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γ-Irradiation of crystalline hexaaquamagnesium trans-2-butenoate dihydrate affords rel-(3S,4R)-1-hexene-3,4-dicarboxylate by a single-crystal-to-single-crystal reaction. The reaction proceeds by a ...

Solid solutions of aripiprazole (APZ) and its active metabolite, dehydro-aripiprazole (dAPZ), have been prepared as free form (neat or nonsolvated), hydrated, or alcohol- solvated modifications wit...

Long-acting injectable (LAI) antipsychotics are an important treatment option for patients with schizophrenia. Advances and variability in formulation technology have provided several LAI antipsychotic treatment options for schizophrenia, with a wide range of doses and dose intervals. However, clinical reviews of LAIs have not focused on formulation development despite its clinical relevance to injection safety and technique. This article reviews the relationship between formulation technology and clinical practices for LAIs, with a focus on aripiprazole lauroxil, a long-acting atypical antipsychotic indicated for the treatment of schizophrenia. The formulation developed for aripiprazole lauroxil is an aqueous-based suspension suitable for use as a prefilled syringe that, after injection, will release aripiprazole slowly into the plasma. The clinical relationship between the aripiprazole lauroxil formulation and proper injection techniques is explained, including why tapping and shaking the syringe to resuspend the drug particles and rapid injection speed are key steps for best injection practices for this formulation.

Clinical and experimental data suggest that pathogenesis in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is driven by ANCA-mediated activation of neutrophils and monocytes. While the role of neutrophils has been extensively investigated, the function of monocytes remains relatively understudied. We have previously demonstrated that stimulation of monocytes with anti-myeloperoxidase (MPO), but not anti-proteinase-3 (PR3), antibodies results in production of the pro-inflammatory cytokine IL-1β. Changes in cellular metabolism, particularly a switch to glycolysis, have recently been linked to activation of immune cells and production of IL-1β. Therefore, we investigated the metabolic profile of monocytes following ANCA stimulation. We found a significant increase in glucose uptake in anti-MPO stimulated monocytes. Interestingly, both anti-MPO and anti-PR3 stimulation resulted in an immediate increase in glycolysis, measured by Seahorse extracellular flux analysis. However, this increase in glycolysis was sustained (for up to 4 h) in anti-MPO- but not anti-PR3-treated cells. In addition, only anti-MPO-treated cells exhibited increased oxidative phosphorylation, a metabolic response that correlated with IL-1β production. These data indicate that monocyte metabolism is altered by ANCA, with divergent responses to anti-MPO and anti-PR3 antibodies. These metabolic changes may underlie pathologic immune activation in ANCA associated vasculitis, as well as potentially contributing to the differing clinical phenotype between PR3- and MPO-ANCA positive patients. These metabolic pathways may therefore be potential targets for therapeutic intervention.

The phase behavior and characterization of two forms of naltrexone hydrochloride dihydrate are presented. A metastable form was isolated first in the solid state under kinetically controlled conditions, namely dehydration of a higher hydrate followed by exposure to ∼38% relative humidity. The second, more thermodynamically stable polymorph was isolated from an aqueous slurry at an elevated temperature. The phase transition boundaries between naltrexone hydrochloride anhydrate and the metastable hydrate species are established through a combination of slurry and moisture sorption experiments to provide a detailed mechanistic understanding of the hydration/dehydration behavior.

Brexpiprazole (BPZ) is an atypical antipsychotic drug indicated for the treatment of schizophrenia and depression. Crystal form screening of BPZ resulted in the formation of three polymorphs (I, II, and III), two methanol solvates, a toluene hemisolvate, and a dihydrate. Thermal analysis and solvent-mediated conversion experiments of the three unsolvated polymorphs established that Form I is the thermodynamically stable form at ambient temperature. All three polymorphs are monotropically related, whereby Forms I and II are the most and least stable forms, respectively. Structural diversity of BPZ was compared with two chemically related analogues, aripiprazole (APZ) and its active metabolite dehydro-aripiprazole (dAPZ). Like APZ and dAPZ, BPZ was shown to form a thermodynamically stable, hydrated crystal form when exposed to an aqueous environment; however, while APZ and dAPZ were characterized as monohydrates, BPZ is a dihydrate. The crystal structure of BPZ dihydrate (S2H2O) showed two water molecules c...

