Antioxidants as agents potentiating the antiinflammatory action of indomethacin.

Nordihydroguaiaretic acid inhibits prostaglandin (PG) biosynthesis in vitro (ID50=228 muM), with a slope of dose-response curve high (b=209) as compared with indomethacin (ID50=0.1 muM, b=72.1). Butylated hydroxyanisole, in contrast to inactive butylated hydroxytoluene, inhibits PG biosynthesis (ID50=107 muM, b=63). Only norihydroguaiaretic acid (100 mug, s.p.) inhibited the postcarrageenin edema of rat paw. Butylated hydroxyanisole (10 mug, s.p.) given together with a subthreshold (1 mug) dose of indomethacin inhibited the paw edema by 35%, while butylated hydroxytoluene and nordihydroguaiaretic acid produced a similar effect only when given at 10-fold higher doses. The results suggest the possibility of potentiation and prolongation of the anti-inflammatory effect of indomethacin by its simultaneous administration with an antioxidant, butylated hydroxyanisole.