Validated stability-indicating RP-HPLC method for the determination of rimonabant in a pharmaceutical dosage form.

A simple RP-HPLC method was developed and validated for the determination of rimonabant in a pharmaceutical dosage form. The separation was performed on a C18 column (150 x 4.6 mm id, 5 microm) with acetonitrile-water (75 + 25, v/v) mobile phase. The detection was achieved with a diode array detector at 215 nm. The method was linear in the concentration range of 0.5-50 microg/mL (r = 1) with an LOQ of 0.24 microg/mL. The specificity and stability-indicating capability of the method were proved through forced degradation studies, and it was shown that there was no increase of the cytotoxicity. Rimonabant was exposed to hydrolytic, oxidative, and photolytic stress conditions, and the samples were analyzed by the proposed method. Under optimized conditions, rimonabant was successfully separated from its degradation products within 10 min, and the resolution was found to be greater than 2. The RSD values for intraday and interday precision were always less than 2%. Interday accuracy ranged from 98.1 to 101.7% (RSD = 1.0%). Moreover, method validation demonstrated acceptable results for sensitivity and robustness. The method was applied for the quantitative analysis of rimonabant in a tablet dosage form to demonstrate its use for improving the QC of pharmaceuticals containing this drug.

A high-throughput liquid chromatography tandem mass spectrometry method for the comparative determination of fluticasone propionate by reversed-phase liquid chromatography and capillary electrophoresis methods in pharmaceutical nasal sprays.

A simple, specific, rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the analysis of fluticasone propionate (FP) in pharmaceutical formulations was developed and validated using deflazacort as internal standard (IS). The LC-MS/MS method was carried out on a C8 column (50 mm) with a mobile phase consisted of methanol : water (95 : 5, v/v) 100 mM formic acid-50 mM ammonium acetate (90 : 5 : 5, v/v/v). The mass spectrometry method was performed employing positive atmospheric pressure chemical ionization technique, operating in multiple reaction monitoring mode. The chromatographic separation was obtained within 1.5 min and it was linear in the concentration range of 10-1000 ng mL(-1). Moreover, method validation demonstrates acceptable results for the specificity, accuracy, precision and robustness. The proposed method was successfully applied for the quantitative analysis of FP nasal sprays and the results were compared to validated liquid chromatography and capillary electrophoresis methods with photodiode array detectors showing non-significant difference (P > 0.05).

Evaluation of the changes in hemostatic parameters induced by etoricoxib in rat model.

The effects of etoricoxib on blood coagulation parameters were evaluated, along with acetylsalicylic acid, in male Wistar rats. Blood samples were collected at the end of the first, second, third and fourth weeks of the administration period and the plasma concentrations of etoricoxib determined by liquid chromatography-tandem mass spectrometry; the samples were also used for the analysis of the hematological parameters. There were no significant changes in the platelet count and fibrinogen levels, and a decrease by 1.9% of the prothrombin time was detected at the third week. The activated partial thromboplastin time assay showed a nonsignificant shortening. The antiactivated factor X and antiactivated factor II activities showed reductions lower than 2.8 and 1.3%, respectively. These findings and the comparison with acetylsalicylic acid can be helpful to support the benefit-to-risk profile, contributing to the safe therapeutic use.

Evaluation of the changes on hemostatic parameters induced by valdecoxib in male Wistar rats / Avaliação dos efeitos do valdecoxibe sobre os parâmetros hemostáticos de ratos Wistar

The effects of the cyclooxygenase (COX)-2 selective inhibitor, valdecoxib, on blood coagulation parameters were evaluated, along with aspirin in male Wistar rats. Groups of animals were administered a daily oral dose of 10 mg/kg rat of valdecoxib, 100 mg/kg rat of aspirin and the vehicle alone during 4 weeks. Blood samples were collected at the end of 1, 2, 3 and 4 weeks of administration period and the plasma concentrations of valdecoxib were determined by RP-HPLC giving mean values of 101.1, 113.5, 164.0 and 184.6 ng/mL, respectively. The same plasma samples were used for the analysis of hematological parameters and the results compared to the controls. Valdecoxib induced significant activated partial thromboplastin time reduction (18 percent) after 2 weeks and prothrombin time reduction (12.2 percent) after 3 weeks (P<0.05). There were no significant changes in the platelet count and fibrinogen levels. The anti-factor Xa and anti-factor IIa activities showed slight reductions, but only significant for the anti-factor Xa on the 3rd week (6.7 percent). The results showed that valdecoxib at the dose tested with the plasmatic concentrations induced some changes in the hemostatic function of rats, which can be helpful to understand the side effects and the safe use of the drug.

Avaliaram-se os efeitos do valdecoxibe, um inibidor seletivo da cicloxigenase-2 (COX-2), sobre os parâ­metros sangüíneos da coagulação em ratos Wistar utilizando-se paralelamente a aspirina. Os animais foram divididos em grupos e submetidos à administração oral diária de 10 mg/kg animal para o valdecoxib, 100 mg/kg animal para a aspirina e veículo para o grupo controle, durante quatro semanas. A coleta do sangue foi efetuada após uma, duas, três e quatro semanas, e as concentrações plasmáticas do valdecoxibe determinadas por cromatografia líquida, obtendo-se valores médios de 101,1 - 113,5 - 164 e 184,6 ng/ml, respectivamente. As amostras de plasma foram também usadas para as análises hematológicas e os resultados comparados aos dos controles. O valde­coxibe apresentou redução significativa no TTPA (18 por cento) após duas semanas, e redução do TP (12,2 por cento) após três semanas (P<0.05). Os efeitos observados na contagem de pla­quetas e nos níveis plasmáticos de fibrinogênio não foram significativos. As atividades anti-fator Xa e anti-fator IIa apresentaram redução, porém os resultados foram significativos somente para o anti-fator Xa na terceira semana (6,7 por cento). Os resultados experimentais com as concentrações plasmáticas alcan­çadas demonstram que o valdecoxibe pode induzir alterações nos parâ­metros hematológicos dos ratos. Esses dados poderão contribuir para a melhor compreensão dos efeitos colaterais e uso do fármaco com segurança.