Clinicians using long-acting injectable (LAI) antipsychotics may assume that there is uniformity in the injection technique for all LAIs. However, because LAIs have significant differences in their formulation, each requires a specific administration procedure. Here, we focus on how the formulation properties of the atypical LAI aripiprazole lauroxil impact its administration.The history of LAI formulations is presented as a background to recent advances in formulation technology. A shared challenge for new LAIs is to adapt the formulation of insoluble drugs to aqueous-based suspensions.The early LAIs kept the drug product dissolved as oil-based solutions, which were stable and did not require mixing prior to injection. However, oil-based solutions tend to be viscous and cause injection-site reactions (ISRs).New LAI formulations tend to be aqueous-based suspensions and need to be resuspended or reconstituted before injection. Beyond this common element, formulation properties lead to differences in administration for each of the available LAIs.We reviewed the formulations of LAIs indicated for the treatment of schizophrenia and how they impact instructions for use, with a focus on aripiprazole lauroxil.Aripiprazole monohydrate and olanzapine pamoate are lyophilized powders that require reconstitution before administration and should be injected slowly. Risperidone is formulated as microspheres in powder form that require reconstitution before injection, although the injection speed is not specified. Paliperidone palmitate is a ready-to-use aqueous suspension of crystalline particles and should be injected slowly. Aripiprazole lauroxil is an aqueous-based, ready-to-use suspension of crystalline particles. Unlike other LAIs, the formulation of aripiprazole lauroxil contains particles that are loosely associated to facilitate resuspension. Because loosely associated suspensions are shear-thinning, meaning the viscosity of the formulation decreases with higher injection force, the injection must be given rapidly. Vigorous shaking and rapid injection are key aspects of administration and have been accepted by patients and investigators in clinical trials. In a pivotal phase 3 study of aripiprazole lauroxil, the incidence of ISRs was low (3.9% and 5.8% for aripiprazole lauroxil 441mg and 882mg , respectively) and mostly associated with the first injection.Advances in formulation technology have increased LAI options for patients with schizophrenia. The aripiprazole lauroxil formulation differs from other LAIs in that the particles are loosely associated to support use as a ready-to-use pre-filled syringe. Because the suspension is shear-thinning, aripiprazole lauroxil requires rapid injection, which is not required when using other LAIs. An understanding of the differences in formulation design and how they impact the specific techniques associated with an LAI is essential for successful administration.Funding Acknowledgements: This study was funded by Alkermes, Inc.

A new polymorph of aripiprazole has been discovered, making it the most polymorphic drug to date with twelve reported anhydrous forms, and a record-breaking ninth solved crystal structure. The new form was induced by seeding with crystals of the active metabolite dehydro-aripiprazole.

Tapered THz coplanar waveguides (CPWs) formed from Co/Cu multilayers with embedded low-temperature-grown gallium arsenide photoconductive switches were designed in order to observe giant magnetoresistance (GMR). Pulsed THz radiation was excited using the switches, and was transmitted through both straight and tapered CPWs. GMR-induced changes in the transmitted THz pulse amplitude were demonstrated.

Crystal form exploration of dehydro-aripiprazole (dAPZ), the active metabolite of the antipsychotic drug aripiprazole (APZ), elucidated five polymorphs (I, II, III, IV, and V), two methanol solvates, and a monohydrate. The forms were characterized by thermal microscopy, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), single and powder X-ray diffraction (SCXRD and PXRD), and infrared spectroscopy. DSC analysis showed monotropic relationships among polymorphs I, II, III, and IV and enantiotropic relationships for the two form pairs I ↔ V and II ↔ V. Solvent-mediated conversion experiments indicated that Form V is the thermodynamically stable form in the temperature range 5–60 °C and Form I is the stable form at ≥70 °C, where a transition temperature lies between 60 and 70 °C. Two polymorphs of the methanol solvate (SMeOH1 and SMeOH2) were crystallized from methanol solutions in 1:1 dAPZ/methanol molar ratio. SMeOH2 is the thermodynamically stable form of the two methanol solvate...

Current biomarkers of renal disease in systemic vasculitis lack predictive value and are insensitive to early damage. To identify novel biomarkers of renal vasculitis flare, we analysed the longitudinal urinary metabolomic profile of a rat model of anti-neutrophil cytoplasmic antibody (ANCA) vasculitis. Wistar-Kyoto (WKY) rats were immunised with human myeloperoxidase (MPO). Urine was obtained at regular intervals for 181 days, after which relapse was induced by re-challenge with MPO. Urinary metabolites were assessed in an unbiased fashion using nuclear magnetic resonance (NMR) spectroscopy, and analysed using partial least squares discriminant analysis (PLS-DA) and partial least squares regression (PLS-R). At 56 days post-immunisation, we found that rats with vasculitis had a significantly different urinary metabolite profile than control animals; the observed PLS-DA clusters dissipated between 56 and 181 days, and re-emerged with relapse. The metabolites most altered in rats with active or relapsing vasculitis were trimethylamine N-oxide (TMAO), citrate and 2-oxoglutarate. Myo-inositol was also moderately predictive. The key urine metabolites identified in rats were confirmed in a large cohort of patients using liquid chromatography–mass spectrometry (LC-MS). Hypocitraturia and elevated urinary myo-inositol remained associated with active disease, with the urine myo-inositol:citrate ratio being tightly correlated with active renal vasculitis.

