Zoniporide (CP-597396) HCl hydrate is a novel highly potent and specific inhibitor of sodium-hydrogen exchanger type 1 (NHE-1) with cardioprotective effects against myocardial injuries and ischemic insults. Zoniporide HCl hydrate inhibits human NHE-1 (IC50=14 nM), and has >150-fold selectivity versus other NHE isoforms. Zoniporide HCl hydrate highly potently inhibits ex vivo NHE-1-dependent swelling of human platelets (IC50=59 nM).