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In the present study, the induction of oxidative stress was examined in the testis of alloxan-induced diabetic rabbits. In addition, the protective effect of repaglinide, an oral anti-diabetic, at a dose of 1 mg daily was studied after four and eight weeks of the treatment. For these purposes, the levels of superoxide dismutase (Cu,Zn-SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R), glutathione (GSH), ascorbic acid (AA), lipid peroxidation products (LPO) and protein carbonyl groups (PCG) were quantified. Hyperglycemia resulted in significant increases in the antioxidative enzymes, Cu, Zn-SOD, CAT, GSH-Px, and GSSG-R after four and eight weeks, respectively. There was also an increase in GSH level, and a decrease in the level of AA. These effects were accompanied by an elevation in testicular LPO levels and PCG levels. Repaglinide was found to normalize the activity of GSSG-R and levels of GSH and AA, and blunted the increased lipid peroxidation, however no decrease in PCG levels were observed. In conclusion, some oxidative changes provoked in the testis of rabbits by hyperglycemia, were found to be reduced with repaglinide treatment at therapeutic dose. [ABSTRACT FROM AUTHOR]

In the present study, DNA oxidative damage was elevated and superoxide dismutase (Cu,Zn-SOD) metabolism was disturbed in the kidney of alloxan-induced diabetic animals. The effects of pioglitazone and repaglinide, new oral antidiabetics, on 8-hydroxy-2′-deoxyguanosine (8-OHdG) and Cu,Zn-SOD were studied. Diabetic versus control levels (mean ± SE) of 8-OHdG were 24.9 ± 0.2 vs. 21.8 ± 0.1 and 21.5 ± 0.2 vs 20.1 ± 0.2 pmol/µg DNA after 4 and 8 weeks, respectively. At p<0.05, pioglitazone diminished this parameter in diabetic animals (22.0 ± 0.2 and 20.1 ± 0.3 pmol/µg DNA). The level was not affected in diabetic groups receiving repaglinide (24.9 ± 0.2 and 21.5 ± 0.3 pmol/µg DNA). In diabetic kidney, Cu,Zn-SOD mRNA was diminished relative to control animals and was modulated by pioglitazone and repaglinide treatments. Simultaneously, Cu,Zn-SOD activity was also diminished (1.5 ± 0.2 vs. 2.8 ± 0.3 and 1.8 ± 0.1 vs 2.9 ± 0.3 U/mg protein after 4 and 8 weeks, respectively) and partly changed after pioglitazone (2.1 ± 0.4 and 2.3 ± 0.3 U/mg protein) and repaglinide (2.0 ± 0.1 and 2.4 ± 0.2 U/mg protein). These results suggest that a reduction in oxidative stress in diabetic kidney can be achieved with the administration of pioglitazone and to some extent using repaglinide treatment. [ABSTRACT FROM AUTHOR]

The methods for quantitative determination of meloxicam and mefenamic acid in pharmaceuticals by classic spectrophotometry - zero order derivative, first and second order derivatives spectrophotometry is described, using "peak - peak" (P-P) and "peak - zero" (P-O) measurements. The calibration curves are linear within the concentration range of 4.0 - 14.0 microg/mL for meloxicam and 14.0 - 24.0 microg/mL for mefenamic acid. The procedure is simple, rapid and the results are reliable.

A method using capillary zone electrophoresis was developed for the simultaneous separation of 14 antiarrhythmic drugs belonging to various classes. The drugs are separated on a fused-silica capillary, 90 cm x 75 microm (72 cm effective length), with phosphate and acetate buffers as background electrolytes and UV detection at 217 nm. The effects of buffer pH, temperature, and applied voltage on the migration of the drugs were studied. The pH was found to be the most significant factor determining effective separation. The antiarrhythmic compounds are completely separated within a relatively short time (< 7 min) by using 70 mM phosphate buffer at pH 7.91, an applied voltage of 28 kV, and a temperature of 32 degrees C. Mexiletine (MEX) and flecainide (FLE) were quantified under conditions of the optimum separation. The calibration graphs were constructed over the concentration range of 4.0-14.0 microg/mL for both drugs with good correlation (r > or = 0.9999). Detection and quantitation limits were found to be 0.5 and 1.5 microg/mL for FLE and 0.7 and 2.1 microg/mL for MEX, respectively. The proposed method was used for the determination of both drugs in their commercial forms with satisfactory precision (relative standard deviations of 0.36-1.21% for FLE and 0.78-1.66% for MEX) and accuracy (relative standard errors of 0.13-1.17% for FLE and 0.35-1.18% for MEX).