A specific biomarker that can separate active renal vasculitis from other causes of renal dysfunction is lacking, with a kidney biopsy often being required. Soluble CD163 (sCD163), shed by monocytes and macrophages, has been reported as a potential biomarker in diseases associated with excessive macrophage activation. Thus, we hypothesized that urinary sCD163 shed by crescent macrophages correlates with active glomerular inflammation. We detected sCD163 in rat urine early in the disease course of experimental vasculitis. Moreover, microdissected glomeruli from patients with small vessel vasculitis (SVV) had markedly higher levels of CD163 mRNA than did those from patients with lupus nephritis, diabetic nephropathy, or nephrotic syndrome. Both glomeruli and interstitium of patients with SW strongly expressed CD163 protein. In 479 individuals, including patients with SW, disease controls, and healthy controls, serum levels of sCD163 did not differ between the groups. However, in an inception cohort, including 177 patients with SW, patients with active renal vasculitis had markedly higher urinary sCD163 levels than did patients in remission, disease controls, or healthy controls. Analyses in both internal and external validation cohorts confirmed these results. Setting a derived optimum cutoff for urinary sCD163 of 0.3 ng/mmol creatinine for detection of active renal vasculitis resulted in a sensitivity of 83%, specificity of 96%, and a positive likelihood ratio of 20.8. These data indicate that urinary sCD163 level associates very tightly with active renal vasculitis, and assessing this level may be a noninvasive method for diagnosing renal flare in the setting of a known diagnosis of SW.

Pharmaceutical cocrystals have gained increased attention at least in part because of their potential for enhancing physicochemical and biopharmaceutical properties of existing drugs. As a result, design, screening, and large-scale preparation of pharmaceutical cocrystals have been emphasized in recent research. The design of pharmaceutical cocrystals has focused primarily on determining the empirical guidelines regarding the hierarchy of supramolecular synthons. However, this approach is typically less predictive when considering drugs that are complex in nature, such as those having a multiplicity of functional groups and/or numerous degrees of conformational flexibility. In this manuscript, we report a crystal engineering design strategy to facilitate the synthesis of multicomponent crystal forms of the atypical antipsychotic drug olanzapine, marketed as a drug product under the trade name Zyprexa. Comprehensive analysis and data mining of existing crystal structures of olanzapine were followed by grou...

Reconstituted parenteral solutions of three surface-active anti-infective small-molecule drugs and solutions of sodium dodecyl sulfate (SDS, a model surfactant) were studied to quantify the impact of sample preparation and handling on particle counts. Turbidimetry and light obscuration profiles were recorded as a function of agitation and shearing with and without the introduction of foam into the solutions. SDS solutions at concentrations above the critical micelle concentration (CMC) show significantly greater sensitivity to shear and foam presence than SDS solution below the CMC: Values of >10 μm particles increased 8 fold over control (an unsheared sample) in the micellar solution vs. 4 fold particle count increase over control at a sub-micellar concentration. An even more significant increase in the ratio of particle count in sheared/unsheared solution is seen for >25 μm unit counts, due to the increased interference of foam with the measurement. Two commercial products, injection formulations of teicoplanin and cefotaxime sodium, as well as an investigational compound 1, showed an increase in scattering as a function of foam production. The impact of foaming was significant, resulting in an increase of turbidity and light obscuration measurements in all solutions. The results illustrate some of the challenges that are inherent to optically clear, homogeneous pharmaceutical injections containing compounds which have a tendency toward self-association and surfactant-like behavior.

Crystalline hydrates and propylene glycol solvates of celecoxib sodium salt (Cel-Na) were prepared and characterized with the aim of improving oral drug absorption by breaking up the H-bonding interactions present in crystals of the poorly soluble marketed form of the drug (Cel-III). The hydrate grows rapidly from aqueous alkaline solution, forming a thick slurry of thin plates. Thicker plates for structure determination were successfully grown by adding up to 1% benzyl alcohol to the solution. The structure of the pentahydrate of the sodium salt is comprised of a bilayer motif where three waters are coordinated to sodium ions in a discrete layer, while the other two waters reside in a one-dimensional channel. At a given temperature, the hydration state changes rapidly and reversibly as a function of relative humidity (RH). The hydrated salt is physically stable in a sealed vial, but reverts rapidly to the crystalline free base if exposed to ambient CO2 in air at 40% RH or higher. The propylene glycol (PG) solvate of Cel-Na exists in an anhydrous and trihydrate form. The trihydrated PG solvate of Cel-Na is physically stable above ∼15% RH and does not react measurably with CO2 at 66% RH over 4 days, making it the most suitable form for use in solid pharmaceutical formulations.

60Co γ-irradiation of bis(trans-2-butenoato)calcium (4) and triaquabis(trans-2-butenoato)magnesium (11) affords cyclodimerization products cis,trans- and trans,trans-nepetic acids (5 and 15), respectively. The products are produced in high yield, based upon conversion, by a γ-ray induced radical chain pathway and provide unprecedented, stereospecific, one-pot syntheses of two of the four possible nepetic acid diastereomers, adding significant generality to the synthetic scope of the γ-ray induced reactions of crystalline metal trans-2-butenoates. Stereochemical analysis of the products from the analogous trans-2-butenoato-3-d complexes 19 and 27 establishes unequivocally that hydrogen atom transfer is also stereospecific and not part of a random process. The stereochemistry of the diastereomers is that predicted by the analysis of crystal packing, consistent with the least-motion principles of the topochemical postulate. Analysis of the crystal structures, with respect to the nearest neighbors, is consistent with the hypothesis that the formation of both carbon–carbon bonds and hydrogen atom transfer are topochemical and controlled by the crystal lattice. Analysis of the packing diagrams provides a pathway for chain propagation throughout the crystal that consumes all the molecules in the unit cell.

