| 1. |
- Ahmed, Hamzah, et al.
(författare)
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Relationship between mechanical properties and crystal structure in cocrystals and salt of paracetamol
- 2017
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Ingår i: Drug Development and Industrial Pharmacy. - : Taylor & Francis. - 0363-9045 .- 1520-5762. ; 43:1, s. 89-97
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Tidskriftsartikel (refereegranskat)abstract
- Objectives were to study mechanical properties of various solid forms of paracetamol and relate to their crystal structures. Paracetamol Form I (PRA), its cocrystals with oxalic acid (PRA-OXA) and 4,4-bipyridine (PRA-BPY) and hydrochloride salt (PRA-HCL) were selected. Cocrystals and salt were scaled-up using rational crystallization methods. The resulting materials were subjected to differential scanning solid-state characterization. The powders were sieved and 90-360 µm sieve fraction was considered. These powders were examined by scanning electron microscopy (SEM) and densities were determined. Tablets were made at applied pressures of 35-180 MPa under controlled conditions and the tablet height, diameter and hardness were measured. Tensile strength and porosity of the tablets were estimated using well known models. Crystal structures of these systems were visualized and slips planed were identified. Cocrystal and salt of PRA were physically pure. Sieved powders had comparable morphologies and particle size. The apparent and theoretical densities of powders were similar but no clear trends were observed. The tensile strengths of these compacts were increased with increasing pressure whereas tabletability decreased in the order oxalic acid > PRA-HCL ≈ PRA-OXA > BPY > PRA-BPY. Tablet tensile strength decreases exponentially with increasing porosity with the exception of PRY-BPY and BPY. Slip plane prediction based on attachment energies may not be independently considered. However, it was possible to explain the improved mechanical properties of powders based on the crystal structure. Cocrystallization and salt formation have introduced structural features that are responsible for improved tableting properties of PRA.
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| 2. |
- Al-Hayali, Amani Ibraheem Younis, et al.
(författare)
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Dissolution and precipitation behavior of ternary solid dispersions of Ezetimibe in biorelevant media : AAPS annual meeting and Exposition2014 USA
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- PurposeTo prepare ternary solid dispersions of Ezetimibe (EZ) and investigate their powder dissolution and precipitation behavior(supersaturation) in simulated gastric and intestinal fluidsMethodsTernary solid dispersions of EZ were prepared with PVPK30 and Poloxamer 188 at different ratios. Spray drying and meltquenching methods were used for the preparation of these solid dispersions. The solid dispersions were characterized bybasic to advanced solid-state tools including Modulated differential scanning calorimetry (MDSC), Powder X-ray diffractionand Fourier transform infrared spectroscopy .Biorelevant simulated media (FaSSIF pH 6.5 and FaSSGF pH1.6) were used tostudy the supersaturating solubility of the ternary solid dispersions. HPLC was used to determine the drug concentrationsResultsTernary solid dispersions were successfully prepared by spray drying and melt quench methods. All prepared soliddispersions showed broadening of the XRD peaks indicating amorphous nature. MDSC analysis revealed disappearance ofthe melting peak of Ezetimibe indicating that molecular dispersion of the drug in polymer matrix. The solid dispersions withhigher PVPK30 content showed single Tg at 158.54 °C (spray drying) and 169.32 °C (melt quench). About 10 folds increasein the apparent solubility was observed for solid dispersions prepared by both methods. However, melt quenched soliddispersions had maintained the supersaturation solubility in FaSSIF longer than spray dried solid dispersions. Dissolutionstudies in FaSSGF are ongoingConclusionAmorphous ternary solid dispersions of Ezetimibe containing PVP K30 and Poloxamer 188 could be prepared by spraydrying and melt quenching methods. These solid dispersions showed improved solubility and prolonged supersaturation inbiorelevant media
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| 3. |
- Al-Hayali, Amani Ibraheem Younis, et al.
