7 research outputs found
Synthesis of chitosan succinate and chitosan phthalate and their evaluation as suggested matrices in orally administered colon-specific drug delivery systems.
Impiego del chitosano e di suoi derivati in formulazioni a rilascio controllato
Dottorato di ricerca in scienze farmaceutiche. 9. ciclo. Coordinatore D. Spinelli. Tutore V. ZecchiConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal
Stability Study of Etoricoxib a Selective Cyclooxygenase-2 Inhibitor by a New Single and Rapid Reversed Phase HPLC Method
Cyclooxygenase-2 (COX-2) is an enzyme responsible for inflammation and pain. Etoricoxib is the most recent selective (COX-2) inhibitor that has a higher COX-2 selectivity than the other COX-2-selective nonsteroidal anti-inflammatory drugs (NSAIDs), which significantly improves its gastric safety profile. The current therapeutic indications of etoricoxib includes the treatment of several painful conditions, such as osteoarthritis, acute gout, ankylosing spondylitis, and rheumatoid arthritis. To the best of found knowledge, no decent method has been reported that can be used for the routine determination of etoricoxib and additives in pharmaceutical suspensions by a single, rapid and cost-effective run of HPLC, using an UV-Vis detector. Earlier reported methods, such as liquid chromatography-mass spectrometry (LC-MS), high performance thin layer chromatography (HPTLC), capillary zone electrophoresis, and ultra performance liquid chromatography (UPLC), are all tedious and time consuming. A reversed phase high performance liquid chromatography (RP-HPLC) was used as a first reported single run method to achieve developed and validated simultaneous determination for sodium saccharin, vanillin, methyl paraben, etoricoxib, and butyl paraben, in prepared oral suspensions of etoricoxib. Reversed phase column of octadecylsilane (ODS) C18 with isocratic mobile phase containing methanol, and phosphate buffer of pH 6 in a ratio of 70:30 (v/v). Celecoxib is used as an internal standard at a detection wavelength of 215 nm. This method separates the analytes in a total running time less than 13 min. Linearity is obtained in the calibration curve for all analytes with a R2 value of > 0.999. Furthermore, beta-cyclodextrin (β-CD) and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) were added, either alone or combined, to prevent the crystal formation, and any unpleasant taste of etoricoxib in oral formulations. After testing both HP-β-CD and β-CD at 3% w/w for each, the results showed that HP-β-CD is more efficient in preventing the crystal formation of etoricoxib in suspensions at room temperature than β-CD is
Effect on drug concentration in the monomer/cross-linker mixture on the loading levels and the release kinetics of non-steroidal anti-inflammatory drugs from ethylene glycol dimethacrylate cross-linked polyhydroxyethyl methacrylate microspheres
Colloidal Stability of Citrate and Mercaptoacetic Acid Capped Gold Nanoparticles upon Lyophilization: Effect of Capping Ligand Attachment and Type of Cryoprotectants
For
various applications of gold nanotechnology, long-term nanoparticle
stability in solution is a major challenge. Lyophilization (freeze–drying)
is a widely used process to convert labile protein and various colloidal
systems into powder for improved long-term stability. However, the
lyophilization process itself may induce various stresses resulting
in nanoparticle aggregation. Despite a plethora of studies evaluating
lyophilization of proteins, liposomes, and polymeric nanoparticles,
little is known about the stability of gold nanoparticles (GNPs) upon
lyophilization. Herein, the effects of lyophilization and freeze–thaw
cycles on the stability of two types of GNPs: Citrate-capped GNPs
(stabilized via weakly physisorbed citrate ions, Cit-GNPs) and mercaptoacetic
acid-capped GNPs (stabilized via strongly chemisorbed mercaptoacetic
acid, MAA-GNPs) are investigated. Both types of GNPs have similar
core size and effective surface charge as evident from transmission
electron microscopy and zeta potential measurements, respectively.
Plasmon absorption of GNPs and its dependence on nanoparticle aggregation
was employed to follow stability of GNPs in combination with dynamic
light scattering analysis. Plasmon peak broadening index (PPBI) is
proposed herein for the first time to quantify GNPs aggregation using
nonlinear Gaussian fitting of GNPs UV–vis spectra. Our results
indicate that Cit-GNPs aggregate irreversibly upon freeze–thaw
cycles and lyophilization. In contrast, MAA-GNPs exhibits remarkable
stability under the same conditions. Cit-GNPs exhibit no significant
aggregation in the presence of cryoprotectants (molecules that are
typically used to protect labile ingredients during lyophilization)
upon freeze–thaw cycles and lyophilization. The effectiveness
of the cyroprotectants evaluated was on the order of trehalose or
sucrose > sorbitol > mannitol. The ability of cryoprotectants
to prevent
GNPs aggregation was dependent on their chemical structure and their
ability to interact with the GNPs as assessed with zeta potential
analysis
Colloidal Stability of Citrate and Mercaptoacetic Acid Capped Gold Nanoparticles upon Lyophilization: Effect of Capping Ligand Attachment and Type of Cryoprotectants
For
various applications of gold nanotechnology, long-term nanoparticle
stability in solution is a major challenge. Lyophilization (freeze–drying)
is a widely used process to convert labile protein and various colloidal
systems into powder for improved long-term stability. However, the
lyophilization process itself may induce various stresses resulting
in nanoparticle aggregation. Despite a plethora of studies evaluating
lyophilization of proteins, liposomes, and polymeric nanoparticles,
little is known about the stability of gold nanoparticles (GNPs) upon
lyophilization. Herein, the effects of lyophilization and freeze–thaw
cycles on the stability of two types of GNPs: Citrate-capped GNPs
(stabilized via weakly physisorbed citrate ions, Cit-GNPs) and mercaptoacetic
acid-capped GNPs (stabilized via strongly chemisorbed mercaptoacetic
acid, MAA-GNPs) are investigated. Both types of GNPs have similar
core size and effective surface charge as evident from transmission
electron microscopy and zeta potential measurements, respectively.
Plasmon absorption of GNPs and its dependence on nanoparticle aggregation
was employed to follow stability of GNPs in combination with dynamic
light scattering analysis. Plasmon peak broadening index (PPBI) is
proposed herein for the first time to quantify GNPs aggregation using
nonlinear Gaussian fitting of GNPs UV–vis spectra. Our results
indicate that Cit-GNPs aggregate irreversibly upon freeze–thaw
cycles and lyophilization. In contrast, MAA-GNPs exhibits remarkable
stability under the same conditions. Cit-GNPs exhibit no significant
aggregation in the presence of cryoprotectants (molecules that are
typically used to protect labile ingredients during lyophilization)
upon freeze–thaw cycles and lyophilization. The effectiveness
of the cyroprotectants evaluated was on the order of trehalose or
sucrose > sorbitol > mannitol. The ability of cryoprotectants
to prevent
GNPs aggregation was dependent on their chemical structure and their
ability to interact with the GNPs as assessed with zeta potential
analysis