Cocrystallization experiments were carried out to study the efficacy of Benzo-[18]crown-6 (B18C6) as a cocrystallizing agent (CA). Traditional solution cocrystallization, high-throughput cocrystallization, dry grinding and solvent-drop grinding cocrystallization have led to the discovery of five new cocrystals of B18C6 with urea, thiourea, and their derivatives. The cocrystals have been characterized by a variety of methods, including X-ray diffraction, vibrational spectroscopy (infrared), and optical microscopy (HSM). We have also examined the structures in order to determine the viability and the reproducibility of the R21(6) motif between the donor hydrogen and the ether group of B18C6.

The search for co-crystals of amines as bifunctional hydrogen-bond donors with bidentate oxygens as bifunctional hydrogen-bond acceptors, as part of a program to investigate the utility of using the (8) hydrogen-bonding motif, has yielded three co-crystals of benzidine with p-benzoquinone, diphenyl sulfoxide, and triphenylphosphine oxide. The crystal structures for all three materials are reported. Only the co-crystal structure of benzidine/diphenyl sulfoxide/water reveals the desired motif.

In 2000, Gardner and Collins reported the construction of a fundamental genetic regulatory device, the bi-stable toggle switch, in E. coli. We report here our work on a natural extension of this powerful device, a tri-stable genetic toggle switch capable of switching among three stable states. Like the bi-stable switch, the tri-stable switch consists of repressible promoters that produce inhibitory proteins and requires only a transient pulse of chemical inducer to switch among stable states. Our proof-of-principal construct is designed to control the expression of three different fluorescent reporters using the pBad/AraC, pLacI/LacI, and pTetR/TetR systems; though a tri-stable switch can theoretically be constructed from any three repressible promoters that satisfy a certain mathematical relationship. We have modelled the system extensively, creating both a simple continuous deterministic model based on the work of Gardner and Collins (Gardner and Collins, 2000) and a more complex discrete stochastic model based on the work of Isaacs (Isaacs, 2003). The tri-stable switch, designed, modelled, and partially constructed as an iGEM 2006 project at Brown University, is to be composed entirely of Biobricked parts from the Registry of Standard Biological Parts. In addition to providing support for the iGEM hypothesis, the tri-stable toggle switch has implications for biotechnology and gene therapy.

The BCR-ABL oncogene is the hallmark of chronic myeloid leukemia, a clonal hematopoietic stem cell disorder. BCR-ABL displays constitutive tyrosine kinase activity, required for its transformation ability. Although the molecular mechanisms behind this malignancy are not fully understood, a role for phosphatidylinositol (PI) 3-kinase has been repeatedly described. Here we report the specific up-regulation of the class I(B) catalytic subunit of PI 3-kinase (p110gamma) in response to BCR-ABL expression. We demonstrate that this upregulation is due to increased transcription and is dependent on both PI 3-kinase and MEK activity. We performed in vitro kinase activity assays and show that BCR-ABL also leads to increased p110gamma activity and that this activation requires both G protein-coupled receptor and Ras signaling. In addition, by transfection of cells with dominant negative p110gamma, we determined that this specific PI 3-kinase isoform is involved in both proliferation and the apoptosis resistance associated with chronic myeloid leukemia. The data presented here define for the first time the ability of BCR-ABL to alter the expression levels of PI 3-kinase isoforms and also demonstrate a previously unreported link between BCR-ABL and p110gamma.

The crystal structure of crotonohydroxamic acid, CH3CH˭CHC(O)NHOH 5 contains centrosymmetrically-related pairs of acid molecules, with a short contact of 3.36 A between the α-carbon atoms. The observed arrangement provides excellent alignment for a solid-state ene reaction, but, apparently, the threshold temperature for such a process cannot be realized. The hydrogen bonding patterns observed include C(5) chains and both and ring systems. Facile preparation of metal salts of the acid is reported, as well as discussion of the effect of heating and 60Co γ-irradiation of the materials.

High-throughput (HT) crystallization experiments were conducted with sertraline free base in the presence of mono-, di- and triacidic salt formers. Over 3600 crystallization trials were conducted, leading to the identification and characterization of 18 crystalline salt forms. Due to the large number of crystallization conditions for a given salt type, it was possible to gauge the propensity of a given salt form to exhibit polymorphism. Four salt forms were found to exist (in this limited screen) as monomorphic materials. Unlike the HCl salt in the marketed drug product, the HBr salt appears resistant to polymorphism, crystallizing as a single form from over 140 discrete trials. This observation underscores the lack of predictability of polymorphic behavior of pharmaceuticals even when seemingly minor changes to the composition are made. The experiments highlight the importance of coupling salt selection studies with simultaneous polymorph screening to gain a more comprehensive understanding of solid form...

