COST-EFFECTIVENESS OF BRINZOLAMIDE VERSUS DORZOLAMIDE IN THE TREATMENT OF OCULAR HYPERTENSION AND PRIMARY OPEN ANGLE GLAUCOMA

OBJECTIVE: The aim of this study was to compare the cost-effectiveness of brinzolamide, a new topical carbonic anhydrase inhibitor (CAI), with topical dorzolamide in France, Italy and Portugal for the treatment of ocular hypertension (OH) and primary open-angle glaucoma (POAG). METHODS: High intra-ocular pressure (IOP) is the major prognostic factor of POAG, and these two drugs were developed to control it. Successful treatment was defined as an IOP decrease of at least 5 mm Hg or any reduction to a value below 21 mm Hg. Four double-masked well-controlled randomised trials, three lasting 3-month and one 12-months, compared the response rate of brinzolamide bid and tid versus dorzolamide tid, and the response rate of brinzolamide bid versus bid dorzolamide timolol combination bid. The local tolerance upon instillation of the 2 drugs was compared through 2 dedicated studies. The consequence of the instillation tolerance was valued through an American HMO data base. The daily cost of each drug took into account the number of drops in a bottle, valued through a well-balanced analysis of variance. In case of failure, either due to intolerance or inadequate efficacy, the patients were treated with latanoprost. A model was developed to evaluate the cost of initiating a treatment with a CAI (dorzolamide versus brinzolamide) over 3 months. The economic perspective taken was that of society. RESULTS: As a mono-therapy, brinzolamide bid was found to be as efficacious as dorzolamide tid. Brinzolamide bid plus timolol was also as efficacious as a combination of dorzolamide and timolol bid. Stinging upon instillation with brinzolamide was far less (P<0.0001) than with dorzolamide. The probability that brinzolamide-treated patients would change therapy was 1.28 (HMO study, P<0.05) less than the one of dorzolamide-treated patients. The size of the brinzolamide drop is 18.7% smaller allowing 7 more therapy days per bottle than dorzolamide mono-therapy when brinzolamide is used bid and 5 days when used tid. Consequently, the breakeven price of brinzolamide was 10% higher than dorzolamide in France and Portugal and 15% in Italy, where CAIs were more often prescribed as mono-therapy. CONCLUSION: Because (1) the daily cost of brinzolamide is lower (2) brinzolamide can be prescribed bid in mono-therapy (3) and brinzolamide stings less, our model suggested that brinzolamide is a cost-effective alternative in the treatment of OH and POAG.