Dissolution testing of oral film preparations: Experimental comparison of compendial and non-compendial methods

In vitro dissolution testing is one of the most frequently used tests in pharmaceutical quality control, since evaluation of the drug release profile and estimation of the dosage form performance is enabled. However, for oral film preparations no standardized compendial dissolution method or specifications are available worldwide. Therefore, four different dissolution methods described in the literature, namely the basket method, the paddle and glass disc (PGD) method, the flow-through cell with adapted film sample holders produced via 3D printing (FTC + FH3D) and the "Punch and Filter" (PAF) method were chosen and their suitability to investigate oral films with different release properties was compared. For this purpose, oral films with immediate (ODF_IR) and prolonged theophylline release (ODF_PR) as well as double layer films (ODF_DL) were produced and investigated. All produced ODFs disintegrated rapidly in 27-46 s and showed content uniformity with acceptance values between 7.3 and 11.3%. The FTC + FH3D and the PGD method showed increased discriminatory power and were suitable to investigate the integrity of the shielding layer of ODF_DL as shown by linear prolonged release (mean dissolution time at 80% drug release (MDT₈₀) of 366.8 and 217.1 min for FTC + FH3D and PGD method), which was not possible applying the basket and PAF method. These methods did not allow clear discrimination between ODF_IR and ODF_DL, since immediate release profiles with MDT₈₀ values of 4.1 and 11.0 min for the basket method and 6.8 and 15.5 min for the PAF method were found for both, ODF_IR and ODF_DL respectively. The FTC + FH3D method provided high flexibility, which may be used to simulate gastrointestinal transit. The PAF method reflects physiological conditions of the oral cavity and enables mimicking the in vivo film application. These methods are particularly valuable for research and development purposes. Due to the simple and well standardized instrumental setup as well as high robustness, the basket and PGD method are particularly suitable for use in pharmaceutical quality control.