1-(1-Naphthyl)piperazine (1-NP) is a drug which is a phenylpiperazine derivative.

It acts as a non-selective, mixed serotonergic agent, exerting partial agonism at the 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1E, and 5-HT1F receptors,[1][2][3] while antagonizing the 5-HT2A, 5-HT2B, and 5-HT2C receptors.

[4][5][6] It has also been shown to possess high affinity for the 5-HT3, 5-HT5A, 5-HT6, and 5-HT7 receptors,[7][8][9][10] and may bind to 5-HT4 and the SERT as well.

[11][12] In animals it produces effects including hyperphagia,[13][14][15] hyperactivity,[16][17] and anxiolysis,[17][18][19][20] of which are all likely mediated predominantly or fully by blockade of the 5-HT2C receptor.

Derivatives of naphthylpiperazine include CSP-2503, F-11,461, S-14506, and S-14671.