Anodic polarographic determination of ciclopirox olamine in pure and certain pharmaceutical preparations

Degradation and Impurity Profile Study of Ciclopirox Olamine after Pre-column Derivatization: A Risk Based Approach

The present study focus on ICH prescribed stress degradation of ciclopirox olamine after precolumn derivatization. For establishing stability-indicating assay, the reaction solutions in which different degradation products were formed were mixed, and the separation was optimized by applying principle of QbD. A risk-analysis tools based on cause-effect risk assessment matrix with control-noise-experimentation (CNX) approach was utilized for identifying the high risk variable affecting the analytical attributes. Plackett Burman and central composite design was then used to screen and optimize experimental variables for DOE studies to resolve ciclopirox olamine and four of its degradation related impurities with good peak asymmetry and theoretical plates using C18 column. The method was validated according to ICH and ISO guidelines. To ensure reliability of the result, evaluation of risk profile, combined standard uncertainty and expanded uncertainty were also studied. One process related and four unknown degradation products were identified and characterized by LC-MS/MS study. The degradation pathways of degradants were proposed based on m/z values.

Voltammetric assay of anti-anginal drug nicorandil in different solvents

Voltammetric behaviour and assay of nicorandil were investigated using square-wave and cyclic voltammetry. Voltammograms in Britton-Robinson (BR) buffer exhibited one well-defined and two merged reduction peaks. The influence of different buffers, electrolytes, pH, scan rates, and concentration of the drug on cathodic peak current was studied. On the basis of electrochemical behaviour of nicorandil, a direct square-wave voltammetric procedure for quantitation of nicorandil has been developed and validated. The proposed square-wave voltammetric method allows quantitation over the range 12.5-62.5 µg mL(-1) with correlation coefficient of 0.992. The limit of quantification and limit of detection were 21.95 µg mL(-1) and 6.58 µg mL(-1) , respectively. Precision and accuracy were also checked and found within limits. The developed square-wave method has also been successfully applied for the determination of nicorandil in pharmaceutical formulations.

Adsorptive stripping voltammetric behavior of nortriptyline hydrochloride and its determination in surfactant media

The effect of adding surface active agents to electrolytes containing nortriptyline hydrochloride on the voltammetric response of a hanging mercury drop electrode (HMDE) was studied. The current signal due to the reduction process was a function of the amount of nortriptyline hydrochloride, pH of the medium, type of the surfactant, and accumulation time at the electrode surface. Addition of Tween-20 to the nortriptyline hydrochloride containing electrolyte enhances the reduction current signal. Voltammograms of the drug with Tween-20 in Britton Robinson buffers of pH 2-11 exhibit a single well-defined reduction peak, which may be due to the reduction of -C horizontal lineC group. The reduction process was irreversible over the entire pH range, and the mechanism of reduction was postulated on the basis of controlled potential electrolysis and coulometry. Application of Tween-20 in the electrochemical determination of nortriptyline hydrochloride using square-wave voltammetry at the HMDE enhanced the detection limit of the analyte concentration from 8.24 ng/mL in the absence of surfactant to 0.92 ng/mL when present.

Adsorptive stripping voltammetric behavior and determination of anticholinergic agent oxybutynin chloride on a mercury electrode

Oxybutynin chloride is an antispasmodic, anticholinergic agent indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and frequency. Its electrochemical behavior in phosphate buffers of pH range 2-10 at a hanging mercury drop electrode has been investigated using cyclic voltammetry, differential pulse cathodic adsorptive stripping voltammetry (DPCAdSV), and squarewave cathodic adsorptive stripping voltammetry (SWCAdSV). Voltammograms of the drug in phosphate buffer of pH 2-10 exhibited a single two-electron wave and it may be attributed to the reduction of the C[triple bond]C center. Based on the high adsorptive character of oxybutynin chloride onto the mercury electrode, a validated direct squarewave cathodic adsorptive stripping voltammetric and differential pulse cathodic adsorptive stripping voltammetric procedure has been developed for the determination of drug in bulk form and pharmaceutical formulation. The proposed SWCAdS and DPCAdS voltammetric methods allow quantitation over the range 1-18 and 1-17.6 microg mL(-1) with detection limits of 0.1 and 0.23 microg mL(-1), respectively. Precision and accuracy were also checked and were within the limits.