A validated stripping voltammetric procedure for quantification of the anti-hypertensive and benign prostatic hyperplasia drug terazosin in tablets and human serum

The electrochemical behavior of terazosin at the hanging mercury drop electrode was studied in Britton–Robinson buffer (pH 2–11), acetate buffer (4.5–5.5), and in 0.1 M solution of each of sodium sulfate, sodium nitrate, sodium perchlorate and potassium chloride as supporting electrolytes. The square-wave adsorptive cathodic stripping voltammogram of terazosin exhibited a single well-defined two-electron irreversible cathodic peak which may be attributed to the reduction of CO double bond of the drug molecule. A fully validated, simple, high sensitive, precise and inexpensive square-wave adsorptive cathodic stripping voltammetric procedure was described for determination of terazosin in bulk form, tablets and human serum. A mean recovery for 1×10−8 M terazosin in bulk form, following preconcentration onto the hanging mercury drop electrode for 60 s at a −1.0 V (versus Ag/AgCl/KCls), of 99±0.7% (n=5) was obtained. Limits of detection (LOD) and quantitation (LOQ) of 1.5×10−11 and 5×10−11 M bulk terazosin were achieved, respectively. The proposed procedure was successfully applied to determination of the drug in its Itrin® tablets and human serum samples. The achieved LOD and LOQ of the drug in human serum samples were 5.3×10−11 and 1.8×10−10 M THD, respectively. The pharmacokinetic parameters of the drug in human plasma were estimated as: Cmax=77.5 ng ml−1, tmax=1.75 h, AUC0–t=602.3 ng h ml−1, Ke=0.088 h−1 and t1/2=11.32 h) which are favorably compared with those reported in literature.