Monoclonal antibodies requiring higher doses for exerting therapeutic effect but having lower stability, are administered as dilute infusions, or as two (low concentration) injections both resulting in reduced patient compliance . Present research summarizes impact of manufacturing conditions on ultra-high concentration (≥150mg/mL) IgG1 formulation, which can be administered as one subcutaneous injection . IgG1 was concentrated to ∼200mg/mL using tangential flow filtration (TFF). Alternatively, spray dried (SPD) and spray freeze dried (SFD) IgG1, was reconstituted in 30% v/v propylene glycol to form ultra-high concentration (∼200 mg/mL) injectable formulation . Reconstituted, SPD and SFD IgG1 formulations, increased viscosity beyond an acceptable range for subcutaneous injections (< 20 cP). Formulations developed by reconstitution of SPD IgG1, demonstrated increase in high and low molecular weight impurities, at accelerated and stressed conditions . Whereas, the stability data suggested reconstituted SFD IgG1 was comparable to control IgG1 formulation concentrated by TFF . Also, formulation of IgG1 diafiltered with proline using TFF, reduce viscosity from ∼21.9 cP to ∼11 cP at 25°C and had better stability . Thus, conventional TFF technique stands to be one of the preferred methods for manufacturing of ultra-high concentration IgG1 formulations . Additionally, SFD could be an alternative method for long term storage of IgG1 in a dry powder state.