Surveys of crystal form diversity of two test compounds, 1 (an experimental angiotensin II antagonist) and 2 (sertraline HCl, the active drug in Zoloft), have been performed with high-throughput (HT) crystallization. Compound 1 was found to have at least 18 crystal forms based on a HT recrystallization experiment using diverse solvents, compared with nine forms originally reported from a traditional screening effort. The efficiency of screening in HT mode is estimated to be about 2 orders of magnitude greater than traditional bench-scale approaches. The multiple patented forms of 2 have been summarized and evaluated based on published information, which is found to include several transient species and at least one mixture of known phases. A comparison between results of HT experiments and data on the disclosed forms shows that the HT effort generates the viable crystal forms; highly unstable hydrates and one metastable polymorph IV were not observed. In attempting to recover form IV, a novel acetic acid ...

A mild, base mediated conversion of an azetidin-2-one to the [1,4]-diazapinedione system is reported and a putative mechanistic pathway is proposed.

From two related series of 2-(alkylthio)-pyrimidones, a novel series of 1-((amidolinked)-alkyl)-pyrimidones has been designed as nanomolar inhibitors of human lipoprotein-associated phopholipase A 2 . These compounds show greatly enhanced activity in isolated plasma. Selected derivatives such as compounds 51 and 52 are orally active with a good duration of action.

Starting from two weakly active hits from high throughput screening, a novel series of 2-(alkylthio)-pyrimidin-4-ones with high potency and selectivity for lipoprotein-associated phospholipase A2 has been designed. In contrast to previously known inhibitors, these have been shown to act by a non-covalent and substrate competitive mechanism.

A novel and potent azetidinone inhibitor of the lipoprotein-associated phospholipase A2 (Lp-PLA2), i.e. platelet-activating factor acetylhydrolase, is described for the first time. This inhibitor, SB-222657 (Ki = 40±3 nM, kobs/[I] = 6.6×105 M-1·s-1), is inactive against paraoxonase, is a poor inhibitor of lecithin:cholesterol acyltransferase and has been used to investigate the role of Lp-PLA2 in the oxidative modification of lipoproteins. Although pretreatment with SB-222657 did not affect the kinetics of low-density lipoprotein (LDL) oxidation by Cu2+ or an azo free-radical generator as determined by assay of lipid hydroperoxides (LOOHs), conjugated dienes and thiobarbituric acid-reacting substances, in both cases it inhibited the elevation in lysophosphatidylcholine content. Moreover, the significantly increased monocyte chemoattractant activity found in a non-esterified fatty acid fraction from LDL oxidized by Cu2+ was also prevented by pretreatment with SB-222657, with an IC50 value of 5.0±0.4 nM. The less potent diastereoisomer of SB-222657, SB-223777 (Ki = 6.3±0.5 µM, kobs/[I] = 1.6×104 M-1·s-1), was found to be significantly less active in both assays. Thus, in addition to generating lysophosphatidylcholine, a known biologically active lipid, these results demonstrate that Lp-PLA2 is capable of generating oxidized non-esterified fatty acid moieties that are also bioactive. These findings are consistent with our proposal that Lp-PLA2 has a predominantly pro-inflammatory role in atherogenesis. Finally, similar studies have demonstrated that a different situation exists during the oxidation of high-density lipoprotein, with enzyme(s) other than Lp-PLA2 apparently being responsible for generating lysophosphatidylcholine.

Low molecular weight hydrogelators typically require a stimulus such as heat, antisolvent, or pH adjustment to produce a gel. This study examines gelation of a novel histamine H4 receptor antagonist that forms hydrogels spontaneously at room temperature.To elucidate the mechanism and structural moieties responsible for this unusual gelation, hydrogels were characterized by rheology, optical microscopy, and XRD. SEM was performed on xerogels; NMR measurements were conducted in gelator solutions in the presence of a gel-breaker. The influence of temperature, concentration, pH, and ionic strength on elastic and viscous moduli of the hydrogels was evaluated; gel points were established via thorough rheological criteria.The observed are "true" gels with a fibrillar texture and lamellar microstructure. On a molecular level, the gels are composed of aggregates of partially ionized species stabilized by hydrophobic interactions of aromatic moieties. The gel-to-sol transition occurs at physiologically relevant temperatures and is concentration-, pH-, and ionic strength-dependent.We hypothesize that this spontaneous gelation is due to the so-called "spring" effect, a high energy salt form that transiently increases aqueous solubility above its equilibrium limit. Upon equilibration, this supersaturated system undergoes aggregation that avoids crystallization and produces a hydrogel.

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a serine lipase that is associated with low density lipoprotein (LDL) in human plasma. Substrates include oxidised phosphatidylcholine (PC), which is hydrolysed by Lp-PLA2 to lyso-PC and oxidised fatty acids. Both products are bioactive and proinflammatory, and implicated in monocyte infiltration into the developing plaque, deposition of foam cells, and plaque progression and instability. Lp-PLA2 has recently been shown to be a risk factor for coronary events in previously asymptomatic, hypercholesterolaemic men. A series of azetidinones was designed as potent and selective inhibitors of this enzyme; SB-222657 inhibited release of the chemotactic cleavage products from oxidised LDL, and SB-244323 reduced atherosclerotic plaque development in a 3 month rabbit study. A series of pyrimidones has been designed from a screening hit, and nanomolar inhibitors identified. Oral efficacy in inhibiting plasma Lp-PLA2 in rabbits has been demonstrated with a variety of structural classes.

