Implementation of mechanistic modeling and global sensitivity analysis (GSA) for design, optimization, and scale-up of a roller compaction process.

The pharmaceutical industry has been shifting towards the application of mechanistic modeling to improve process robustness, enable scale-up, and reduce time to market. Modeling approaches have been well-developed for processes such as roller compaction, a continuous dry granulation process. Several mechanistic models/approaches have been documented with limited application to high drug-loaded formulations. In this study, the Johanson model was employed to optimize roller compaction processing and guide its scale-up for a high drug loaded formulation. The model was calibrated using a pilot-scale Minipactor and was validated for a commercial-scale Macropactor. Global sensitivity analysis (GSA) was implemented to determine the impact of process parameter variations (roll force, gap, speed) on a quality attribute [solid fraction (SF)]. The throughput method, which estimates SF values of ribbons using granule production rate, was also studied. The model predicted SF values for all 14 Macropactor batches within ± 0.04 SF. The throughput method estimated SF with ± 0.06 SF for 7 out of 11 batches. GSA confirmed that roll force had the largest impact on SF. This case study represents a process modeling approach to build quality into the products/processes and expands the use of mechanistic modeling during drug product development.

High-throughput blend segregation evaluation using automated powder dispensing technology.

Due to the complexity in the interactions of variables and mechanisms leading to blend segregation, quantifying the segregation propensity of an Active Pharmaceutical Ingredient (API) has been challenging. A high-throughput segregation risk prediction workflow for early drug product development has been developed based on the dispensing mechanism of automated powder dispensing technology. The workflow utilized liquid handling robots and high-performance liquid chromatography (HPLC) with a well-plate autosampler for sample preparation and analysis. Blends containing three different APIs of varying concentrations and particle sizes of different constituents were evaluated through this automated workflow. The workflow enabled segregation evaluation of different API blends in very small quantities (~7g) compared to other common segregation testers that consume hundreds of grams. Segregation patterns obtained were well explained with vibration induced percolation-based segregation phenomena. Segregation risk was translated quantitatively using relative standard deviation (RSD) calculations, and the results matched well with large-scale segregation studies. The applied approach increased the throughput, introduced a simple and clean walk-up method with minimized equipment space and API exposures to conduct segregation studies. Results obtained can provide insights about optimizing particle size distributions, as well as selecting appropriate formulation constituents and secondary processing steps in early drug product development when the amount of available API is very limited.

Underpinning mechanistic understanding of the segregation phenomena of pharmaceutical blends using a near-infrared (NIR) spectrometer embedded segregation tester.

The segregation of an active pharmaceutical ingredient (API) within a powder blend is one of the major manufacturing obstacles in achieving content uniformity. Segregation can be due to differences in physicochemical properties of formulation components and/or perturbations experienced during secondary processing steps, such as granulation, fluidization, die-filling and compression. A near-infrared (NIR) spectrometer embedded segregation tester, which could mimic the external stimulations (vibration and fluidization) experienced by a blend in a manufacturing facility, was used to evaluate and predict blend segregation. Two different GlaxoSmithKline (GSK) product blends with variations in the API particle size and concentration were tested. Drug content was further measured at different locations along the powder bed by NIR to sketch the segregation profile and calculate the overall segregation intensity of each blend. The study indicated that the segregation potential was dependent on the particle sizes of API and excipients, as well as the type of stimulus applied (vibration vs fluidization). Drug concentration profiles obtained from this mode of analysis decoded the underlying segregation mechanisms (sieving, trajectory and air elutriation) easily. The employed NIR-based segregation tester proved to be a useful small-scale predictive tool to evaluate and rank the segregation risk of the studied pharmaceutical blends.

Evaluation of tablet punch configuration on mitigating capping by a quality by design approach.

Capping is a common problem in the manufacture of some types of tablets and unless resolved, the tableting process cannot proceed. Hence, all factors that can help to lessen the likelihood of capping without unnecessarily reduce turret speed and/or compaction force would be tenable. This study investigated the influence of tablet punch configuration on mitigation of tablet capping. Tablets were prepared from high-dose paracetamol-potato starch granules in a rotary tablet press with flat face plain (FFP), flat face bevel edge (FFBE) and flat face radius edge (FFRE) punch configurations. The directly compressible (DC) fillers tested were microcrystalline cellulose (MCC), pre-gelatinised starch (PGS) and lactose. Design of experiments (DoE), a tool of quality by design (QbD) paradigm, was used and the interaction of input variables (compression force, tablet punch configuration and DC filler) affecting the response factors (tablet hardness and capping rating) were evaluated. FFP punches were able to mitigate capping best. FFRE punches showed more potential than FFBE punches at alleviating capping in a particular compression force range, without the limitations of the FFP punches that produce cylindrical tablets that were more friable. Incorporation of PGS in the tablet formulation was observed to be more efficient at mitigating capping than the other DC fillers when FFBE and FFRE punches were used. Overall, this study serves as a model for prospective product development based on the QbD framework and the optimal use of compaction tools.

