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The introduction of preservative-free topical β-blockers and carbonic anhydrase inhibitors has proved extremely useful in the management of patients requiring anti-glaucomatous therapy who have intolerance, or allergy, to the most commonly used preservative, namely benzalkonium chloride (BAC).
Prostaglandin analogues (PG) are now commonly prescribed as first-line topical anti-glaucomatous agents, since they are highly efficacious with few side effects. However, no preservative-free prostaglandin is currently available for clinical use. Indeed, it has been voiced that BAC was required to aid prostaglandin penetration into the eye. Richard Lewis et al. (311) and the Travoprost BAC-free Study Group should, therefore, be congratulated on their study, which elegantly demonstrated that travoprost 0.004% without BAC is equivalent to travoprost 0.004% with BAC in both safety and efficacy. The study was an adequately powered, double-masked, parallel group, multicentre, non-inferiority designed clinical trial, with 690 patients randomised to the two arms. Only 29 patients were excluded from the final data-set. Mean IOP reductions at the times of the study visits (8 AM, 10 AM and 4 PM at 2 weeks, 6 weeks and 3 months) ranged from 7.3-8.5 mmHg for the unpreserved preparation and 7.4-8.4 mmHg for the preserved drug. Adverse events were similar for both treatment groups, hyperaemia being less common in the BAC-free group (6.4% cf 9.0%).
The preservative BAC has been implicated in inducing sub-clinical inflammation, reduced epithelial barrier function, tear film instability, dry eye and ocular irritation, cataract formation and a reduced success rate of any subsequent glaucoma filtration surgery. There is now evidence that BAC-free travoprost is an effective and safe formulation that if made available would be beneficial to patients with BAC intolerance. Suitable pricing of a BAC-free prostaglandin would make it a very popular product for the growing number of clinicians that prefer to prescribe preservative-free preparations for patients requiring chronic therapy.