A medication delivery apparatus, comprising: a reservoir for holding a liquid medication; and a metering device (25, 150) coupled to the reservoir for supplying a dose of the liquid medication to the reservoir, the metering device including: an upper chamber (70, 165); a lower chamber (75, 170) coupled to the upper chamber; a piston (90, 185), the piston being selectively moveable within the upper chamber and the lower chamber along a longitudinal axis of the upper chamber and the lower chamber to apply force to a portion of liquid medication in the lower chamber through the upper chamber; and a first valve (85, 180), the first valve providing selective fluid communication between the lower chamber and the reservoir, wherein the first valve is such that the lower chamber is not in fluid communication with the reservoir under a static pressure of the portion of liquid medication in the lower chamber, and such that the lower chamber is in fluid communication with the reservoir in response to movement of the piston to cause at least a part of the portion to exit the lower chamber and be received in the reservoir; wherein the piston is part of a cap (65, 160) that is structured to be selectively coupled to the upper chamber and the piston includes a central bore (130, 215) and a second valve (135, 210) in the central bore, wherein the central bore is vented to atmosphere through a hole provided in the cap. a reservoir for holding a liquid medication; and a metering device (25, 150) coupled to the reservoir for supplying a dose of the liquid medication to the reservoir, the metering device including: an upper chamber (70, 165); a lower chamber (75, 170) coupled to the upper chamber; a piston (90, 185), the piston being selectively moveable within the upper chamber and the lower chamber along a longitudinal axis of the upper chamber and the lower chamber to apply force to a portion of liquid medication in the lower chamber through the upper chamber; and a first valve (85, 180), the first valve providing selective fluid communication between the lower chamber and the reservoir, wherein the first valve is such that the lower chamber is not in fluid communication with the reservoir under a static pressure of the portion of liquid medication in the lower chamber, and such that the lower chamber is in fluid communication with the reservoir in response to movement of the piston to cause at least a part of the portion to exit the lower chamber and be received in the reservoir; wherein the piston is part of a cap (65, 160) that is structured to be selectively coupled to the upper chamber and the piston includes a central bore (130, 215) and a second valve (135, 210) in the central bore, wherein the central bore is vented to atmosphere through a hole provided in the cap. an upper chamber (70, 165); a lower chamber (75, 170) coupled to the upper chamber; a piston (90, 185), the piston being selectively moveable within the upper chamber and the lower chamber along a longitudinal axis of the upper chamber and the lower chamber to apply force to a portion of liquid medication in the lower chamber through the upper chamber; and a first valve (85, 180), the first valve providing selective fluid communication between the lower chamber and the reservoir, wherein the first valve is such that the lower chamber is not in fluid communication with the reservoir under a static pressure of the portion of liquid medication in the lower chamber, and such that the lower chamber is in fluid communication with the reservoir in response to movement of the piston to cause at least a part of the portion to exit the lower chamber and be received in the reservoir;