Growth in high viscosity drugs is being driven by advances in biotechnology and host-vector engineering – advances that have led to a steady stream of biologics for a number of ailments and conditions. These powerful drugs come with a high cost-per-dose and the risk of significant side effects – factors that place an elevated emphasis on administration efficiency, safety and reliability. Many drugs in this class are characterized by physical properties and sensitivities that challenge the drug commercialization ecosystem. For example, monoclonal antibodies, perhaps the most significant category in terms of therapeutic and commercial importance, typically possess viscosities that are well above the normal limits of subcutaneous injection devices and techniques. Drug developers and device designers are increasingly working in collaboration to insure the commercial success of handheld devices for high viscosity injectables.