IDENTIFICATION AND DETERMINATION OF RUPATADINE AND FEXOFENADINE BY DENSITOMETRIC METHOD.

Simple, precise and accurate densitometric methods were developed for the determination of two antihistamine drugs. rupatadine and fexofenadine. Silica gel 60 F254 HPTLC plates were used as stationary phase, while mixtures of acetonitrile - water - 25% ammonia (90 : 10 : 1, v/v/v) and acetonitrile - methanol -acetate buffer at pH 5.5 (3 : 2 : 5, v/v/v) were used as mobile phases for rupatadine and fexofenadine, respectively. The detection of rupatadine and fexofenadine was conducted out at 256 and 210 nm, respectively. The limit of detection and the limit of quantification for rupatadine were found to be 0.3 and 0.1 µg/spot, respectively, and for fexofenadine, 5 and 2 µg/spot, respectively.

DEVELOPMENT OF CHROMATOGRAPHIC METHOD FOR DETERMINATION OF DRUGS REDUCING CHOLESTEROL LEVEL--STATINS AND EZETIMIBE.

The presented developed HPLC method and GC method may be used to separate and determine all analyzed 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) and ezetimibe using a single columns and a uniform methodology. In order to perform qualitative and quantitative tests of statins and ezetimibe the Symmetry C18 column 250 mm x 4.6 mm, 5 µm, the mobile phase: acetonitrile:water (70:30, v/v), adjusted to pH = 2.5 and a spectrophotometric detector for the HPLC method were used. For GC method column HP-1; 30 m x 0.25 mm x 0.25 µm and FID detector were selected. All results and statistical data obtained indicate good method sensitivity and precision. The RSD values are appropriate for both newly developed methods.

IMPACT OF STRESS FACTORS ON OPTICAL ISOMERISM OF BENAZEPRIL HYDROCHLORIDE.

Benazepril hydrochloride contains two stereogenic centers, but is currently available as single enantiomer (S,S configuration) for the treatment of hypertension. Its enantiomer (R,R configuration) and the diastereoisomeric pair (R,S and S,R) can be regarded as impurities. Stereochemical stability of S,S isomer of benazepril hydrochloride and its potential susceptibility to conversion in the.active substance and in Lisonid tablets were examinated. The separation with the use of the TLC method with the following system: chromatographic plates Chiralplate and a mobile phase: methanol - acetonitrile - 1 mM copper(II) acetate (4 : 2 : 4, v/v/v) with saturation of glacial acetic acid for 1 h and the HPLC method system: Chiral AGP column (150 x 4.0 man x 5 µm) and a mobile phase: phosphate buffer pH = 6.0 - methanol (80 : 20, v/v) were obtained. Active substance - benazepril hydrochloride and Lisonid tablets 20 mg were subjected to the impact of different stress factors. Samples were examined after 1 and 6 weeks. It was found that none of the applied stress factors caused the transformation of the S,S enantiomer of benazepril hydrochloride in the substance and tablets to other identified stereoisomers - only the compound decomposition has occurred.

Identification and determination of selected histamine antagonists by densitometric method.

The conditions for identification were determined for four histamine antagonists: clemastine fumarate, loratadine, cetirizine dihydrochloride and desloratadine by TLC (thin-layer chromatography) method. The selected chromatographic conditions were used to develop a densitometric method for the content determination of the histamine antagonists in medicinal products and substances. The statistical data showed adequate accuracy and precision of the developed methods.

Identification and determination of ketotifen hydrogen fumarate, azelastine hydrochloride, dimetindene maleate and promethazine hydrochloride by densitometric method.

Conditions for determination of: ketotifen hydrogen fumarate, azelastine hydrochloride, dimetindene maleate and promethazine hydrochloride by densitometric method in substances and pharmaceuticals were provided. Maximum wavelenghts were: 228 nm for ketotifen hydrogen fumarate, 295 nm for azelastine hydrochloride, 265 nm for dimetindene maleate and 255 nm for promethazine hydrochloride. The limits of quantification were in the ranges of 0.2-5 microg/spot. The statistical data showed adequate accuracy and precision of developed methods.

Identification and determination of selected angiotensin II receptor antagonist group drugs by HPLC method.

Losartan potassium, valsartan, telmisartan, irbesartan, eprosartan mesylate and candesartan cilexitil, the angiotensin II receptor antagonists, were analyzed in bulk substances and in tablets: Lorista tablets 50 mg, Diovan tablets 160 mg, Micardis tablets 20 mg, Aprovel tablets 300 mg, Teveten tablets 600 mg and Blopress tablets 16 mg. The conditions for identification by HPLC method in a gradient system and for determination of those compounds in isocratic systems were developed. The determination was carried out using Zorbax SB-Phenyl column with UV-VIS detector set at 230 nm and the following mobile phases: 0.1 mol/L sodium acetate (pH = 5.5) - acetonitrile - methanol in 35:9:6 v/v/v ratio for eprosartan mesylate and valsartan, in 15:6:4 v/v/v ratio for losartan potassium and irbesartan and in 10:9:6 v/v/v ratio for telmisartan and candesartan cilexitil. The recovery from simulated tablets was determined and amounted to: for eprosartan mesylate - 99.04%, valsartan - 100.0%, losartan potassium - 100.03%, irbesartan - 100.35%, telmisartan - 100.06% and candesartan cilexitil - 100.40%.

Identification and determination of antihypertonics from the group of angiotensin-convertase inhibitors by densitometric method in comparition with HPLC method.

Conditions have been elaborated for the identification of all the compounds belonging to the group of angiotensin convertase inhibitors: lisinopril, quinapril, ramipril, spirapril, moexipril, trandolapril, benazepril, cilazapril, fosinopril, captopril, enalapril, imidapril and zofenopril by thin-layer chromatography. The selected conditions were used to design the densitometric method for the content determination of the above mentioned compounds in substances and medicines. The statistical data obtained for the designed method indicate adequate accuracy and precision.