Analysis of Denosumab by a Validated CZE Method and Determination of Sialic Acids by the RP-HPLC Method

A capillary zone electrophoresis (CZE) method was developed and validated to quantitate the monoclonal antibody denosumab (DmAb) and its charge variants in pharmaceutical products, demonstrating excellent precision, linearity and accuracy. Separations were obtained with migration times of 11.3 min for DmAb and the calibration curve was linear in the range of 0.95-20 mg/mL. The analytical comparability of seven batches of Prolia® showed mean differences of the estimated content/potencies of 1.87% lower, and 0.84 and 1.21% higher compared with the size-exclusion and reversed-phase liquid chromatography (SE-HPLC and RP-HPLC) methods and the osteoclast antiproliferative bioassay, respectively, with non-significant differences (P > 0.05). An RP-HPLC method with fluorescence detection (RP-HPLC-F), performed on a Kinetex® EVO C18 column (5 μm, 100 Å, 250 mm × 4.6 mm), was optimized to determine the levels of sialic acids of DmAb biomolecules, giving mean concentrations of 0.16 and 0.17 μg N-acetylneuraminic acid/mg DmAb for Prolia® and Xgeva® pharmaceutical products, respectively. The results demonstrated the capability of each one of the methods, and their use in combination constitutes a strategy to monitor instability, thereby assuring the quality and the batch-to-batch consistency of the biotechnology-derived medicine.

Validation of a Stability-Indicating RP-HPLC Method for the Determination of Entecavir in Tablet Dosage Form

An RP-HPLC method was validated for the determination of entecavir in tablet dosage form. The HPLC method was carried out on a Gemini C18 column (150 4.6 mm id) maintained at 30C. The mobile phase consisted of acetonitrilewater (95 + 5, v/v)/potassium phosphate buffer (0.01 M, pH 4; 9 + 91, v/v) pumped at a flow rate of 1.0 mL/min. Photodiode array detection was at 253 nm. The chromatographic separation was obtained with a retention time of 4.18 min, and the method was linear in the range of 0.5200 g/mL (r2 0.9998). The specificity and stability-indicating capability of the method was proven through forced degradation studies, which also showed that there was no interference of the excipients and an increase of the cytotoxicity only by the basic condition. The accuracy was 101.19, with bias lower than 1.81. The LOD and LOQ were 0.39 and 0.5 g/mL, respectively. Method validation demonstrated acceptable results for precision and robustness. The proposed method was applied for the analysis of tablet formulations, to improve QC and assure therapeutic efficacy.

Validation of the Antifactor Xa and Antifactor IIa Assays for the Potency Assessment of Nadroparin in Pharmaceutical Formulations

The low-molecular weight heparin nadroparin calcium is used clinically for the prevention and treatment of venous and arterial thrombosis. The antifactor Xa and antifactor IIa assays were validated by investigating the parameters of range, linearity (r2 0.9905 and r2 0.9914, respectively) precision, accuracy, and robustness. The 2 methods incorporated a chromogenic endpoint and detection at 405 nm, yielding good results with detection limits of 0.004 and 0.01 IU/mL and quantitation limits of 0.01 and 0.03 IU/mL, respectively, for the antifactor Xa and antifactor IIa assays. Nadroparin calcium pharmaceutical products were evaluated by the antifactor Xa assay and the antifactor IIa assay, giving potencies between 93.86 and 109.88%, with an antifactor Xa/antifactor IIa ratio between 3.2 and 3.7. The results demonstrated the validity of the assays that are useful methodologies for the routine quality control of nadroparin in pharmaceutical formulations.

