Utilization of an enantiomer as a solution to a pharmaceutical problem: application to solubilization of 1,2-di(4-piperazine-2,6-dione)propane.

An enantiomer of the cytotoxic agent (+/-)-1,2-di(4-piperazine-2,6-dione)propane [(+/-)-I] (ICRF 159) was utilized to overcome a solubility problem in the preparation of a solution suitable for intravenous use. The enantiomers were about five times more soluble and melted at about 40 degrees lower than the racemic compound. This study appears to be the first reported instance in which the difference in the physical properties of a racemic compound and its enantiomers was utilized to improve a pharmaceutical formulation. The expected differences in the physical properties of racemic solids and their corresponding enantiomers are discussed briefly in relation to the three racemic modifications known to exist.