Dorzolamide and timolol are combined in one eye drop and are indicated for controlling intra ocular pressure in such conditions like glaucoma.
Dorzolamide is a carbonic anhydrase inhibitor which reduces the production of the fluid - aqueous humour - found in the eye ball. The build up of this fluid increases the pressure in the eye ball and leads to glaucoma. Timolol is a beta blocker which improves drainage of aqueous humour from the eye ball.
This combination is associated with side effects of the individual agents. Eye irritation - burning, conjunctivitis, inflammation, itching is the most reported. These effects may diminish with time. Dorzolamide may produce a bitter taste.
Timolol can worsen asthma and heart failure, and people with these conditions should avoid the product.
Drugs Future 1996;21:413
The relevant product monographs must be regarded as the appropriate sources of prescribing information.