OBJECTIVE: To compare the cost and effectiveness of brinzolamide and dorzolamide using data collected in the United-Kingdom General Practitioner Research Database METHODS: Files of patients with a diagnosis of ocular hypertension or glaucoma, or treated with a topical IOP lowering treatment were extracted. Patients starting treatment with dorzolamide or brinzolamide from August 2000 were selected. A treatment failure was defined as a regimen change (adding or removing a topical treatment). Time to treatment failure was compared using a Cox model. The economic perspective was that of the NHS. The annual cost of therapy changes by treatment line (first, second, etc.) was calculated for year 2000; visit, medication and hospitalization costs were included. RESULTS: Of 49,799 patients selected, 146 were treated with brinzolamide and 1,230 with dorzolamide. No statistically significant differences were found between the 2 groups in terms of patient and disease characteristics. Patients averaged 72.9 years old and were 56% female. Prescriptions totaling 21.1% of the prescriptions involved monotherapy and 14.8% were for first line treatment. After one year, 29.8% of the brinzolamide patients experienced a treatment failure compared to 46.0% with dorzolamide (P <0.01). Seventy-five percent of the patients had a treatment duration longer than 203 days when treated with brinzolamide versus 140 days with dorzolamide. The probability of a failure was 1.61 (P <0.02) times higher with dorzolamide, after adjusting for treatment line and the number of drugs prescribed. The yearly glaucoma treatment cost for a patient with a treatment failure was found to be higher (GBP 15.21) than for patients who continued their treatment. CONCLUSION: In comparison to dorzolamide, patients treated with brinzolamide experienced fewer treatment failures, leading to cost savings.