Analysis of streptokinase by validated liquid chromatography methods and correlation with an in vitro bioassay

Reversed-phase and size-exclusion liquid chromatography methods were validated for the assessment of streptokinase. The reversed-phase method was carried out on a Jupiter C₄ column (250 mm × 4.6 mm id) maintained at 25°C. The mobile phase consisted of 50 mM sodium sulfate solution pH 7.0 and methanol (90:10, v/v), run isocratically at a flow rate of 0.8 mL/min. The size-exclusion method was carried out on a Protein KW 802.5 column (300 mm × 8.0 mm id), at 25°C. The mobile phase consisted of 40 mM sodium acetate solution pH 7.0, run isocratically at a flow rate of 1.0 mL/min. Retention times were 19.3 min, and 14.1 min, and calibration curves were linear over the concentration range of 0.25-250 μg/mL (25.75-25 750 IU/mL) (r² = 0.9997) and 5-80 μg/mL (515-8240 IU/mL) (r² = 0.9996), respectively, for reversed-phase and size exclusion, with detection at 220 and 204 nm. Chromatographic methods were employed in conjunction with the in vitro bioassay for the content/potency assessment of Streptokinase, contributing to improve the quality control and ensure the efficacy of the biotherapeutic.

Evaluation of recombinant human parathyroid hormone by CZE method and its correlation with in vitro bioassay and LC methods

A stability-indicating capillary zone electrophoresis (CZE) method was validated to assess the content/potency of the recombinant human parathyroid hormone (rhPTH 1-34), using ranitidine as internal standard (IS). A fused-silica capillary, (i.d. of 50µm; effective length of 40cm) was used at 25°C; the applied voltage was 20kV. The background electrolyte solution consisted of 50mmolL^-1 sodium dihydrogen phosphate solution at pH 3.0. Injections were performed using a pressure mode at 50 mbar for 45s, with detection by photodiode array (PDA) detector set at 200nm. Separation was obtained with a migration time of 5.3min, and was linear over the concentration range of 0.25-250µgmL^-1 (r² =0.9992). Specificity and stability-indicating capability were established in degradation studies, which also showed that there was no interference of the excipients. The accuracy was 100.28% with bias lower than 0.85%. Analyses of the same batches showed mean differences of the estimated content/potencies of 0.61%, 1.31% higher and 0.86% lower as compared to the validated reversed-phase and size exclusion liquid chromatography methods, and to the UMR-106 cell culture bioassay, respectively, with non-significant differences (p>0.05). Degraded forms were also subjected to the in vitro cytotoxicity test. The results obtained showed the capabilities of each one of the methods, and constitute an alternative strategy to monitor stability, improve the quality control and ensure the batch-to-batch consistency of bulk and finished biotechnology-derived medicine.

Validation of a stability-indicating RP-HPLC method for the determination of entecavir in tablet dosage form

An RP-HPLC method was validated for the determination of entecavir in tablet dosage form. The HPLC method was carried out on a Gemini C18 column (150 x 4.6 mm id) maintained at 30 degrees C. The mobile phase consisted of acetonitrile-water (95 + 5, v/v)/potassium phosphate buffer (0.01 M, pH 4; 9 + 91, v/v) pumped at a flow rate of 1.0 mL/min. Photodiode array detection was at 253 nm. The chromatographic separation was obtained with a retention time of 4.18 min, and the method was linear in the range of 0.5-200 microg/mL (r2 = 0.9998). The specificity and stability-indicating capability of the method was proven through forced degradation studies, which also showed that there was no interference of the excipients and an increase of the cytotoxicity only by the basic condition. The accuracy was 101.19%, with bias lower than 1.81%. The LOD and LOQ were 0.39 and 0.5 microg/mL, respectively. Method validation demonstrated acceptable results for precision and robustness. The proposed method was applied for the analysis of tablet formulations, to improve QC and assure therapeutic efficacy.

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).

Validation of a capillary zone electrophoresis method for the comparative determination of etoricoxib in pharmaceutical formulations

A CZE method was developed and validated for the analysis of etoricoxib in pharmaceutical dosage forms, using prilocaine as an internal standard. The CZE method was carried out on a fused-silica capillary (50 microm id, effective length 40 cm). The BGE consisted of 25 mM tris-phosphate solution at pH 2.5. The capillary temperature was maintained at 35 degrees C, the applied voltage was 25 kV, the injection was performed using the pressure mode at 50 mbar for 5 s, with detection at 234 nm using a photodiode array detector. The method was linear in the range of 2-150 microg/mL (r(2) = 0.9999). The specificity and stability-indicating capability were proven through the degradation studies and showing also that there was no interference of the excipients of the formulation. The accuracy was 99.49% with RSD of 0.66%. The limits of quantitation and detection were 2 and 0.58 microg/mL, respectively. Moreover, method validation demonstrated acceptable results for the precision, sensitivity, and robustness. The proposed method was successfully applied for the quantitative analysis of etoricoxib pharmaceutical formulations, and the results compared to the HPLC and LC-MS/MS methods, showing nonsignificant difference (p >0.05).

