Adapter (10) intended to be mounted on a distal tip (2) of a medication delivery device (1), said distal tip defining an axial conduit (3) for transferring a product contained in said medication delivery device, said adapter having a longitudinal axis A aligned on said axial conduit, the adapter comprising connection means (34) for connecting said adapter to a connector, characterized in that said adapter further comprises: - an internal ring (20) detachably coupled on said distal tip, - compressor means (30, 32), separated from said inner ring and provided to be inseparably adjusted by pressure on said inner ring, coupled on said distal tip by the proximal movement of said compressor means with respect to said inner ring, said compressor means being able to exert a centripetal pressure on said inner ring to avoid thus the axial movement of said inner ring with respect to said distal tip, wherein said inner ring comprises a circular wall (21) capable of being expanded radially outward at a pressure exerted radially outwardly on an inner face (21c) of said circular wall, and capable of being compressed radially inwardly at a pressure exerted radially inwardly on an outer face (21d) of said circular wall, said compressing means comprises an outer ring (30) capable of receiving said inner ring, at least partially, said outer ring comprising an inner radial trim (32) capable of exerting a centripetal pressure on said outer face (21d) of said circular wall (21) when said compressor means is adjusted by pressure on said inner ring, wherein said circular wall (21) is provided with a longitudinal section (23) along a portion of its circumference, said longitudinal section extending from one end mo proximal to a distal end of said circular wall (21).Adaptador (10) previsto para montarse sobre una punta distal (2) de un dispositivo de administración de medicamentos (1), definiendo dicha punta distal un conducto axial (3) para la transferencia de un producto contenido en dicho
