An unexpected high-pressure stability domain for a lower density polymorph of benzophenone.

For over a century, it was thought that the crystalline polymorph II of benzophenone does not possess a stable domain in the pressure-temperature phase diagram. With a combination of new experimental results and literature data, this case of crystalline dimorphism has finally been solved and it is shown that form II possesses a stable domain at high pressure and high temperature, even though its density is lower than that of form I, the stable form under ordinary pressure and temperature conditions. The phase diagram of benzophenone is a clear demonstration of the fact that to understand the phase behaviour of a chemical substance both the exchange of heat (due to the change in intermolecular interactions) and work (due to the change of volume at a given pressure) need to be taken into account.

On the dimorphism of prednisolone: The topological pressure-temperature phase diagram involving forms I and II.

The dimorphism of the corticosteroid anti-inflammatory drug prednisolone has been investigated by the construction of a topological pressure-temperature phase diagram, using crystallographic and calorimetric data. The system is enantiotropic, because the temperature of the I-II equilibrium under atmospheric conditions (400-463 K) is lower than that of the two melting equilibria (518.7 K for form II and 526.3 K for form I). The slope of the I-II equilibrium in the pressure-temperature phase diagram is negative and relatively steep; therefore, form II, which is the stable form at room temperature, will not easily encounter conditions where form I will become stable even under industrial processing conditions. On the other hand, extreme small amounts of form I have been observed to spontaneously transform into form II in a time interval of about six years at room temperature and it can be concluded that although form I is very persistent under ambient conditions, it does slowly convert into form II. Moreover, the system does not obey the density rule.

On the dimorphism and the pressure-temperature state diagram of gestodene, a steroidal progestogen contraceptive.

The pressure-temperature phase diagram of the dimorphism of the contraceptive drug gestodene is constructed using the temperature and enthalpy of fusion of form I (469.5K, 107Jg-1), and those of the endothermic transition from form II to form I (311K, 8.52Jg-1). At ordinary pressure, the sign of the enthalpy of this transition indicates that these polymorphs are enantiotropically related and that form II, whose melting temperature is calculated to be about 452K, is the stable form at room temperature. Considering the inequality in the specific volumes of the two polymorphs, it is shown that the two forms remain enantiotropically related on increasing pressure, because the I-II equilibrium and the melting equilibria I-L and II-L diverge as a consequence of the negative slope dP/dT of the solid-solid equilibrium. In addition, it is demonstrated that the heats of dissolution, inferred from solubility measurements, lead to virtually the same value of the heat of transition from II to I as for the differential scanning calorimetry measurements.

Experimental and topological determination of the pressure-temperature phase diagram of racemic etifoxine, a pharmaceutical ingredient with anxiolytic properties.

Information about the solid-state properties of etifoxine has been lacking, even if the active pharmaceutical ingredient has been used for its anxiolytic properties for decennia. The crystal structure of the racemic compound possesses a monoclinic space group P21/n with cell parameters a = 8.489(2) Å, b = 17.674(2) Å, c = 20.883(3) Å, ß = 98.860(10)° and a unit-cell volume of 3095.8(9) Å3 at 293 K. The unit cell contains 8 molecules, while 2 independent molecules with different conformations are present in the asymmetric unit. The density of the crystal is 1.291 g/cm3 and its melting point was found at 362.6 ±â€¯0.3 K with a melting enthalpy of 85.6 ±â€¯3.0 J g-1. Its thermal expansion in the liquid and the solid state and the change in volume on melting and between the vitreous state and the crystalline solid have been studied. The results confirm the tendency of small organic molecules to increase about 11% in volume on melting, while the volume difference between the glass and the crystal at the glass transition temperature is about half this value at 6%. These values can be used in the construction of phase diagrams in the case that the experimental data for a given system is incomplete.

A network of weak hydrogen bonds in the crystal structure of Tetrazepam.