A mild, base mediated conversion of an azetidin-2-one to the [1,4]-diazapinedione system is reported and a putative mechanistic pathway is proposed.

The cocrystal of celecoxib and nicotinamide (Cel:Nic) was crystallized from chloroform in a 1:1 ratio, and the structure has been solved from powder X-ray diffraction data. The dissolution and solubility of Cel:Nic are medium dependent and can be attributed to differences in conversion of Cel:Nic to celecoxib polymorphs I and III (Cel-I and Cel-III). The presence of low concentrations of surfactants facilitates the rapid conversion of neat Cel:Nic to large aggregates of Cel-III that dissolve more slowly than commercial Cel-III into 1% SDS solution. In contrast, combinations of Cel:Nic with both 1-10% solid SDS and PVP wet rapidly and convert to a mixture of amorphous celecoxib and a micron-sized crystalline celecoxib form IV (Cel-IV), which has recently been shown to be up to 4-fold more bioavailable than marketed Cel-III. More than 90% of the suspended material dissolves within 2 min at 37 degrees C when transferred to 1% SDS solution. This example highlights the importance of exploring the form conversion of cocrystals in aqueous media prior to pharmacokinetic studies, and illustrates the potential of simple formulations to overcome the limitations caused by rapid dissociation of cocrystals and recrystallization of poorly soluble forms in aqueous media.

Crystalline hydrates of hydrolytically susceptible pharmaceuticals are commonly encountered, and are particularly prevalent in the beta-lactam class of antibiotics. In order to rationalize how the apparent chemical incompatibility between water and beta-lactams is reduced through crystallization, a review of the published literature and available structural information on the solid state stability was undertaken. A search in the CSD yielded a total of 32 crystal structures of water-containing beta-lactams which were examined and classified in terms of hydrogen-bonded networks. In most cases the waters of hydration in the single crystal structures were found to fulfill structural roles and were not sufficiently close in proximity to react with the beta-lactam ring. Published data for the solid-state of several hydrates were also considered. In general, the stability data indicate high thermal stability for the crystalline hydrates. Moreover, even when water molecules are in appropriate proximity and orientation with respect to the beta-lactam moiety for a reaction to occur, the crystalline solids remain stable. The use of the crystal structure information along with computational modeling suggests that a combination of proximal relationships, steric and mechanistic arguments can explain the observed solid-state stability of crystalline beta-lactam hydrates.

The carbamazepine: saccharin co-crystal (1) was studied in terms of a series of attributes, including suitability for multi-gram scale-up, propensity for crystal polymorphism, physical stability, in vitro dissolution and oral bioavailability, with the goal of comparing 1 with the marketed form of carbamazepine (Tegretol®). Preparation of 1 was achieved on a 30 g scale with a conventional cooling crystallization process from alcohol solution without seeding. The compound is not overtly polymorphic. This finding is in contrast to the form diversity of pure carbamazepine, which has four known polymorphs and a host of solvates, including a dihydrate, which is the stable form in the presence of water. Physical and chemical stability of the co-crystal is also shown to be quantitatively similar to the pure drug in the marketed product (Tegretol®). Finally, comparison of oral bioavailability of 1 with Tegretol® tablets in dogs shows the co-crystal to be a viable alternative to the anhydrous polymorph in formulated solid oral products. The balance of properties and performance of 1 as a model co-crystal is discussed.

The carboxylic acid-primary amide supramolecular heterosynthon is exploited for the generation of pharmaceutical co-crystals that contain two active pharmaceutical ingredients that are polymorphic in their pure forms.

Crystalline organic hydrates in the Cambridge Structural Database have been surveyed to better understand water coordination environments and hydration likelihood. Particular emphasis has been paid to the subsets of bioactive organic hydrates and five classes of compound that are important in terms of pharmaceutical activity. Bioactive compounds are found to exhibit a greater hydration likelihood than general small organic compounds, but the distribution of environments remains the same, with the most common by far being where water accepts once and donates twice (DDA, 49.8%).

The synthesis of analogues of SB-253514, a novel natural product derived inhibitor of lipoprotein associated phospholipase A2 (Lp-PLA2), is described together with their ability to inhibit Lp-PLA2.

The synthesis of analogues of SB-253514, a novel natural product derived inhibitor of lipoprotein associated phospholipase A2 (Lp-PLA2), is described together with their ability to inhibit Lp-PLA2.

A weak HTS hit at the CCR2B receptor has been converted into a potent antagonist by array SAR studies. Selectivity over the closely related CCR5 receptor is also achieved.

SKF 97426-A is a novel bile acid sequestrant that is threefold more potent than cholestyramine at increasing bile acid excretion in the hamster. SKF 97426-A is a quaternary alkylammonium polymethacrylate that was selected for comparison with cholestyramine in vivo because of its superior in vitro bile acid binding properties. Association, dissociation, affinity, and capacity experiments were performed under physiologically relevant conditions with the most abundant bile acids found in human bile. The bile acids came to equilibrium with SKF 97426-A and cholestyramine within approximately 30 min and 6 min, respectively. SKF 97426-A and cholestyramine had similar capacities for all the bile acids (between 2.5 and 4 mmol/g) and both had similar, very high affinities and slow dissociation rates for the dihydroxy bile acids. However, SKF 97426-A had much higher affinities for the trihydroxy bile acids glycocholic acid and taurocholic acid than did cholestyramine. Dissociation of glycocholic acid and taurocholic acid from SKF 97426-A was also much slower (27 and 25%, respectively, dissociated after 60 min) than from cholestyramine (89 and 84%, respectively, dissociated after 60 min). The higher affinities and slower dissociation rates of the trihydroxy bile acids for and from SKF 97426-A probably account for the increased potency of SKF 97426-A over cholestyramine in vivo.

