Characterization of the thermal properties of powder particles using microthermal analysis

Development of solid lipid microparticles by melt-emulsification/spray-drying processes as carriers for pulmonary drug delivery

The aim of this study was to optimize the parameters of the complex melt-emulsification process coupled with the spray-drying, in order to maintain the balance between solid lipid microparticles (SLMs) powders aerodynamic performance and salbutamol sulfate release rate. Quality target product profile was identified and risk management and principal component analysis were used to guide formulation development. Obtained dry powders for inhalation (DPIs) were evaluated in terms of SLMs size distribution, morphology, true density, drug content, solid state characterization studies, in vitro aerosol performance and in vitro drug release. SLMs micrographs indicated spherical, porous particles. Selected powders showed satisfactory aerosol performance with a mean mass aerodynamic diameter of around 3 μm and acceptable fine particle fraction (FPF). Addition of trehalose positively affected SLMs aerodynamic properties. The results of in vitro dissolution testing indicated that salbutamol sulfate release from the tested SLMs formulations was modified, in comparison to the raw drug release. In conclusion, SLMs in a form of DPIs were successfully developed and numerous factors that affects SLMs properties were identified in this study. Further research is required for full understanding of each factor's influence on SLMs properties and optimization of DPIs with maximized FPFs.

The Role of Toll-like Receptors in the Immune-Adrenal Crosstalk

Sepsis and septic shock remain major health concerns worldwide, and rapid activation of adrenal steroid release is a key event in the organism's first line of defense during this form of severe illness. Toll-like receptors (TLRs) are critical in the early immune response upon bacterial infection, and recent data from our lab demonstrate a novel link between the innate immune system and the adrenal stress response mediated by TLRs. Glucocorticoids and TLRs regulate each other in a bidirectional way. Bacterial toxins acting through TLRs directly activate adrenocortical steroid release. TLR-2 and TLR-4 are expressed in human and mice adrenals and TLR-2 deficiency is associated with an impaired glucocorticoid response. Furthermore, TLR-2 deficiency in mice is associated with marked cellular alterations in adrenocortical tissue. TLR-2-deficient mice have an impaired adrenal corticosterone release following inflammatory stress induced by bacterial cell wall compounds. This defect appears to be associated with a decrease in systemic and intraadrenal cytokine expression. In conclusion, TLRs play a crucial role in the immune-adrenal crosstalk. This close functional relationship needs to be considered in the treatment of inflammatory diseases requiring an intact adrenal stress response.

Physical and thermal characterisation of chiral omeprazole sodium salts

The physical properties of drug substances may affect stability, manufacturing, dissolution and bioavailability. Variations in the degree of crystallinity in a pharmaceutical substance may exhibit physicochemical differences that impact at therapeutic, manufacturing, commercial and legal levels, yet no reference has been found on the physical properties of micronised omeprazole. This study reports on the physical and thermal characterisation of the sodium salts of S- and R-omeprazole, using diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), microthermal analysis (microTA) and powder X-ray diffraction (XRPD). DSC experiments were performed in order to determine not only their thermal stability, but also the thermal history of both forms. SEM results indicate similar morphology, particle size and shape of powdered drug, while, microTA of processed discs shows different topographical images for S- and R-omeprazole, exhibiting a smoother surface for the S-form, indicative of the smoother particle size not evident in the SEM results. The low level of crystallinity of both enantiomers was confirmed by DRIFT spectroscopy and XRPD. Thermal stability by DSC of S- and R-omeprazole sodium salts was superior to that of the neutral omeprazole. This study has examined the physical and thermal properties of both forms and in highlighting their differences provides an explanation for the potential differences in bioavailability and therapeutic efficacy.

Uniformity and physical states of troglitazone in solid dispersions determined by electron probe microanalysis and microthermal analysis

Solid dispersions of troglitazone with PVP K30 in a weight ratio of 1:2 were prepared by the closed melting method. Solid dispersions that exhibit different degrees of crystallinity (0 and 36%) were prepared by changing the charged amount of water, which functions as a plasticizer for PVP K30. Electron probe microanalysis (EPMA) and microthermal analysis (micro TA) of the solid dispersions were performed to investigate the uniformity and physical state of troglitazone in the solid dispersions. The EPMA study confirmed that troglitazone was dispersed homogeneously in the sample whose apparent crystallinity was 0%. However, the sample with a 36% crystallinity was heterogeneous. The micro TA study showed that the sample with a 36% crystallinity was present in two states, crystal and amorphous. EPMA and micro TA would be useful tools to confirm the uniformity and physical states, respectively, of solid dispersions.