CELLOPT: improved unit-cell parameters for electron diffraction data of small-molecule crystals.

Electron diffraction enables structure determination of organic small molecules using crystals that are too small for conventional X-ray crystallography. However, because of uncertainties in the experimental parameters, notably the detector distance, the unit-cell parameters and the geometry of the structural models are typically less accurate and precise compared with results obtained by X-ray diffraction. Here, an iterative procedure to optimize the unit-cell parameters obtained from electron diffraction using idealized restraints is proposed. The cell optimization routine has been implemented as part of the structure refinement, and a gradual improvement in lattice parameters and data quality is demonstrated. It is shown that cell optimization, optionally combined with geometrical corrections for any apparent detector distortions, benefits refinement of electron diffraction data in small-molecule crystallography and leads to more accurate structural models.

Formulating Amorphous Solid Dispersions: Impact of Inorganic Salts on Drug Release from Tablets Containing Itraconazole-HPMC Extrudate.

Amorphous solid dispersions (ASD) are increasingly used to improve the oral bioavailability of poorly water-soluble compounds. However, hydrophilic polymers in ASD have high water-binding properties and, upon water contact, they often form a gel on the surface of the tablet, impacting the rate and extent of drug release. Most inorganic salts decrease water solubility of organic solutes, changing the gel properties of hydrophilic polymers. In this study, the effect of inorganic salts on drug release from a tablet formulation containing an itraconazole (ITZ)-hydroxypropyl methyl cellulose (HPMC) extrudate was investigated. The cloud point of a 1% HPMC solution with and without inorganic salts (KCl, KH2PO4, KHCO3, and potassium iodate (KI)) was determined to classify the salts according to their salting-out or salting-in effect. A kosmotropic effect on HPMC was observed for KCl, KH2PO4, and KHCO3, whereas KI exhibited a chaotropic effect. To prove the effect of these salts on drug release, tablets containing 66% of ITZ-HPMC extrudate (20:80 w/w %), 4% croscarmellose sodium, 30% microcrystalline cellulose, and different types and amounts of KHCO3, KH2PO4, KCl, and KI were compressed (same solid fraction of 0.83-0.85). Tablets without salts showed a slow release and low peak concentrations during dissolution in simulated gastric fluids. By adding the kosmotropic salts to the tablets, the rate and extent of drug release were increased, whereas the chaotropic anion iodide had no effect. The effect was pronounced even with the addition of as little as 2% of inorganic salts and tended to increase with the increasing amount of salt in the formulation. Tablets without salt stored under either dry or humid conditions exhibited a large difference in dissolution profiles, whereas little variation was observed for tablets with kosmotropic salts. In conclusion, the effect of inorganic salts was mechanistically clarified on ASD containing commonly used HPMC. This approach can be beneficial to successfully develop robust formulations containing ASD.

Characteristics of a capsule based dry powder inhaler for the delivery of indacaterol.

OBJECTIVE: To report performance characteristics and robustness of the Breezhaler device, a new capsule based dry powder inhaler (DPI) with low resistance (0.07 cm H(2)O(½)/L/min) facilitating high inspiratory flow rates. This device was developed to deliver the novel, inhaled once-daily ultra long-acting ß(2)-agonist indacaterol, formulated as an inhalation powder in a capsule, and other investigational drugs including NVA237 and QVA149. RESEARCH DESIGN AND METHODS: Peak inspiratory flow rates via the DPI device were determined in patients with chronic obstructive pulmonary disease (COPD) using an Inhalation Profile Recorder. The flow-rate dependency of the in vitro performance (delivered dose and fine particle mass) of indacaterol in the DPI device was examined. Data on patient experience were captured throughout the indacaterol phase III registration program, and the robustness of the device was investigated after mechanical stress. RESULTS: Twenty-six patients with COPD that ranged from mild to very severe were recruited (aged 49-84 years); 25 patients were able to generate flow rates in excess of 60 L/min via the DPI device. The mean delivered dose of indacaterol (150 and 300 µg) remained within 15% of the target dose, with a consistent fine particle mass at flow rates of 50-100 L/min. In the indacaterol registration program, patients with mild to very severe COPD were able to use the device successfully, with a low device complaint rate (<0.03%) and no device failures from approximately 90,000 devices. In mechanical stress tests, drop testing resulted in, at most, only cosmetic damage, with no effect on the delivered dose. CONCLUSION: The capsule based DPI device is a low resistance device, suitable for use by patients with a wide range of COPD severities, delivering a consistent dose irrespective of disease severity and age. The device provided consistent delivery of indacaterol with no reported device failures in clinical trials.

Electron diffraction, X-ray powder diffraction and pair-distribution-function analyses to determine the crystal structures of Pigment Yellow 213, C23H21N5O9.

The crystal structure of the nanocrystalline alpha phase of Pigment Yellow 213 (P.Y. 213) was solved by a combination of single-crystal electron diffraction and X-ray powder diffraction, despite the poor crystallinity of the material. The molecules form an efficient dense packing, which explains the observed insolubility and weather fastness of the pigment. The pair-distribution function (PDF) of the alpha phase is consistent with the determined crystal structure. The beta phase of P.Y. 213 shows even lower crystal quality, so extracting any structural information directly from the diffraction data is not possible. PDF analysis indicates the beta phase to have a columnar structure with a similar local structure as the alpha phase and a domain size in column direction of approximately 4 nm.

The crystal structure of anhydrous beta-caffeine as determined from X-ray powder-diffraction data.

The crystal structure of the low-temperature form of anhydrous caffeine has been determined by using X-ray powder-diffraction data with a combined simulated-annealing/Rietveld method. Anhydrous caffeine crystallizes with five crystallographically independent molecules in a monoclinic C-centred unit cell with dimensions of a=43.0390(17), b=15.0676(6) and c=6.95314(14) A and a beta angle of 99.027(2) degrees.