Voltammetric analysis of trazodone HCl in pharmaceuticals and biological fluids.

The voltammetric behavior of trazodone (TRZ) HCl was studied using direct current (DC(t)), differential pulse (DPP) and alternating current (AC(t)) polarography. The drug manifests cathodic waves over the pH range of 10-14. The waves were characterized as being irreversible, diffusion-controlled with limited adsorption properties. At pH 10, the diffusion current-concentration relationship was found to be rectilinear over the range 4-32 and 0.8-24 microg ml(-1) using DC(t) and DPP modes, respectively, with minimum detectability (S/N=2) of 0.104 microg ml(-1) (2.45 x 10(-6) M) and 0.314 microg ml(-1) (7.397 x 10(-6) M) using the DPP and DC(t) modes, respectively. The diffusion-current constant (I(d)) is 4.31+/-0.02 (n=6). The proposed method was successfully applied to the determination of the studied compound either in pure form or in formulations. The results obtained were favorably compared with those given using a reference method. Furthermore, the proposed method was applied to the determination of TRZ in spiked human urine and plasma adopting the DPP technique. No prior extraction step is needed in case of urine. The percentage recoveries were 98.43+/-0.79 and 97.44+/-0.705 (n=4) in spiked human urine and plasma, respectively. A pathway for the electrode reaction was postulated.