Tablet coating by injection molding technology - Optimization of coating formulation attributes and coating process parameters.

We developed and evaluated a solvent-free injection molding (IM) coating technology that could be suitable for continuous manufacturing via incorporation with IM tableting. Coating formulations (coating polymers and plasticizers) were prepared using hot-melt extrusion and screened via stress-strain analysis employing a universal testing machine. Selected coating formulations were studied for their melt flow characteristics. Tablets were coated using a vertical injection molding unit. Process parameters like softening temperature, injection pressure, and cooling temperature played a very important role in IM coating processing. IM coating employing polyethylene oxide (PEO) based formulations required sufficient room humidity (>30% RH) to avoid immediate cracks, whereas other formulations were insensitive to the room humidity. Tested formulations based on Eudrajit E PO and Kollicoat IR had unsuitable mechanical properties. Three coating formulations based on hydroxypropyl pea starch, PEO 1,000,000 and Opadry had favorable mechanical (<700MPa Young's modulus, >35% elongation, >95×104J/m3 toughness) and melt flow (>0.4g/min) characteristics, that rendered acceptable IM coats. These three formulations increased the dissolution time by 10, 15 and 35min, respectively (75% drug release), compared to the uncoated tablets (15min). Coated tablets stored in several environmental conditions remained stable to cracking for the evaluated 8-week time period.

Differential diagnosis of otitis media with effusion using label-free Raman spectroscopy: A pilot study.

Otitis media with effusion (OME) is an important and common condition affecting hearing in pediatric patients characterized by the presence of fluid in the middle ear space. The fluid is normally described as serous or mucoid based on differences in the fluid viscosity. The differential diagnosis of two OMEs, namely serous and mucoid is of significant clinical value because while the former is self-limiting, surgical procedure is commonly required for the latter. However, accurate identification of fluid types remains a challenging target unattainable with current clinical modalities due to unavailability of nonperturbative molecular tools. Here, we report an emerging spectroscopy approach featuring Raman scattering and multivariate analysis of spectral patterns to discern serous and mucoid fluids, obtained from pediatric patients undergoing myringotomy and tube placement, by providing information of differentially expressed molecules with high specificity. We demonstrate the feasibility of Raman spectroscopy-based approach to categorize middle ear effusion based on the characteristic spectral markers, notably of mucin, with classification accuracy of 91% and 93% for serous and mucoid, respectively. Our findings pave the way for further development of such a tool for fully noninvasive application that will lead to objective and accurate diagnosis thereby reducing unnecessary visits and surgical procedures.

Demonstration of pharmaceutical tablet coating process by injection molding technology.

We demonstrate the coating of tablets using an injection molding (IM) process that has advantage of being solvent free and can provide precision coat features. The selected core tablets comprising 10% w/w griseofulvin were prepared by an integrated hot melt extrusion-injection molding (HME-IM) process. Coating trials were conducted on a vertical injection mold machine. Polyethylene glycol and polyethylene oxide based hot melt extruded coat compositions were used. Tablet coating process feasibility was successfully demonstrated using different coating mold designs (with both overlapping and non-overlapping coatings at the weld) and coat thicknesses of 150 and 300 µm. The resultant coated tablets had acceptable appearance, seal at the weld, and immediate drug release profile (with an acceptable lag time). Since IM is a continuous process, this study opens opportunities to develop HME-IM continuous processes for transforming powder to coated tablets.

Integrated hot-melt extrusion - injection molding continuous tablet manufacturing platform: Effects of critical process parameters and formulation attributes on product robustness and dimensional stability.

This study provides a framework for robust tablet development using an integrated hot-melt extrusion-injection molding (IM) continuous manufacturing platform. Griseofulvin, maltodextrin, xylitol and lactose were employed as drug, carrier, plasticizer and reinforcing agent respectively. A pre-blended drug-excipient mixture was fed from a loss-in-weight feeder to a twin-screw extruder. The extrudate was subsequently injected directly into the integrated IM unit and molded into tablets. Tablets were stored in different storage conditions up to 20 weeks to monitor physical stability and were evaluated by polarized light microscopy, DSC, SEM, XRD and dissolution analysis. Optimized injection pressure provided robust tablet formulations. Tablets manufactured at low and high injection pressures exhibited the flaws of sink marks and flashing respectively. Higher solidification temperature during IM process reduced the thermal induced residual stress and prevented chipping and cracking issues. Polarized light microscopy revealed a homogeneous dispersion of crystalline griseofulvin in an amorphous matrix. DSC underpinned the effect of high tablet residual moisture on maltodextrin-xylitol phase separation that resulted in dimensional instability. Tablets with low residual moisture demonstrated long term dimensional stability. This study serves as a model for IM tablet formulations for mechanistic understanding of critical process parameters and formulation attributes required for optimal product performance.

