Absorption and Safety of Topical Timolol to Treat Chronic Wounds

Overview

Topical timolol has been used primarily as eye drops to treat glaucoma for many years. Recent clinical experience has broadened its off-label use for a number of skin conditions, including slow-healing wounds. While there have been extensive safety studies performed on timolol administration to treat the eye, to date, no studies have documented absorption of timolol after applied on chronic wounds. Thus, the purpose of this study is to determine the blood levels of timolol in patients after topical administration to a chronic wound, and compare these levels with those of patients after administration of the same drug formulation on the eye for the indication of glaucoma.

Chronic wounds, such as diabetic foot ulcers, venous leg ulcers and pressure ulcers are serious problems in our health system, with limited therapeutic options available to improve healing. Our laboratory and animal work has suggested that timolol, a safe medication, currently used as an eye drop for treatment of glaucoma, can heal these ulcers. Timolol, is a nonselective, beta1/beta2 adrenergic receptor antagonist, widely used for the management of ocular hypertension or open-angle glaucoma. Most recently, there have been many case reports published that suggest that timolol can be used topically to aid in the healing of chronic, recalcitrant ulcers and wounds; however, concern over the medication's systemic effects needs to be further explored and elucidated. The systemic absorption of timolol eye drops and the medications systemic side effects have been well established; however, this has not before been examined in patients receiving topical timolol for chronic wounds. Now that this beta blocker has promising evidence for a role in the topical management of chronic wounds, the safety of this drug in topical use is of interest. The importance of this study is in the exploration of the safety of timolol in the topical treatment of chronic wounds. If the systemic absorption from topical application to chronic wounds is found to be equivalent or less than that from ophthalmic drops, then a strong argument can be made regarding the relative safety of Timolol. To investigate the safety profile of topical timolol application, blood levels will be measured to determine the systemic absorption of timolol. To do this, we proposed an observational cross-sectional comparative study with two groups of patients: one group receiving topical timolol for chronic wounds and the other receiving ophthalmic timolol for the management of glaucoma. Serum levels of timolol will be quantified using high performance liquid chromatography (HPLC), and the levels between the two groups will be compared.