Determination of estredox, a compound with sustained estradiol function, and its impurity profile by HPLC.

The HPLC methods described here for the assay and purity test of Estredox (E2CDS), a molecule with a redox-based, brain-targeted chemical delivery system for estradiol, allow reliable conclusions to be made on the potency and purity of API and E2CDS/HPCD complex samples. Extensive work was done to isolate and characterize the major, potential contaminants, and ensure the required stability of solutions of E2CDS, an inherently labile compound by design. Both the sample solvent and the eluent were thoroughly tested to avoid unwanted changes in sample solutions during analyses. The 12 minute isocratic assay method at 220 or 360 nm is simple, well-founded, highly precise and accurate. Purity profiling of E2CDS raised several problems in detection, stability and accuracy, owing to the fact that the pattern of the UV spectra and the stability of the compound and those of the potential contaminants often differed greatly. As a result of meticulous analysis of the UV spectra and the factors influencing the behaviour, in solution, of the compounds concerned, the 20 minute gradient method developed for the purity test, at 220 nm, of E2CDS and E2CDS/HPCD complex samples has proved to be a reliable means of adequately resolving 15-20 peaks of known and unknown compounds, and establishing the purity of various E2CDS samples. Sample impurity can be expressed as area % at 220 nm, and/or as approximate w/w % (if needed), since the relative response factors, at 220 nm, of the 6 major, potential contaminants have also been determined.

Preparation and biological effects of pure stereoisomeric novel soft anticholinergics.

A series of pure stereoisomeric soft glycopyrrolate analogues 3, 4 and 5 was synthesized using chiral intermediates and by careful separation of the stereoisomers formed during the last quaternization step of the synthesis. The stereochemistry of the products was elucidated using various 1D and 2D NMR techniques. Anticholinergic activity of the new compounds was determined by receptor binding studies and performing tests on isolated organs and by in vivo tests. Receptor binding revealed that in the higher alkyl ester series the (2R, 1'R, 3'R) and the (2R, 1'S, 3'S) isomers were the compounds showing the highest receptor affinity furthermore it demonstrated the confines of the length of the alkyl chain. In vitro isolated organ experiments correlated well with the receptor binding results, and in vivo investigations indicated the soft character of the compounds.

Etiprednol dicloacetate, a new soft glucocorticoid drug candidate. Development of chemistry.

During development of chemistry of the soft drug candidate etiprednol dicloacetate (BNP-166) 1) optimization studies on the three-step chemical synthesis resulted in a process that could be scaled-up to the kg level, 2) the impurity profile was determined, 3) synthetic routes were developed for the preparation of the radiolabeled target compound, and 4) a series of hydroxylated metabolites was prepared.

HPLC separation of related impurities in etiprednol dicloacetate, a novel soft corticosteroid.

Etiprednol dicloacetate (ethyl 17alpha-dichloroacetoxy-11beta-hydroxy-androsta-1,4-diene-3-one-17beta-carboxylate, code-named: BNP-166) has been prepared in a 3-step synthesis from prednisolone as starting material. The primary aim of the present work was to develop HPLC methods for the separation of all the impurities found in experimental pilot plant batches of BNP-166 at concentrations > or = 0.10 area %. Besides BNP-166, a total of 19 compounds, eight of them potential impurities, were involved in the HPLC studies in which several HPLC systems were examined and tested to optimize the separation. Of the parameters influencing chromatographic behaviour column type, the nature and composition of the mobile phase and column temperature were varied, while the pH of the eluent was kept constant at 4.5, a pH value at which stability of the BNP-166 ester bonds was found to be the highest. A comparison of the RRT values obtained allowed some conclusions to be drawn concerning the physico-chemical forces governing separation. The isocratic reversed-phase HPLC system (V02) chosen to be used for various GXP studies on BNP-166 affords baseline separation of nearly all the compounds concerned, and also the quantitation of the drug candidate (BNP-166). By means of this system, it was shown that the target compound prepared by the standardized synthesis method on a pilot plant scale, never contained more than 2-3 impurities with area % values higher than 0.10.