Patent ID: 8734384

Claim:
A method of delivering a formulation from a needle free injector, comprising: actuating a needle free injector to pressurize a liquid formulation and cause the formulation to be injected through an orifice of the injector; continuing to pressurize the formulation to create a pressure profile vs. time curve after actuation which curve comprises a skin puncture phase comprising a main pressure peak with a maximum pressure; and further continuing to pressurize the formulation through a delivery phase following the skin puncture phase which delivery phase occurs at a lower pressure compared to the maximum pressure of the main pressure peak, the delivery phase characterized by a delivery time per 0.5 mL of injectate per orifice, wherein the delivery time and the peak pressure are chosen to satisfy the relationship: 17.4*MPP (MPa)−TotIT 0.5 (ms/0.5 ml)≧505.4 wherein TotIT 0.5 represents total injection time measured in milliseconds per 0.5 milliliters of formulation delivered per orifice and MPP represents peak pressure measured in MPa of the main peak of the puncture phase.