Solid-State NMR Studies of Form I of Atorvastatin Calcium

Solid-state 13C, 19F, and 15N
magic angle spinning NMR studies of Form I of atorvastatin calcium
are reported, including chemical shift tensors of all resolvable carbon
sites and fluorine sites. The complete 13C and 19F chemical shift assignments are given based on an extensive analysis
of 13C–1H HETCOR and 13C–19F HETCOR results. The solid-state NMR data indicate that
the asymmetric unit of this material contains two atorvastatin molecules.
A possible structure of Form I of atorvastatin calcium (ATC-I), derived
from solid-state NMR data and density functional theory calculations
of various structures, is proposed for this important active pharmaceutical
ingredient (API).