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As vixotrigine (1) entered a later clinical phase for trigeminal neuralgia (Zakrzewska, J. M.; et al. Lancet Neurol. 2017, 16, 291−300), the development of a sustainable late-stage process was requ...

To utilize a particle engineering strategy to improve the manufacturability of a cohesive and poorly compactable API at high drug loading for direct compression of mini-tablets.A high-shear mixer was used for wet milling during the API manufacturing process to obtain target particle size distributions. The targeted particles were characterized and formulated into blends by mixing with excipients. The formulated blends were compressed directly into mini-tablets using a compaction simulator. The tablet hardness, weight variation, and friability of the mini-tablets were characterized and compared with mini-tablets prepared with hammer milled APIs.Compared to the hammer milled APIs, the wet milled APIs, had smoother surface, narrower particle size distributions and demonstrated a better flow properties. Moreover, the mini-tablets produced with the wet milled APIs exhibited better weight uniformity, robust tablet mechanical strength and ultimately better friability. In addition, unlike the hammer milled process, the wet milling process is controllable and easy to scale up.This study successfully implemented API particle engineering through a high shear wet milling process to produce particles suitable for robust drug product manufacturing.

The bulk properties of a powder are dependent on the preparation, treatment, and storage of the sample, that is, how it was handled. The particles can be packed to have a range of bulk densities and, moreover, the slightest disturbance of the powder bed may result in a changed bulk density. Thus, the bulk density of a powder is often difficult to measure with good reproducibility and, in reporting the results, it is essential to specify how the determination was made. In this article, we measured the bulk density, tapped density, and calculated the Hausner ratio of commonly used excipients with similar tapped density testers and followed the United States Pharmacopeia 30-National Formulary 25-S1 testing procedure. Based on the analysis, within lot and lot-to-lot variability and the relative errors for bulk density, tapped density, and Hausner ratio were found to be acceptable. Lot-to-lot differences were generally not measurable using this test as they were found to be within the variability of the test. The results also indicated that there was no statistically significant bias between sites for tapped density and Hausner ratio, but there was a marginally significant bias in the bulk density data set.

Appropriate lubrication is important in tablet manufacturing as it lowers punch sticking propensity and protects tooling by reducing friction between die wall and tablet during tablet manufacturing. Most commercial lubricants negatively impact tabletability and dissolution. A delicate balance is usually attained by trial and error to identify the optimal level of lubricant in a tablet formulation. In this work, we have evaluated the effectiveness of sodium lauryl sulfate (SLS), a surfactant, as a tableting lubricant. If adequate lubrication efficiency is achieved, the use of SLS may be suitable to mitigate problems associated with hydrophobic lubricants. Results show that SLS, when applied in the proper amount to typical pharmaceutical powder mixtures, achieved lubrication efficiency comparable to a grade of magnesium stearate (MgSt) without deteriorating tabletability. Moreover, SLS-containing tablets of celecoxib also exhibited improved in vitro dissolution compared to MgSt-containing tablets. The enhancement in dissolution properties was attributed to the improved wetting by the dissolution medium due to the presence of SLS.

We report the crystallization of a metastable small-molecule solvate and the effect of the isolation method on the physical and material properties of the resulting anhydrous material. The anhydrous crystalline products obtained from two different isolation routes using either a temperature-driven form change or a solvent-wash-mediated form change were analyzed by a suite of material-sparing characterization methods probing both physical form and material properties such as particle size distribution and powder flow behavior. The temperature-driven desolvation method was found to be time-consuming and undesirable. A relatively rapid desolvation approach was obtained using an ethyl acetate wash-mediated process. However, this method leads to powder with a broader particle size distribution, poorer flowability, higher interparticulate friction, and lower bulk density compared with the powder obtained by the temperature-driven desolvation process. The direct impact of the method of isolation on the material ...

