Photostability of barnidipine in combined cyclodextrin-in-liposome matrices

The improvement of barnidipine photostability was investigated in cyclodextrin or liposome matrices and in appropriate combinations of these matrices. These supramolecular systems allowed the preparation of liquid formulations, as an alternative to the current solid commercial specialties.

Photodegradation stressing tests were performed according to the ICH rules and monitored by derivative spectrophotometry. Optimization was evaluated in terms of drug-inclusion efficiency.

The photodegradation rate of barnidipine in ethanol proved rapid (residual percentage of 29.81%) after a radiation exposure of 225 kJ/m(2). The residual concentrations detected for liposome and cyclodextrin complexes were 42.90 and 72.03%, respectively. The best results were obtained when the drug-cyclodextrin complex was in turn entrapped in liposomes (residual percentage of 90.78%).

The stability of the drug-in-cyclodextrin-in-liposome system increased significantly with a value close to that of solid formulations whose residual percentage was 96.03%.