fumaric-acid and glutaric-acid

Cocrystallization and salt formation were used to produce new multicomponent forms of a novel antimalarial imidazopyridazine drug lead (MMV652103) that displayed improved physicochemical properties. The drug lead had earlier shown good in vitro potency against multidrug resistant (K1) and sensitive (NF54) strains of the human malaria parasite Plasmodium falciparum, and high in vivo efficacy in both Plasmodium berghei and Plasmodium falciparum mouse models. A major drawback of MMV652103 is its limited aqueous solubility. Various new supramolecular products, including several multicomponent solid forms, are reported here, namely 3 cocrystal forms with the dicarboxylic acid coformers adipic acid, glutaric acid, and fumaric acid, and a salt form with malonic acid. These were characterized by thermal methods and their structures elucidated by single-crystal X-ray diffraction. A customized solubility experiment was performed in fasted-state simulated intestinal fluid for comparison of the solubility behavior of each new form of the drug lead with that of the untreated starting material. All of the multicomponent forms showed an improvement in the maximum concentrations (C

Topics: Adipates; Antimalarials; Crystallization; Crystallography, X-Ray; Dicarboxylic Acids; Fumarates; Glutarates; Imidazoles; Malonates; Powder Diffraction; Pyridines; Sodium Chloride; Solubility; X-Ray Diffraction

The properties of nitrogen centres acting either as hydrogen-bond or Brønsted acceptors in solid molecular acid-base complexes have been probed by N 1s X-ray photoelectron spectroscopy (XPS) as well as (15)N solid-state nuclear magnetic resonance (ssNMR) spectroscopy and are interpreted with reference to local crystallographic structure information provided by X-ray diffraction (XRD). We have previously shown that the strong chemical shift of the N 1s binding energy associated with the protonation of nitrogen centres unequivocally distinguishes protonated (salt) from hydrogen-bonded (co-crystal) nitrogen species. This result is further supported by significant ssNMR shifts to low frequency, which occur with proton transfer from the acid to the base component. Generally, only minor chemical shifts occur upon co-crystal formation, unless a strong hydrogen bond is formed. CASTEP density functional theory (DFT) calculations of (15)N ssNMR isotropic chemical shifts correlate well with the experimental data, confirming that computational predictions of H-bond strengths and associated ssNMR chemical shifts allow the identification of salt and co-crystal structures (NMR crystallography). The excellent agreement between the conclusions drawn by XPS and the combined CASTEP/ssNMR investigations opens up a reliable avenue for local structure characterization in molecular systems even in the absence of crystal structure information, for example for non-crystalline or amorphous matter. The range of 17 different systems investigated in this study demonstrates the generic nature of this approach, which will be applicable to many other molecular materials in organic, physical, and materials chemistry.

Topics: Benzenesulfonates; Benzoates; Citric Acid; Crystallography, X-Ray; Fumarates; Glutarates; Hydrochloric Acid; Hydrogen Bonding; Malonates; Models, Molecular; Molecular Structure; Oxalic Acid; Protons; Quantum Theory; Salicylates; Spectrophotometry; X-Rays

Acyclovir is a well-known antiviral agent. It can be administered in very high doses (from 200 to 1000 mg even three-four times daily). It has absorption problems mainly due to its poor solubility in water (about 0.2 g/100 mL at 25°C) and its oral bioavailability is approximately 15%-20% with a half-life of about 3 h. To improve acyclovir solubility and/or its dissolution properties, two cocrystals of this drug were successfully produced with glutaric acid (AGA1:1) and fumaric acid (AFA1:1) as conformers, using a cogrinding method. Their effective formation was investigated by a broad range of techniques: thermal analysis, Fourier transform infrared spectroscopy, X-ray powder diffraction, solid state nuclear magnetic resonance, and scanning electron microscopy coupled with energy dispersive X-ray spectrometry. The water solubility of the AGA1:1 cocrystal was not improved in comparison to acyclovir, while AFA1:1 showed a slight increased solubility at equilibrium. The main difference was detected in terms of intrinsic dissolution rates (IDR). The IDR of the new phases were much faster compared with acyclovir, particularly at neutral pH. AFA1:1 showed the most rapid dissolution behavior in water; within 10 min, the drug was released completely, while just 60% of acyclovir was dissolved in 1 h.

Topics: Acyclovir; Antiviral Agents; Calorimetry, Differential Scanning; Fumarates; Glutarates; Magnetic Resonance Spectroscopy; Powder Diffraction; Solubility; X-Ray Diffraction

