Development and validation of a HPLC method for the determination of cetirizine in pharmaceutical dosage forms.

A rapid, simple and accurate HPLC method is described for the assay of cetirizine in commercial dosage forms. Methanol was found to be a suitable extraction solvent for tablets and for preparing solutions from drops and oral liquids. The samples were chromatographed on a Nova-Pak C18 column and UV detected at 227 nm. The elution was achieved isocratically with a mobile phase of 0.067 M phosphate buffer pH 3.40/acetonitrile (1:1, v/v). Ketotifen was applied as an internal standard. The method was validated for linearity, precision, accuracy and limit of detection. The recovery (mean +/- SD) for tablets was 100.88% +/- 0.8967, for drops 100.35% +/- 0.4062 and for solutions 101.20% +/- 1.1698.

Determination of moclobemide, paroxetine, and fluvoxamine in tablets by HPLC.

A simple, accurate high performance liquid chromatography procedure is presented in order to determine moclobemide in Aurorix-tablets, paroxetine in Seroxat-tablets and fluvoxamine in Fevarin tablets. These drugs were chromatographed on a Nova-Pak C18, (dp = 4 microm), 150x3.9 mm i.d. column using methanol/phosphate butter adjusted to pH 2.65 with phosphoric acid (7:3, v/v) as the mobile phase to determining of the moclobemide and methanol/tetrahydrofuran/phosphate buffer at pH 2.65 (53:5:4, v/v) for determining of paroxetine and fluvoxamine. The detection was carried at 235 nm. The method was tested for linearity over the range 5-50 microg/ml. The relative standard deviation for moclobemide is 1.16, but for paroxetine and fluvoxamine is less than 1% (0.25 and 0.46 respectively).

Thin-layer chromatographic analysis of fludarabine and formycin A in human plasma.

Fludarabine and formycin A, extracted from plasma, were separated by TLC method on silica gel and aluminium oxide by horizontal development, using suitable mobile phases. The substances were visualized by UV irradiation. After extraction from plasma it was possible to detect 100 ng of fludarabine and 200 ng of formycin A. These results suggested that the TLC system is useful for the initial detection and identification of these drugs in emergencies.

Determination of zopiclone in tablets by HPLC and UV-spectrophotometry.

Rapid, simple and accurate chromatographic (HPLC) and spectrophotometric methods for the determination of zopiclone in tablets were elaborated. Acetonitrile was found to be a suitable extraction solvent. The samples were chromatographed on Nova-Pak C18 column and UV detection at 304 nm. The elution was achieved isocratically with a mobile phase of 0.067 M phosphate buffer pH 7.95 - acetonitrile (55:45, v/v). Diazepam was applied as an internal standard. The method was validated for precision, linearity, accuracy and limit of detection. The recovery (mean +/- SD) in HPLC was 99.85 + 0.04% and in the UV-spectrophotometry 100.08 +/- 0.09%.

High-performance liquid chromatographic assay of formycin A in plasma after solid-phase extraction.

A new, simple and accurate high-performance liquid chromatography (HPLC) method for the determination of formycin A in plasma is presented. The samples were chromatographed on a LiChrosórb RP-18 column after purification using a Bakerbond SPE column. The mobile phase was methanol-0.067 M phosphate buffer, pH 4.20 (1:4, v/v) containing 0.005 M sodium hexanesulfonate. Azathioprine was applied as an internal standard. UV detection was carried out at 293 nm. The method was tested for linearity (over the range 0.1-9.0 micrograms/ml). The recovery was 91.89% (mean). The described method has been successfully applied to the quantitative determination of formycin A in plasma and should be useful for clinical and bioavailability investigations.

Preliminary pharmacokinetic studies of Ukrain in rats.

Ukrain (thiophosphoric acid derivative of Chelidonium majus L. alkaloids) was administered to rats i.p. at a dose of 28 mg/kg (equivalent to 0.1 LD50). A high performance liquid chromatography (HPLC) method for rapid determination of Ukrain in plasma has been described. It was found that Ukrain rapidly penetrated into the plasma of the rats and the elimination of the drug from the plasma was slower. The results obtained were as follows: absorption rate constant ka = 0.0432 [min-1]; elimination rate constant K = 0.0113 [min-1]; drug half-life t1/2 = 61.32 min; actual concentration of Ukrain in the plasma C = 33 e-0.0113t - 39 e-0.0432t [microgram/ml]; and delay in drug absorption T0 = 5.23 min.

Determination of fluoxetine in human plasma using reserved phase HPLC.

A rapid, simple, accurate method for the determination of fluoxetine in human plasma is presented. Liquid-liquid extraction of fluoxetine was carried out using diethyl ether. Chlorprothixene was applied as an internal standard. The samples were chromatographed on a LiChrosorb RP-18 (10 microns) column and the mobile phase was acetonitrile/phosphate buffer pH 2.70 (9:1). The detection was carried at 254 nm. A linear quantitative response curve was generated over a concentration range of 100-600 ng/ml. Overall extraction efficiency of the extraction procedure was found to be 86 to 91% with a correlation coefficient of 0.992.

Chromatographic analysis (TLC) of fluoxetine, doxepine, imipramine and opipramol in human plasma.

Fluoxetine, imipramine, doxepine and opipramol after liquid-liquid extraction were separated by TLC on silica gel 60 GF254 by ascending and horizontal technique using suitable mobile phases. The substances were identified by UV irradiation at 254 nm and by spraying of Amelinka's reagnet (up to the amount 0.25 microgram fluoxetine and 0.05 microgram imipramine, doxepine and opipramol).

Determination of fludarabine phosphate in human plasma using reversed phase high-performance liquid chromatography.

