An injector assembly comprises a collapsible container for containing a liquid medicament (15) and pressurising means (21, 101) arranged to apply a first force to the collapsible container to continuously pressurise the liquid medicament 15 during storage of the liquid medicament 15. The pressurising means (21, 101) is actuatable to apply a second force, which is greater than the first force, to the collapsible container.
