Adaptor for a needleless access device and method for connecting said device thereon

1. An adaptor for connecting a drug delivery device to a needleless access device provided with a straight external thread having a constant external diameter, the adaptor comprising a globally tubular body having a proximal region and a distal region, and a proximal inner rim that is radially expandable, said proximal region adapted for mounting said adaptor on the drug delivery device, said distal region having on an inner wall an internal thread intended to cooperate with said external thread on a determined length of said internal thread so as to connect said needleless access device to said adaptor, said internal thread having on a distal part of said determined length, said distal part having a length, a first major diameter of constant value equal to the constant external diameter over the length of said distal part mating that of said straight external thread, wherein said internal thread has on a proximal part of said determined length a second major diameter, where said second major diameter is strictly smaller than said first major diameter such that there is greater friction between the external thread and the proximal part as the needleless access device is introduced into the adaptor, wherein said internal thread further comprises a tapered threaded portion linking said proximal part to said distal part, said tapered portion having a length, and wherein said proximal part having a length, said second major diameter has a constant value over the length, wherein a ratio of said second major diameter to said first major diameter ranges from 0.95 to 0.98.

2. The adaptor according to claim 1 , wherein a ratio of the length of the distal part to the length of the tapered portion ranges from 0.9 to 1.1.

3. The adaptor according to claim 1 , comprising a proximal inner rim frictionally engageable on a distal tip of the drug delivery device.

4. The adaptor according to claim 1 , wherein a ratio of the length of the distal part to the length of the proximal part ranges from 1.125 to 1.325.

5. The adaptor according to claim 1 , wherein a ratio of the length of the tapered portion to the length of the proximal part ranges from 1.125 to 1.325.

6. A drug delivery device comprising a distal tip defining an axial passageway for a transfer of a product contained in said drug delivery device, wherein the drug delivery device further comprises at least one adaptor according to claim 1 mounted on said distal tip.

7. The drug delivery device according to claim 6 , wherein the distal tip is made of glass.

8. The drug delivery device according to claim 6 , wherein the distal tip is conical and distally tapered.

9. A method for connecting a needleless access device provided with a straight external thread onto an adaptor according to claim 1 , comprising at least the step of screwing said straight external thread into the internal thread of the adaptor on said determined length of said internal thread.

10. A method for connecting a drug delivery device to a needleless access device provided with a straight external thread, comprising the following steps:

providing an adaptor according to claim 1 ,

engaging said adaptor on the drug delivery device, and

screwing said straight external thread into the internal thread of the adaptor on said determined length of said internal thread.