Novel Method of Analysis for the Determination of Residual Formaldehyde by High-Performance Liquid Chromatography.

Formaldehyde is commonly used as an alkylating agent in the pharmaceutical industry. Consequently, its residual level in drug substances and/or their intermediates needs to be accurately quantified. Formaldehyde is a small, volatile molecule with a weak chromophore (the carbonyl group), and its direct analysis by GC-FID and HPLC-UV is difficult. For these reasons, the majority of papers found in the literature are based upon a derivatisation process (most commonly using the desensitised explosive 2,4-dinitrophenylhydrazine) prior to the analysis of formaldehyde. A novel high-performance liquid chromatography (HPLC) method with UV detection for its quantification in a pharmaceutical is described in this paper. The method proposed herein is based upon a derivatisation reaction between formaldehyde and 4-methylbenzenesulfonohydrazide (MBSH) before analysis by HPLC-UV. Selectivity, linearity, limit of quantification, accuracy, repeatability, intermediate precision, and solution stability were successfully assessed as per ICH guideline Q2(R1), and the method has also been validated in a good manufacturing practice (GMP) laboratory in the UK.

Cellular Models of Aggregation-dependent Template-directed Proteolysis to Characterize Tau Aggregation Inhibitors for Treatment of Alzheimer Disease.

Alzheimer disease (AD) is a degenerative tauopathy characterized by aggregation of Tau protein through the repeat domain to form intraneuronal paired helical filaments (PHFs). We report two cell models in which we control the inherent toxicity of the core Tau fragment. These models demonstrate the properties of prion-like recruitment of full-length Tau into an aggregation pathway in which template-directed, endogenous truncation propagates aggregation through the core Tau binding domain. We use these in combination with dissolution of native PHFs to quantify the activity of Tau aggregation inhibitors (TAIs). We report the synthesis of novel stable crystalline leucomethylthioninium salts (LMTX®), which overcome the pharmacokinetic limitations of methylthioninium chloride. LMTX®, as either a dihydromesylate or a dihydrobromide salt, retains TAI activity in vitro and disrupts PHFs isolated from AD brain tissues at 0.16 µM. The Ki value for intracellular TAI activity, which we have been able to determine for the first time, is 0.12 µM. These values are close to the steady state trough brain concentration of methylthioninium ion (0.18 µM) that is required to arrest progression of AD on clinical and imaging end points and the minimum brain concentration (0.13 µM) required to reverse behavioral deficits and pathology in Tau transgenic mice.

Activation and reduction of diethyl ether by low valent uranium: formation of the trimetallic, mixed valence uranium oxo species [U(CpRR')(mu-I)2]3(mu3-O) (CpRR' = C5Me5, C5Me4H, C5H4SiMe3).

The reaction of UI3 and KCpRR' (CpRR' = pentamethylcyclopentadienyl, trimethylsilylcyclopentadienyl or tetramethylcyclopentadienyl) in diethyl ether results in the two-electron reduction of the solvent to form trimetallic, mixed valence uranium oxo species.