Identification and preliminary characterization of a potent, safe, and orally efficacious inhibitor of acyl-CoA:diacylglycerol acyltransferase 1.

A high-throughput screen against human DGAT-1 led to the identification of a core structure that was subsequently optimized to afford the potent, selective, and orally bioavailable compound 14. Oral administration at doses ≥0.03 mg/kg significantly reduced postprandial triglycerides in mice following an oral lipid challenge. Further assessment in both acute and chronic safety pharmacology and toxicology studies demonstrated a clean profile up to high plasma levels, thus culminating in the nomination of 14 as clinical candidate ABT-046.

Normal phase and reverse phase HPLC-UV-MS analysis of process impurities for rapamycin analog ABT-578: application to active pharmaceutical ingredient process development.

ABT-578, an active pharmaceutical ingredient (API), is a semi-synthetic tetrazole derivative of the fermented polyene macrolide rapamycin. Reverse phase (RP)-HPLC-UV-MS and normal phase (NP)-HPLC-UV-MS methods employing an LC/MSD trap with electrospray ionization (ESI) have been developed to track and map all significant impurities from the synthetic process. Trace-level tracking of key impurities occurring at various process points was achieved using complimentary methodologies, including a stability indicating reverse phase HPLC method capable of separating at least 25 starting materials and process-related impurities from the API (YMC-Pack Phenyl column, UV-MS, 210 nm) and a targeted reverse phase HPLC method capable of separating very polar compounds from crude reaction mixtures (Phenomenex Synergi Polar RP column, UV, 265 nm). In addition, a normal phase HPLC method condition with post-column modifier infusion is described for the separation of epimeric impurities, and analysis of aqueous-sensitive reactive species (YMC-Pack SIL column, UV-MS, 278 nm). Process control strategies were established with these combinations of analytical technologies for impurities analyses to enable a rich understanding of the ABT-578 process.

An intramolecular ionic hydrogen bond stabilizes a cis amide bond rotamer of a ring-opened rapamycin-degradation product.

Rapamycin (1), a macrolide immunosuppressant, undergoes degradation into ring-opened acid products 2 and 3 under physiologically relevant conditions. The unsaturated product (3) was isolated and studied in this work. Unlike 1, which has its amide primarily in a trans conformation in solution, 3 has both cis and trans conformations in approximately a 1:1 ratio in dimethyl sulfoxide (DMSO). The amount of cis rotamer was increased dramatically in the presence of an organic base such as triethylamine. The detailed NMR results indicate that the cis rotamer is stabilized through an intramolecular ionic hydrogen bond of the carboxylate anion with the tertiary alcohol as part of a nine-membered ring system. This hydrogen bond was characterized further in organic media and the trans-cis rotamer equilibria were used to estimate the relative bond strengths in several solvents. The additional stabilization arising from this ionic hydrogen bond in the cis rotamer was determined to be 1.4 kcal mol(-1) in DMSO-d6, 2.0 kcal mol(-1) in CD3CN and 1.1 kcal mol(-1) in CD3OD.