An injector system for delivery of a pharmacological agent to biological tissue having a plurality of needles arranged in an array, a plurality of reservoirs configured to receive a pharmacological composition therein, the reservoirs being in fluid communication with a respective one of the plurality of needles, a pneumatic pressure source, a pneumatic drive system that is configured to induce a first discharge of the pharmacological composition out of the reservoirs and needles in a plurality of delivery modes, agent delivery volume control means for controlling volume of the pharmacological composition discharged from the needles, and a control system having actuation control means for controlling said pneumatic drive system. The control system is programmed to control the delivery modes.
