Sustained-release protamine sulphate-impregnated microspheres may reduce the frequent administration of recombinant interferon -2b in ovarian cancer

Parenteral administration of recombinant interferon--2b (rINF--2b) at a dose of 50×106IU once a week for 8 weeks is recommended for ovarian cancer. However, short half-life, small therapeutic index and proteolytic degradation cause fluctuations in plasma level and pose barriers in the development of a clinically viable dosage form. Therefore, in the present investigation, fluorescein isothiocynate-tagged rINF--2b was loaded into stearic acid (rINF--2b-SMs), pectin (rINF--2b-PMs) and gelatin (rINF--2b-GMs) microspheres. Parameters such as particle size, potential, encapsulation efficiency and in-vitro release were studied to follow the optimization process. The formulation, rINF--2b-GMs of particle size 8.3±2.1 m with an encapsulation efficiency of 76.0±7.4, offered 97.4 of rINF--2b release at 288 h. Thus, negatively charged extended-release formulation rINF--2b-GMs was then tethered with a gradient concentration (5–20 mgml) of a cationic arginine-rich protein stabilizer, protamine sulphate (Pt). The nanoformulation, rINF--2b-Pt-GMs-15 superimposed with 15 mgml of Pt, released 95.0 of rINF--2b at 336 h and was designated as the optimized formulation. The optimized formulation also conserved the primary and secondary structure of rINF--2b as analysed by gel electrophoresis and circular dichroism. Moreover, in-vitro cytotoxicity analysis of SKOV3 cells of the optimized nanoformulation reported significantly (one-way analysis of variance test, P<0.05) lower IC50(414.3 IUml) compared with rINF--2b-GMs (514.3 IUml) and pure rINF--2b (628.6 IUml) at 72 h by offering a prolonged cytotoxic effect. Therefore, rINF--2b-Pt-GMs-15, a promising nanomedicine, warrants further in-depth in-vivo study to scale up the technology for clinical translation.