A comparison of timolol maleate and levobunolol.  Length of use per 5-ml bottle. 
The authors analyzed the actual length of use of commercially available 5-ml bottles of 0.5% timolol maleate (Timoptic) and 0.5% levobunolol (Betagan) among patients who routinely use topical beta-blockers (1 drop twice daily in both eyes) for glaucoma treatment.  Patients were randomized to receive two 5-ml bottles of either timolol or levobunolol in a double-blind fashion.  The patients used the drops independently and the bottles in sequence.  The dates were recorded when each of the two 5-ml bottles were used.  Sixty patients were enrolled, 15 were excluded from the study, and the data from the remaining 45 were analyzed.  There was a 21% greater length of use per 5-ml bottle among patients who were randomized to 0.5% timolol maleate (36.6 +/- 10.4 days) compared with 0.5% levobunolol (28.9 +/- 8.1 days) (P = 0.009).  The length of use of the first bottle versus the second bottle was compared and was found not to be significantly different in either group.  There was no statistical difference in intraocular pressure control among patients before and after the study.  There is a markedly greater length of use of the 5-ml bottle of timolol compared with the 5-ml bottle of levobunolol.  The difference is believed to be due to the configuration of the levobunolol's bottle tip and the vehicle used to deliver the drug.  The data may be extrapolated to a substantial patient savings and should be considered in prescription recommendations.