Absorption of sodium diclofenac after ocular administration in rabbit.

Sodium diclofenac (DCF, CAS 1507-79-6) is a non-steroidal anti-inflammatory drug whose activity is mainly due to an inhibitory effect on the synthesis of the prostaglandins. At present, a tendency towards its topical use in the treatment of the inflammatory state of the anterior segment of the eye as an alternative to the steroid drugs is observed. The pharmacokinetics of DCF was studied in rabbits by assessing the ocular and systemic absorption of DCF after administering DCF eye drops. The chromatographic methods available were not sensitive enough to quantify the extremely low drug concentrations which appeared in the biological fluids after ocular treatment. For this reason, the concentrations of DCF in plasma and aqueous humor were evaluated by a coupled liquid chromatography/gas chromatography (LC/GC) method. DCF was absorbed well through the cornea with the aqueous humor concentration peak being 757.8 ng/ml at 120 min. This good ocular absorption of DCF was confirmed by the concentrations observed in plasma. The presence of tramazoline (TMZ, CAS 74195-73-6) in the eye drops increases the levels of DCF in aqueous humor.