Solubility determination from clear points upon solvent addition

A method is described for determining the solubility of multicomponent crystalline compounds from clear points upon sample dilution at a constant temperature. Clear points are established by continuously adding a solvent mixture to a suspension of known composition until a clear solution appears. For validation, this solvent addition method is compared to the traditional equilibrium concentration method at constant temperature and the more recent temperature variation method with which clear point temperatures are determined upon increasing the sample temperature. Solubility data of binary systems (1 solute, 1 solvent) measured using the solvent addition method are obtained relatively quickly compared to the equilibrium concentration method. These solubility data are consistent with those of the temperature variation and the equilibrium concentration method. For the temperature variation method, the results are dependent on the heating rate. Likewise, for the solvent addition method, they are dependent on the addition rate. Additionally, for ternary systems involving antisolvent or cocrystals, solubilities are determined at a constant temperature using the solvent addition method. The use of the solvent addition method is especially valuable in the case of solvent mixtures and other complex multicomponent systems, in which the temperature variation method cannot be applied easily

Induction of annexin-1 at transcriptional and post-transcriptional level in rat brain by methylprednisolone and the 21-aminosteroid U74389F

Brain tissue of rats pretreated with methylprednisolone or with the 21-aminosteroid U74389F, and that of untreated control rats, was assessed for the expression of annexin-1 (Anx-1) and the transcription of its mRNA. For this purpose Anx-1 cDNA was amplified and simultaneously a T7-RNA-polymerase promoter was incorporated into the cDNA using a polymerase chain reaction (PCR). Then digoxigenin-11-UTP was incorporated into the transcribed cRNA with T7-RNA-polymerase. With this probe in situ hybridization was carried out on sections of the brain. The probe was visualized by an immunoassay using an antidigoxigenin antibody conjugate. Anx-1 protein was assessed by means of immunohistochemistry using a polyclonal antibody. The various brain areas of the control animals showed an appreciable amount of Anx-1 at mRNA or protein level; on the other hand, the animals which had been pretreated with either steroid, showed a more intense Anx-1 mRNA signal than the controls in many areas. In the pretreated animals Anx-1 immunostaining was unchanged in cortex, basal ganglia, amygdala and septum, but more intense in hippocampus, hypothalamus and thalamus. In ependyma, choroid plexus, meninges, and vascular walls there was no Anx-1 mRNA transcription detectable. An opposite profile was shown by the Anx-1 immunoreactivity, the protein was present in control animals as well as the steroid-pretreated animals, suggesting that here the protein was either from systemic origin, or has diffused from adjacent structures. The results indicated that Anx-1 mRNA transcription is upregulated by either steroid, and that in the untreated animals there is a resting level of Anx-1 mRNA transcription, presumably reflecting physiological influences on Anx-1 expression

A structured approach to cope with impurities during industrial crystallization development

The perfect separation with optimal productivity, yield, and purity is very difficult to achieve. Despite its high selectivity, in crystallization unwanted impurities routinely contaminate a crystallization product. Awareness of the mechanism by which the impurity incorporates is key to understanding how to achieve crystals of higher purity. Here, we present a general workflow which can rapidly identify the mechanism of impurity incorporation responsible for poor impurity rejection during a crystallization. A series of four general experiments using standard laboratory instrumentation is required for successful discrimination between incorporation mechanisms. The workflow is demonstrated using four examples of active pharmaceutical ingredients contaminated with structurally related organic impurities. Application of this workflow allows a targeted problem-solving approach to the management of impurities during industrial crystallization development, while also decreasing resources expended on process development

Co-crystals of diflunisal and isomeric pyridinecarboxamides – a thermodynamics and crystal engineering contribution

Diflunisal is an anti-inflammatory, non-steroidal drug, class II of the Biopharmaceutical Classification System, which has recently been the subject of renewed interest due to its potential for use in the oral therapy of familial amyloid polyneuropathy. In this study, a thermodynamics based approach is used to investigate binary mixtures (diflunisal + picolinamide and diflunisal + isonicotinamide) in order to identify solid forms that are potentially useful to improve the biopharmaceutical performance of this active pharmaceutical ingredient. Special emphasis is placed on the research of co-crystals and on the influence of structural changes in the pyridinecarboxamide co-former molecules for co-crystal formation with diflunisal. The thermodynamics based methodology described by ter Horst et al. in 2010 indicates that the formation of co-crystals is thermodynamically feasible for both systems. The binary solid–liquid phase diagrams were built and allowed unequivocal identification of the formation of co-crystals of diflunisal with each of the two isomers and also their stoichiometry of 1 : 1, (diflunisal : co-former) in the case of pyridine-2-carboxamide (picolinamide) and (2 : 1) for pyridine-4-carboxamide (isonicotinamide). Two binary eutectic mixtures, potentially relevant for pharmaceutical application, were also identified. Infrared spectroscopy allowed the identification of the acid⋯N-pyridine heterosynthon in the three co-crystals formed by diflunisal with the isomeric pyridinecarboxamides. However, the results clearly differentiated pyridine-2-carboxamide from pyridine-3-carboxamide and pyridine-4-carboxamide, that share similar crystalline arrangements, at least with respect to the supramolecular synthons

Cost-effectiveness of hepatitis C virus screening, and subsequent monitoring or treatment among pregnant women in the Netherlands

Background The prevalence of diagnosed chronic hepatitis C virus (HCV) infection among pregnant women in the Netherlands is 0.26%, yet many cases remain undiagnosed. HCV screening and treatment of pregnant HCV carriers could reduce the burden of disease and limit vertical transmission from mother to child. We assessed the impact of HCV screening and subsequent treatment with new direct-acting antivirals (DAAs) among pregnant women in the Netherlands. Methods An HCV natural history Markov transition state model was developed, to evaluate the public-health and economic impact of HCV screening and treatment. Besides all 179,000 pregnant women in the Netherlands (cohort 1), we modelled 3 further cohorts: all 79,000 first-time pregnant women (cohort 2), 33,000 pregnant migrant women (cohort 3) and 16,000 first-time pregnant migrant women (cohort 4). Each cohort was analyzed in various scenarios:i no intervention, i.e., the current practice,ii screen-and-treat, i.e., the most extensive approach involving treatment of all individuals found HCV-positive, andiii screen-and-treat/monitor, i.e., a strategy involving treatment of symptomatic (F1-F4) patients and follow-up of asymptomatic (F0) HCV carriers with subsequent treatment only at progression. Results For all cohorts, comparison betweenscenarios(ii) and (i) resulted in ICERs between euro9,306 and euro10,173 per QALY gained and 5 year budget impacts varying between euro6,283,830 and euro19,220,405. For all cohorts, comparison betweenscenarios(iii) and (i) resulted in ICERs between euro1,739 and euro2,749 per QALY gained and budget impacts varying between euro1,468,670 and euro5,607,556. For all cohorts, the ICERs (scenario iiiversusii) involved in delayed treatment of asymptomatic (F0) HCV carriers varied between euro56,607 and euro56,892, well above the willingness-to-pay (WTP) threshold of euro20,000 per QALY gained and even above a threshold of euro50,000 per QALY gained. Conclusion Universal screening for HCV among all pregnant women in the Netherlands is cost-effective. However, it would be reasonable to consider smaller risk groups in view of the budget impact of the intervention