The disclosure is related to a device and a method for expelling a medically active liquid, the device including: a first chamber having a first variable volume, the first chamber configured to receive and to expel a medically active liquid, the first chamber including an inner cylinder and an outer cylinder with relative translation between the inner cylinder and the outer cylinder forming the first variable volume of the first chamber; a reservoir to provide the medically active liquid to the first chamber through the inner cylinder or the outer cylinder; a second chamber mechanically coupled to the first chamber and having a second variable volume, the second chamber configured to receive a pressurized gas; wherein the pressurized gas increases the second variable volume of the second chamber, which is translated to the first chamber causing the first variable volume to decrease and expel the medically active liquid.