Effect of prednisolone on prostaglandin synthesis by rectal mucosa in ulcerative colitis: investigation by laminar flow bioassay and radioimmunoassay.

The effect of two concentrations of prednisolone on synthesis of prostaglandin E2 (PGE2) by 40 rectal biopsies in organ culture was investigated using both laminar flow bioassay and radioimmunoassay (RIA). Prednisolone (concentration 8.33 x 10(-7)M) reduced mean synthesis of PGE2 to 36.4% of control values (measured by bioassay) or 26.2% of control values (measured by RIA). With prednisolone (concentration 5.66 X 10(-4) M) synthesis of PGE2 was 7.7% of control values (RIA). The two concentrations are similar respectively to those achieved in plasma after oral prednisolone and delivered topically by prednisolone enemata. Inhibition of PG synthesis may thus explain prednisolone's anti-inflammatory action in the treatment of ulcerative colitis.