Soft sensor for content prediction in an integrated continuous pharmaceutical formulation line based on the residence time distribution of unit operations

In this study, a concentration predicting soft sensor was achieved based on the Residence Time Distribution (RTD) of an integrated, three-step pharmaceutical formulation line. The RTD was investigated with color-based tracer experiments using image analysis. Twin-screw wet granulation (TSWG) was directly coupled with a horizontal fluid bed dryer and an oscillating mill. Based on integrated measurement, we proved that it is also possible to couple the unit operations in silico. Three surrogate tracers were produced with a coloring agent to investigate the separated unit operations and the solid and liquid inputs of the TSWG. The soft sensor’s prediction was compared to validating experiments of a 0.05 mg/g (15% of the nominal) concentration change with High-Performance Liquid Chromatography (HPLC) reference measurements of the active ingredient proving the adequacy of the soft sensor (RMSE < 4%)

Continuous Manufacturing of Homogeneous Ultralow-Dose Granules by Twin-Screw Wet Granulation

Homogeneous ultralow-dose (30 mg) tablets were prepared from perfectly free-flowing granules manufactured by continuous Twin-Screw Wet Granulation. The gravimetrically fed mixture of lactose and potato starch of low particle size was successfully agglomerated and the size enlargement technology proved to be very robust. Since the incorporated drug was dissolved in ethanol-based granulation liquid, the resulting homogeneity largely depended on the dosing of the applied liquid administering units.A&nbsp;peristaltic pump generated higher deviation of the drug content in tablets (Relative Standard Deviation (RSD): 7.7 %) compared to&nbsp;a syringe pump (RSD: 2.3 %) or a piston pump (RSD: 4.6 %). This is due to the pulsation of the liquid flow generated by the peristaltic pump according to the real-time measured mass of the fed liquid. A good correlation was found between the RSD of the liquid mass flow (calculated from the recorded masses) and the RSD of the drug content. Based on the results, the goodness of Content Uniformity, as&nbsp;the most relevant critical quality attribute of low-dose products, was determined by the characteristics of the applied dosing units. The feeding characteristic of the different pumps could be easily measured by the introduced balance-based method and therefore, the applicability of the pumps could be evaluated

Process Design of Continuous Powder Blending Using Residence Time Distribution and Feeding Models

The present paper reports a thorough continuous powder blending process design of acetylsalicylic acid (ASA) and microcrystalline cellulose (MCC) based on the Process Analytical Technology (PAT) guideline. A NIR-based method was applied using multivariate data analysis to achieve in-line process monitoring. The process dynamics were described with residence time distribution (RTD) models to achieve deep process understanding. The RTD was determined using the active pharmaceutical ingredient (API) as a tracer with multiple designs of experiment (DoE) studies to determine the effect of critical process parameters (CPPs) on the process dynamics. To achieve quality control through material diversion from feeding data, soft sensor-based process control tools were designed using the RTD model. The operation block model of the system was designed to select feasible experimental setups using the RTD model, and feeder characterizations as digital twins, therefore visualizing the output of theoretical setups. The concept significantly reduces the material and instrumental costs of process design and implementation