A Validated Adsorptive Stripping Voltammetric Determination of Antidiabetic Agent Pioglitazone HCl in Tablets and Biological Fluids

Abstract

Square-wave adsorptive cathodic stripping voltammetry was used to determine pioglitazone HCl in Britton Robinson buffer of pH5. The adsorptive cathodic peak was observed at -1.5 V vs. Ag/AgCl. The peak response was characterized with respect to pH, supporting electrolyte, frequency, scan increment, pulse-amplitude, accumulation potential and pre-concentration time. Under optimal conditions, the peak current is proportional to the concentration of pioglitazone HCl, and a linear calibration graphs were obtained within the concentration levels of 10(-8) and 10(-4) M following different accumulation time periods (0-300 s). The obtained results were analyzed and the statistical parameters were calculated. The detection limit is 8.08 × 10(-9) M (3.17 ng ml(-1)) using 300 s pre-concentration time, whereas the quantitative limit is 2.45 × 10(-8) M (9.63 ng ml(-1)). The proposed method was applied to assay the drug in pharmaceutical formulations and biological fluids. The pharmacokinetic parameters of drug in human plasma were estimated as: C max=785.8 ng ml(-1), t max=1.5 h, K e=0.125 h(-1) and t 1/2=8 h which are favorably compared with those reported in literature.

Keywords: actos tablets; adsorptive stripping voltammetry; biological fluids; pharmacokinetic; pioglitazone HCl; square-wave.

Figure 1

Structure of pioglitazone HCl.

Figure 2

Influence of pH (B–R buffers) on the SWAdCS voltammetric peak current (i_p) of 5 × 10^-5 M pioglitazone HCl; frequency f=120 Hz, scan increment ΔE_s=10 mV and pulse-amplitude E_sw=25 mV, with t_acc=30 s at –1.5 V.

Figure 3

SWAdCS voltammetry of (a) 5 × 10^-5 M pioglitazone HCl in B–R buffer of pH5 (—), (b) B–R buffer of pH5 (---); frequency f=120 Hz, scan increment ΔE_s=10 mV, pulse-amplitude E_sw=25 mV and t_acc=30 s at E_acc = –1.5 V.

Figure 4

Effect of accumulation potential (E_acc) on the SWAdCS voltammetric peak current (i_p) of 5 × 10^-5 M pioglitazone HCl in B–R buffer of pH5; frequency f=120 Hz, scan increment ΔE_s=10 mV and pulse-amplitude E_sw=25 mV, following preconcentration for t_acc= 30 s.

Figure 5

Peak current vs. accumulation time in the presence of B–R buffer of pH5, accumulation potential –1.5 V for: (a) 1 × 10^-6 M; (b) 3 × 10^-6 M; (c) 5 × 10^-6 M; (d) 7 × 10^-6 M; (e) 9 × 10^-6 M of pioglitazone HCl.

Figure 6

Cyclic voltammograms of 5 × 10^-4 M pioglitazone HCl in B–R buffer of pH5; without preconcentration (t_acc=0 s) (dashed curve), following preconcentration for 30 s (curve 1) and its repetitive cycle at the same mercury drop (curve 2), Scan rate ν=100 mV s^-1 and E_acc =-1.5 V.

Figure 7

Plasma concentration-time profile for healthy female volunteer after oral administration of 30 mg pioglitazone HCl tablet.