The crystal structure of tetrazepam, a benzodiazepine derivative formerly used for its muscle relaxant properties, has been solved and found to be monoclinic, space group P21/c, with lattice parameters a=12.7386(7)Å, b=11.3774(7)Å, c=10.3084(7)Å, ß=103.175(5) and Vunit-cell=1454.69(16) Å3 at room temperature (293K) with Z=4 molecules in the unit-cell. A network of weak hydrogen bonds involving aliphatic hydrogen atoms plays an important role in the formation of this structure.

High levels of coagulation factors and venous thrombosis risk: strongest association for factor VIII and von Willebrand factor.

Essentials Elevated procoagulant levels are associated with an increased risk of venous thrombosis (VT). The dependency on concurrent increased factor levels and VT was analyzed in a large study. Factor VIII (FVIII) and von Willebrand factor (VWF) were associated with the highest VT risk. The risks for other procoagulant factor levels were largely explained by FVIII and VWF. SUMMARY: Background Coagulation factors are essential for robust clot formation. However, elevated levels of procoagulant factors are associated with an increased risk of venous thrombosis (VT). The precise contribution of these factors to the development of VT is not yet understood. Objectives We determined the thrombosis risk for the highest levels of eight selected coagulation factors. Furthermore, we analyzed which of these coagulation factors had the strongest impact on the supposed association. Methods We used data of 2377 patients with a first VT and 2940 control subjects in whom fibrinogen, von Willebrand factor (VWF), factor II, FVII, FVIII, FIX, FX and FXI levels were measured. Results The odds ratios (ORs) for the various coagulation factor levels (> 99th percentile versus ≤ 25th percentile) varied between 1.8 and 4, except for FVIII (OR 23.0; 95% confidence interval [CI] 14.7-36.0) and VWF (OR 24.0; 95% CI 15.3-37.3). Adjustment for FVIII and VWF in a mediation analysis reduced the risks of the other factors to unity, with the exception of FIX and FXI (remaining ORs between 1.7 and 1.9). Conversely, the ORs for FVIII and VWF levels remained high after adjustment for all other procoagulant factors (FVIII: 16.0; 95% CI 9.7-26.3; VWF: 17.6; 95% CI 10.7-28.8). Conclusions Our results imply that the observed relationship between VT and coagulation factor levels can be largely explained by FVIII and VWF. FVIII and VWF levels were also associated with the highest VT risk.

On the dimorphism and the pressure-temperature state diagram of racemic m-nisoldipine, a dihydropyridine calcium ion antagonist.

The pressure-temperature phase diagram of the dimorphism of racemic m-nisoldipine is constructed using temperatures and enthalpies of fusion of forms A and B. At ordinary pressure, the transition from form B to form A is found to occur around 192K, which indicates that these polymorphs are enantiotropically related and that form A is stable at room temperature. Nevertheless, the phase relationship turns to be monotropic when pressures become greater than about 100MPa, which indicates that form B becomes the sole stable phase.

Pressure-temperature phase diagram of the dimorphism of the anti-inflammatory drug nimesulide.

Understanding the phase behavior of active pharmaceutical ingredients is important for formulations of dosage forms and regulatory reasons. Nimesulide is an anti-inflammatory drug that is known to exhibit dimorphism; however up to now its stability behavior was not clear, as few thermodynamic data were available. Therefore, calorimetric melting data have been obtained, which were found to be TI-L=422.4±1.0K, ΔI→LH=117.5±5.2Jg-1,TII-L=419.8±1.0K and ΔII→LH=108.6±3.3Jg-1. In addition, vapor-pressure data, high-pressure melting data, and specific volumes have been obtained. It is demonstrated that form II is intrinsically monotropic in relation to form I and the latter would thus be the best polymorph to use for drug formulations. This result has been obtained by experimental means, involving high-pressure measurements. Furthermore, it has been shown that with very limited experimental and statistical data, the same conclusion can be obtained, demonstrating that in first instance topological pressure-temperature phase diagrams can be obtained without necessarily measuring any high-pressure data. It provides a quick method to verify the phase behavior of the known phases of an active pharmaceutical ingredient under different pressure and temperature conditions.

