Objective assessment of the variation in number of doses of generic timolol eye drops along with their cost effectiveness.

Abstract

First, this study aims to ascertain if truly the generic timolol eye drops circulating in Abuja and it environ are interchangeable. Secondly, we explore their cost effectiveness in naira based on the dispensing position. Using official guidelines, we assessed seven generic timolol ophthalmic preparations for organoleptic, pH, viscosity, sterility, and assay test. After this, they were tested in the vertical (90 ⁰) and horizontal (30 ⁰) positions for filled volume in a bottle, the total number of drops per bottle, drops per mL; and eventually the total number of bottles needed per year, cost per year and their cost effectiveness per mmHg were extrapolated. All brands were colorless and devoid of particulate contamination. Assay, pH, and viscosity values were within the compendia specification (BP and USP) for eye drops. The sterility assay showed no evidence of bacterial or fungi growth. All brands had actual filled volume less than or equal to the stated label claim. Their drops per 5 mL bottle range from 141-169 and 122-139 when dispensed in vertical and horizontal positions respectively; while for brands with 10 mL label volume, they range from 305-321 and 299-309 drops per bottle for vertical and horizontal dispensing respectively. Brand T1 (which is the most expensive) would need two bottles less in a year if the medication were to be dispensed vertically, amounting to N 3,200.00 ($ 7.04) reduction in treatment cost and a 45 % improvement in cost-effectiveness per intraocular pressure (IOP) reduction per year. In conclusion, the dispensing technique played a significant role in the number of drops per bottle, this would however impact on the treatment cost of glaucoma patient placed on timolol eye drop.