Simultaneous liquid chromatographic determination of ezetimibe and simvastatin in pharmaceutical products

A reversed-phase liquid chromatographic (LC) method was developed and validated for the simultaneous determination of ezetimibe and simvastatin in pharmaceutical dosage forms. The LC method was carried out on a Synergi fusion C18 column (150 mm x 4.6 mm id) maintained at 45 degrees C. The mobile phase consisted of phosphate buffer 0.03 M, pH 4.5-acetonitrile (35 + 65, v/v) run at a flow rate of 0.6 mL/min, and detection was made using a photodiode array detector at 234 nm. The chromatographic separation was obtained within 15.0 min, and calibration graphs were linear in the concentration range of 0.5-200 microg/mL. Validation parameters such as specificity, linearity, precision, accuracy, and robustness were evaluated, giving results within the acceptable range for both compounds. Moreover, the proposed method was successfully applied for the routine quality control analysis of pharmaceutical products.

Validation of the Anti-Factor Xa Assay for the Potency Assessment of Enoxaparin in Pharmaceutical Formulations

Enoxaparin is a low-molecular weight heparin used clinically for the prevention and treatment of venous and arterial thrombosis. An anti-factor Xa assay was used to evaluate the potency of the final drug preparation. Method validation investigated parameters such as the range, linearity (r2 = 0.9971), precision, accuracy, and robustness; the biological assay incorporated a chromogenic endpoint and detection at 405 nm. The method yielded good results with a quantitation limit of 0.037 IU/mL and a detection limit of 0.011 IU/mL. The results demonstrated the validity of the anti-factor Xa assay for the determination of enoxaparin.

Validation of the anti-factor Xa assay for the potency assessment of enoxaparin in pharmaceutical formulations

Enoxaparin is a low-molecular weight heparin used clinically for the prevention and treatment of venous and arterial thrombosis. An anti-factor Xa assay was used to evaluate the potency of the final drug preparation. Method validation investigated parameters such as the range, linearity (r2 = 0.9971), precision, accuracy, and robustness; the biological assay incorporated a chromogenic endpoint and detection at 405 nm. The method yielded good results with a quantitation limit of 0.037 IU/mL and a detection limit of 0.011 IU/mL. The results demonstrated the validity of the anti-factor Xa assay for the determination of enoxaparin.

Biological evaluation of recombinant human erythropoietin in pharmaceutical products

The potencies of mammalian cell-derived recombinant human erythropoietin pharmaceutical preparations, from a total of five manufacturers, were assessed by in vivo bioassay using standardized protocols. Eight-week-old normocythemic mice received a single subcutaneous injection followed by blood sampling 96 h later or multiple daily injections with blood sampling 24 h after the last injection. Reticulocyte counting by microscopic examination was employed as the end-point using the brilliant cresyl blue or selective hemolysis methods, together with automated flow cytometry. Different injection schedules were investigated and dose-response curves for the European Pharmacopoeia Biological Reference Preparation of erythropoietin were compared. Manual and automated methods of reticulocyte counting were correlated with respect to assay validity and precision. Using 8 mice per treatment group, intra-assay precision determined for all of the assays in the study showed coefficients of variation of 12.1-28.4% for the brilliant cresyl blue method, 14.1-30.8% for the selective hemolysis method and 8.5-19.7% for the flow cytometry method. Applying the single injection protocol, a combination of at least two independent assays was required to achieve the precision potency and confidence limits indicated by the manufacturers, while the multiple daily injection protocol yielded the same acceptable results within a single assay. Although the latter protocol using flow cytometry for reticulocyte counting gave more precise and reproducible results (intra-assay coefficients of variation: 5.9-14.2%), the well-characterized manual methods provide equally valid alternatives for the quality control of recombinant human erythropoietin therapeutic products.

