Timolol is a beta-blocker. Patients with reactive airway disease (asthma) who use an inhaler for their allergy attack can DIE if they take topical beta blockers for their glaucoma. So, it is very important to take a thorough history and make sure they don't have asthma before putting them on beta blockers.
Beta blockers block the action of the sympathetic nerve endings in the ciliary epithelium. This leads to a decrease in the formation of aqueous humor and a reduction in IOP of 20-30%. They have little effect during the night and are best given in the morning. Patients taking oral beta blockers will not benefit as much as patients not taking oral beta blockers. When administered to one eye, there is a drop in pressure in the other eye. This indicates that the drop is absorbed systemically to some degree. The drop can decrease HDL cholesterol and increase overall cholesterol. Other side effects can include depression, aggravation of myasthenia gravis, masking of hypoglycemia symptoms, and decreased libido. They typically have a yellow colored top.
Common beta blockers that are used are timolol (Timpotic), levobunolol (Betagan), Carteolol (Ocupress), and Betaxolol (Betoptic).
