A mechanical infusion pump device for injecting medication into a patients IV, includes an IV reservoir and a syringe communicated to the IV reservoir and having a syringe plunger which is moved in a first direction against a mechanical biasing element by engagement with a manually operable, independently movable filling plunger to fill the syringe with fluid medication. The mechanical biasing element is provided for exerting bias on the syringe plunger in a second syringe-discharging direction to dispense medication from the syringe into the patients IV when the filling plunger is released. Only a calibrated amount of medicine can be discharged to the patents IV over time as determined by calibration of the biasing element and a metering element located between the syringe and the patients IV for a given viscosity of the medication.
