A bi-injection molded housing of a locking cap for a pharmaceutical vial includes a first material forming an upper ring, legs having upper ends rigidly connected to the upper ring, and bridges connecting lower ends of the legs in pairs, at least some bridges comprising a flexible tab configured to engage under a flange of the vial. The housing further includes a second elastomer material forming a stopper configured to seal the vial when the flexible tabs engage under the flange. At least one inner face of the upper ring made of the first material is rigidly connected to the stopper made of the second material.