(författare)
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Dissolution and precipitation behavior of ternary solid dispersions of ezetimibe in biorelevant media
- 2017
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Ingår i: Drug Development and Industrial Pharmacy. - : Informa UK Limited. - 0363-9045 .- 1520-5762. ; 43:1, s. 79-88
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Tidskriftsartikel (refereegranskat)abstract
- The effects of different formulations and processes on inducing and maintaining the supersaturation of ternary solid dispersions of ezetimibe (EZ) in two biorelevant media fasted-state simulated intestinal fluid (FaSSIF) and fasted-state simulated gastric fluid (FaSSGF) at different temperatures (25 °C and 37 °C) were investigated in this work.Ternary solid dispersions of EZ were prepared by adding polymer PVP-K30 and surfactant poloxamer 188 using melt-quenching and spray-drying methods. The resulting solid dispersions were characterized using scanning electron microscopy, differential scanning calorimetry (DSC), modulated DSC, powder X-ray diffraction and Fourier transformation infrared spectroscopy. The dissolution of all the ternary solid dispersions was tested in vitro under non-sink conditions.All the prepared solid dispersions were amorphous in nature. In FaSSIF at 25 °C, the melt-quenched (MQ) solid dispersions of EZ were more soluble than the spray-dried (SD) solid dispersions and supersaturation was maintained. However, at 37 °C, rapid and variable precipitation behavior was observed for all the MQ and SD formulations. In FaSSGF, the melting method resulted in better solubility than the spray-drying method at both temperatures.Ternary solid dispersions show potential for improving solubility and supersaturation. However, powder dissolution experiments of these solid dispersions of EZ at 25 °C may not predict the supersaturation behavior at physiologically relevant temperatures.
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| 4. |
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| 5. |
- Alhalaweh, Amjad, et al.
(författare)
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1:1 and 2:1 urea-succinic acid cocrystals : structural diversity, solution chemistry, and thermodynamic stability
- 2010
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 10:11, s. 4847-4855
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to study the crystal structures of 1:1 and 2:1 urea-succinic acid (U-SA) cocrystals and to investigate the role of solution chemistry in the formation and stability of different stoichiometric cocrystals. The structural diversity of other urea-dicarboxylic acid cocrystals is also discussed. The 1:1 U-SA cocrystal was stabilized by an acid-amide heterosynthon while acid-amide heterosynthons and amide-amide homosynthons stabilized the 2:1 cocrystals. The hydrogen bonding motifs in 1:1 and 2:1 U-SA cocrystals were consistent with other urea-dicarboxylic acid systems with similar stoichiometries. The 1:1 cocrystals were transformed to 2:1 cocrystals upon slurrying in various solvents at 25 °C. The phase solubility diagram was used to define the stability regions of different solid phases in 2-propanol at 25 °C. While no phase stability region for 1:1 cocrystal could be found, the stable regions for the 2:1 cocrystals and their pure components were defined by eutectic points. The solubility of the 2:1 cocrystals was dependent on the concentration of the ligand in the solution and explained by the solubility product and 1:1 solution complexation. The mathematical models predicting the solubility of the 2:1 cocrystals were evaluated and found to fit the experimental data
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| 6. |
- Alhalaweh, Amjad, et al.
(författare)
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Effects of polymer and surfactant on the dissolution and transformation profiles of cocrystals in aqueous media
- 2014
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 14:2, s. 643-648
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Tidskriftsartikel (refereegranskat)abstract
- Capturing solubility advantages of cocrystals is of great interest, and thus to understand the mechanism by which different excipients could maintain the supersaturation generated by cocrystals at the course of absorption in aqueous media is essential. To achieve this aim, the impact of different excipients on dissolution behavior of indomethacin-saccharin (IND-SAC) were monitored by measuring the concentrations of cocrystal components in the absence and presence of various concentration of excipients by HPLC, and solid phases were analyzed by differential scanning calorimetry after each experiment and the potential of Raman spectroscopy for monitoring phase transformations in situ was tested. No dissolution advantage was offered by cocrystals in the absence of any solution additive. The polymer and surfactant used in the study increased the solubility of IND but not SAC. This differential solubilization effect is believed to have stabilized the cocrystals for a relevant period for the absorption to take place. This could be attributed to either decreased gap between supersaturation and saturation of the drug or drug interaction with the additives. Understanding the effects of excipients type and concentration on the transformation profile is vital for designing enabling formulations for cocrystals. The eutectic constant may be useful in selecting excipients for stabilizing cocrystals.
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| 7. |
- Alhalaweh, Amjad, et al.
(författare)
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Formation of cocrystals by spray drying
- 2010
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Ingår i: Journal of Pharmacy and Pharmacology (JPP). - : Oxford University Press (OUP). - 0022-3573 .- 2042-7158. ; 62:10 - Special issue, s. 1332-1333
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Spray drying is a widely used technique for material processing and scale-up. The cocrystals formation by spray drying is studied. In contrast to solvent evaporation method, spray drying of stiochiometric solutions of incongruently saturating cocrystals had generated pure cocrystals. The formation phenomena in spray drying could be kinetically controlled or mediated by glassy state.