Sildenafil is a drug used to treat erectile dysfunction and pulmonary arterial hypertension. Because of poor aqueous solubility of the drug, the citrate salt, with improved solubility and pharmacokinetics, has been marketed. However, the citrate salt requires an hour to reach its peak plasma concentration. Thus, to improve solubility and bioavailability characteristics, cocrystals and salts of the drug have been prepared by treating aliphatic dicarboxylic acids with sildenafil; the N-methylated piperazine of the drug molecule interacts with the carboxyl group of the acid to form a heterosynthon. Salts are formed with oxalic and fumaric acid; salt monoanions are formed with succinic and glutaric acid. Sildenafil forms cocrystals with longer chain dicarboxylic acids such as adipic, pimelic, suberic, and sebacic acids. Auxiliary stabilization via C-H···O interactions is also present in these cocrystals and salts. Solubility experiments of sildenafil cocrystal/salts were carried out in 0.1N HCl aqueous medium and compared with the solubility of the citrate salt. The glutarate salt and pimelic acid cocrystal dissolve faster than the citrate salt in a two hour dissolution experiment. The glutarate salt exhibits improved solubility (3.2-fold) compared to the citrate salt in water. Solubilities of the binary salts follow an inverse correlation with their melting points, while the solubilities of the cocrystals follow solubilities of the coformer. Pharmacokinetic studies on rats showed that the glutarate salt exhibits doubled plasma AUC values in a single dose within an hour compared to the citrate salt. The high solubility of glutaric acid, in part originating from the strained conformation of the molecule and its high permeability, may be the reason for higher plasma levels of the drug.

Topics: Animals; Area Under Curve; Biological Availability; Crystallization; Dicarboxylic Acids; Fumarates; Glutarates; Male; Oxalic Acid; Permeability; Pimelic Acids; Piperazine; Piperazines; Purines; Rats; Rats, Sprague-Dawley; Salts; Sildenafil Citrate; Solubility; Succinic Acid; Sulfones; Water

A gas chromatography tandem mass spectrometry method using an ion trap GC/MS system was developed to quickly screen urine samples for 14 organic acids associated with multiple organic acidemias. The following organic acids are used as diagnostic markers: methylmalonic acid, glutaric acid, 2-ketoisocaproic acid, succinylacetone, 3-methylcrotonylglycine, tiglylglycine, isovalerylglycine, fumaric acid, butyrylglycine, propionylglycine, hexanoylglycine, adipic acid, suberic acid, and sebacic acid. 2-ketocaproic acid is used as an internal standard. The samples are prepared using a solid-phase extraction and converted to trimethylsilyl derivatives. The extraction efficiency for the 14 compounds is between 57 and 106%. A derivatized standard mixture of the 14 markers is run prior to the patient samples to determine the accurate absolute and relative retention times. The samples are then injected and the product ion spectra monitored. For data analysis, one characteristic product ion plot is extracted for each of the 14 marker compounds, and the presence of a peak with the expected retention time is determined. The areas of the product ion peaks are compared with the reference range determined from 30 normal controls. Ten samples of patients with known organic acidemias were measured. For all patients, diagnostic peaks at the expected retention times of at least five times the upper limit of the reference range were detected. The method, with its relatively fast sample preparation, short 10.0 min run time and simple data analysis, is suitable for use as a quick metabolic screen of very sick patients in whom there is concern regarding the possibility of a treatable inborn error.

Topics: Acids; Adipates; Automation; Biomarkers; Caprylates; Decanoic Acids; Dicarboxylic Acids; Fumarates; Gas Chromatography-Mass Spectrometry; Glutarates; Humans; Keto Acids; Mass Screening; Metabolism, Inborn Errors; Methylmalonic Acid; Reference Values; Sensitivity and Specificity; Urinalysis

The prevalence of 3-methylglutaconic aciduria was evaluated among children with developmental language disorders. A urine specimen was obtained from 40 children referred for developmental language delay to the Tel-Aviv Child Development Center during 12/96-6/97 and from 50 age-matched controls. Urine organic acids were analysed by gas chromatography-mass spectrometry. Urinary 3-methylglutaconic acid was quantified. A mildly increased excretion of 3-methylglutaconic acid was found in 8 children with developmental language delay. The combined excretion of 3-methylglutaconic and 3-methylglutaric acid was increased in 9 patients. There were no differences in the excretion of other organic acids. The patients with elevated 3-methylglutaconic acid did not differ from the other patients with developmental language disorders in any of the parameters evaluated. Mildly elevated urinary levels of 3-methylglutaconic acid may be a marker of a still undefined metabolic disorder presenting with developmental language delay. A further study in large groups of children with different developmental disorders is mandatory.

Topics: Child; Child, Preschool; Female; Fumarates; Glutarates; Humans; Language Development Disorders; Male; Malonates; Mass Screening; Meglutol

The rates of p-aminohippurate (PAH) and of uric acid uptake by basolateral membrane vesicles isolated from proximal tubules of rat kidney have been investigated. Accumulation of both substrates against the concentration gradient within the vesicles was shown to occur in the presence of alpha-ketoglutarate (alpha-KG) and Na+ gradient in the incubation medium. The mechanism of the coupling between Na(+)-dicarboxylate symport and organic anion transport is discussed based on the differences between the rates of PAH and of uric acid uptake. It is proposed that the limiting step of coupling between two transporters is the step of alpha-KG-organic anion exchange.

Topics: Animals; Anion Transport Proteins; Anions; Biological Transport; Carrier Proteins; Cell Membrane; Cell Polarity; Citric Acid; Dicarboxylic Acids; Fumarates; Glutarates; Ion Transport; Isocitrates; Ketoglutaric Acids; Kidney Tubules, Proximal; Oxaloacetic Acid; p-Aminohippuric Acid; Rats; Sodium; Sodium Channels; Succinic Acid; Uric Acid