Doxapram is racemic and exists as a racemate with positive ( ) and negative (−) enantiomers. The respiratory stimulant properties of doxapram would be stereoselective and could be evaluated by chirally separating doxapram into its ( ) enantiomer (GAL-054) and (−) enantiomer (GAL-053). Pre-clinically we demonstrated that the ( ) enantiomer, GAL-054, and not the (−) enantiomer, GAL-053, dose-dependently increased minute volume when administered intravenously to drug naïve and opioid challenged rats and cynomolgus monkeys. Moreover, the deleterious side-effects of agitation and seizures were restricted to GAL-053. There were minimal behavioral changes observed in rats and monkeys receiving GAL-054. Thus, GAL-054 is the eutomer and GAL-053 the distomer of doxapram. Unfortunately, in conscious rats GAL-054 increased blood pressure approximately 15–20% above baseline values at doses that were moderately respiratory stimulant. This effect was confirmed in a Phase 1 clinical trial evaluating the effects of GAL-054 in healthy volunteers (Galleon Pharmaceuticals, unpublished data). Thus, the ventilatory stimulant and pressor effects of doxapram cannot be separated by enantiomeric separation of the racemate.