The Effect of Process Variables and Binder Concentration on Tabletability of Metformin Hydrochloride and Acetaminophen Granules Produced by Twin Screw Melt Granulation with Different Polymeric Binders

Ten years of the manufacturing classification system: a review of literature applications and an extension of the framework to continuous manufacture

The MCS initiative was first introduced in 2013. Since then, two MCS papers have been published: the first proposing a structured approach to consider the impact of drug substance physical properties on manufacturability and the second outlining real world examples of MCS principles. By 2023, both publications had been extensively cited by over 240 publications. This article firstly reviews this citing work and considers how the MCS concepts have been received and are being applied. Secondly, we will extend the MCS framework to continuous manufacture. The review structure follows the flow of drug product development focussing first on optimisation of API properties. The exploitation of links between API particle properties and manufacturability using large datasets seems particularly promising. Subsequently, applications of the MCS for formulation design include a detailed look at the impact of percolation threshold, the role of excipients and how other classification systems can be of assistance. The final review section focusses on manufacturing process development, covering the impact of strain rate sensitivity and modelling applications. The second part of the paper focuses on continuous processing proposing a parallel MCS framework alongside the existing batch manufacturing guidance. Specifically, we propose that continuous direct compression can accommodate a wider range of API properties compared to its batch equivalent.

Elucidation of Granulation Mechanisms along the Length of the Barrel in Continuous Twin-Screw Melt Granulation

In the pharmaceutical industry, innovative continuous manufacturing technologies such as twin-screw melt granulation (TSMG) are gaining more and more interest to process challenging formulations. To enable the implementation of TSMG, more elucidation of the process is required and this study provides a better understanding of the granule formation along the length of the barrel. By sampling at four different zones, the influence of screw configuration, process parameters and formulation is investigated for the granule properties next to the residence time distribution. It showed that conveying elements initiate the granulation by providing a limited heat transfer into the powder bed. In the kneading zones, the consolidation stage takes place, shear elongation combined with breakage and layering is occurring for the reversed configurations and densification with breakage and layering for the forward and neutral configurations. Due to the material build-up in the reversed configurations, these granules are larger, stronger, more elongated and less porous due to the higher degree of shear and densification. This configuration also shows a significantly longer residence time compared to the forward configuration. Hence, the higher level of shear and the longer period of time enables more melting of the binder resulting in successful granulation.

Application of Twin-Screw Melt Granulation to Overcome the Poor Tabletability of a High Dose Drug

Pharmaceutical tablet manufacturing has seen a paradigm shift toward continuous manufacturing and twin-screw granulation-based technologies have catalyzed this shift. Twin-screw granulator can simultaneously perform unit operations like mixing, granulation, and drying of the granules. The present study investigates the impact of polymer concentration and processing parameters of twin-screw melt granulation, on flow properties and compaction characteristics of a model drug having high dose and poor tabletability. Acetaminophen (AAP) and polyvinylpyrrolidone vinyl acetate (PVPVA) were used as a model drug (90-95% w/w) and polymeric binder (5-10%w/w), respectively, for the current study. Feed rate (~650-1150 g/h), extruder screw speed (150-300 rpm), and temperature (60-150°C) were used as processing variables. Results showed the reduction in particle size of drug in the extrudates (D₉₀ of 15-25 μm from ~80 μm), irrespective of processing condition, while flow properties were a function of polymer concentration. Overall, good flowability of the products and their tablets with optimum tensile strength can be obtained through using high polymer concentration (i.e., 10% w/w), lower feed rate (~650 g/h), lower extruder screw speed (150 rpm), and higher processing temperatures (up to 120°C). The findings from the current study can be useful for continuous manufacturing of tablets of high dose drugs with minimal excipient loading in the final dosage form.

