Stability and compatibility of an aerosol mixture including N-acetylcysteine, netilmicin and betamethasone

The physicochemical stability and the compatibility between N-acetylcysteine (1 g/5 ml), betamethasone (4 mg/1 ml) and netilmicin (100 mg/1 ml) were studied at room temperature (25±2°C) over 1 h. During this study, drug concentrations were measured using three separate HPLC methods with UV detection at t=0, 5, 10, 20, 30, and 60 min. The pH of the mixture was determined. Degradation products of the drugs were assayed using HPLC. This study demonstrates the stability and compatibility of the mixture over 1 h at room temperature. The pinkish non-remnant coloration observed when pouring N-acetylcysteine into a recipient has no effect on the stability of the drug. Copyright (C) 1999 Elsevier Science B.V.