To the Editor.
—Timolo maleate (Timoptic) and levobunolol hydrochloride (Betagan) are nonselective β-adrenergic blockers that have been found equally effective in reducing intraocular pressure in patients with all types of glaucoma.1 No statistical differences exist between the two in the amount of pressure-lowering effect using a twice-a-day treatment regimen. Therefore, levobunolol offers no apparent clinical advantage compared with timolol for the treatment of glaucoma. However, levobunolol has been offered to pharmacists at a lower per-bottle cost, thereby creating an incentive for using it rather than timolol. In a cost-conscious society where the usual dose of a β-adrenergic blocker is one drop twice a day in each eye, the total number of drops delivered per equivalent size bottle (10 mL) is an important issue. We compared the number of drops (doses) per 10-mL bottle of timolol and levobunolol.To simulate the method of drop delivery customarily used by patients, ten
Schwartz JS, Christensen RE, Lee DA. Comparison of Timolol Maleate and Levobunolol: Doses and Volume per Bottle. Arch Ophthalmol. 1989;107(1):17-18. doi:10.1001/archopht.1989.01070010019010