SYNTHESIS AND IDENTIFICATION OF THE PRIMARY DEGRADATION PRODUCT IN A COMMERCIAL OPHTHALMIC FORMULATION USING NMR, MS, AND A STABILITY-INDICATING HPLC METHOD FOR ANTAZOLINE AND NAPHAZOLINE

HPLC analysis of an anti-infective ophthalmic solution (Albalon-A), co ntaining the active drugs naphazoline and antazoline, revealed a degra dation peak of unknown identity. To elucidate the identity of the degr adant, the active drugs were each hydrolyzed by refluxing at high pH, and their respective hydrolysis products were isolated and spectrally characterized by NMR, FT-IR, and MS for conclusive structure elucidati on. The degradant's identity was confirmed by HPLC-MS analysis of Alba lon-A ophthalmic solution to be the antazoline hydrolysis product N[(N -benzylanilino)acetyl]ethylenediamine (IV). A stability-indicating HPL C method was then developed which was able to resolve IV from the acti ve drugs. This HPLC method was then validated for quantitating the act ive drugs and IV. Validation studies demonstrated linear UV response a t 280 nm, recovery > 98%, good reproducibility, and a detection limit of 2 mu g/mL IV. Overall, the data demonstrated that the HPLC method w as quantitative and specific for antazoline, naphazoline, and IV. Anal ysis of an expired stabilitry lot of the ophthalmic solution indicated the concentration of IV was 0.002% (w/v).