 Non-steroidal anti-inflammatory drugs NSAIDs are widely used for inflammation control and pain relief. However, while adjunct use of NSAIDs is avoided for periodontal therapy because of related side effects, cyclic administration of NSAIDs may reduce or eliminate these effects. The investigators evaluated the effect of a cyclic diclofenac potassium regimen on clinical parameters and levels of prostaglandin E2 PGE2 and interleukin-1beta IL-1beta in the gingival crevicular fluid GCF of subjects with periodontitis. Forty-one subjects with moderate to chronic periodontitis 33 men, 8 women were divided into two groups test and control after initial periodontal therapy. During this 6-month, randomized, double-blind, placebo-controlled study, test n 28 and control n 13 groups were administered a cyclic regimen of diclofenac potassium 50 mg, twice daily or placebo. Clinical measurements of disease severity and GCF sample collections were made at baseline, 2, 4 and 6 months. GCF levels of PGE2 and IL1-1beta were determined using EIA and ELISA kits, respectively. 