Optimizing powder flow and compaction properties are critical for ensuring a robust tablet manufacturing process. The impact of flow and compaction properties of the active pharmaceutical ingredient (API) becomes progressively significant for higher drug load formulations, and for scaling up manufacturing processes. This study demonstrated that flow properties of a powder blend can be improved through API particle engineering, without critically impacting blend tabletability at elevated drug loadings. In studying a jet milled API (D 50 = 24 μm) and particle engineered wet milled API (D 50 = 70 μm and 90 μm), flow functions of all API lots were similarly poor despite the vast difference in average particle size ( ff c 4). This finding strays from the common notion that powder flow properties are directly correlated to particle size distribution. Upon adding excipients, however, clear trends in flow functions based on API particle size were observed. Wet milled API blends had a much improved flow function ( ff c > 10) compared with the jet milled API blends. Investigation of the compaction properties of both wet and jet milled powder blends also revealed that both jet and wet milled material produced robust tablets at the drug loadings used. The ability to practically demonstrate this uncommon observation that similarly poor flowing APIs can lead to a marked difference upon blending is important for pharmaceutical development. It is especially important in early phase development during API selection, and is advantageous particularly when material-sparing techniques are utilized.

Lubricants are important for both preserving the tooling of high-speed tablet presses and attaining quality tablets. Magnesium stearate (MgSt) is most commonly used due to its superior lubrication efficiency; however, it can lead to negative effects on tabletability and dissolution. In this study, we have systematically evaluated two poloxamers, P188 and P407, for their suitability as alternative tablet lubricants. For two excipients with different mechanical properties, i.e., microcrystalline cellulose and lactose, both poloxamers exhibit acceptable lubrication efficiency without negatively impacting tabletability. Compared to 1% MgSt, the performance of 2% of both poloxamers in an experimental tablet formulation of ritonavir led to better lubrication, higher tabletability, and enhanced in vitro drug release. Thus, the use of P188 and P407 as alternative tablet lubricants deserves further evaluations.

Multiple unit pellet system(s), MUPS, is one of the most commonly used means for achieving modified drug release through oral administration. MUPS is usually delivered as capsules that contain drug bearing beads coated with a release modulating functional layer. While the routine manufacture of tablets of MUPS by direct compression is highly desired, it is faced with the problem of poor tableting properties or altered drug release behavior due to the rupture of the functional coating layer. The use of a significant amount of cushion material alleviates these problems, but is also challenged with the problem of segregation and reduced drug loading. We hypothesize that top-coating the beads with a layer of highly bonding polymer can enable direct tableting of beads without compromising the functional coating layer and avoid segregation problem. Using functionally coated pyridoxine and caffeine beads, we confirmed that top coating with Polyvinylpyrrolidone sufficiently plasticized with water can enable the preparation of strong tablets at even low compaction pressures. Drug release profiles of tablets are comparable to those of uncompressed beads, indicating negligible amount of damage, if any, to the functional coating layer. In conclusion, it has been demonstrated that top polymer coating may provide a promising universally applicable strategy to realize the goal of delivering MUPS in the form of tablet.

Lack of a conventional quantitative characterization method for filament printability has been recognized as a critical barrier to fused deposition modeling (FDM) 3D printing application. In this study, a small molecule drug, indomethacin, was utilized as a model compound. Polymers with various solubility were mixed with model drug and extruded into filaments using hot melt extrusion method. Thirty-two filaments with or without indomethacin were evaluated by texture analyzer to study the correlation between mechanical properties and the printability. Three different texture analysis methods were utilized and compared, and a parameter "toughness" calculated by stiffness test was identified to quantitatively describe the printability of filaments in the FDM 3D printer. The toughness threshold value of printable filament was defined as a process window of certain FDM printing. This study provides a quantitative way to evaluate and predict filament printability, and it has great potential to be applied to FDM filament development and quality control in the pharmaceutical industry.

Although the bonding area (BA) and bonding strength (BS) interplay is used to explain complex tableting behaviors, it has never been experimentally proven. The purpose of this study is to unambiguously establish the distinct contributions of each by decoupling the contributions from BA and BS. To modulate BA, a Soluplus® powder was compressed into tablets at different temperatures and then broken following equilibration at 25°C. To modulate BS, tablets were equilibrated at different temperatures. To simultaneously modulate BA and BS, both powder compression and tablet breaking test were carried out at different temperatures. Lower tablet tensile strength is observed when the powder is compressed at a lower temperature but broken at 25°C. This is consistent with the increased resistance to polymer deformation at lower temperatures. When equilibrated at different temperatures, the tensile strength of tablets prepared under identical conditions increases with decreasing storage temperature, indicating that BS is higher at a lower temperature. When powder compression and tablet breaking are carried out at the same temperature, the profile with a maximum tensile strength at 4°C is observed due to the BA-BS interplay. By systematically varying temperature during tablet compression and breaking, we have experimentally demonstrated the phenomenon of BA-BS interplay in tableting.