The topological phase diagram of cimetidine: A case of overall monotropy.

Cimetidine is a histamine H2-receptor antagonist used against peptic ulcers. It is known to exhibit crystalline polymorphism. Forms A and D melt within 0.35 degrees from each other and the enthalpies of fusion are similar as well. The present paper demonstrates how to construct a pressure-temperature phase diagram with only calorimetric and volumetric data available. The phase diagram provides the stability domains and the phase equilibria for the phases A, D, the liquid and the vapor. Cimetidine is overall monotropic with form D the only stable solid phase.

X-ray crystallography, an essential tool for the determination of thermodynamic relationships between crystalline polymorphs.

After a short review of the controversies surrounding the discovery of crystalline polymorphism in relation to our present day understanding, the methods of how to solve the stability hierarchy of different polymorphs will be briefly discussed. They involve either theoretical calculations, or, more commonly, experimental methods based on classical thermodynamics. The experimental approach is mainly carried out using heat-exchange data associated to the transition of one form into another. It will be demonstrated that work-related data associated to the phase transition should be taken into account and the role of X-ray crystallography therein will be discussed. X-ray crystallography has become increasingly precise and can nowadays provide specific volumes and their differences as a function of temperature, and also as a function of pressure, humidity, and time.

The topological pressure-temperature phase diagram and crystal structures of the dimorphic system spiperone.

The topological pressure-temperature phase diagram for the dimorphism of spiperone, a potent neuroleptic drug, has been constructed using literature data and improved crystal structures obtained with new crystallographic data from single-crystal X-ray diffraction at various temperatures. It is inferred that form II, which is the more dense form and exhibits the lower melting temperature, becomes the more stable phase under pressure. Under ambient conditions, form I is more stable.

The topological pressure-temperature phase diagram of ritonavir, an extraordinary case of crystalline dimorphism.

A topological pressure-temperature phase diagram involving the phase relationships of ritonavir forms I and II has been constructed using experimental calorimetric and volumetric data available from the literature. The triple point I-II-liquid is located at a temperature of about 407 K and a pressure as extraordinarily small as 17.5 MPa (175 bar). Thus, the less soluble solid phase (form II) will become metastable on increasing pressure. At room temperature, form I becomes stable around 100 MPa indicating that form II may turn into form I at a relatively low pressure of 1000 bar, which may occur under processing conditions such as mixing or grinding. This case is a good example for which a proper thermodynamic evaluation trumps "rules of thumb" such as the density rule.

Characterization of molecular associations involving L-ornithine and α-ketoglutaric acid: crystal structure of L-ornithinium α-ketoglutarate.

The crystal structure of L-ornithinium α-ketoglutarate (C5H13N2O2, C5H5O5) has been solved by direct methods using single crystal X-ray diffraction data. It crystallizes in the monoclinic system, space group P21, unit cell parameters a=15.4326(3), b=5.2015(1), c=16.2067(3) Å and ß=91.986(1)°, containing two independent pairs of molecular ions in the asymmetric unit. An extensive hydrogen-bond network and electrostatic charges due to proton transfer provide an important part of the cohesive energy of the crystal. The conformational versatility of L-ornithine and α-ketoglutaric acid is illustrated by the present results and crystal structures available from the Cambridge Structural Database.

Differentiating amorphous mixtures of cefuroxime axetil and copovidone by X-ray diffraction and differential scanning calorimetry.

The amorphous, molecular solid dispersion of cefuroxime axetil and copovidone with the mass ratio 71/29 is compared to its pure components in the amorphous state and to an amorphous mechanical mixture with the same mass ratio. Calorimetric studies demonstrate that all these materials are vitreous. By using X-ray diffraction profiles, a clear difference can be observed between the local order of the solid dispersion and that of the mechanical mixture. More generally, it is shown how the presence or absence of additivity in the diffraction data can be used to distinguish between different amorphous mixtures.

