Erythromycin A dimethyl sulfoxide disolvate 1.43-hydrate.

The title compound, C(37)H(67)NO(13)·2C(2)H(6)OS·1.43H(2)O, is a macrolide anti-biotic with better solubility and better dermal penetration abilities than erythromycin A itself. The asymmetric unit of this form contains one erythromycin A mol-ecule, two dimethyl sulfoxide (DMSO) solvent mol-ecules, a fully occupied water mol-ecule and a partially occupied water mol-ecule 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 mol-ecules is disordered over two orientations; the orientation depends on the presence or absence of the second, partially occupied, water mol-ecule. In the crystal, erythromycin mol-ecules are connected by O-H⋯O hydrogen bonds involving the hy-droxy groups and the fully occupied water mol-ecule 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 mol-ecule.