A portable medicament dispensing device having a mechanism which is not susceptible to jamming for dispensing the medication to a user. The device employs employs a coupling for coupling the relative motion between reciprocating body members housing the ancillary components and a barrel plunger associated with the syringe. One embodiment provides a pivoting coupling whereas an alternate uses a rack and pinion system. The advantage of simplifying such mechanisms results in a structure which has smooth unemcumbered motion with fewer parts to avoid mechanical jamming during use.