A form of bumetanide potassium trihydrate that is structurally similar to bumetanide sodium trihydrate was identified. Structural analysis indicated however that the change from sodium to potassium salt resulted in meaningful changes in the packing arrangement and even greater changes on physicochemical properties. The potassium trihydrate salt was five times more soluble in water relative to the sodium trihydrate salt (27 mg mL−1vs. 5.6 mg mL−1). Both salts underwent complete dehydration to their corresponding anhydrate forms following exposure to low humidity or elevated temperature. Arrhenius plots for the dehydration between 20–30 °C yielded a lower activation barrier for the potassium trihydrate compared to the sodium trihydrate (14.9 kcal mol−1vs. 19.9 kcal mol−1), translating into a 15–20-fold difference in the rate of dehydration. Such a 5.0 kcal mol−1 gap suggests that the H2O molecules are more tightly bound in the sodium trihydrate compared to potassium trihydrate. These differences in solubility and rate of dehydration further illustrate that changes to chemical composition can have a meaningful and unpredictable impact on the physicochemical properties of closely related pharmaceutical salt forms.

Clarity around the intended definitions of isostructurality in solid forms is highlighted with respect to the pharmaceutical industry and the patenting of crystalline forms. The analysis of structural similarity is a difficult problem and especially so when additional components are included such as counterions in salt forms. In this study we investigate the structural similarity of sodium and potassium salts using a range of methods. It is clear that for this type of multi-component system, where one or more components change between forms, PXRD similarity is not sufficient to determine isostructurality, and careful examination of the 3D crystal structure coordinates is needed. Substantial and unpredictable changes in physical properties have been observed for even small deviations away from isostructurality. Finally, it is noted that sodium salt hydrates tend to exhibit a greater hydration level than potassium salt hydrates, and this trend is hypothesised to be due to the differing solution behaviour of the two cations.

60Co γ-irradiation of both lithium trans-2-butenoate (11) and lithium trans-2-butenoate·formamide (12) affords the same dimer, dilithium trans-5-methyl-2-heptenedioate (13). However, stereochemical analysis of products 22 and 24 from the analogous trans-2-butenoate-2-d salts 21 and 23 established that C–C and C–H bond formation occur stereospecifically by syn addition to the double bond in lithiumtrans-2-butenoates 11 and 21 and anti addition to the double bond in lithium trans-2-butenoate·formamide complexes 12 and 23. These reactions, which provide an unprecedented, chemospecific one step synthesis of dicarboxylate 13, add significantly to the synthetic scope of the γ-ray induced reactions of crystalline metal trans-2-butenoates that lead to cyclic and acyclic dimers and acyclic trimers by γ-ray initiated radical chain reactions. The stereochemistry of products 22 and 24 is that predicted by analysis of crystal packing, consistent with least-motion principles of the topochemical postulate as shown in Fig. 12 and 13. Analysis of the crystal structures, with respect to nearest neighbors, is consistent with the hypothesis that formation of carbon–carbon bonds in propagation step 1 and hydrogen atom transfer in propagation step 2 are topochemical and controlled by the crystal lattice. Analysis of the packing diagrams provides a pathway for chain propagation throughout the crystal that consumes all the molecules in the unit cell. The dimerization of 12 is much more rapid and proceeds in much higher yield than that of 11, probably as a result of significantly shorter C⋯C contacts and a more robust pathway for hydrogen transfer.

SK&F 97426-A is a novel bile acid sequestrant which was selected for comparison with cholestyramine in vivo because of its superior in vitro bile acid binding properties. The effects of the two sequestrants on faecal bile acid excretion, plasma total cholesterol, VLDL + LDL and HDL cholesterol and triglyceride concentrations and on liver enzymes involved in the synthesis and metabolism of cholesterol were investigated in normocholesterolaemic hamsters. Four studies were conducted to determine the relative potencies of the two resins using a range of doses of the sequestrants over treatment periods of up to 2 weeks. Curves fitted to the resulting data allowed common maximum responses and separate ED 50 s to be calculated for each sequestrant. The maximum response of both sequestrants was to increase bile acid excretion by 352% and lower plasma total cholesterol by 37–58%. LDL + VLDL and HDL cholesterol were reduced by 56–75% and 25–41%, respectively. SK&F 97426-A was 3 times more potent than cholestyramine at increasing the excretion of bile acids in the faeces and 2.1–3.4-fold and 2.3–3.2-fold more potent at lowering total plasma cholesterol and LDL plus VLDL cholesterol, respectively. In some of the experiments SK&F 97426-A was also more potent than cholestyramine at lowering HDL cholesterol. Plasma triglycerides were also lowered by both sequestrants by up to 31 % after 1 week but the relative potency could not be determined. These HDL cholesterol and total triglyceride lowering effects of bile acid sequestrants in the hamster are known not to occur in people treated with cholestyramine. There were minimal differences between hamsters treated for 1 or 2 weeks in the relative potencies or ED 50 s calculated for the total plasma cholesterol, LDL + VLDL and HDL cholesterol. Both sequestrants may have been slightly more efficacious on these parameters after 2 weeks of treatment. Liver weights were reduced by about 15% by both sequestrants at 2% (w/w) in the diet for 1 week. The activities of the liver HMG-CoA reductase and cholesterol 7a-hydroxylase were increased as expected, whilst the activity of the acyl-CoA:cholesterol acyltransferase was reduced by both sequestrants at this dose. SK&F 97426-A was, therefore, 2–3-fold more potent as a bile acid sequestrant and hypocholesterolaemic agent than cholestyramine when tested in the hamster.