Development of Maltodextrin-Based Immediate-Release Tablets Using an Integrated Twin-Screw Hot-Melt Extrusion and Injection-Molding Continuous Manufacturing Process.

The combination of hot-melt extrusion and injection molding (HME-IM) is a promising process technology for continuous manufacturing of tablets. However, there has been limited research on its application to formulate crystalline drug-containing immediate-release tablets. Furthermore, studies that have applied the HME-IM process to molded tablets have used a noncontinuous 2-step approach. The present study develops maltodextrin (MDX)-based extrusion-molded immediate-release tablets for a crystalline drug (griseofulvin) using an integrated twin-screw HME-IM continuous process. At 10% w/w drug loading, MDX was selected as the tablet matrix former based on a preliminary screen. Furthermore, liquid and solid polyols were evaluated for melt processing of MDX and for impact on tablet performance. Smooth-surfaced tablets, comprising crystalline griseofulvin solid suspension in the amorphous MDX-xylitol matrix, were produced by a continuous process on a twin-screw extruder coupled to a horizontally opening IM machine. Real-time HME process profiles were used to develop automated HME-IM cycles. Formulation adjustments overcame process challenges and improved tablet strength. The developed MDX tablets exhibited adequate strength and a fast-dissolving matrix (85% drug release in 20 min), and maintained performance on accelerated stability conditions.

Encapsulation of volatiles by homogenized partially-cross linked alginates.

Cross-linked calcium alginate gels are too viscous to be efficaciously incorporated into spray dried formulations. Thus, viscosity reduction is essential to ensure the processability of calcium alginate gels to be sprayed. Viscosity reduction by high pressure homogenization can open new formulation possibilities. Presently, testing of microcapsule integrity is also limited because either single particle tests neglect collective particle behaviours in bulk or bulk testing methods are often associated with single compressions which may not fully characterize individual particle strengths. The aim of this study was sub-divided into three objectives. First objective was to evaluate the impact of high pressure homogenization on gel viscosity. Second objective was to explore the use of the homogenized gels with modified starch for microencapsulation by spray drying. The final objective was to develop a stamping system as microcapsule strength tester that can assess microcapsules in bulk and evaluate the impact of multiple compressions. Collectively, this study would lead towards developing a pressure-activated patch of microcapsules with encapsulated volatiles and the method to assess the patch efficacy. The alginate gels largely experienced an exponential decay in viscosity when homogenized. Furthermore, the homogenized gels were successfully incorporated in spray drying formulations for microencapsulation. The custom-designed microcapsule strength tester was successfully used and shown to possess the required sensitivity to discern batches of microcapsules containing volatiles to have different release profiles. Addition of homogenized gels strengthened the microcapsules only at high wall to core ratios with low mass-load alginate gels. High mass-load gels weaken the microcapsules, exhibiting a higher release at low stamping pressures and wrinkling on the microcapsules surface.

Assessment of disintegration of rapidly disintegrating tablets by a visiometric liquid jet-mediated disintegration apparatus.

The aim of this study was to develop a responsive disintegration test apparatus that is particularly suitable for rapidly disintegrating tablets (RDTs). The designed RDT disintegration apparatus consisted of disintegration compartment, stereomicroscope and high speed video camera. Computational fluid dynamics (CFD) was used to simulate 3 different designs of the compartment and to predict velocity and pressure patterns inside the compartment. The CFD preprocessor established the compartment models and the CFD solver determined the numerical solutions of the governing equations that described disintegration medium flow. Simulation was validated by good agreement between CFD and experimental results. Based on the results, the most suitable disintegration compartment was selected. Six types of commercial RDTs were used and disintegration times of these tablets were determined using the designed RDT disintegration apparatus and the USP disintegration apparatus. The results obtained using the designed apparatus correlated well to those obtained by the USP apparatus. Thus, the applied CFD approach had the potential to predict the fluid hydrodynamics for the design of optimal disintegration apparatus. The designed visiometric liquid jet-mediated disintegration apparatus for RDT provided efficient and precise determination of very short disintegration times of rapidly disintegrating dosage forms.