A new high-performance liquid chromatography method was developed and validated for the quantitation of gliclazide and repaglinide in pharmaceutical formulations. Determination was performed using a LiChroCART RP-18 column, a mobile phase containing acetonitrile-phosphate buffer (pH 2.1; 60 + 40, v/v), and ultraviolet (UV) detection at 225 nm. Repaglinide was used as an internal standard for gliclazide determination and gliclazide for repaglinide assay. The method was validated with respect to linearity, precision, robustness, ruggedness, accuracy, and specificity. The calibration graphs ranged from 0.015 to 0.09 mg/mL for gliclazide and 0.06 to 0.36 mg/mL for repaglinide. Intra- and interday relative standard deviation values for the standard solutions were 0.70 and 1.01% for gliclazide and 0.78 and 0.93% for repaglinide, respectively. Total recoveries of gliclazide and repaglinide from the laboratory-prepared mixtures were 99.82 +/- 0.58 and 101.50 +/- 0.46% for gliclazide and repaglinide, respectively [mean +/- standard deviation (SD)]. In forced degradation studies, the effect of acid, base, oxidation, UV light, and temperature on both drugs was also investigated. Finally, the method was applied for the quality control of commercial gliclazide and repaglinide tablets. Total recovery was 100.40 +/- 0.35 and 104.46 +/- 0.23% for gliclazide and repaglinide, respectively (mean +/- SD).

A methods for the determination of fenbufen and ketoprofen in pharmaceuticals by classical spectrophotometry--zero order derivative, first and second order derivatives spectrophotometry is described. using "peak-peak" (P-P) and, "peak-zero" (P-O) measurements. The calibration curves are linear within the concentration range of 2.0 - 12.0 microg x mL(-1) for fenbufen and ketoprofen. The procedure is simple, rapid and the results are reliable.

A first order derivative UV-spectrophotometric method for the determination of diltiazem hydrochloride and mexiletine hydrochloride has been developed and validated. In the assay, the first- and second-order measurements with the use of the "peak-zero" and "peak-peak" techniques were applied. The linear correlation (r < 0.9999) between the amplitude of the peak and the concentration of the examined drugs in the range of 3.0-8.0 microg mL(-1) for diltiazem and 50-100 microg mL(-1) for mexiletine was obtained. The proposed method was successfully applied for accurate (mean recovery about 100%), precise (RSD about 1%) and selective determination of the studied drug in the pure and dosage forms.

Polyvinyl chloride matrix membrane ion-selective electrodes for the determination of methiaden hydrochloride based on the ion-pair of methiaden cation with tetraphenylborate anion were prepared using bis(2-ethylhexyl)sebacate, (electrode A), 2-nitrophenyl octyl ether (electrode B). 2-nitrophenyl dodecyl ether (electrode C) and 1-isopropyl-4-nitrobenzene (electrode D) as the membrane solvents. The electrodes exhibit near-Nernstian response in different concentration ranges, depending on the used membrane solvents. The basic analytical parameters of these electrodes were evaluated. The potentiometric titration method was used to determine methiaden hydrochloride with good precision and accuracy.

A method for the determination of cetirizine dihydrochloride in pharmaceuticals by first-, second-, third- and fourth- order derivative spectrophotometry is described, using "peak-peak" (P-P), and "peak-zero" (P-0) measurements. The calibration curves are linear within the concentration range of 7.5-22.5 microg ml(-1) for cetirizine dihydrochloride. The procedure is simple, rapid and the results are reliable.