Multiple use computerized injector

A computer-controlled injector comprising:

• a housing arranged along a longitudinal axis and configured to receive a cassette assembly, containing a medicament cartridge;
• said housing includes a cassette assembly receiving volume and a cassette assembly insertion and removal opening communicating with said cassette assembly receiving volume;
• at least one locking element for locking said cassette assembly with respect to said housing upon axial insertion of said cassette assembly into said housing;
• at least one lock release element;
• and
• an injection drive mechanism including a computer-controlled motor for driving a plunger rod to displace a piston, forming part of said medicament cartridge, for injecting a medicament,
• and wherein rearward displacement of said plunger rod urges rearward displacement of said lock release element and thereby is operative to release said cassette assembly from said housing.