Polymorphism 10034C>T is located in a region regulating polyadenylation of FGG transcripts and influences the fibrinogen gamma'/gammaA mRNA ratio.

BACKGROUND: Fibrinogen gamma haplotype 2 (FGG-H2) is associated with reduced fibrinogen gamma' levels and fibrinogen gamma'/total fibrinogen ratios and with an increased deep-venous thrombosis (DVT) risk. Two FGG-H2 tagging single nucleotide polymorphisms (SNPs), 9615C>T and 10034C>T, are located in the region of alternative FGG pre-mRNA processing. 10034C>T is located in a GT-rich downstream sequence element (DSE) that comprises a putative cleavage stimulation factor (CstF) binding site. OBJECTIVES: To investigate the functionality of SNPs 9615C>T and 10034C>T, and the importance of the DSE containing 10034C>T. METHODS: Different minigene constructs containing FGG exon 9, intron 9, exon 10 and the 3' region were transiently transfected into HepG2 cells and quantitative real-time polymerase chain reaction was used to measure relative polyadenylation (pA) signal usage (pA1/pA2 ratio). RESULTS: Compared with the reference construct CC (9615C-10034C; FGG-H1; pA1/pA2 ratio set at 100%), the pA1/pA2 ratio of construct TT (9615T-10034T; FGG-H2) was 1.4-fold decreased (71.5%, P = 0.015). The pA1/pA2 ratio of construct CT (9615C-10034T) was almost 1.2-fold decreased (85.3%, P = 0.001), whereas the pA1/pA2 ratio of construct TC (9615T-10034C) did not differ significantly from the reference construct (101.6%, P = 0.890). Functionality of the putative CstF binding site was confirmed using constructs in which this site was deleted or its sequence altered by point mutations. CONCLUSIONS: SNP 10034C>T is located in a GT-rich DSE involved in regulating the usage of the pA2 signal of FGG, which may represent a CstF binding site. We propose that the 10034C>T change is the functional variation in FGG-H2 that is responsible for the reduction in the fibrinogen gamma'/total fibrinogen ratio and the increased DVT risk.

An insulin-like growth factor-I gene polymorphism modifies the risk of microalbuminuria in subjects with an abnormal glucose tolerance.

OBJECTIVE: Microalbuminuria (MA) is related to cardiovascular disease both in diabetic patients and non-diabetic subjects. DESIGN: We investigated whether a polymorphism near the promoter region of the IGF-I gene was related to the development of MA. METHODS: For this study, 1069 participants of the Rotterdam study were selected (440 participants with an abnormal glucose tolerance (AGT), 220 participants with type 2 diabetes and 254 subjects with pre-diabetes, and 595 subjects with a normal glucose tolerance (NGT). RESULTS: 787 subjects were carriers of the wild type IGF-I genotype (73.6%) and 282 subjects were variant carriers (26.4%) of this IGF-I gene polymorphism. Compared to subjects with NGT the risk for microalbuminuria was higher (Odds Ratio (OR): 3.1 (95% CI: 1.2-7.7); P = 0.02) in variant carriers with AGT than in carriers of the wild type of this IGF-I gene polymorphism (OR: 2.2 (95% CI: 1.2-4.0); P = 0.009). Compared with wild type carriers with AGT, the relative risk for MA was unadjusted and non-significantly increased in variant carriers with AGT (1.6; 95% CI: 0.8-2.9). However, after adjustment for possible confounding factors (age, gender, mean blood pressure, fasting insulin, fasting glucose and smoking) this risk became significant (OR: RR 2.1; 95% CI:1.1-4.4; P = 0.04). CONCLUSIONS: In subjects with AGT, a higher risk for MA was observed in variant carriers than in carriers of the wild type genotype of this IGF-I gene polymorphism. Since MA is primarily associated with cardiovascular disease in subjects with AGT, our study suggests that variant carriers have a higher risk for cardiovascular disease than carriers of the wild type when they develop an AGT.

