The present invention provides an intravenous liposomal formulation of a low dose polymyxin B or a pharmaceutical composition thereof. The present invention also provides methods utilizing the intravenous liposomal formulation or its pharmaceutical composition for increasing the therapeutic efficacy during treatment of a bacterial infection in a subject, for decreasing exposure of renal tissue to the polymyxin B during a course of polymyxin B treatment and for lowering exposure to polymyxin B in renal tissues in a subject receiving polymyxin B treatment.
