On the interaction of azithromycin mono­hydrate with metallic containers

The monohydrate form of azithromycin (an antibiotic semisynthetic derivative of erythromycin A) is difficult to manipulate due to its great propensity to stick to metallic surfaces (during crystallization, drying, grinding, etc.). In this paper, this behaviour is explained on the basis of the conformation and packing of the azithromycin molecules in this crystal form. In particular, the crystal habit favours interaction between the N and O atoms with the metal through one particular crystal face.