Cohesive, multicomponent, dense powder flow characterization by NIR

An innovative sampling interface for monitoring flowing pharmaceutical powder mixtures

A chute was designed following the principles of the Theory of Sampling to minimize the variations in powder flow and provide all particles in the flowing blends with the same opportunity of being selected as a sample. The design also reduces the thickness of the chute to allow the analysis of a higher portion of the flowing blends by a near infrared spectrometer. The blends that flowed through the chute had Carr's index values that fluctuated between 23 and 25 percent, indicating passable flowability. A powder fowling evaluation demonstrated that there was no powder accumulation at the inspection window of the chute. The mass flow rate profiles indicated that the system achieves mass steady-state in approximately 30 s and a throughput of 30 kg/h which makes it suitable for continuous manufacturing operations. An in-line NIR calibration model was developed to quantify caffeine concentrations between 1.51 and 4.52 % w/w. The spectra obtained from each experiment had minimal baseline variation. The developed NIR method was robust to throughput changes up to approximately ±7 %. The test blends in the caffeine concentration range between 2.02 % w/w and 4.02 % w/w met the dose uniformity requirements of the Ph.Eur. 9.0, chapter 2.9.47. Variographic analysis was done to estimate the analytical and sampling errors which yielded values below 0.01 (%w/w)². The obtained results showed that this chute could also be used in a continuous manufacturing line or other applications with flowing powders.

Blend uniformity evaluation during continuous mixing in a twin screw granulator by in-line NIR using a moving F-test

This study focuses on the twin screw granulator of a continuous from-powder-to-tablet production line. Whereas powder dosing into the granulation unit is possible from a container of preblended material, a truly continuous process uses several feeders (each one dosing an individual ingredient) and relies on a continuous blending step prior to granulation. The aim of the current study was to investigate the in-line blending capacity of this twin screw granulator, equipped with conveying elements only. The feasibility of in-line NIR (SentroPAT, Sentronic GmbH, Dresden, Germany) spectroscopy for evaluating the blend uniformity of powders after the granulator was tested. Anhydrous theophylline was used as a tracer molecule and was blended with lactose monohydrate. Theophylline and lactose were both fed from a different feeder into the twin screw granulator barrel. Both homogeneous mixtures and mixing experiments with induced errors were investigated. The in-line spectroscopic analyses showed that the twin screw granulator is a useful tool for in-line blending in different conditions. The blend homogeneity was evaluated by means of a novel statistical method being the moving F-test method in which the variance between two blocks of collected NIR spectra is evaluated. The α- and β-error of the moving F-test are controlled by using the appropriate block size of spectra. The moving F-test method showed to be an appropriate calibration and maintenance free method for blend homogeneity evaluation during continuous mixing.

Monitoring blend potency in a tablet press feed frame using near infrared spectroscopy

A near-infrared (NIR) probe was installed into the feed frame of a rotary tablet press to monitor API concentration as a function of time. A series of step change experimental trials were completed, where a placebo blend was initially charged into the feed frame, and an active blend was layered above. The compression process was initiated, and process parameters, such as mass throughput rate, and feed frame paddle wheel speed were systematically varied. For the range of mass throughput rates studied, excellent correlations were shown between the NIR signal and weight corrected tablet potency from stratified tablet samples. A similar correlation was demonstrated for higher feed frame paddle wheel speeds. However, for lower feed frame paddle wheel speeds, a bias was observed between weight corrected tablet potency and the NIR signal. This finding suggests that compression process parameters, such as paddle wheel rotational speed and NIR probe location, must be optimized for different tablet press geometries to ensure that the NIR process signal can be related to tablet potency. This emerging application of Process Analytical Technology (PAT) may be used to identify powder segregation events during discharge of powder from an intermediate bulk container (IBC) or as a development tool to further understand powder mixing dynamics occurring within the feed frame. This may also be used as a diagnostic tool for fault detection during tablet compression. Finally, this PAT application may also be integrated with the tablet press control system as a gating or reject device for sub or super-potent tablets or enable Real-Time-Release testing (RTRt) through the continuous monitoring of the potency and homogeneity of powder circulating within the feed frame.

Use of near-infrared spectroscopy to quantify drug content on a continuous blending process: influence of mass flow and rotation speed variations

The aim of this study was to develop a quantitative Near-Infrared (NIR) method which monitors the homogeneity of a pharmaceutical formulation coming out of a continuous blender. For this purpose, a NIR diode array spectrometer with fast data acquisition was selected. Additionally, the dynamic aspects of a continuous blending process were studied; the results showed a well-defined cluster for the steady state, and the paths for the start-up and emptying stages were clearly identified. The end point of the start-up phase was detected by moving block of standard deviation, relative standard deviation, and principal component analysis. A partial least square (PLS) model was generated for the quantification of the drug, with a standard error of prediction of 0.2% m/m. The PLS model was successfully applied for monitoring the drug level at the outlet of the continuous blender. Furthermore, the PLS model was tested under different flow and stirring rates. Flow and stirring rate variations caused different powder flow dynamics, which were reflected on the NIR measurements. Therefore, the PLS model was sensitive to changes in mass flow and rotation speeds.

Rapid evaluation for heterogeneities in monoclonal antibodies by liquid chromatography/mass spectrometry with a column-switching system

The development of therapeutic antibodies has grown over the last several years. Most of the recombinant monoclonal antibodies (mAbs) produced by mammalian cells are glycoproteins. Glycosylation of the mAbs can be associated with effector functions, such as antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity, as well as immunogenicity and clearance. Thus, mAb glycan heterogeneity is a significant characteristic associated with the safety and efficacy of the products. Therefore, glycan heterogeneity should be evaluated during research and development (R&D) and during development of mAbs manufacturing processes to identify the process parameters that affect glycan heterogeneity and to enhance understanding of the manufacturing process. There is an increasing need for a rapid, easy, and automated evaluation method for glycan heterogeneity. Liquid chromatography/mass spectrometry (LC/MS) is a method that can be used to analyze glycoforms. LC/MS is marked by the ability to measure the oligosaccharide composition of each glycoform, whereas other general methods, such as capillary electrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and ion-exchange chromatography, cannot. However, a laborious off-line purification of mAbs is required to evaluate glycan heterogeneities. In this study, we demonstrate the use of a rapid, easy, and automated evaluation system for mAb glycoforms by LC/MS. This LC/MS system uses a column-switching system equipped with 2 columns, a protein A affinity column and a reversed-phase column (desalting column). We devised 2 column-switching systems: one that targeted intact mAbs (system 1) and one that targeted the light and heavy chains of the mAbs (system 2). Our results show that the proposed systems are applicable as a tool to evaluate the glycoforms in several situations, including the research, development, and production processes of mAbs. Additionally, we hope that our systems are useful as process analytical technology (PAT) for molecular heterogeneities containing glycoforms of mAbs in implementation of quality by design (QbD).