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 (ODFIR) and prolonged theophylline release (ODFPR) as well as double layer films (ODFDL) 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 ODFDL 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 ODFIR and ODFDL, 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, ODFIR and ODFDL 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.

3D-Printed Isoniazid Tablets for the Treatment and Prevention of Tuberculosis-Personalized Dosing and Drug Release.

The aim of the present work was to produce 3D-printed oral dosage forms with a sufficient drug dose displaying various release profiles. Hot-melt extrusion was utilized to produce drug-loaded feedstock material that was subsequently 3D-printed into 6, 8, and 10 × 2.5 mm tablets with 15% and 90% infill levels. The prepared formulations contained 30% (w/w) isoniazid in combination with one or multiple pharmaceutical polymers possessing suitable properties for oral drug delivery. Thirteen formulations were successfully hot-melt extruded of which eight had properties suitable for fused deposition modeling 3D printing. Formulations containing HPC were found to be superior regarding printability in this study. Filaments with a breaking distance below 1.5 mm were observed to be too brittle to be fed into the printer. In addition, filaments with high moisture uptake at high relative humidity generally failed to be printable. Different release profiles for the 3D-printed tablets were obtained as a result of using different polymers in the printed formulations. For 8 mm tablets printed with 90% infill, 80% isoniazid release was observed between 40 and 852 min. Drug release characteristics could further be altered by changing the infill or the size of the printed tablets allowing personalization of the tablets. This study presents novel formulations containing isoniazid for prevention of latent tuberculosis and investigates 3D printing technology for personalized production of oral solid dosage forms enabling adjustable dose and drug release properties.

Prolonged release from orodispersible films by incorporation of diclofenac-loaded micropellets.

Prolonged drug release provided by multiple-unit dosage forms is highly beneficial to enhance the compliance and safety of the pharmacotherapy even for patients with swallowing deficiencies. To facilitate the intake for these patients, multiple-unit tablets and capsules have to be crushed or opened. An attempt to overcome these issues has been made by the introduction of orodispersible films (ODFs), which rapidly disintegrate within the oral cavity and facilitate the intake of oral solid dosage forms. The aim of this study was to develop a rapidly disintegrating ODF with prolonged release properties by incorporation of small-sized micropellets (MPs). MPs with a drug load of 70% were produced by wet extrusion and spheronization using Vivapur® MCG as pelletizing aid and diclofenac sodium (DS) as model drug. MPs were film-coated with an Eudragit® RS/RL coating and incorporated into the ODF-forming hypromellose solution. ODFs were produced by solvent casting technique. Disintegration times were determined using the PharmaTest® disintegration tester equipped with sample holders for ODFs. Dissolution studies were performed for MPs and ODFs. X-ray micro-computed tomography was used to visualize internal and external surface structures of MPs before and after release studies. MP-loaded ODFs show fast disintegration within 30 s, whereby film-coated MPs remain intact. Uncoated MPs are disintegrating thus revealing immediate DS release. In comparison, DS release was prolonged for film-coated MPs and corresponding ODFs. Incorporation of different amounts of MPs had no effect on the dissolution, but on mechanical properties of ODFs, which decrease with increasing amounts of MPs. The production of rapidly disintegrating ODFs with prolonged release properties for DS, representing a freely water-soluble drug, was feasible.

Novel Dissolution Method for Oral Film Preparations with Modified Release Properties.

