An applicator device (10) is provided for applying a patch (44) having an array of microprotrusions (90) to the stratum corneum. The applicator device (10) includes a device body (12) and a piston moveable within the device body (12). A cap (16) is provided on the device body (12) for activating the device (10) to impact the stratum corneum with a microprotrusion array (44,90). The device (10) is capable of being cocked by one handed operation of the user which allows the device (10) to be used by patients having neither the strength nor the manual dexterity to cock other types of applicator devices.