In an investigation of novel potential bile acid sequestrants, the affinities of the sodium salts of the glycine and taurine conjugates of naturally occurring bile acids (cholate, deoxycholate, chenodeoxycholate and lithocholate) for several cationic ammonium bile acid derivatives have been investigated by measurements of the extent to which the derivatives are able to precipitate the bile acids. This is roughly proportional to the lipophilicity of the interacting species. Thus, amino and ammonium derivatives of cholic acid do not precipitate taurocholate or glycocholate to any great extent, whereas ammonium derivatives of deoxycholate and lithocholate are much more effective. To complement the precipitation measurements, high resolution 13C-NMR has been applied to investigate the weaker interactions between the ammonium cholate derivative and glycocholate, glycodeoxycholate and glycochenodeoxycholate. Addition of either of the latter two bile acids to the cationic ammonium compound results in considerable broadening of the 13C resonances of both species, indicating the formation of relatively rigid structures. In addition, we have used T2 relaxation enhancement induced by spin-labelled fatty acids to examine the mechanism of interaction with bile acids of amphiphilic anions, which might compete with bile acids for sites on bile acid sequestrants. Low concentrations of 16-DOXY L-Stearate dramatically broaden the 13C-NMR resonances of deoxycholate carbons 19, 18 and 7 in particular, while 5-DOXY L-Stearate exerts much less specific effects. These results have been incorporated into a snapshot model of bile acid-fatty acid interactions.

1. Octimibate, 8-[(1,4,5-triphenyl-1H-imidazol-2-yl)oxy]octanoic acid, is reported to have antithrombotic properties. This is in addition to its antihyperlipidaemic effects which are due to inhibition of acylCoA:cholesterol acyltransferase (ACAT). The aim of this study was to investigate the mechanism of the antithrombotic effect of octimibate, and to determine whether the effects of octimibate are mediated through prostacyclin receptors. 2. In suspensions of washed (plasma-free) human platelets, octimibate is a potent inhibitor of aggregation; its IC50 is approx. 10 nM for inhibition of aggregation stimulated by several different agonists, including U46619 and ADP. The inhibitory effects of octimibate on aggregation are not competitive with the stimulatory agonist; the maximal response is suppressed but there is no obvious shift in potency of the agonist. In platelet-rich plasma, octimibate inhibits agonist-stimulated aggregation with an IC50 of approx. 200 nM. 3. Octimibate also inhibits agonist-stimulated rises in the cytosolic free calcium concentration, [Ca2+]i, in platelets. Both Ca2+ influx and release from intracellular stores are inhibited. The effects of octimibate on aggregation and [Ca2+]i are typical of agents that act via elevation of adenosine 3':5'-cyclic monophosphate (cyclic AMP). Similar effects are seen with forskolin, prostacyclin (PGl2) and iloprost (a stable PGl2 mimetic). 4. Octimibate increases cyclic AMP concentrations in platelets and increases the cyclic AMP-dependent protein kinase activity ratio. Octimibate stimulates adenylyl cyclase activity in human platelet membranes, with an EC50 of 200 nM. The maximal achievable activation of adenylyl cyclase by octimibate is 60% of that obtainable with iloprost. Octimibate has no effect on the cyclic GMP-inhibited phosphodiesterase (phosphodiesterase-ITI), which is the major cyclic AMP-degrading enzyme in human platelets.5. Octimibate inhibits, apparently competitively, the binding of [3H]-iloprost (a stable PGl2 mimetic) to platelet membranes; the estimated Ki is 150 nm. 6. The platelets of different species show considerable differences in the apparent potency of their inhibition of aggregation by octimibate; platelets from cynomolgus monkeys are 3 fold more sensitive than those from humans, while rat, cat and cow platelets are 50, 100, and 250 fold less sensitive than human platelets. The sensitivity of these different species to iloprost, however, varies over a range of only 10 fold with no obvious difference between primates and non-primates. 7. Octimibate appears to be a potent agonist (aggregation), or partial agonist (adenylyl cyclase), at prostacyclin receptors and is the first non-prostanoid agent of this type to be identified. The species differences in relative potency of octimibate and iloprost may reflect the existence of receptor subtypes.