Until recently, approved handheld auto-injectors (AIs) have been limited to volumes ≤ 2 mL. A prototype rapid high-volume AI (HVAI) that can deliver 10 mL in 30 s was developed to administer therapeutics co-formulated with a proprietary recombinant human hyaluronidase PH20 (rHuPH20). This phase I, open-label study assessed the tolerability of subcutaneous (SC) injections of 10% (100 mg/mL) immunoglobulin G (IgG) solution co-ad...