Bottom-up production of injectable itraconazole suspensions using membrane technology.

Bottom-up production of active pharmaceutical ingredient (API) crystal suspensions offers advantages in surface property control and operational ease over top-down methods. However, downstream separation and concentration pose challenges. This proof-of-concept study explores membrane diafiltration as a comprehensive solution for downstream processing of API crystal suspensions produced via anti-solvent crystallization. It involves switching the residual solvent (N-methyl-2-pyrrolidone, NMP) with water, adjusting the excipient (d-α-Tocopherol polyethylene glycol 1000 succinate, TPGS) quantity, and enhancing API loading (solid concentration) in itraconazole crystal suspensions. NMP concentration was decreased from 9 wt% to below 0.05 wt% (in compliance with European Medicine Agency guidelines), while the TPGS concentration was decreased from 0.475 wt% to 0.07 wt%. This reduced the TPGS-to-itraconazole ratio from 1:2 to less than 1:50 and raised the itraconazole loading from 1 wt% to 35.6 wt%. Importantly, these changes did not adversely affect the itraconazole crystal stability in suspension. This study presents membrane diafiltration as a one-step solution to address downstream challenges in bottom-up API crystal suspension production. These findings contribute to optimizing pharmaceutical manufacturing processes and hold promise for advancing the development of long-acting API crystal suspensions via bottom-up production techniques at a commercial scale.

Continuous Microfluidic Antisolvent Crystallization as a Bottom-Up Solution for the Development of Long-Acting Injectable Formulations.

A bottom-up approach was investigated to produce long-acting injectable (LAI) suspension-based formulations to overcome specific limitations of top-down manufacturing methods by tailoring drug characteristics while making the methods more sustainable and cost-efficient. A Secoya microfluidic crystallization technology-based continuous liquid antisolvent crystallization (SCT-CLASC) process was optimized and afterward compared to an earlier developed microchannel reactor-based continuous liquid antisolvent crystallization (MCR-CLASC) setup, using itraconazole (ITZ) as the model drug. After operating parameter optimization and downstream processing (i.e., concentrating the suspensions), stable microsuspensions were generated with a final solid loading of 300 mg ITZ/g suspension. The optimized post-precipitation feed suspension consisted of 40 mg ITZ/g suspension with a drug-to-excipient ratio of 53:1. Compared to the MCR-CLASC setup, where the post-precipitation feed suspensions contained 10 mg ITZ/g suspension and had a drug-to-excipient ratio of 2:1, a higher drug concentration and lower excipient use were successfully achieved to produce LAI microsuspensions using the SCT-CLASC setup. To ensure stability during drug crystallization and storage, the suspensions' quality was monitored for particle size distribution (PSD), solid-state form, and particle morphology. The PSD of the ITZ crystals in suspension was maintained within the target range of 1-10 µm, while the crystals displayed an elongated plate-shaped morphology and the solid state was confirmed to be form I, which is the most thermodynamically stable form of ITZ. In conclusion, this work lays the foundation for the SCT-CLASC process as an energy-efficient, robust, and reproducible bottom-up approach for the manufacture of LAI microsuspensions using ITZ at an industrial scale.

Tailoring the use of excipients in bottom-up production of naproxen crystal suspensions via membrane technology.

Long-acting crystal suspensions of active pharmaceutical ingredients (API) mostly comprised of an API, a suspension media (water) and excipients and provide sustained API release over time. Excipients are crucial for controlling particle size and to achieve the stability of the API crystals in suspension. A bottom-up process was designed to produce long-acting crystal suspensions whilst investigating the excipient requirements during the production process and the subsequent storage. PVP K30 emerged as the most effective excipient for generating stable naproxen crystals with the desired size of 1 to 15 µm, using ethanol as solvent and water as anti-solvent. Calculations, performed based on the crystal properties and assuming complete PVP K30 adsorption on the crystal surface, revealed lower PVP K30 requirements during storage compared to initial crystal generation. Consequently, a membrane-based diafiltration process was used to determine and fine-tune PVP K30 concentration in the suspension post-crystallization. A seven-stage diafiltration process removed 98 % of the PVP K30 present in the suspension thereby reducing the PVP-to-naproxen ratio from 1:2 to 1:39 without impacting the stability of naproxen crystals in suspension. This work provides insights into the excipient requirements at various production stages and introduce the membrane-based diafiltration for precise excipient control after crystallization.

