Comparison of separation efficiency of early phase active pharmaceutical intermediates by steady state recycle and batch chromatographic techniques.

Chromatographic resolution of enantiomers has become the accepted method for generation of active pharmaceutical intermediates (APIs) in early phase development. Continuous processes such as simulated moving bed (SMB) are recognized as alternative approaches for manufacturing of larger quantities of enantiomerically pure compounds. Steady state recycle (SSR) technology was initially described in 1998 [C.M. Grill, L. Miller, J. Chromatogr. A 827 (1998) 359] and has recently become a common technique in some laboratories. Batch chromatography, SSR, and SMB processes should be considered "phase appropriate" technologies. Phase appropriate technology refers to the scale of separation required in a step of the drug development process. SSR is phase appropriate technology for producing 100 g to several kilogram quantities of material. In this report, we will describe development and scale up of chiral separations utilizing the SSR technique for six different APIs utilizing several different chiral stationary phases and compare the efficiencies of both SSR and batch chromatographic techniques.

Development of analytical and preparative chromatographic separations of novel growth hormone secretagogue compounds.

Chromatographic separations of new growth hormone secretagogue compounds were developed to support structure-activity relationship (SAR) studies in conjunction with lead optimization. These new compounds differed from Merck's MK-677 by having two chiral centers and thus diastereomeric mixtures were generated. Separation of initial compounds in the SAR was achieved on a Kromasil C18 column using an ammonium acetate buffer and acetonitrile. However, additional candidates were not separable on C18 columns and a chiral Kromasil CHI-DMB column was used to resolve the diastereomeric compounds. The Kromasil CHI-DMB packing was also used in a preparative chromatographic system to resolve multigram quantities of secretagogue candidates for testing. Chiral separations of different intermediates were also developed in support of evolution of an asymmetric synthetic route. This report summarizes development of the preparative chromatographic system used to purify diastereomeric mixtures and chiral separations of intermediates in the synthesis.

Evaluation of the macrocyclic antibiotic LY333328 as a chiral selector when used as a mobile phase additive in narrow bore HPLC.

The macrocyclic antibiotic LY333328 has been evaluated as a chiral selector for the enantioseparation of nine dansylated amino acids. This macrocyclic glycopeptide was used as a chiral mobile phase additive (CMPA) in conjunction with narrow bore high-performance liquid chromatography (HPLC). The key mobile phase parameters of LY333328 concentration and buffer pH were varied, along with variations in stationary phases consisting of C8, phenyl, cyano, and silica. After observing and plotting changes in retention and resolution based on corresponding variation in these parameters, a better understanding of the behavior of this chiral selector was obtained. The pKa values of the dansyl amino acid analytes and LY333328 were measured and used to gain a better understanding of the microenvironment in which these enantioseparations occur. Optimized conditions resulted in the baseline separation of eight of nine dansyl amino acids.