Erythromycin A dimethyl sulfoxide disolvate 1.43-hydrate

The title compound, C₃₇H₆₇NO₁₃·2C₂H₆OS·1.43H₂O, is a macrolide anti­biotic with better solubility and better dermal penetration abilities than erythromycin A itself. The asymmetric unit of this form contains one erythromycin A mol­ecule, two dimethyl sulfoxide (DMSO) solvent mol­ecules, a fully occupied water mol­ecule and a partially occupied water mol­ecule with an occupancy factor of 0.432 (11). The 14-membered ring of the erythronolide fragment has a conformation which differs considerably from that in erythromycin A dihydrate [Stephenson, Stowell, Toma, Pfeiffer & Byrn (1997). J. Pharm. Sci. 86, 1239–1244]. One of the two DMSO mol­ecules is disordered over two orientations; the orientation depends on the presence or absence of the second, partially occupied, water mol­ecule. In the crystal, erythromycin mol­ecules are connected by O—H...O hydrogen bonds involving the hy­droxy groups and the fully occupied water mol­ecule to form layers parallel to (010). These layers are connected along the b-axis direction only by a possible hydrogen-bonding contact involving the partially occupied water mol­ecule.