US Patent 9402961 Drug delivery device having a spring element

A drug delivery device having a spring element that provides dispense assistance. The drug delivery device includes a variable dose setting mechanism, a fixed dose setting mechanism, and a mechanical coupling having a spring element. The variable dose setting mechanism is operably coupled to a first reservoir holding a first medicament, and the variable dose setting mechanism comprises a dose setter. The fixed dose setting mechanism is operably coupled to a second reservoir holding a second medicament. The mechanical coupling operably couples the variable dose setting mechanism and the fixed dose setting mechanism. Further, the variable dose setting mechanism is configured to set a variable dose of the first medicament upon activation of the dose setter, and the fixed dose setting mechanism is configured to set a fixed dose of the second medicament during variable dose setting. Still further, the spring element is configured to store energy during dose setting and to transfer stored energy to the fixed dose setting mechanism to assist with dispense of the fixed dose.