Moisture Sorption by Polymeric Excipients Commonly Used in Amorphous Solid Dispersions and its Effect on Glass Transition Temperature: II. Cellulosic Polymers

Moisture sorption by polymeric carriers used for the development of amorphous solid dispersions (ASDs) plays a critical role in the physical stability of dispersed drugs since moisture may decrease glass transition temperature (T_g) and thereby increase molecular mobility of drugs leading to their crystallization. To assist the selection of appropriate polymers for ASDs, we conducted moisture sorption by five types of cellulosic polymers, namely, hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC), hydroxypropyl methyl cellulose acetate succinate (HPMCAS), hydroxypropyl methyl cellulose phthalate (HPMCP), and ethyl cellulose (EC), as functions of relative humidity (10 to 90% RH) and temperature (25 and 40 °C). The moisture sorption was in the order of HPC>HPMC>HPMCP>HPMCAS>EC, and there was no significant effect of the molecular weights of polymers on moisture uptake. There was also less moisture sorption at 40 °C than that at 25 °C. Glass transition temperatures (T_g) of the polymers decreased with the increase in moisture content. However, the plasticizing effect by moisture on HPC could not be determined fully since, despite being amorphous, there were very little baseline shifts in DSC scans. There was also very shallow baseline shift for HPMC at >1% moisture content. In contrast, T_g of HPMCAS and HPMCP decreased in general agreement with the Gordon-Taylor/Kelley-Bueche equation, and EC was semicrystalline having both T_g and melting endotherm, with only minor effect of moisture on T_g. The results of the present investigation would lead to a systematic selection of polymeric carriers for ASDs.

Commercial scale transfer of a twin-screw melt granulation process for high drug load fevipiprant tablets

OBJECTIVE

This work summarizes select methodology of twin-screw melt granulation and process analytical technology that were used in the successful scaling-up and commercial transfer of high drug load (80.5% w/w) immediate release fevipiprant tablets.

SIGNIFICANCE

The unique and compelling learnings from this industry work are (1) insights into Novartis AG's commercial scale transfer using twin-screw melt granulation (2) rapid, non-destructive NIR methodology as a PAT tool for RTR testing. No prior literature combines these two aspects at the level of detail we present/disclose.

METHODS

Scaling up of twin-screw melt granulation (TSMG) was guided by specific energy values obtained for the 27 mm (pilot scale) and 50 mm (commercial scale) twin-screw extruders (TSE). Proven acceptable ranges (PAR) were confirmed by varying the critical process parameters (CPPs) for granulation (screw speed) and tableting (dwell time, crushing strength) at three process levels (upper, target, lower). An at-line NIR method was developed and validated for real-time release testing.

RESULTS

The combination of CPPs were selected to have the same effect on critical quality attributes (CQAs) i.e., lower (-) and upper (+) process level challenged tablet aspect/appearance and dissolution, respectively. TSMG was performed using a 50 mm extruder at constant feed rate. Compression of the six final blends (∼300 kg) showed no impact of varied granulation and compression process conditions on both CQAs. A near-infrared spectroscopy method was validated to determine content uniformity, assay, identity, and to predict CQAs on uncoated tablets in preparation for a real time release testing (RTRT) of future batches.

Metformin hydrochloride entrapment in sorbitan monostearate for intestinal permeability enhancement and pharmacodynamics

Penetration enhancement of metformin hydrochloride via its molecular dispersion in sorbitan monostearate microparticles is reported. This represents basic philosophy to maximize its entrapment for maximum penetration effect. Drug dispersion in sorbitan monostearate with different theoretical drug contents (TDC) were prepared. Products showed excellent micromeritics and actual drug content (ADC) increased by increasing TDC. The partition coefficient of the drug products showed huge improvement. This indicates the drug entrapped in the polar part of sorbitan monostearate as a special image which effects on the drug release. The drug permeation profiles from the different products are overlapped with nearly equal permeation parameters. The permeation results suggested the main driving force for improving the drug paracellular pathway is its dispersion in sorbitan monostearate and is independent of ADC. Pharmacodynamic of the products showed a significant improvement than the drug alone at p ˂ 0.05. ANOVA test indicated the insignificant pharmacodynamic difference between the low, middle, and high ADC of the products. An excellent correlation founded between the drug permeation and pharmacodynamic precents. Drug permeation driving force via the paracellular pathway is its entrapment in sorbitan monostearate and independent on ADC. The technique is simple and the products had excellent micromeritics.