Development of long-acting injectable suspensions by continuous antisolvent crystallization: An integrated bottom-up process.

Our present work elucidated the operational feasibility of direct generation and stabilization of long-acting injectable (LAI) suspensions of a practically insoluble drug, itraconazole (ITZ), by combining continuous liquid antisolvent crystallization with downstream processing (i.e., centrifugal filtration and reconstitution). A novel microchannel reactor-based bottom-up crystallization setup was assembled and optimized for the continuous production of micro-suspension. Based upon the solvent screening and solubility study, N-methyl pyrrolidone (NMP) was selected as the optimal solvent and an impinging jet Y-shaped microchannel reactor (MCR) was selected as the fluidic device to provide a reproducible homogenous mixing environment. Operating parameters such as solvent to antisolvent ratio (S/AS), total jet liquid flow rates (TFRs), ITZ feed solution concentration and the maturation time in spiral tubing were tailored to 1:9 v/v, 50 mL/min, 10 g/100 g solution, and 96 h, respectively. Vitamin E TPGS (0.5% w/w) was found to be the most suitable excipient to stabilize ITZ particles amongst 14 commonly used stabilizers screened. The effect of scaling up from 25 mL to 15 L was evaluated effectively with in situ monitoring of particle size distribution (PSD) and solid-state form. Thereafter, the suspension was subjected to centrifugal filtration to remove excess solvent and increase ITZ solid fraction. As an alternative, an even more concentrated wet pellet was reconstituted with an aqueous solution of 0.5% w/w Vitamin E TPGS as resuspending agent. The ITZ LAI suspension (of 300 mg/mL solid concentration) has the optimal PSD with a D10 of 1.1 ± 0.3 µm, a D50 of 3.53 ± 0.4 µm and a D90 of 6.5 ± 0.8 µm, corroborated by scanning electron microscopy (SEM), as remained stable after 548 days of storage at 25 °C. Finally, in vitro release methods using Dialyzer, dialysis membrane sac were investigated for evaluation of dissolution of ITZ LAI suspensions. The framework presented in this manuscript provides a useful guidance for development of LAI suspensions by an integrated bottom-up approach using ITZ as model API.

(E,E)-N-(2,3,4,5,6-Penta-fluoro-benzyl-idene)-N-(3,4,5-trimeth-oxy-benzyl-idene)benzene-1,4-diamine.

The title compound, C(23)H(17)F(5)N(2)O(3), forms a layered centrosymmetric crystal structure in which C-H⋯F inter-actions are responsible for the formation of planar ribbons along [110], meth-oxy-meth-oxy (C-H⋯O) inter-actions for the formation of layers parallel to [[Formula: see text]13], and OCH(3)⋯π and C-F⋯π inter-actions for the stacking of these layers.

(E)-4-[2-(3,4,5-trimethoxyphenyl)ethenyl]nitrobenzene and its 'bridge-flipped' analogues.

The solid-state structures of three push-pull acceptor-π-donor (A-π-D) systems differing only in the nature of the π-spacer have been determined. (E)-1-Nitro-4-[2-(3,4,5-trimethoxyphenyl)ethenyl]benzene, C(17)H(17)NO(5), (I), and its 'bridge-flipped' imine analogues, (E)-3,4,5-trimethoxy-N-(4-nitrobenzylidene)aniline, C(16)H(16)N(2)O(5), (II), and (E)-4-nitro-N-(3,4,5-trimethoxybenzylidene)aniline, C(16)H(16)N(2)O(5), (III), display different kinds of supramolecular networks, viz. corrugated planes, a herringbone pattern and a layered structure, respectively, all with zero overall dipole moments. Only (III) crystallizes in a noncentrosymmetric space group (P2(1)2(1)2(1)) and is, therefore, a potential material for second-harmonic generation (SHG).

4,4'-Bis[2-(3,5-dimeth-oxy-phen-yl)ethen-yl]biphen-yl.

The title compound, C(32)H(30)O(4), crystallizes with three different conformers of the same mol-ecule in the asymmetric unit, which explains the unusually large unit cell volume. The supra-molecular structure is based on inter-actions involving the meth-oxy groups [C⋯O contacts between 3.090 (2) and 3.204 (2) Å, and C-H⋯O contacts between (normalized) 2.40 and 2.71 Å], π-π stacking of the electron-rich meth-oxy-substituted rings [centroid-centroid distances of 3.6454 (9)-3.738 (1) Å] and C-H⋯π contacts (normalized, 2.62-2.97Å).

