“…This was indeed confirmed in an early study in which COX inhibitors reduced both the levels of PGF 2a and pain in small numbers of dysmenorrheic women (Chan and Dawood, 1980). Numerous randomized, placebo-controlled studies have investigated the efficacy and safety of NSAIDs in treating dysmenorrhea, and have shown that several NSAID formulations, including naproxen sodium, zomepirac sodium, mefenamic acid, ketoprofen, ibuprofen, and diclofenac, provide effective pain relief in women with primary dysmenorrhea (Hanson et al, 1978;Ingemanson et al, 1981;Riihiluoma et al, 1981;Budoff, 1982;Mehlisch, 1988Mehlisch, , 1990Marchini et al, 1995;Facchinetti et al, 2002;Milsom et al, 2002;Letzel et al, 2006;Chantler et al, 2008Chantler et al, , 2009aIacovides et al, 2014a). Further, a meta-analysis of 31 studies on the efficacy of NSAIDs in primary dysmenorrhea revealed that compared with placebo, naproxen, ibuprofen and mefenamic acid all provided significant pain relief (Zhang and Li Wan Po, 1998).…”