Biomedical subjects

Poul Bertelsen

Publications and source records attributed to Poul Bertelsen.

3 recordsLinked to original sources

PubMed2006

Acoustic monitoring of a fluidized bed coating process.

The aim of the study was to investigate the potential of acoustic monitoring of a production scale fluidized bed coating process. The correlation between sensor signals and the estimated amount of film applied and percentage release, respectively, were investigated in coating potassium chloride (KCl) crystals with ethylcellulose (EC). Vibrations were measured with two different types of accelerometers. Different positions for placing the accelerometers and two different product containers were included in the study. Top spray coating of KCl was chosen as a 'worst case' scenario from a coating point perspective. The acoustic monitoring has the potential of summarising the commonly used means to monitor the coating process. The best partial least squares (PLS) regressions, obtained by the high frequency accelerometer, showed for the release a correlation coefficient of 0.92 and a root mean square error of prediction (RMSEP) of 5.84% (31-82.8%), and for the estimated amount of film applied a correlation coefficient of 0.95 and RMSEP of 0.52% (0.6-6%). The results of the preliminary investigation are considered promising. There is however a need for further investigations on sampling procedures and product characterisation before a final conclusion on the applicability of acoustic monitoring can be made.

Acceleration↗

PubMed2003

Validation of an image analysis method for estimating coating thickness on pellets.

A digital image analysis method for the estimation of mean pellet size and coating thickness employing optical microscopy was evaluated. The coating thickness was expressed as the difference in mean projected area radius of the uncoated and the coated pellets. The repeatability, the intermediate precision and the robustness of the image analysis method were investigated. The repeatability and the intermediate precision of the image analysis method was excellent with a low degree of scatter between the measurements. The robustness investigation on the image analysis method illustrated the importance of controlling and monitoring the illumination technique utilised. Calibration of the image analysis equipment was of the highest importance. Using pellets with a high degree of sphericity and narrow size distribution, it was sufficient to use 1000 pellets to estimate the mean pellet size and the coating thickness with an accuracy of +/-1.2 microm. An equation is presented for an approximation of the number of pellets necessary to achieve a given accuracy in the estimation of mean pellet size and coating thickness.

Drug Implants↗

PubMed2003

A new process control strategy for aqueous film coating of pellets in fluidised bed.

The parameters with effect on maximum spray rate and maximum relative outlet air humidity when coating pellets in a fluidised bed were investigated. The tested variables include type of water based modified release film coating (Eudragit NE 30D, Eudragit RS 30D, Aquacoat ECD) coating principle (top spray, bottom spray), inlet air humidity and type of pellets (sugar spheres, microcrystalline cellulose pellets). The maximum spray rate was not influenced by the coating principles. The highest spray rate was obtained for the film polymer with the lowest tackiness which is assumed to be the controlling factor. The type of pellets affected the maximum spray rate. A thermodynamic model for the coating process is employed throughout the process and not just during steady state. The thermodynamic model is incorporated into a new process control strategy. The process control strategy is based on in-process calculation of degree of utilisation of the potential evaporation energy (DUE) of the outlet air and the relative outlet air humidity (RH). The spray rate is maximised using set points of DUE and RH as control parameters. The product temperature is controlled simultaneously by regulating the inlet air temperature.

Drug Implants↗