Conformational polymorphism of (E,E)-N,N'-bis(4-nitrobenzylidene)benzene-1,4-diamine.

Two polymorphs of (E,E)-N,N'-bis(4-nitrobenzylidene)benzene-1,4-diamine, C(20)H(14)N(4)O(4), (I), have been identified. In each case, the molecule lies across a crystallographic inversion centre. The supramolecular structure of the first polymorph, (I-1), features stacking based on π-π interactions assisted by weak hydrogen bonds involving the nitro groups. The second polymorph, (I-2), displays a perpendicular arrangement of molecules linked via the nitro groups, combined with weak C-H···O hydrogen bonds. Both crystal structures are compared with that of the carbon analogue (E,E)-1,4-bis[2-(4-nitrophenyl)ethenyl]benzene, (II).

Dynamic disorder in the crystal structure of an organic semiconductor: an unusual phase transition involving the heat capacity.

(E,E)-1-[2-(4-Nitrophenyl)ethenyl]-4-[2-(2,4-dimethoxyphenyl)ethenyl]benzene was characterised by X-ray diffraction and shown to be dynamically disordered at room temperature. The structure was re-determined over a range of temperatures to infer the thermodynamic parameters related to this disorder. A phase transition of third order according to the Ehrenfest classification scheme was discovered. To the best of our knowledge, this is the first experimentally observed phase transition of formal third order. It can be explained by the involvement of long-range lattice vibrations.

Synthesis and structures of substituted triphenyl(phenylimino)phosphoranes.

Three substituted triphenyl(phenylimino)phosphoranes, namely (4-cyanophenylimino)triphenylphosphorane, C(25)H(19)N(2)P, (I), (4-nitrophenylimino)triphenylphosphorane, C(24)H(19)N(2)O(2)P, (II), and (3-nitrophenylimino)triphenylphosphorane, C(24)H(19)N(2)O(2)P, (III), were synthesized as precursors for the preparation of substituted diphenylcarbodiimides. All three compounds display a supramolecular arrangement in which the substituted benzene rings are organized in an antiparallel fashion. The nitro group on the ring participates in C-H...O and O...pi interactions, forming intermolecular dimers. Compound (III) shows disorder which involves the rotation of one of the phenyl rings of the triphenylphosphine group.

(E)-1-(2,4,6-Trimeth-oxy-phen-yl)pent-1-en-3-one.

The title compound, C(14)H(18)O(4), was obtained unintentionally as the major product of an attempted synthesis of (E,E)-2,5-bis-[2-(2,4,6-trimeth-oxy-phen-yl)ethen-yl]pyrazine. The crystal packing features layers based on two weak C-H⋯O hydrogen bonds involving the O atom of the carbonyl group and two O(meth-oxy)⋯C(meth-oxy) inter-actions [3.109 (2) Å]. The sheets are inter-connected via meth-oxy-meth-oxy dimers and C-H⋯π inter-actions.

3-(2-Formyl-phen-oxy)propanoic acid.

In the structure of the title compound, C(10)H(10)O(4), the carboxyl group forms a catemer motif in the [100] direction instead of the expected dimeric structures. The carboxylic acid group is found in the syn conformation and the three-dimensional organization in the crystal is based on C-H⋯O and O-H⋯O interactions.

4-[(E)-2-(2,4,6-Trinitro-phenyl)ethyl-idene]benzonitrile.

In the crystal of the title compound, C(15)H(8)N(4)O(6), the mol-ecules are organized in layers due to their linkage by weak C-H⋯N hydrogen bonds. The layers are themselves inter-connected by weak C-H⋯O hydrogen bonds and π-π inter-actions [centroid-centroid distances = 3.8690 (15) and 3.9017 (16) Å]. The dihedral angle between the rings is 31.9 (1)°.

2-(4-Formyl-2,6-dimeth-oxy-phenoxy)-acetic acid.

In the title compound, C(11)H(12)O(6), the aldehyde group is disordered over two sites in a 0.79:0.21 ratio. The carb-oxy-lic acid chain is found in the [ap,ap] conformation due to two intramolecular O-H⋯O hydrogen bonds.