Electrochemical studies and differential pulse polarographic analysis of lansoprazole in pharmaceuticals.

The electrochemical reduction of lansoprazole was investigated by cyclic voltammetry and direct current and differential pulse polarography. The reduction potential was -1.32 V vs. Ag/AgCl with a dropping mercury electrode in a supporting electrolyte consisting of phosphate buffer (pH 9.0)-tetramethylammonium iodide (4 + 1). The reversibility of the electrode reaction and the type of limiting current were studied. The temperature coefficient and the diffusion constant were determined. A mechanism for the electrode reaction was proposed. A new simple and sensitive differential pulse polarographic method was also developed for the quantification of lansoprazole. A linear calibration graph was obtained in the range 0.04-11.35 micrograms ml-1. The limit of detection was 0.03 microgram ml-1 and the intra- and inter-day precisions were 0.84-2.32 and 0.72-3.09%, respectively. The developed method was applied to six different commercial pharmaceutical capsule preparations containing enteric-coated granules. The relative standard deviations ranged from 1.36 to 2.85%. Recovery studies for the accuracy of the method were performed by adding a synthetic mixture to known amounts of lansoprazole and the mean recovery was 100.45%. The data obtained from commercial preparations were compared with those from a published spectrophotometric method. No difference was found statistically.

Determination of Lansoprazole in pharmaceutical dosage forms by two different spectroscopic methods.

Two different ultraviolet (UV) spectroscopic methods were developed for determination of Lansoprazole in pharmaceutical dosage forms. The solutions of the standard and the sample were prepared in 0.1 M NaOH and phosphate buffer pH 6.6. Both UV spectrophotometric and derivative spectroscopic techniques were applied. Second-order derivative spectra were generated between 200 and 400 nm at N = 9, deltalambda = 31.5. The linear range for the UV spectrophotometric method was 3.0-25.0 microg ml(-1) and that for the derivative spectroscopic method was 0.5-25.0 microg ml(-1). The developed methods were applied to three different pharmaceutical preparations. The percentage recovery was 100.2%.

Intracellular magnesium depletion relates to increased urinary magnesium loss in type I diabetes.

We investigated whether erythrocyte magnesium (Mg) depletion exists in subjects with Type I diabetes. To this end, Mg levels in plasma, erythrocytes and urine were determined in 12 patients with Type I diabetes and compared with 12 healthy control subjects. Mean plasma Mg concentrations were comparable between diabetic patients and control subjects (0.90 +/- 0.29 mmol/l vs 1.04 +/- 0.14 mmol/l, respectively; p = 0.16). Mean erythrocyte Mg concentration was significantly lower in the diabetic group compared with the control group (1.41 +/- 0.56 mmol/l vs. 2.94 +/- 1.13 mmol/l, respectively; p < 0.0001). Mean urine Mg excretion was significantly elevated in the diabetic group with respect to the controls (6.86 +/- 3.5 mmol/g creatinine/24 h vs. 4.03 +/- 1.65 mmol/g creatinine/24 h, respectively; p = 0.02). As to the diabetic group, erythrocyte Mg concentration showed a significant inverse correlation with urine Mg excretion (r = -0.58, p = 0.049). There was no correlation between urine Mg concentration and glycosylated hemoglobin or fasting plasma glucose level. The data suggest that intracellular Mg depletion without significant hypomagnesemia is related to increased urinary Mg loss in patients with Type I diabetes. The urinary Mg loss is not correlated with the degree of metabolic control.

Determination of omeprazole in pharmaceuticals by derivative spectroscopy.

A new derivative UV spectroscopic method was developed for the analysis of omeprazole in borate buffer (pH 10.0; 0.1 M). Second derivative spectra were generated between 200-400 nm at N = 9, delta gamma = 31.5. The linearity range for values obtained from second derivative spectra was 0.2-40.0 micrograms ml-1. The developed method was applied to five different commercial preparations of hard gelatin capsules containing enteric coated granules. The relative standard deviations were found to be 2.24% (brand A), 1.87% (brand B), 2.80% (brand C), 4.55% (brand D) and 1.09% (brand E). The data were compared with ones obtained from the polarographic method given in the literature and no difference was found statistically.

Polarographic determination of antihistamines by complexation with Cd(II).

the polarographic behavior of the complexes formed by Cd(II) ion with ethanolamine derivative antihistamines such as diphenhydramine hydrochloride, dimenhydrinate, and chlorphenoxamine hydrochloride was studied. Antihistamines form spontaneous complexes with Cd(II) ion in the presence of KNO3. In addition, pH 8.00 borate buffer was added to increase the differential pulse polarogram peak height, and tetraalkyl ammonium salts were added to increase the linear range. The method of determination developed has been applied to commercial tablet, capsule, elixir, and injection forms of ethanolamine derivative drugs and has been compared with official methods.