We have prepared as-grown iron oxide nanoparticle by a solution method using reducing agents (urea and NH4OH) in alkaline phase. The nanoparticles were characterized by UV/vis, FT-IR, and Raman spectroscopy, powder X-ray diffraction, and field-emission scanning electron microscopy. They were deposited on a glassy carbon electrode (GCE, surface area, 0.0316 cm(2)) to give a sensor with a fast response towards Aprepitant (APPT) drug in buffer phase. The sensor also exhibits good sensitivity and long-term stability as well as enhanced electrochemical response. The calibration plot is linear (r(2) = 0.9703) over the 2.2 nM to 4.1 mu M APPT concentration range. The sensitivity is similar to 2.5316 +/- 0.5 mu A cm(-2) mM(-1), and the detection limit is 0.38 +/- 0.02 nM (at a signal-to-noise-ratio of 3) in short response time (10s). This method could also be employed for the determination of drugs in quality control of formulation using a reliable I-V method. (C) 2012 Elsevier Ltd. All rights reserved.