Ruben Lozano

Development of a Reversed-Phase HPLC Impurity Method for a UV Variable Isomeric Mixture of a CRF Drug Substance Intermediate with the Assistance of Corona CAD

The compound studied, an antagonist of corticotropin-releasing factor (CRF) receptor 1, was under development for the treatment of major depressive disorder and generalized anxiety disorder. To control the quality of intermediate compounds in the synthetic pathway, the preference is to develop a single HPLC method that could determine impurities of the sequential and structurally similar intermediates. However, the chemical nature of one of those intermediates, Compound C, posed a number of challenges to the development of a suitably rugged impurity method for this isolated intermediate. In the solid state, Compound C is a stable mixture of its trans-isomer and semicarbazone forms. In most solution states, Compound C interchanges between the trans and semicarbazone forms as well as degrades rapidly to impurity X, resulting in sample solution instability. Furthermore, the trans-isomers and semicarbazone exhibited different UV response factors, but reference standards of the two forms were not available to determine the relative response factor. Consequently, irreproducibility was observed during the HPLC analysis when conventional UV detection was applied directly. This article describes the following approaches that were employed to meet these challenges: (1) diluent screening was performed to select a \solvent that afforded adequate sample solution stability; (2) appropriate chromatographic conditions were selected to eliminate or minimize any on-column degradation; (3) alternate HPLC detection, Corona charged aerosol detection, in conjunction with UV analysis, was used to determine relative amounts of the isomeric forms which subsequently permitted the use of conventional UV detection for routine analysis. The validation data of this reversed-phase liquid chromatographic method are also discussed.

Impurities in a Lyophilized Formulation of BMS-204352: Identification and Role of Sanitizing Agents

The purpose of this study was to identify two impurities in the parenteral lyophilized formulation of BMS-204352, investigate the role of sanitizing agents as their potential source, evaluate their effect on drug product stability, and develop a strategy to prevent their contamination of the drug product. The two impurities were identified as o-phenylphenol and 4-t-amylphenol based on liquid chromatography/mass spectroscopy (LC/MS) and chromatographic comparison to authentic samples. The LC/MS spectra of commercially available o-phenylphenol and 4-t-amylphenol showed identical patterns of fragmentation and the same retention times as the impurities identified in the BMS-204352 lyophilized product. Levels of these impurities were low and ranged between 0.2–0.3 μg/vial as determined by HPLC and using an authentic external reference standard. To confirm the hypothesis that the commercial sanitizing agents used in the sterile area were the source of these phenolic impurities, several product samples were spiked with the sanitizing agents. Both o-phenylphenol and 4-t-amylphenol were detected in the spiked samples. Further investigation revealed that o-phenylphenol and 4-t-amylphenol are active ingredients of these commercial sanitizing agents. Drug product samples containing the phenolic impurities showed no potency loss following storage at 30, 50, and 70°C indicating these impurities had no adverse effect on product stability. These studies suggest that sanitizing agents used in the sterile area, although may be present at trace levels below typical cleaning procedure detection methods, need to be properly controlled and closely monitored during the manufacturing of injectable products, particularly highly potent drugs. Sanitizing agents, even though not used on product contact surfaces, may potentially contaminate a product through vapor transfer in an open environment.