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| 8. |
- Alhalaweh, Amjad, et al.
(författare)
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Formation of cocrystals from stoichiometric solutions of incongruently saturating systems by spray drying
- 2010
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 10:8, s. 3302-3305
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Tidskriftsartikel (refereegranskat)abstract
- Spray drying is a well established technique for material processing and scale-up. This study investigated the formation of pharmaceutical cocrystals by spray drying. The cocrystal formation mechanisms in spray-drying and solution methods, based on triangular phase diagrams, are discussed. The solvent evaporation of stoichiometric solutions of incongruently saturating cocrystals resulted in a mixture of phases, as dictated by the thermodynamic phase diagram. In contrast, spray drying of similar solutions of incongruently saturating systems generated pure cocrystals. It is thus suggested that the formation of cocrystals by spray drying could be kinetically controlled and/or mediated by the glassy state of the material.
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| 9. |
- Alhalaweh, Amjad, et al.
(författare)
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pH-dependent solubility of indomethacin-saccharin and carbamazepine-saccharin cocrystals in aqueous media
- 2012
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Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 9:9, s. 2605-2612
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Tidskriftsartikel (refereegranskat)abstract
- Cocrystals constitute an important class of pharmaceutical solids for their remarkable ability to modulate solubility and pH dependence of water insoluble drugs. Here we show how cocrystals of indomethacin-saccharin (IND-SAC) and carbamazepine-saccharin (CBZ-SAC) enhance solubility and impart a pH-sensitivity different from that of the drugs. IND-SAC exhibited solubilities 13 to 65 times higher than IND at pH values of 1 to 3, whereas CBZ-SAC exhibited a 2 to 10 times higher solubility than CBZ dihydrate. Cocrystal solubility dependence on pH predicted from mathematical models using cocrystal K(sp), and cocrystal component K(a) values, was in excellent agreement with experimental measurements. The cocrystal solubility increase relative to drug was predicted to reach a limiting value for a cocrystal with two acidic components. This limiting value is determined by the ionization constants of cocrystal components. Eutectic constants are shown to be meaningful indicators of cocrystal solubility and its pH dependence. The two contributions to solubility, cocrystal lattice and solvation, were evaluated by thermal and solubility determinations. The results show that solvation is the main barrier for the aqueous solubility of these drugs and their cocrystals, which are orders of magnitude higher than their lattice barriers. Cocrystal increase in solubility is thus a result of decreasing the solvation barrier compared to that of the drug. This work demonstrates the favorable properties of cocrystals and strategies that facilitate their meaningful characterization.
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| 10. |
- Alhalaweh, Amjad, et al.
(författare)
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Pharmaceutical cocrystals of nitrofurantoin : Screening, characterization and crystal structure analysis
- 2012
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033 .- 1466-8033. ; 14:15, s. 5078-5088
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to screen and prepare cocrystals of the poorly soluble drug nitrofurantoin (NTF) with the aim of increasing its solubility. Screening for cocrystals of NTF using 47 coformers was performed by high-throughput (HT) screening using liquid assisted grinding (LAG) methods. Raman spectroscopy and powder X-ray diffraction (PXRD) were used as the primary analytical tools to identify the new crystalline solid forms. Manual LAG and reaction crystallization (RC) experiments were carried out to confirm and scale-up the hits. Seven hits were confirmed to be cocrystals. The cocrystals were characterized by PXRD, Raman and IR spectroscopy, thermal analysis (DSC and TGA) and liquid-state NMR or elemental analysis. The solution stability of the scaled-up cocrystals in water was tested by slurrying the cocrystals at 25 °C for one week. NTF forms cocrystals with a 1:1 stoichiometric ratio with urea (1), 4-hydroxybenzoic acid (2), nicotinamide (3), citric acid (4), l-proline (5) and vanillic acid (6). In addition, NTF forms a 1:2 cocrystal with vanillin (7). All but one of the NTF cocrystals transformed (dissociated) in water, resulting in NTF hydrate crystalline material or NTF hydrate plus the coformer, which indicates that the transforming cocrystals have a higher solubility than the NTF hydrate under these conditions. The crystal structures of 1:1 NTF-citric acid (4) and 1:2 NTF-vanillin (7) were solved by single-crystal X-ray diffraction. The crystal structures of these two cocrystals were analyzed in terms of their supramolecular synthons.
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