Task: Please answer the following question about the molecule with SMILES O=c1[nH]c2ccccc2n1CCCN1CCN(C(c2ccccc2)c2ccccc2)CC1.
Description: Please provide a description of this drug's mechanism of action.
Answer: Histamine H1 receptor antagonist
Task: Please answer the following question about the molecule with {SMILES__description} {SMILES#}.
{#Description|Question|Request!}: {quest#}
{#Result|Answer|Completion!}: {answ#}
O=c1[nH]c2ccccc2n1CCCN1CCN(C(c2ccccc2)c2ccccc2)CC1
O=c1[nH]c2ccccc2n1CCCN1CCN(C(c2ccccc2)c2ccccc2)CC1
3-[3-(4-benzhydrylpiperazin-1-yl)propyl]-1H-benzimidazol-2-one
Please provide a description of this drug's mechanism of action.