolol. In numerous clinical studies, BAK has been associated with ocular surface changes, dry eye, and discomfort when taken long term or in patients with a sensitivity. In these patients, a preservative-free form of timolol maleate ophthalmic solution 0.01% (Timoptic, Aton Pharma) dispensed via the sterile ophthalmic unit dose dispenser (Ocudose, Aton Pharma) may help avoid the sensitivity reactions sometimes seen with long-term treatment.

Case presentation

Upon examination, the patient's best-corrected visual acuity was OD 20/20, OS 20/20 at both distance and near.

IOPs were OD 21 mm Hg and OS 30 mm Hg at 2:10 p.m. Pachymetry readings were OD 589 μm and OS 598 μm. Anterior segment examination was remarkable for mild nuclear sclerotic cataracts OU.

Posterior segment examination revealed a cup-to-disc ratio of OD 0.05 and OS 0.15, with healthy rim tissue and no evident notching, significant peripapillary atrophy, or optic nerve head hemorrhages. The macula was flat and healthy OU, and the periphery showed no holes, tears, or retinal detachments 360 degrees.

The patient was being treated with hydrochlorothiazide for hypertension and had no known family history of glaucoma.

This patient was a glaucoma suspect secondary to elevated intraocular pressure readings. He was asked to return in 1 to 2 months for threshold visual field, scanning laser polarimetry, IOP measurement, and gonioscopy.

At the return examination 2 months later, IOPs were OD 18 mm Hg and OS 25 mm Hg at 2:20 p.m. Gonioscopy revealed open angles 360 degrees OU. Threshold visual fields were full OU. Scanning laser polarimetry revealed retinal nerve fiber layer (RNFL) thickness OD within the normal range and that of the OS to be below the normal range inferiorly.

These findings were discussed with the patient, and he was advised of the risk factors consistent with early (preperimetric) glaucoma, and his increased risk for developing further damage due to the elevated IOP readings and the decreased RNFL thickness OS. Upon further discussion with the patient, it was agreed that he would begin glaucoma therapy.

Because of the possible local side effects of a prostaglandin analogue, including increased eyelash length, iris color changes, the patient was prescribed monocular treatment with timolol maleate ophthalmic solution OS 0.5% each morning, and asked to return in 1 month.

At 1-month follow-up, IOPs were OD 17 mm Hg and OS 12 mm Hg at 2:40 p.m. For the next several years, this patient exhibited stable visual fields, RNFL thickness, and IOPs remained in the mid-to-high teens OU.

Sensitivity manifests

After several years of treatment and stable IOPs, the patient began to complain of mild ocular discomfort OS. Examination revealed mild conjunctival hyperemia with inferior corneal staining OS.

The patient was asked to discontinue timolol for 1 month in an attempt to minimize the local side effects OS and to determine if the IOP would remain in the normal range.

When the patient returned 1 month later, he reported resolution of ocular symptoms. IOPs measured at 8:45 a.m., however, were OD 18 mm Hg and OS 26 mm Hg. After a discussion about his ocular surface concerns, the preservative-free form of timolol (Timoptic) in the unit dose dispenser (Ocudose) was prescribed.

In this formulation, preservative-free timolol is provided in a clear low-density polyethylene unit dose container as a sterile, isotonic, buffered, aqueous solution in two dosage strengths, 0.25% and 0.5%. Each individual unit contains 0.2 ml of solution, and is packaged in a foil laminate over-wrapped pouch with 60 individual unit doses.

Over the past year, the patient's IOPs have remained in the normal range, and he has had minimal ocular symptoms.

FYI

Mile Brujic, OD
Phone: 419/261-9161
E-mail: brujic@prodigy.net

Dr. Brujic has received honoraria for speaking, writing, or acting in an advisory capacity from Alcon and Aton Pharma.