Estudo de métodos cromatográficos para avaliação de potência de filgrastima e correlação com ensaio biológico

Abstract

The granulocyte-colony stimulating factor (G-CSF) is a hematopoietic cytokine that stimulates and regulates the proliferation and differentiation of neutrophil precursor cells of the bone marrow. The recombinant hormone (rhG-CSF) non-glycosylated, filgrastim, is used to treat the neutropenia induced by chemotherapy and bone marrow transplantion. The identification and characterization was carried out by electrophoresis and western blotting, showing the typical band in the region of 18.8 kDa. The neutropenia mouse bioassay was standardized with the BALB/c strain, previously treated with ifosfamide and used for the potency assessment of pharmaceutical products. A gradient reversed-phase liquid chromatography (RP-LC) was validated for the analysis of rhG-CSF in pharmaceutical formulations. The LC method was carried out on a Jupiter C4 column 300 Å (250 mm x 4.6 mm i.d.), maintained at ambient temperature. The mobile phase A consisted of water:acetonitrila (90:10, v/v) with 0.1% trifluoroacetic acid and the mobile phase B was water:acetonitrile (20:80, v/v) with 0.1% trifluoroacetic acid, run at a flow rate of 0.5 mL/min with detection at 280 nm. The chromatographic separation was obtained with the retention time of 31.9 minutes and the method was linear in the range of 10 300 μg/mL. Validation parameters such as sensitivity, precision, accuracy, detection limit, quantitation limit and robustness were evaluated giving results in the acceptable range. The specificity was evaluated by the peak purity of the rhG-CSF biological reference preparation subjected to oxidative conditions. The proposed method was applied for the analysis of filgrastim pharmaceutical products, evaluating the sulphoxides and deamidates forms as well. Moreover, the size-exclusion chromatography (SE-LC) was performed for the potency evaluation of 7 filgrastim, dimers and high-molecular-mass forms. Samples of pharmaceutical formulations were subjected to aggregation, degradation and than each one evaluated by the neutropenia mouse bioassay giving biological activities of 14.60%, 13.47% and 15.63%, for the dimers, high-molecular-mass substances and the sulphoxides/deamidates, respectively. The pharmaceutical samples were analysed by the chromatographyc methods and compared to the bioassay showing mean difference between the estimated potencies of 2.04% lower for the RP-LC, and 4.03% lower for the SE-LC, with significant correlation (p>0.05). Due to the reduced bioactivity of the rhG-CSF-related proteins, the SE-LC is proposed in combination with the RP-LC as an alternative to the bioassay for the potency assessment of filgrastim in pharmaceutical dosage forms. The alternative established represents a contribution towards the replacement of the animals improving the quality control and assuring the safety and efficacy of the biological product.