Daily costs of prostaglandin analogues as monotherapy or in fixed combinations with timolol, in Denmark, Finland, Germany and Sweden

Background: To compare the daily costs of 3 prostaglandin analogues (bimatoprost, latanoprost, travoprost), alone, and associated with timolol in 4 European countries (Denmark, Finland, Germany, and Sweden). Methods: Six glaucoma products were sampled by buying 5 bottles from 1 suburban pharmacy in each of the 4 countries. Drops were weighed by a single operator at 1 site according to standardized procedures. Residual drops were then counted. Unit bottle costs were estimated from tariff lists. Eye-drop weights were entered into a nested analysis of variance comprising drug, instillation day, country, the interaction, and a sample factor nested within the country factor. Effectiveness was represented by treatment failure rates estimated from a meta-analysis and a general practitioner survey. Results: Every drug bottle contained sufficient drops to treat 1 patient for 28/31 days. Drop-size heterogeneity between countries was observed for bimatoprost and bimatoprost/timolol. Mean travoprost and travoprost/timolol drop-sizes were the smallest, and drop-counts per bottle were the lowest for latanoprost, or latanoprost/timolol. In all 4 countries annual costs were least for travoprost and travoprost/timolol. Conclusions: On taking into account drug costs and effectiveness, travoprost and travoprost/timolol were cheaper and more effective than latanoprost and latanoprost/timolol and were cheaper than bimatoprost and bimatoprost/timolol.