Comparative evaluation of the human whole blood and human peripheral blood monocyte tests for pyrogens

Two different in vitro tests for pyrogens, using human peripheral blood monocytes (PBMNC) and diluted whole blood (WBC), respectively, were applied to different classes of parenteral medicinal products. Many of these products did not have a specified endotoxin limit concentration that was established as the maximum valid dilution to comply with the test. The results of the in vitro tests for pyrogens were compared with the results from the Limulus amoebocyte lysate (LAL) and rabbit pyrogen tests. The Second International Standard for endotoxin was used to calibrate all of the assays and the International Standard for IL-6 was used to calibrate the IL-6 ELISA which provided the readout for the in vitro tests for pyrogens. Preparatory tests were conducted to ensure that the "criteria for validity and precision of the standard curve" were satisfied and that the drugs being tested did not interfere in the tests. The PBMNC/IL-6 test had a detection limit of 0.06 EU/ml and spike recoveries were 62-165%. The whole blood/IL-6 test also had a detection limit of 0.06 EU/ml and spike recoveries were 58-132%. The application to the detection of non-endotoxin pyrogens needs to be evaluated in more detail, but the two in vitro tests for pyrogens showed good agreement overall, both with each other and with the LAL test and the rabbit pyrogen test for the detection of endotoxins.

Inclusion complex of piroxicam with beta-cyclodextrin and incorporation in cationic microemulsion. In vitro drug release and in vivo topical anti-inflammatory effect

Topical formulations of piroxicam were evaluated by determination of their in vitro release and in vivo anti-inflammatory effect. The in vitro release assay demonstrated that the microemulsion (ME) systems provided a reservoir effect for piroxicam release. However, the incorporation of the ME into carboxyvinilic gel provoked a greater reduction in the release of piroxicam than the ME system alone. Anti-inflammatory activity was carried out by the cotton pellet granuloma inhibition bioassay. Topical anti-inflammatory effect of the piroxicam inclusion complex/ME contained in carboxyvinilic gel showed significant inhibition of the inflammation process (36.9%, P<0.05). Subcutaneous administration of the drug formulations showed a significant effect on the inhibition of inflammation, 68.8 and 70.5%, P<0.05, when the piroxicam was incorporated in ME and in the combined system beta-cyclodextrin (beta-CD)/ME, respectively, relative to the buffered piroxicam (42.2%). These results demonstrated that the ME induced prolonged effects, providing inhibition of the inflammation for 9 days after a single dose administration.

Piroxicam encapsulated in liposomes: characterization and in vivo evaluation of topical anti-inflammatory effect

Liposomes of soya phosphatidylcholine, cholesterol, and stearylamine (molar ratio 6/3/1) and 0.1% alpha-tocopherol were prepared by the extrusion of multilamellar vesicles through 0.2-micron polycarbonate membrane. Liposomes were characterized by electron transmission microscopy, and the mean structure diameter was 278 nm. The encapsulation efficiency obtained was 12.73%. The topical anti-inflammatory effect was evaluated in vivo by the cotton pellet granuloma method. We analyzed free piroxicam at 4 mg/kg, piroxicam encapsulated in liposomes added to 1.5% hydroxyethylcellulose (HEC) gel at 1.6 mg/kg, and piroxicam encapsulated in liposomes added to HEC gel at 4 mg/kg; the inhibition of inflammation obtained was 21.1%, 32.8%, and 47.4%, respectively. These results showed that the encapsulation of piroxicam produced an increase of topical anti-inflammatory effect, suggesting that the inhibition of inflammation can be obtained with lower drug concentrations.

[Determination of anticoagulant activity of heparin]

Heparin samples from four manufacturers and the First Argentinian Standard Heparin obtained from porcine mucosa were assayed by the Reinert and Winterstein method, modified as suggested by USP and Brazilian Pharmacopeias. Other methods described in the literature and their importance for the evaluation of anticoagulant activity of unfractionated heparins with low molecular weight are discussed.