A patient who had been taking diclofenac sodium for arthritis of mandibular joint developed an acute condition of gastric ulcer. Such side effect of this medicine is caused by inhibition of the following enzyme:

Answer options

1. Monoamine oxidase
2. Lipoxygenase
3. Cyclooxygenase-2 (COX-2)
4. Cyclooxygenase-1 (COX-1)
5. Phosphodiesterase

Explanation

Cyclooxygenase-1 (COX-1) is known to be present in most tissues. In the gastrointestinal tract, COX-1 maintains the normal lining of the stomach so its inhibition could lead to ulcers.