Fixed combination dorzolamide–timolol in the treatment of ocular hypertension and glaucoma

Increased intraocular pressure (IOP) is often associated with glaucoma, a leading cause of irreversible vision loss. Commonly, multiple medications are required to achieve IOP control in glaucoma or ocular hypertension. The fixed combination of timolol and dorzolamide is among the most commonly used antiglaucoma medications. It is more effective than either of its components used as monotherapy, and has an IOP lowering ability that is slightly less than the concomitant use of the components. The fixed combination allows the simplification of a multidrug regimen by reducing the total number of drops and preservative instilled per day, avoids washout effect from rapid sequence instillation of individual drops, and may improve adherence to chronic therapy. Although fixed combination medications are increasingly popular with several combinations available worldwide, the fixed dorzolamide–timolol combination remains the only fixed combination approved in the USA.