A swallowable device for delivering a therapeutic agent preparation into an intestinal wall of a patient's intestinal tract, the swallowable device comprising: a swallowable capsule sized to pass through the intestinal tract, the capsule having a capsule wall, a least a portion of which degrades upon exposure to a selected pH in an intestine while protecting the capsule wall from degradation in a stomach of the patient; at least one expandable member assembly disposed within the capsule comprising a first compartment in at least a partially non-expanded state and a second compartment in at least a partially non-expanded state, the first and second compartments being fluidically separated by a degradable valve which degrades upon exposure to fluid in the intestinal tract; a liquid contained in one of the compartments; a reactant contained in the other compartment, wherein when the valve degrades, the liquid and the reactant mix to produce a gas which expands at least the second compartment; a delivery mechanism coupled to second compartment, the delivery mechanism comprising at least one piston-cylinder assembly, the piston-cylinder assembly positioned horizontally with respect to a lengthwise axis of the at least one expandable member; and at least one tissue penetrating member comprising: a. a proximal portion detachably coupled to the delivery mechanism; and b. a tissue penetrating distal portion; c. and a therapeutic agent preparation for delivery into the intestinal wall, the tissue penetrating member configured to be retained in the intestinal wall; and wherein upon expansion of the second compartment, the piston-cylinder assembly reorients to a vertical position with respect to the lengthwise axis of the at least one expandable member and the at least one tissue penetrating member is advanced into the intestinal wall by the delivery mechanism where it is retained in the intestinal wall so as to deliver the therapeutic agent into the intestine. a swallowable capsule sized to pass through the intestinal tract, the capsule having a capsule wall, a least a portion of which degrades upon exposure to a selected pH in an intestine while protecting the capsule wall from degradation in a stomach of the patient; at least one expandable member assembly disposed within the capsule comprising a first compartment in at least a partially non-expanded state and a second compartment in at least a partially non-expanded state, the first and second compartments being fluidically separated by a degradable valve which degrades upon exposure to fluid in the intestinal tract; a liquid contained in one of the compartments; a reactant contained in the other compartment, wherein when the valve degrades, the liquid and the reactant mix to produce a gas which expands at least the second compartment; a delivery mechanism coupled to second compartment, the delivery mechanism comprising at least one piston-cylinder assembly, the piston-cylinder assembly positioned horizontally with respect to a lengthwise axis of the at least one expandable member; and at least one tissue penetrating member comprising: a. a proximal portion detachably coupled to the delivery mechanism; and b. a tissue penetrating distal portion; c. and a therapeutic agent preparation for delivery into the intestinal wall, the tissue penetrating member configured to be retained in the intestinal wall; and a. a proximal portion detachably coupled to the delivery mechanism; and b. a tissue penetrating distal portion; c. and a therapeutic agent preparation for delivery into the intestinal wall, the tissue penetrating member configured to be retained in the intestinal wall; and wherein upon expansion of the second compartment, the piston-cylinder assembly reorients to a vertical position with respect to the lengthwise axis of the at least one expandable member and the at least one tissue penetrating member is advanced into the intestinal wall by the delivery mechanism where it is retained in the intestinal wall so as to deliver the therapeutic agent into the intestine.