Continuous twin screw granulation: influence of process variables on granule and tablet quality

The aim of the current study was to screen theophylline (125 mg) tablets manufactured via twin screw granulation in order to improve process understanding and knowledge of process variables that determine granule and tablet quality. A premix of theophylline anhydrate, α-lactose monohydrate and PVP (ratio: 30/67.5/2.5,w/w) was granulated with demineralized water. Experiments were done using the high-shear wet granulation module (based on twin screw granulation) of the ConsiGma™-25 unit (a continuous tablet manufacturing system) for particle size enlargement. After drying, granules were compressed using a MODUL™ P tablet press (compression force: 10 kN, tablet diameter: 12 mm). Using a D-optimal experimental design, the effect of several process variables (throughput (10-25 kg/h), screw speed (600-950 rpm), screw configuration (number (2, 4, 6 and 12) and angle (30°, 60° and 90°) of kneading elements), barrel temperature (25-40°C) and method of binder addition (dry versus wet)) on the granulation process (torque and temperature increase in barrel wall), granule (particle size distribution, friability and flowability) and tablet (tensile strength, porosity, friability, disintegration time and dissolution) quality was evaluated. The results showed that the quality of granules and tablets can be optimized by adjusting specific process variables (number of kneading elements, barrel temperature and binder addition method) during a granulation process using a continuous twin screw granulator.

Near infrared and Raman spectroscopy for the in-process monitoring of pharmaceutical production processes

Within the Process Analytical Technology (PAT) framework, it is of utmost importance to obtain critical process and formulation information during pharmaceutical processing. Process analyzers are the essential PAT tools for real-time process monitoring and control as they supply the data from which relevant process and product information and conclusions are to be extracted. Since the last decade, near infrared (NIR) and Raman spectroscopy have been increasingly used for real-time measurements of critical process and product attributes, as these techniques allow rapid and nondestructive measurements without sample preparations. Furthermore, both techniques provide chemical and physical information leading to increased process understanding. Probes coupled to the spectrometers by fiber optic cables can be implemented directly into the process streams allowing continuous in-process measurements. This paper aims at reviewing the use of Raman and NIR spectroscopy in the PAT setting, i.e., during processing, with special emphasis in pharmaceutics and dosage forms.