Complex sentence: Its production is inhibited indirectly by NSAIDs, which inhibit the cyclooxygenase enzymes COX1 and COX2, which convert arachidonic acid to PGH 2, the immediate precursor of prostacyclin.
Split into simpler sentences: Its production is inhibited indirectly by NSAIDs, which inhibit the cyclooxygenase enzymes COX1 and COX2. These convert arachidonic acid to PGH 2, the immediate precursor of prostacyclin.