A 52-year-old patient with rheumatoid arthritis was taking diclofenac sodium capsules. After a while, he began experiencing epigastric pain and discomfort, nausea, and dyspeptic disorders. What mechanism of action of the drug has resulted in this complication?

• A. Inhibition of creatine phosphokinase
• B. Inhibition of cyclooxygenase-2 (COX-2)
• C. Inhibition of lipoxygenase
• D. Inhibition of phosphodiesterase
• E. Inhibition of cyclooxygenase-1 (COX-1) in the gastric mucosa