Poor powder tabletability is a common problem that challenges the successful development of high-quality tablet products. Using noncompressible microcrystalline cellulose beads, we demonstrate that surface coating is an effective strategy for modulating tabletability, almost at will, through judicious selection of coating material. This strategy has broad applicability as tabletability of such particles is dictated by the properties of the outermost layer coat regardless the nature of the core. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:2645–2648, 2015

The harmonized monograph on tablet friability test in United States Pharmacopeia (USP), European Pharmacopeia (Pharm. Eur.), and Japanese Pharmacopeia (JP) is designed to assess adequacy of mechanical strength of a batch of tablets. Currently, its potential applications in formulation development have been limited due to the batch requirement that is both labor and material intensive. To this end, we have developed an expedited tablet friability test method, using the existing USP test apparatus. The validity of the expedited friability method is established by showing that the friability data from the expedited method is not statistically different from those from the standard pharmacopeia method using materials of very different mechanical properties, i.e., microcrystalline cellulose and dibasic calcium phosphate dihydrate. Using the expedited friability method, we have shown that the relationship between tablet friability and tablet mechanical strength follows a power law expression. Furthermore, potential applications of this expedited friability test in facilitating systematic and efficient tablet formulation and tooling design are demonstrated with examples.

Granules prepared by the high shear wet granulation (HSWG) process commonly exhibit the problem of overgranulation, a phenomenon characterized by a severe loss of the ability to form adequately strong tablet. We hypothesize that the incorporation of brittle excipients promotes brittle fracture of granules during compaction, thereby improving tablet mechanical strength by increasing bonding area. On this basis, we have examined the effectiveness of incorporating a brittle excipient into a plastic matrix in addressing the overgranulation problem. A complete loss of tabletability is observed for plastic microcrystalline cellulose (MCC) when ≥55% of granulating water was used. The incorporation of a brittle excipient, either lactose or dibasic calcium phosphate (Dical) into the MCC matrix leads to improved tabletability in a concentration-dependent manner, with higher amount of brittle excipient being more effective. For each mixture, tablet tensile strength goes through a minimum as the granulating water increases, for example, 1.4 MPa for the mixture containing 80% of lactose and 2.1 MPa for the mixture containing 80% Dical. These results, along with scanning electron microscope evidence, show that the addition of brittle excipients to an otherwise plastic powder is an effective formulation strategy to address the overgranulation problem in HSWG. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:2434–2440, 2014

Granulation behavior of microcrystalline cellulose (MCC) in the presence of 2.5% polyvinylpyrrolidone (PVP) was system- atically studied. Complex changes in flowability and tabletability of lubricated MCC granules are correlated to changes in intragranular porosity, morphology, surface smoothness, size distribution, and specific surface area (SSA). With 2.5% PVP, the use of 45% granulation water leads to 84% reduction in tablet tensile strength and 76% improvement in powder flow factor. The changes in powder performance are explained by granule densification and surface smoothing. The granulating water level corresponding to the onset of overgranulation, 45%, is significantly lower than the 70% water required for unlubricated MCC granules without PVP. At more than 45% water levels, MCC-PVP granules flow well but cannot be compressed into intact tablets. Such changes in powder performance correspond to the rapid growth into large and dense spheres with smooth surface. Compared with MCC alone, the onset of the phase of fast granule size enlargement occurs at a lower water level when 2.5% PVP is used. Although the use of 2.5% PVP hastens granule nucleation and growth rate, the mechanisms of overgranulation are the same, that is, size enlargement, granule densification, surface smoothing, and particle rounding in both systems. C � 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:207-215, 2014