Mortality from Creutzfeldt-Jakob disease and related disorders in Europe, Australia, and Canada.

BACKGROUND: An international study of the epidemiologic characteristics of Creutzfeldt-Jakob disease (CJD) was established in 1993 and included national registries in France, Germany, Italy, the Netherlands, Slovakia, and the United Kingdom. In 1997, the study was extended to Australia, Austria, Canada, Spain, and Switzerland. METHODS: Data were pooled from all participating countries for the years 1993 to 2002 and included deaths from definite or probable CJD of all etiologic subtypes. RESULTS: Four thousand four hundred forty-one cases were available for analysis and included 3,720 cases of sporadic CJD, 455 genetic cases, 138 iatrogenic cases, and 128 variant cases. The overall annual mortality rate between 1999 and 2002 was 1.67 per million for all cases and 1.39 per million for sporadic CJD. Mortality rates were similar in all countries. There was heterogeneity in the distribution of cases by etiologic subtype with an excess of genetic cases in Italy and Slovakia, of iatrogenic cases in France and the UK, and of variant CJD in the UK. CONCLUSIONS: This study has established overall epidemiologic characteristics for Creutzfeldt-Jakob disease (CJD) of all types in a multinational population-based study. Intercountry comparisons did not suggest any relative change in the characteristics of sporadic CJD in the United Kingdom, and the evidence in this study does not suggest the occurrence of a novel form of human bovine spongiform encephalopathy infection other than variant CJD. However, this remains a possibility, and countries currently unaffected by variant CJD may yet have cases.

A polymorphic CA repeat in the IGF-I gene is associated with gender-specific differences in body height, but has no effect on the secular trend in body height.

OBJECTIVE: A polymorphism near the promoter region of the IGF-I gene has been associated with serum IGF-I levels, age-related decline of serum IGF-I levels, body height, birth weight and intima media thickness in hypertensive subjects. DESIGN AND METHODS: We investigated the association between the length of the IGF-I alleles of this promoter polymorphism and IGF-I levels and body height. Furthermore, we investigated the potential influence of this polymorphism on final height in relationship to the secular trend of individuals born between 1917 and 1945. All subjects were participants of the Rotterdam Study. RESULTS: We observed, in analyses including only homozygous carriers, the highest IGF-I levels in homozygous carriers of the 192-bp allele (18.7 nmol/l +/- 0.6) and homozygous carriers of the 194-bp allele (17.7 nmol/l +/- 1.4). IGF-I levels were significantly lower in individuals with homozygous longer alleles [> 194-bp (12.0 nmol/l +/- 1.2; P < 0.001)] and homozygous shorter alleles [< 192-bp (15.6 nmol/l +/- 1.4; P < 0.05)] compared to homozygous carriers of the 192-bp and the 194-bp allele. In males and females separately, an optimum for serum IGF-I was also observed in homozygous carriers of the 192-bp and 194-bp allele. Only in males, homozygous carriers of the 192-bp allele were significantly taller than homozygous carriers of the shorter alleles (174.9 cm +/- 0.2 vs. 171.5 cm +/- 1.4; P = 0.01). When all subjects genotyped for the IGF-I promoter polymorphism were included in the analysis, a clear optimum for IGF-I levels and body height was observed in carriers of the 192-bp and/or 194-bp allele in the total population. Between 1917 and 1945, a secular trend in body height was observed in our Dutch population. Mean final body height was significantly higher in carriers of the most frequent alleles (192-bp and/or the 194-bp), than carriers of the remaining shorter and longer genotypes (P-trend < 0.01). CONCLUSIONS: In conclusion, we observed an optimum in IGF-I levels and final body height for the 192-bp and 194-bp allele of the IGF-I gene. A gender-specific effect of the IGF-I alleles on body height was observed. The secular trend in body height observed in our elderly Dutch population was similar for the different genotypes; carriers of the 192-bp and/or the 194-bp allele remained significantly taller throughout time.