Oromucosal film preparations have gained popularity in pharmaceutical research and development. Therefore, oral films have been integrated into the monograph "oromucosal preparations" of the European Pharmacopeia in 2012. Regulatory authorities explicitly demand dissolution studies for films, but neither refer to suitable methods nor established specifications. Test methods described in the literature are often limited to immediate release formulations or not applicable to investigate the drug release of films with prolonged release profiles considering the different stages of gastrointestinal transit. The aims of this study were to develop a dissolution test method, which is suitable to investigate the drug release of film preparations with immediate as well as modified release profiles and to explore the potential of the test setup considering some physiological characteristics. Therefore, a conventional flow-through cell was equipped with in-house built sample holders. Three-dimensional printing technology was used for prototyping one of the sample holders. Four different types of films were investigated, such as ODFs with immediate (ODFIR) and prolonged release (ODFPR) characteristics as well as a double-layer film (ODFDL), produced with a water-insoluble shielding layer. Anhydrous theophylline was used as a model drug for all film types. Introducing special fixtures for oral films to a conventional flow-through cell enables successful determination of the drug release behavior of oral film preparations with immediate as well as modified release properties. Investigating ODFDL, the application of film sample holders with backing plates such as film sample holder with backing plate (FHB) and 3D printed film sample holder (FH3D) showed prolonged release profiles with 14.6 ± 1.30% theophylline dissolved within 2 h for FHB compared to 92.9 ± 3.33% for the film sample holder without backing plate (FH). This indicates their suitability to examine the integrity of the shielding layer. The application of the backing plate further decreased the drug release of ODFPR < 315 to 61.0 ± 1.69% dissolved theophylline within 2 h using FHB compared to 82.3 ± 0.74% using FH, due to a reduced ODF surface exposed to the dissolution medium. The potential of the dissolution test setup to consider physiological conditions of the human gastrointestinal transit was investigated by applying different flow rates and media compositions to simulate conditions within the oral cavity, stomach, and intestine. For the application of a low flow rate of 1 ml/min, comparable to the salivary flow within the oral cavity, decreased theophylline release was observed, while similar release profiles were obtained for flow rates between 2 and 8 ml/min. Substantial impact on the theophylline release was exerted by varying the composition of the dissolution medium. Since the drug release from ODFPR is controlled by diffusion through a water-insoluble matrix, ion species and concentration strongly affect the release behavior. In the future, IVIVC studies have to be performed to explore, whether obtained data can be used to predict drug release behavior of ODFs during the human gastrointestinal transit.

Comparative study on disintegration methods for oral film preparations.

Orodispersible films (ODFs) provide high application comfort due to rapid disintegration in the oral cavity. They increasingly found the approval of pharmaceutical research and development and were added to the European Pharmacopeia in 2012. The European Pharmacopeia explicitly demands disintegration testing for ODFs, but does not refer to a suitable method. The aim of this study was to collect and evaluate existing disintegration methods regarding their suitability to investigate different ODF formulations. Therefore, 21 ODF formulations produced at different gap heights and/or different amounts of suspended microcrystalline cellulose (MCC) particles were manufactured by solvent casting technique, using hypromellose (HPMC) as film-forming polymer. Four disintegration methods described in literature were applied to characterize the disintegration behavior of these formulations. They were the petri dish, the slide frame, slide frame and ball (SFaB) method as well as the PharmaTest® disintegration tester equipped with a film sample holder. All methods show similar tendencies, at which the disintegration time proportionally increases with increasing dry film thicknesses. Reduced disintegration times were observed for ODFs containing insoluble MCC particles compared to their corresponding particle-free formulations. However, the suitability to investigate varying types of ODFs applying the four different test methods highly depends on the intended purpose. Therefore, the slide frame and SFaB method seems to be particularly applicable for research and development purposes, whereas the PharmaTest® disintegration tester and the SFaB method fulfil the demands required for testing methods within the quality control.

Prolonged drug release properties for orodispersible films by combining hot-melt extrusion and solvent casting methods.

Orodispersible films (ODFs) are an advantageous dosage form to accomplish patient convenience and compliance in oral drug delivery. They provide a number of special application features, such as the ease of administration without water and suitability for patients with swallowing problems. However, this promising dosage form has been limited to immediate release formulations so far. The aim of this study was to develop a thin film produced by solvent casting, which is rapidly disintegrating when placed in the mouth, but which provides prolonged drug release characteristics by incorporating drug-loaded matrix particles (MPs). MPs were produced by hot-melt extrusion and subsequent milling, using theophylline anhydrous as model drug and Eudragit® RS as matrix-forming agent enabling prolonged drug release. ODFs were manufactured using hypromellose as film former. Dissolution studies were performed to investigate the kinetics and the duration of drug release. Additionally, disintegration time was determined using the PharmaTest® disintegration tester equipped with a specific sample holder for ODFs. All produced ODFs containing theophylline-loaded MPs show fast disintegration while the drug release was prolonged. The degree of release prolongation increases with increasing sizes of incorporated MPs. Matrix-controlled release kinetics were found for ODFs containing MPs with at least 315 µm in size. In summary, the production of fast disintegrating ODFs with prolonged release properties was feasible. Furthermore, freely adjustable dissolution profiles could be realized for ODFs by incorporating MPs of various particle sizes.