Solid-State NMR Studiesof Form I of AtorvastatinCalcium.

Solid-state 13C, 19F, and 15Nmagic angle spinning NMR studies of Form I of atorvastatin calciumare reported, including chemical shift tensors of all resolvable carbonsites and fluorine sites. The complete 13C and 19F chemical shift assignments are given based on an extensive analysisof 13C–1H HETCOR and 13C–19F HETCOR results. The solid-state NMR data indicate thatthe asymmetric unit of this material contains two atorvastatin molecules.A possible structure of Form I of atorvastatin calcium (ATC-I), derivedfrom solid-state NMR data and density functional theory calculationsof various structures, is proposed for this important active pharmaceuticalingredient (API). [ABSTRACT FROM AUTHOR]