Bioavailability of ambroxol sustained release preparations. Part I: In vitro dissolution studies.

The in vitro dissolution of two ambroxol-HCl containing sustained release preparations (75 mg) and the effect of pH of the dissolution medium on the dissolution rats were investigated. The studies were carried out using the USP XXI paddle method. A new ambroxol HCl sustained release formulation based on a dialyzing membrane for controlled release shows a longer release action as compared to a standard sustained release preparation from commercial source which is based on spheroids constituted by a lipid matrix. The in vitro release rate of the latter product also appears to be more pH dependent.