New compounds of perphenazine and fumaric acid in 2 : 1 and 1 : 2 molar ratios have been prepared by solvent evaporation with the aim of increasing the drug solubility. Their physico-chemical ...properties were thoroughly characterized by differential scanning calorimetry, powder X-ray diffraction, Fourier infrared spectroscopy and scanning electron microscopy coupled with energy dispersive X-ray spectrometry. In addition, the crystal structure of the 2 : 1 salt was determined by single-crystal X-ray diffraction. The pharmaceutical characterization included solubility and dissolution studies in comparison with the commercial product Trilafon®. Perphenazine solubility is strongly pH-dependent: the binary systems show improved solubility and intrinsic dissolution rate compared with perphenazine, but only the capsule formulation containing the 1 : 2 dihydrate sample shows a quick and complete dissolution behaviour at neutral pH. This sample could represent an interesting perphenazine formulation to improve drug bioavailability and perhaps reduce
in vivo
variability even when the gastric fluid pH is increased by the presence of food.
New perphenazine and fumaric acid systems increased drug solubility and could represent an interesting option to also improve bioavailability.
New compounds of perphenazine and fumaric acid in 2 : 1 and 1 : 2 molar ratios have been prepared by solvent evaporation with the aim of increasing the drug solubility. Their physico-chemical ...properties were thoroughly characterized by differential scanning calorimetry, powder X-ray diffraction, Fourier infrared spectroscopy and scanning electron microscopy coupled with energy dispersive X-ray spectrometry. In addition, the crystal structure of the 2 : 1 salt was determined by single-crystal X-ray diffraction. The pharmaceutical characterization included solubility and dissolution studies in comparison with the commercial product Trilafon registered . Perphenazine solubility is strongly pH-dependent: the binary systems show improved solubility and intrinsic dissolution rate compared with perphenazine, but only the capsule formulation containing the 1 : 2 dihydrate sample shows a quick and complete dissolution behaviour at neutral pH. This sample could represent an interesting perphenazine formulation to improve drug bioavailability and perhaps reduce in vivovariability even when the gastric fluid pH is increased by the presence of food.
Carprofen co-crystals with selected co-formers were prepared by solvent evaporation and wet/dry grinding methods. Their effective formation was investigated by thermal analysis, FT-IR, X-ray single ...crystal and powder diffraction and SEM-EDS. This last technique has been applied for the first time to co-crystals since it provides unambiguous confirmation of co-crystal formation. Among the investigated co-formers we studied, only 4,4-dipyridyl yields co-crystals. Two different crystal structures are obtained when the molar ratio of carprofen:4,4-dipyridyl is 2:1 (triclinic cell) and 1:1.5 (monoclinic cell). The asymmetric triclinic cell (
Z
= 2) contains two carprofen and two half 4,4-dipyridyl moieties while the monoclinic cell (
Z
= 4) contains a single carprofen, and one and a half 4,4-dipyridyl moieties. Several hydrogen-bond supramolecular synthons can be identified in the solid state. For both the 2:1 and 1:1.5 co-crystals, the main hydrogen-bond interaction consists of an OHN heterosynthon involving, as a donor, the COOH group of carprofen and, as a H-acceptor, the nitrogen of a 4,4-dipyridyl molecule. The two co-crystals have characteristic FT-IR spectra and slightly different melting temperatures. X-Ray powder diffraction patterns of the 1:1 and 1:2 compositions reveal a mixture of phases, whose amount is quantified with Rietveld analysis.
Co-crystals of carprofen and 4,4-dipyridyl were prepared by solvent evaporation and grinding. Two different crystal structures were identified with the 2:1 and 1:1.5 molar ratio carprofen:4,4-dipyridyl.
A system is said to be resilient if slight deviations from expected behavior during run-time does not lead to catastrophic degradation of performance: minor deviations should result in no more than ...minor performance degradation. In mixed-criticality systems, such degradation should additionally be criticality-cognizant. The applicability of control theory is explored for the design of resilient run-time scheduling algorithms for mixed-criticality systems.
Recent results in control theory have shown how appropriately designed controllers can provide guaranteed service to hard-real-time servers; this prior work is extended to allow for such guarantees to be made concurrently to multiple criticality-cognizant servers. The applicability of this approach is explored via several experimental simulations in a dual-criticality setting. These experiments demonstrate that our control-based run-time schedulers can be synthesized in such a manner that bounded deviations from expected behavior result in the high-criticality server suffering no performance degradation and the lower-criticality one, bounded performance degradation.