A rapid, simple and accurate HPLC method for the determination of fludarabine phosphate in human plasma is presented. Fludarabine phosphate from plasma was successfully purified. The samples were chromatographed on a LiChrosorb RP-18 (10 microns) column after purification using a Bakerbond Spe column. The mobile phase was methanol/phosphoric buffer pH 4.15 (20:80). The detection was carried out at 262 nm. The method was tested for linearity (range from 100 to 900 ng/ml), recovery (ca. 99.8%) and precision (C.V. = 3.2%).

Chromatographic analysis (TLC) of uracil arabinoside, cytosine arabinoside, uracil and cytosine in human plasma.

Cytosine arabinoside, uracil arabinoside, cytosine and uracil after solid-phase extraction from plasma with minicolumns Adsorbex were separated by TLC on silica gel 60 GF254 by ascending and horizontal technique using suitable mobile phases. The substances were identified by UV irradiation at 254 nm and by spraying of 1% KMnO4 solution (up to the amount 500 ng analysed substances).

Determination of aprindine in human plasma using reversed phase HPLC.

A rapid, simple, accurate method is presented for the determination of aprindine in human plasma. Liquid-liquid extraction of aprindine was carried out using diethyl ether. Amiodarone was applied as an internal standard. The samples were chromatographed on LiChrosorb RP-18 (10 microns) column and the mobile phase was methanol/acetonitrile/phosphate buffer pH 2.5 (80:15:5). The detection was carried at 254 nm. The method was tested for linearity (range from 0.5 to 2.5 micrograms/ml), recovery (ca. 90%) and precision (CV = 3.7%).

Determination of nadoxolol in human plasma using reversed-phase high-performance liquid chromatography.

A rapid, simple and accurate HPLC method is presented for the determination of nadoxolol in human plasma. Nadoxolol from plasma was successfully purified using an Adsorbex column. The samples were chromatographed on a LiChrosorb RP-18 (10 microns) column with methanol-acetonitrile-phosphate buffer (pH 3.3) (70:20:10) as the mobile phase. Detection was carried out at 254 nm. The method was tested for linearity (from 5 to 25 micrograms/ml), recovery (85%) and precision (C.V. = 4.5%).

Determination of amiodarone in tablets and plasma by high-performance liquid chromatography.

A method is described for measuring amiodarone in human plasma and tablets using a LiChrosorb RP-18 column, a mobile phase methanol-acetonitrile-phosphate buffer pH 2.6 (80:15:5, v/v) and UV detection at 254 nm. Another antiarrhythmic drug - aprindine was used as an internal standard (i.s.).

Chromatographic analysis (TLC) aprindine and nadoxolol in human plasma.

Aprindine and nadoxolol extracted from plasma were separated by TLC method on silica gel by ascending technique on 5 x 20 cm and 2.5 x 7.5 cm microscopic slides and also by horizontal development, using suitable mobile phases. The substances were identified by reaction with Kiefer reagent (up to the amount 100 ng of aprindine and 300 ng of nadoxolol).

[Determination of piritramid in plasma using high pressure liquid chromatography methods]. / Oznaczanie pirytramidu w osoczu metoda wysokosprawnej chromatografii cieczowej.

After alkalization piritramid and codeine (internal standard) were extracted from plasma thrice with ether, solvent was removed, the residue dissolved in a mobile phase (methanol-phosphate buffer pH 4.5. 7:3) and injected on the column (packing Lichrosorb RP-18). The amount (0.5-2.5 micrograms) of piritramid was determined, average recovery was 88%.

[Determination of methadone in plasma using high pressure liquid chromatography methods]. / Oznaczanie metadonu w osoczu metoda wysokosprawnej chromatografii cieczowej.

High-performance liquid chromatography on the column of LiChrosorb RP-18 was applied to the determination of methadone in plasma, after previous precipitation of proteins with methanol and extraction from alkalized plasma with diethyl ether. Methadone, ion-paired with pentane-1-sulphonic acid added in a mobile phase acetonitrile-methanol-ammonium acetate solution (20:58:22), was monitored at 254 nm. Piritramide was used as an internal standard. The determination range was 0.25-1.25 micrograms/cm3 of plasma and recovery was 88-93%.

[Determination of clozapine in blood serum using high pressure liquid chromatography (HPLC)]. / Oznaczanie klozapiny w surowicy krwi metoda wysokosprawnej chromatografii cieczowej (HPLC).

For the simultaneous determination of clozapine in presence of its metabolite in serum a sensitive reversed phase HPLC method was used. The mobile phase was a mixture of acetonitril-methanol-phosphoric buffer pH 4.5 (5:4:1). The solvent for extracting clozapine from serum was diethyl ether. Dezipramine hydrochloride was used as an internal standard. The method is sufficiently sensitive (25 ng) and reproducible for clinical and pharmacokinetic studies.

[Testing of some dibenzoazepines and dibenzocycloheptadiene derivatives with high pressure thin layer chromatography]. / Badania niektórych pochodnych dibenzoazepiny i dibenzocykloheptadienu metoda chromatografii cienkowarstwoweji wysokosprawnej cieczowej.

An influence of several adsorbents and the composition of the eluent mixtures on the separation of dibenzoazepine and dibenzocycloheptadiene derivatives was examined by thin-layer chromatography. The best system (RP-18 and methanol-buffer solution pH 8.5 19:1) was employed for the separation of amitryptiline and doxepine by HPLC. Both compounds were determined in ng amounts in pharmaceutical preparations and in blood by addition and in patients blood. Doxepine was used as internal standard for the determination of amitryptiline.