Analysis of human parathyroid hormone (1-84) products. Separation of a major impurity in synthetic products by ion-pairing reversed-phase high-performance liquid chromatography

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.

Assessment of recombinant human parathyroid hormone: correlation of LC methods with bioassays

Reversed-phase liquid chromatography (RP-LC) and size exclusion liquid chromatography (SE-LC) methods were validated for the assessment of recombinant human parathyroid hormone (rhPTH 1-34). The gradient RP-LC method was carried out on a Zorbax 300 SB C(18) column (150 mm × 4.6 mm i.d.), maintained at 40 °C. The mobile phase A consisted of 0.1 M sodium sulphate buffer, pH 2.3, and the mobile phase B was acetonitrile. The SE-LC method was carried out on a BioSep-SEC-S 2000 column (300 mm × 7.8 mm i.d.), maintained at 25 °C. The mobile phase consisted of 0.1 M phosphoric acid buffer, pH 2.5, run isocratically at a flow rate of 0.7 mL min(-1). Chromatographic separation was obtained with retention times of 12.2 min, and 13.2 min, and was linear over the concentration range of 1-250 μg mL(-1) (r(2) = 0.9997) and 2-300 μg mL(-1) (r(2) = 0.9993), respectively, for RP-LC and SE-LC, with photodiode array (PDA) detection at 214 nm. Specificity was established in degradation studies, which also showed that there was no interference of the excipients. Equally, the accuracy was 100.49% and 100.22%, with bias lower than 1.12% and 0.81% respectively. Moreover, the in vitro cytotoxicity test of related proteins and higher molecular weight forms showed significant differences (p < 0.05). Chromatographic methods were applied for the content/potency assessment of rhPTH and related proteins in biopharmaceutical injectable dosage forms, and the results were correlated with those of in vitro and in vivo bioassays. It is concluded that the employment of the methods in conjunction allows a great improvement in monitoring stability, contributing to evaluate alternatives which improve the quality control and thereby assure the therapeutic efficacy of the biotechnology-derived medicine.