antiprostaglandin

noun

an·​ti·​pros·​ta·​glan·​din -ˌpräs-tə-ˈglan-dən 

: a substance (such as aspirin or ibuprofen) that blocks the production of prostaglandin or inhibits its action in the body

… they act as antiprostaglandins, preventing both the production of prostaglandins (PGs) and the binding of the PG to its receptor.

—Robert L. Barbieri, Scientific American

Others, specifically the antiprostaglandins, have been widely available for use in treating menstrual cramps only for the past 15 years …

—Susan M. Lark, Menstrual Cramps Self-Help Book