Monitoring apoptosis in intact cells by high-resolution magic angle spinning H NMR spectroscopy.

Apoptosis maintains an equilibrium between cell proliferation and cell death. Many diseases, including cancer, develop because of defects in apoptosis. A known metabolic marker of apoptosis is a notable increase in H NMR-observable resonances associated with lipids stored in lipid droplets.

NMR and Thermal Studies for the Characterization of Mass Transport and Phase Separation in Paracetamol/Copovidone Hot-Melt Extrusion Formulations.

The formulation of drug/polymer amorphous solid dispersions (ASDs) is one of the most successful strategies for improving the oral bioavailability of poorly soluble active pharmaceutical ingredients (APIs). Hot-melt extrusion (HME) is one method for preparing ASDs that is growing in importance in the pharmaceutical industry, but there are still substantial gaps in our understanding regarding the dynamics of drug dissolution and dispersion in viscous polymers and the physical stability of the final formulations. Furthermore, computational models have been built to predict optimal processing conditions, but they are limited by the lack of experimental data for key mass transport parameters, such as the diffusion coefficient.

Indomethacin-Kollidon VA64 Extrudates: A Mechanistic Study of pH-Dependent Controlled Release.

Because of its weakly acidic nature (pKa of 4.5), indomethacin presents an aqueous solubility that significantly increases when changing from acidic to neutral/alkaline pH (1.5 μg/mL at pH 1.

Investigating the Dissolution Performance of Amorphous Solid Dispersions Using Magnetic Resonance Imaging and Proton NMR.

We have investigated the dissolution performance of amorphous solid dispersions of poorly water-soluble bicalutamide in a Kollidon VA64 polymeric matrix as a function of the drug loading (5% vs. 30% bicalutamide). A combined suite of state-of-the-art analytical techniques were employed to obtain a clear picture of the drug release, including an integrated magnetic resonance imaging UV-Vis flow cell system and 1H-NMR.

Monitoring the Dissolution Mechanisms of Amorphous Bicalutamide Solid Dispersions via Real-Time Raman Mapping.

Real-time in situ Raman mapping has been employed to monitor, during dissolution, the crystallization transitions of amorphous bicalutamide formulated as a molecular dispersion in a copovidone VA64 matrix. The dissolution performance was also investigated using the rotating disc dissolution rate methodology, which allows simultaneous determination of the dissolution rate of both active ingredient and polymer. The dissolution behavior of two bicalutamide:copovidone VA64 dispersion formulations, containing 5% (w/w) and 50% (w/w) bicalutamide, respectively, was investigated, with the aim of exploring the effect of increasing the bicalutamide loading on the dissolution performance.

Real time Raman imaging to understand dissolution performance of amorphous solid dispersions.

We have employed for the first time Raman spectroscopic imaging along with multi-variate curve resolution (MCR) analysis to investigate in real time and in-situ the dissolution mechanisms that underpin amorphous solid dispersions, with data being collected directly from the dosage form itself. We have also employed a novel rotating disk dissolution rate (RDDR) methodology to track, through the use of high-performance liquid chromatography (HPLC), the dissolution trends of both drug and polymer simultaneously in multi-component systems. Two formulations of poorly water-soluble felodipine in a polymeric matrix of copovidone VA64 which have different drug loadings of 5% and 50% w/w were used as models with the aim of studying the effects of increasing the amount of active ingredient on the dissolution performance.

Proton NMR: a new tool for understanding dissolution.

We present the use of (1)H NMR as a new measurement approach for improving understanding of the dissolution of pharmaceutical tablets. NMR has benefits over the conventional UV measurement approach in respect to much greater analyte selectivity and the ability to detect non-UV-absorbing species such as sugars. We used an in-line flow cell and water suppression experiments to determine the release profiles of three drug substances and lactose from the same tablet.

Mechanistic insights into the dissolution of spray-dried amorphous solid dispersions.

We have investigated the dissolution mechanisms of spray-dried amorphous solid dispersions of the poorly water-soluble drug felodipine and the water-soluble polymer copovidone using a new combined spectrophotometric and magnetic resonance imaging technique and a mathematical modelling approach. Studies of the dissolution rates of both uncompacted and compacted solid dispersions revealed that compaction leads to a significant decrease in the rate and extent of dissolution and a strong dependence on drug loading, especially for the uncompacted samples. Low drug-loaded compacts [5% and 15% (w/w) felodipine] eroded with linear kinetics at identical rates, pointing to matrix control, whereas for compacts containing a higher proportion of felodipine (≥ 30%, w/w), dissolution performance was dominated by the drug.

Quantitative 35Cl nuclear quadrupole resonance in tablets of the antidiabetic medicine Diabinese.

Pulsed (35)Cl nuclear quadrupole resonance (NQR) experiments have been performed on 250-mg tablets of the antidiabetic medicine Diabinese to establish the conditions needed for noninvasive quantitative analysis of the medicine in standard bottles. One important condition is the generation of a uniform radio-frequency (RF) field over the sample, which has been achieved by two designs of sample coil: one of variable pitch, and the other a resonator that has been fabricated from a single turn of copper sheet with a longitudinal gap bridged by tuning capacitors. The results from blind tests show that the number of tablets in a bottle could be predicted to within +/-3%.

CE hydrogen deuterium exchange-MS in peptide analysis.

CE and hydrogen-deuterium (H/D) exchange MS are useful tools in the analysis and characterisation of peptides. This study reports the facile coupling of these tools in the H/D exchange CE-MS analysis of model and pharmaceutically important peptides, using a sheath flow interface. The peptides varied in mass from 556 (leucine enkephalin) to 1620 Da (bombesin), and in charge state from 0.

Use of ultra-performance liquid chromatography in pharmaceutical development.

Ultra-performance liquid chromatography (UPLC) has been investigated as an alternative to HPLC for the analysis of pharmaceutical development compounds. We present data on three compounds showing that significant reductions in separation time can be achieved without compromising the separation quality. Results from precision and comparative studies indicate that UPLC is a suitable technique for routine pharmaceutical analysis.

UPLC/MS for the identification of beta-blockers.

The beta-blockers Oxprenolol, Metoprolol, Acebutolol, Atenolol, Propranolol, Pindolol, and Alprenolol were analysed by both UPLC/MS and HPLC/MS using mobile phases containing acetonitrile, TFA and either H2O or D2O. UPLC gave superior separation performance and the quality of the mass spectra were at least as good as those from HPLC.

Potential of nuclear quadrupole resonance in pharmaceutical analysis.

Nuclear quadrupole resonance is a radio frequency (rf) spectroscopic technique, closely related to NMR, which can be used to detect signals from solids containing nuclei with spin quantum number >1/2. It is nondestructive, highly specific and noninvasive, requires no static magnetic field, and as such is currently used in the detection of explosives and narcotics. Recent technological advances in pulsed NQR methods have shortened detection times, eliminated spurious signals, and enhanced the sensitivity of detection of 14N frequencies, which lie in the low rf range of 0.

Peak capacity in gradient ultra performance liquid chromatography (UPLC).

A prototype commercial instrument and 2.1 mm i.d.

Polymerised bicontinuous microemulsions as stationary phases for capillary electrochromatography. Effect of pore size on chromatographic performance.

Monolithic columns for capillary electrochromatography (CEC) were prepared by in situ polymerisation of bicontinuous microemulsions containing butyl methacrylate. The resulting monoliths were found to be permeable to mobile phase flow and their behaviour as CEC stationary phases was investigated. It was found that the monoliths were able to separate a simple test mixture of phthalates, but that efficiencies were low.