The present invention provides a syringe cartridge that is sufficiently robust to be used in autoinjectors that generate injection forces sufficient to deliver viscous medicaments. The syringe cartridge of the present invention includes a syringe, a bias mechanism, and a casing. The casing of the syringe cartridge of the present invention includes a collapsible portion and a fixed portion. Advantageously, the collapsible portion of the casing collapses within the fixed portion of the casing as the syringe is driven through its stroke within the syringe cartridge. As the collapsible portion collapses within the fixed portion, the length of the syringe cartridge is effectively reduced, which, in turn, allows the use of a shorter plunger and thereby facilitates the construction of a more compact autoinjector.