The chemical structure of dephenhydramine (A), imipramine (B) and the common substructure of dephenhydramine and imipramine (C). The similarities are as follow: AP Tanimoto: 0.421642, MCS Tanimoto: 0.2500, MCS Size: 8 and SMILES of common substructure: C(C)c1ccccc1. AP, atom pairs; MCS, maximum common substructure; SMILES, simplified molecular-input line-entry system.