Abstract
Purpose: :
When prostaglandin analogues and beta-blockers are dosed once daily in fixed combinations (FC’s), both agents will approach their trough efficacies together around 24 hours post-dose. In addition, the FC will cut the dose frequency of timolol in half compared to monotherapy with timolol bid. Thus it is important to determine if these FC’s maintain adequate intraocular pressure (IOP) control immediately before the next dose is due. This study evaluates the 24-hr post-dose efficacy of travoprost-timolol (TTFC) and latanoprost-timolol (LTFC) in patients not adequately controlled on timolol monotherapy.
Methods: :
Patients were enrolled if initial treatment on timolol 0.5% bid yielded a ≥10% IOP reduction, but IOP remained ≥20mmHg at 0800 and was deemed to be inadequately controlled. After baseline IOP was measured at 0800 on timolol 0.5% bid, patients were randomized in a single-masked, crossover design to receive TTFC or LTFC at 0800 for 6 weeks, and then crossed over to receive the second FC for another 6 weeks. Treatment IOP was measured at 0800 prior to the morning dose at both 6 and 12 weeks. Ethical approval for the study protocol was obtained from Institutional Review Board Services (Aurora, Canada).
Results: :
Thirty eight out of sixty three enrolled patients have completed the study to date. Initial treatment with timolol 0.5% bid significantly (p<0.00001, t-test) reduced IOP by 14.4±9.9% from an untreated IOP of 28.0±3.3mmHg to 23.8±2.6mmHg. Both TTFC and LTFC significantly decreased IOP from the timolol bid baseline to 18.2±3.6mmHg (p<0.00001) and 20.5±3.5mmHg (p<0.00001), respectively. The IOP reduction with TTFC was significantly greater compared to LTFC (23.2±14.2% vs. 13.7±12.1%, p=0.00001). Additionally, the non-responder rate (IOP reduction<10% from timolol baseline) was significantly greater for LTFC compared to TTFC (38% vs. 14% of subjects, p<0.01, chi-squared test).
Conclusions: :
Both TTFC and LTFC effectively reduce IOP when patients are inadequately controlled on timolol monotherapy. When IOP reduction was evaluated at 24-hours post-dose, TTFC provides significantly better IOP control compared to LTFC, possibly due to a longer duration of action of travoprost compared to latanoprost.
Clinical Trial: :
www.clinicaltrials.gov NCT00887029
Keywords: intraocular pressure • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials