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Drug Substance and Excipient Characterization
Published in Dilip M. Parikh, Handbook of Pharmaceutical Granulation Technology, 2021
Parind M. Desai, Lai Wah Chan, Paul Wan Sia Heng
X-ray diffractometry may be carried out using a powder x-ray or a single crystal diffractometer. The latter is used to elucidate the crystal structure while the powder x-ray diffractometer is for general purpose. The polymorphs of material have different crystal packing arrangements and thus produce different x-ray diffractograms with characteristic peaks that are related to lattice distances (Figure 3.8a). The extent of conversion of a crystalline drug to the amorphous form during processing can be determined by comparing the magnitude of their characteristic peaks [47]. The sharp peaks (Figure 3.8a) indicate a crystalline component, whereas broad diffraction peak or features (also referred to as “halo”) indicate an amorphous component (Figure 3.8b). The powder x-ray diffractometry method is non-destructive and requires a very small sample of the material, which can be examined without further processing. For structural determination, good single crystals are used in a single crystal diffractometer. Synchrotron sources have been employed to obtain high-resolution electron diffraction patterns for very small crystals or crystals of complex compounds. Very sensitive charge-coupled detectors have enabled electron diffraction patterns to be recorded in a few seconds using very low electron currents. In addition, microdiffractometers with 2D area detectors have been developed for quick data acquisition [48].
Nanosuspensions as Nanomedicine: Current Status and Future Prospects
Published in Debarshi Kar Mahapatra, Sanjay Kumar Bharti, Medicinal Chemistry with Pharmaceutical Product Development, 2019
Shobha Ubgade, Vaishali Kilor, Abhay Ittadwar, Alok Ubgade
Mean particle size and polydispersity index (PI) is an essential characteristic parameter of nanosuspensions since it affects the saturation solubility, dissolution velocity, physical stability, and biological performance. It is determined by photon correlation spectroscopy (PCS). The mean particle diameter of nanosuspension can be determined rapidly and accurately using PCS. The wide particle size distribution, also known as polydispersity index can also be measured using PCS. The PI for nanosuspension should be as low as possible for long-term stability of the formulation. The PI value of 0.1–0.25 indicates a fairly narrow size distribution whereas a PI value greater than 0.5 indicates a very broad distribution. The measuring range of PCS is limited to approximately 3 nm–3 μm. Therefore, additionally laser diffractometry (LD) is used to detect any content of particles in the micrometer range or aggregates of drug nanoparticles. Laser diffractometry yields a volume size distribution and can be used to measure particles ranging from 0.05–80 μm and in certain instruments particle sizes up to 2000 μm can be measured. The typical LD characterization includes determination of diameter 50% LD [50] and diameter 99% LD [99] values, which indicate that either 50 or 99% of the particles are below the indicated size. Nanosuspensions meant for parenteral or pulmonary delivery should be analyzed by LD to minimize the risk of capillary blockade or emboli formation associated with particles having the size greater than 5–6 μm. Data obtained from these two techniques are not the same because LD data are volume based and the PCS mean diameter is the light intensity weighted size. The nanosuspensions can be suitably diluted with deionized water before carrying out PCS or LD analysis [22, 24]. Coulter counter technique is much more efficient technique than LD for particle size analysis as it helps in accurate quantification of microparticulate drug content. It is used in case of intravenous administration of nanosuspension and gives an absolute number of particles per volume unit for the different size of classes [22].
Fabrication and transplantation of chitosan-selenium biodegradable nanocomposite conduit on transected sciatic nerve: a novel study in rat model
Published in Neurological Research, 2020
Salar Dolkhani, Alireza Najafpour, Rahim Mohammadi
The structural characterization and size of selenium nanoparticles were studied using Field Emission Scanning Electron Microscope (FESEM) and Transmission Electron Microscope (TEM). In order to study the interaction between nanoparticles and polymer, fourier transform infrared spectrophotometry (FTIR) (Shimadzu, FTIR-8400) analysis was conducted to verify the occurrence of chemical bonds between the drug and the polymer. The samples were scanned in the IR range from 500 to 4000 cm−1 and carbon black was used as a reference. The detector was purged carefully with clean dry helium gas to increase the signal level and reduce moisture (Figure 1). Philips diffractometer was used to obtain X-ray diffraction pattern. X-ray diffraction (XRD) patterns were acquired from 2θ = 10° to 80° using Cu Kα1 radiation. Transmission electron microscope (Philips ES 30 KW0 was used to determine size of nanoparticles. The size distribution of the nanoparticles was detected through Zetasizer Nano ZS (Malvern Instruments Limited)) particle analyzer.
Feasibility of electrospray deposition for rapid screening of the cocrystal formation and single step, continuous production of pharmaceutical nanococrystals
Published in Drug Development and Industrial Pharmacy, 2018
Shahram Emami, Mohammadreza Siahi-Shadbad, Mohammad Barzegar-Jalali, Khosro Adibkia
PXRD was used to identify crystalline phases and as a qualitative indicator of crystallinity of samples. Patterns were recorded at room temperature using a Bruker D8 Advance diffractometer (Bruker, Karlsruhe, Germany) at an accelerating voltage of 40 kV and the current of 40 mA with CuKα source radiation (λ = 1.540598 Å). Powder samples were placed onto a glass plate surface and scanned from 10° to 45° (2θ) at a 2°/min scanning rate (step size of 0.02°, 1 s time per step). The diffractometer was calibrated with lanthanum hexaboride standard. Data management was performed in the X’Pert High Score Plus software package (Version 2.2b, PANalytical Inc., Almelo, Netherlands). Calculated PXRD patterns of cocrystals were generated by Mercury software (Version 3.8, Cambridge, UK)) from the crystallographic information files (CIF) that have been deposited on Cambridge Crystallographic Data Centre (CCDC) for IMC-SAC (CCDC number 639251), NPX-NIC (CCDC number 904098) and NPX-INA (CCDC number 815241) cocrystals.
Synergistic co-delivery of doxorubicin and melittin using functionalized magnetic nanoparticles for cancer treatment: loading and in vitro release study by LC–MS/MS
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Marjan Hematyar, Majid Soleimani, Ali Es-haghi, Ali Rezaei Mokarram
X-ray diffraction studies were carried out by a Bruker D8 Discover diffractometer (Bruker, Rheinstetten, Germany). Transmission electron microscopy (TEM) was performed by a 300 kV Philips CM30 (Philips, Amsterdam, Netherlands), field emission scanning electron microscopy (FESEM) was carried out by MIRA3 TESCAN-XMU (Brno, Czech Republic), Infra-red spectra were recorded with an FTIR spectrometer (Bruker, Rheinstetten, Germany). Zeta potential and hydrodynamic size were measured by Zetasizer 3000HSA (Malvern Instruments, Malvern, UK). The magnetic properties were evaluated with a vibrating sample magnetometer (Meghnatis Daghigh Kavir, Kashan, Iran).