Characterization of polymorphs of a novel quinolinone derivative, TA-270 (4-hydroxy-1-methyl-3-octyloxy-7-sinapinoylamino-2(1H)-quinolinone)

Characterization and Thermodynamic Stability of Polymorphs of Di(arylamino) Aryl Compound ASP3026

ASP3026 (N-{2-methoxy-4-[4-(4-methylpiperazin-1-yl)piperidin-1-yl]phenyl}-N'-[2-(propane-2-sulfonyl)phenyl]-1,3,5-triazine-2,4-diamine) was developed in Astellas Pharma Inc. as a novel and selective inhibitor of the fusion protein EML4-ALK. We investigated the thermodynamic stability of five polymorphs of ASP3026 (A01, A02, A03, A04, and A05) in detail. To determine the most stable form at ambient temperature, powder X-ray diffraction, differential scanning calorimetry, and solubility measurements were conducted. Of the five polymorphs, A04 was the most stable and A05 was the least stable. The relationship between A04 and A03 and A04 and A01 were mutually monotropic, while that between A01 and A02 was enantiotropic. The transition temperature from A02 to A01 was estimated as 325 K. A02 was more thermodynamically stable at ambient temperature than A01. Furthermore, the method to estimate polymorphic transition temperatures using solution calorimetry was found to be effective. The systematic characterization of ASP3026 polymorphs presented in this study enables the selective crystallization of the most stable form and design of solid formulations.

Impact of crystal polymorphism on the systemic bioavailability of rifaximin, an antibiotic acting locally in the gastrointestinal tract, in healthy volunteers

Background

Rifaximin is an antibiotic, acting locally in the gastrointestinal tract, which may exist in different crystal as well as amorphous forms. The current marketed rifaximin formulation contains polymorph alpha, the systemic bioavailability of which is very limited. This study compared the pharmacokinetics of this formulation with those of the amorphous form.

Methods

Amorphous rifaximin was specifically prepared for the study and formulated as the marketed product. Two doses (200 mg and 400 mg) of both formulations were given to two groups of 12 healthy volunteers of either sex according to a single-blind, randomized, two-treatment, single-dose, two-period, cross-over design. Plasma and urine samples were collected at preset times (for 24 hours or 48 hours, respectively) after dosing, and assayed for rifaximin concentrations by high-performance liquid chromatography-mass spectrometry.

Results

For both dose levels, peak plasma concentration, area under the concentration-time curve, and cumulative urinary excretion were significantly higher after administration of amorphous rifaximin than rifaximin-α. Ninety percent confidence intervals for peak plasma concentration, area under the concentration-time curve, and urinary excretion ratios were largely outside the upper limit of the accepted (0.80–1.25) range, indicating higher systemic bioavailability of the amorphous rifaximin. The few adverse events recorded were not serious and not related to the study medications.

Conclusion

Rifaximin-α, a crystal polymorph, does differ from the amorphous form, the latter being systemically more bioavailable. In this regard, care must be taken when using – as a medicinal product – a formulation containing even small amounts of amorphous form, which may alter the peculiar pharmacologic properties of this poorly absorbed antibiotic.

Is generic rifaximin still a poorly absorbed antibiotic? A comparison of branded and generic formulations in healthy volunteers

Rifaximin is an antibiotic, locally acting in the gastrointestinal tract, which may exist in different crystal as well as amorphous forms. The branded rifaximin formulation contains the polymorph rifaximin-α, whose systemic bioavailability is very limited. This study was performed to compare the pharmacokinetics of this formulation with that of a generic product, whose composition in terms of solid state forms of the active pharmaceutical ingredient was found to be different. Two tablets (2×200mg) of branded and generic formulations were given to 24 healthy volunteers of either sex, according to a single-blind, randomized, two-treatment, single-dose, two-period, cross-over design. Plasma and urinary samples were collected at preset times (for 24h or 48h, respectively) after dosing, and assayed for rifaximin concentrations by high-performance liquid chromatography-mass spectrometry. Rifaximin plasma and urine concentration-time profiles showed relevant differences when generic and branded rifaximin were compared. Most pharmacokinetic parameters were significantly higher after administration of generic rifaximin than after rifaximin-α. In particular, the differences for Cmax, AUC and cumulative urinary excretion between the generic formulation and the branded product ranged from 165% to 345%. The few adverse events recorded were not serious and not related to study medications. The results of the present investigation demonstrate different systemic bioavailability of generic and branded formulations of rifaximin. As a consequence, the therapeutic results obtained with rifaximin-α should not be translated sic et simpliciter to the generic formulations of rifaximin, which do not claim containing only rifaximin-α and will display significantly higher systemic absorption in both health and disease.

NMR studies of organic polymorphs and solvates

This review article describes the applications of NMR to the study of polymorphs and related forms (solvates) of organic (especially pharmaceutical) compounds, for which it is of increasing academic and practical importance. The nature of the systems covered is briefly introduced, as are the techniques constituting solid-state NMR. The methodologies involved are then reviewed under a number of different headings, ranging from spectral editing through relaxation times to shielding tensors and NMR crystallography. In each case the relevant applications are described. Whilst most studies concentrate on structural matters, motional effects are not neglected. A special section discusses studies of solvates (especially hydrates), and another reviews quantitative analysis.

New strategies in the treatment and prevention of allergic diseases

Allergic diseases (AD) are more prevalent today than 30 years ago but over the same period, few novel efficacious drugs have been discovered to treat, control or even cure these disorders. Topical or systemic glucocorticosteroids combined with symptom-relieving medications, such as beta 2 -adrenoceptor agonists, leukotriene inhibitors or antihistamines, are still the mainstay of antiallergic treatment. Modified glucocorticosteroids with less adverse effects, better bronchodilators and new selective mediator inhibitors may improve symptom control in the future. Only specific immunotherapy has shown potential for long-lasting disease-modifying effects. Immunomodulation is a therapeutic goal, aiming to modify the dominant helper T cell Type 2 inflammation to a helper T cell Type 1 response using modified allergens, mycobacteria or CpG oligodeoxynucleotides. Humanised monoclonal anti-IgE antibodies are an exciting new immunomodulatory medication that are expected to reach the clinical practice and have recently been licensed in Australia and the US. Advances in molecular, cellular and genetic research of the immunopathophysiology of AD have led to the development of new antagonists for cytokines, chemokines, receptors, second messengers and transcription factors that may become available for clinical use in the next 10 years. Specific diets supplemented with antioxidants or probiotics need further study but offer promise as safe and cheap preventative medicine. The strong genetic component of AD and the Human Genome Project have opened a new field of research, and modification or replacement of target genes has a curative potential with exciting new therapeutic developments in the years ahead.