An ingestible device (10) for delivery of a therapeutic agent into a lumen wall of a gastrointestinal tract of a patient, the device comprising a capsule (20) sized to pass through the intestinal tract; and a tissue penetrating member (40) carried by the capsule and having a tissue penetration end, the tissue penetrating member formed from a solid therapeutic agent comprising at least one therapeutic agent, wherein the therapeutic agent preparation would chemically degrade if released within the lumen of the gastrointestinal tract, the tissue penetrating member shaped and configured to be inserted into the lumen wall from the application of mechanical force on the tissue penetrating member from an actuator disposed within the capsule, wherein the tissue penetrating member releases the therapeutic agent into the blood stream from the lumen wall without substantial chemical degradation of the therapeutic agent in the lumen of the gastrointestinal tract.