Cathodic adsorptive stripping square-wave voltammetric determination of nifedipine drug in bulk, pharmaceutical formulation and human serum

Fast Determination of Auramine O in Food by Adsorptive Stripping Voltammetry

The electrochemical behaviour of auramine O on the hanging mercury drop electrode has been investigated by cyclic and square wave voltammetry method. Reduction peak of auramine O was irreversible and adsorptive on the hanging mercury drop electrode. The optimal conditions were chosen to be Briton-Robinson buffer pH 9.0, accumulation potential -0.5 V vs. Ag/AgCl/KCl, accumulation time 60 s, pulse amplitude 250 mV·s^-1, and frequency 50 Hz. At the optimum experimental conditions, the peak of the target analyte was sharp and asymmetric. The linearity of the peak current depending on the concentration ranged from 4.0 × 10^-8 to 6.4 × 10^-7 mol L^-1. The limit of detection and limit of quantitation were 2.46 × 10^-8 mol L^-1 and 8.21 × 10^-8 mol L^-1, respectively. The recovery and relative standard deviation were 94.9% and 2.0% (n = 5). The developed method was successfully applied to determine auramine O in chicken samples with an appropriate sample preparation.

Simultaneous determination of nifedipine and atenolol in combined dosage forms using a boron-doped diamond electrode with differential pulse voltammetry

Combinations of nifedipine (NIF) and atenolol (ATN) are used for the treatment of arterial hypertension. Dosages values different from those presented on the label of pharmaceuticals can significantly impact a consumer’s health. To control the quality of the pharmaceuticals effectively, a method for the simultaneous determination of these both drugs using an anodically pretreated boron-doped diamond electrode coupled to differential pulse voltammetry technique was developed. The influence of supporting electrolyte, pH and scan rate on the current response of these both antihypertensives was examined to select the optimum experimental conditions. It was found that NIF and ATN provided two well-shaped and reproducible oxidation peaks at 0.97 V and 1.36 V (vs. Ag/AgCl electrode), respectively, in TRIS buffer solution (pH 8.0). At optimized differential pulse voltammetric parameters, the current response of NIF and ATN was proportionally linear in the concentration range of 3.98–107 μmol L–1 and 1.99–47.2 μmol L–1, with detection limit of 0.612 and 0.999 μmol L−1, respectively. The proposed method was successfully applied in analysis of several commercial combined dosage forms, whose accuracy was attested by good agreement of the results (paired t test at a 95% confidence level) with those obtained using high performance liquid chromatography.

Development and validation of LC/MS/MS method for the simultaneous determination of montelukast, gliclazide, and nifedipine and its application to a pharmacokinetic study

Background

Montelukast is a leukotriene receptor antagonist for treatment of asthma, gliclazide is an oral hypoglycemic antidiabetic agent, and nifedipine is a calcium channel blocker used for treatment of angina pectoris and hypertension. These drugs may be prescribed to patients suffering from these chronic diseases. A survey of the literature reveals that there is no reported method for the simultaneous determination of montelukast, gliclazide, and nifedipine in pharmaceutical preparations or biological fluids.

Results

A simple, sensitive, and rapid method for the simultaneous quantification of montelukast, gliclazide, and nifedipine in human plasma was developed and validated. Montelukast, gliclazide, and nifedipine were resolved using rapid resolution LC/MS/MS Agilent system and SB-C₁₈ (50 × 4.6 mm) 1.8 μm particle size column. The mobile phase consisted of acetonitrile: 0.1% formic acid (84:16). The three drugs were simultaneously extracted from plasma by protein precipitation with acetonitrile using zaferolukast as an internal standard. The method was validated according to FDA guidelines with good reproducibility and linearity of 0.999 and the limits of quantification were 0.11, 0.04, and 0.07 ng/mL for montelukast, gliclazide, and nifedipine, respectively. The accuracies of the three QCs for the three drugs were 99.48% (montelukast), 106.53% (gliclazide), and 108.03% (nifedipine) in human plasma. The validated method was applied to a pharmacokinetic study in human volunteers after oral administration of the three drugs. The applied LC/MS/MS method was shown to be sufficiently sensitive and suitable for pharmacokinetic studies.

Conclusion

The LC/MS/MS method was validated and successfully applied for the determination of montelukast, gliclazide, and nifedipine concentrations in human plasma.

A new colorimetric method for the determination of nifedipine tablets by derivatization using 4-carboxyl-2,6-dinitrobenzene diazonium ion

Background

A new sensitive colorimetric determination of nifedipine has been developed following azo dye formation with 4-carboxyl-2,6-dinitrobenzenediazonium ion (CDNBD). Judging from the various generic brands currently now available, this research was conceived as a means of developing an alternative cost-effective and readily adaptable method for the assay of nifedipine in tablets and for which official high performance liquid chromatographic technique may not be readily available.

Results

Nifedipine was reduced with Zn/HCl reduction system and then the diazo coupling reaction was carried out with the CDNBD reagent to generate a new azo adduct with optimal wavelength at 470 nm representing a bathochromic shift relative to nifedipine, reduced nifedipine and CDNBD reagent. Optimal temperature and time for coupling were selected as 50 oC and 15 minutes. A linear response was observed over 2.9 -14.5 µg/mL of nifedipine with a correlation coefficient of 0.9985 and the drug combined with CDNBD at a stoichiometric ratio of 2:1. The method has limits of detection and quantitation of 0.1344 µg mL-1 and 0.4074 µg mL-1 respectively. The Sandell’s sensitivity obtained is 4.673 ng/cm2 and the method was reproducible over a three day assessment. Intra- and inter-day accuracies (in terms of errors) were of the order -0.008 to 3.22 % while precisions were generally less than 3.1 % (RSD).

Conclusions

The developed spectrophotometric method is of equivalent accuracy (p > 0.05) with USP 2007 HPLC method. It has the advantages of speed, simplicity, sensitivity and more affordable instrumentation and could find application as a rapid and sensitive analytical method for nifedipine. It is the first described method by azo dye derivatization for the analysis of nifedipine in bulk samples and dosage forms.