Crystal structure of pirfenidone (5-methyl-1-phenyl-1 H-pyridin-2-one): an active pharmaceutical ingredient (API)

Abstract

The crystal structure of pirfenidone, C₁₂H₁₁NO [alternative name: 5-methyl-1-phenyl-pyridin-2(1H)-one], an active pharmaceutical ingredient (API) approved in Europe and Japan for the treatment of Idiopathic pulmonary fibrosis (IPF), is reported here for the first time. It was crystallized from toluene by the temperature gradient technique, and crystallizes in the chiral monoclinic space group P2₁. The phenyl and pyridone rings are inclined to each other by 50.30 (11)°. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds involving the same acceptor atom, forming undulating layers lying parallel to the ab plane.

Keywords: active pharmaceutical ingredient (API); crystal structure; hydrogen bonding; idiopathic pulmonary fibrosis (IPF); pirfenidone.

Figure 1

A view of the mol­ecular structure of pirfenidone with the atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2

A view along the a axis of the crystal packing of pirfenidone. The C—H⋯O hydrogen bonds (see Table 1 ▸) are shown as dashed lines.

Figure 3

A view along the c axis of the crystal packing of pirfenidone. The C—H⋯O hydrogen bonds (see Table 1 ▸) are shown as dashed lines.