Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2001-04-16
2003-07-22
Look, Edward K. (Department: 3754)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S187000
Reexamination Certificate
active
06595961
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a transfer or storage device particularly, but not exclusively, for delivery or storage of a medicament, drug or vaccine, such as a syringe, transfer set, injection device or vial, wherein the major component of the delivery or storage device is preferably formed of a cyclic olefin polymer.
The development of cyclic olefin polymers has suggested the use of such polymers for manufacture of medical devices because medical devices formed of such polymers are transparent, exhibit excellent chemical resistance and may be sterilized by autoclaving or the like without damage. See European patent application EP 436,732A2. However, it has been found that medical devices, such as syringes, transfer devices and vials formed of cyclic olefin polymers are subject to stress cracking, particularly during or following sterilization, limiting the use of such polymers for medical devices. Stress cracking is defined as the crazing or cracking that may occur when a plastic under tensile stress is exposed to aggressive chemicals. The potential for environmental stress cracking is of major concern when plastics are used in medical devices because stress cracking may compromise the mechanical integrity of the device and contaminate the medicament, drug or vaccine transferred through or stored within the medical device.
Another problem with the use of cyclic olefin polymers for medical devices, such as storage or delivery devices, is adhesion of many polymers to cyclic olefin polymers following sterilization at elevated temperatures, such as autoclaving. For example, a syringe assembly includes a plunger having a stopper which withdraws fluid through the barrel tip when the stopper is withdrawn and drives fluid through the barrel tip when the stopper is advanced. Syringe stoppers are conventionally formed of a resilient synthetic rubber, such as bromo-butyl rubber, having an initial diameter greater than the internal diameter of the tubular syringe body, providing a good seal. However, when the syringe assembly is heated to the sterilization temperature of the cyclic olefin polymer and the bromo-butyl rubber stopper, the stopper firmly adheres to the cyclic olefin polymer syringe barrel making it difficult, if not impossible, to telescopically move the plunger through the tubular syringe barrel.
A similar problem exists with removable syringe tip caps or tip shields which firmly adhere or fuse to the syringe tip following heating to the sterilization temperature of the assembly. The tip caps and tip shields formed of certain polymers cannot be removed from the syringe following heating. It has also been found by the assignee of this patent application that this adhesion between various polymers and cyclic olefin polymeric transfer and storage devices following heating may also promote stress cracking. Thus, the use of cyclic olefin polymers for medical transfer and storage devices has been severely limited by these problems.
The sterilizable transfer or storage device and method of this invention solves these problems by selecting a polymer for the component in contact with the cyclic olefin polymer transfer or storage device which does not interact with the cyclic olefin polymer, even at elevated temperatures, thus permitting the use of cyclic olefin polymers for medical transfer and storage devices of the type described herein.
SUMMARY OF THE INVENTION
As set forth above, the present invention relates to sterilizable medical transfer or storage devices, such as syringes, transfer sets, vials, injection devices and the like, wherein a component, generally the major component, is formed of a cyclic olefin polymer and the device includes a second component formed of a second polymer in contact with the cyclic olefin component. More specifically, the present invention relates to the selection of the polymeric material for the second component which assures that the second component does not chemically interact with, dissolve or attack the cyclic olefin polymeric component or cause stress cracking, particularly at the elevated temperatures required for sterilization.
The polymers selected for the second member or component of the sterilizable transfer or storage device and method of this invention is based upon solubility parameters and cohesion properties explained by Charles Hansen in “
The Three Dimensional Solubility Parameter and Solvent Diffusion Coefficient
” by Charles M. Hansen, Copenhagen Danish Technical Press (1967) and the Hansen values for polymers are reported in Chapter 14 of “
The CRC Handbook and Solubility Parameters and Cohesion Parameters
,” Edited by Allan F. M. Barton (1999). Each material is defined by three points in 3D space and these three points are known as the Hansen Solubility Parameters (HSP). The Hansen Solubility Parameters may be defined as follows.
The Hansen solubility region consists of a point in 3D space defined by a non-polar dispersion interaction (Delta-D) axis, a polar or dipole interaction (Delta-P) axis and hydrogen bonding interaction (Delta-H) axis. From the location (Delta-D, Delta-P, Delta-H), a radius is projected to form a sphere which encompasses the region where liquids having HSP parameters within the inside of this sphere are generally the “attacking” the material in question, and liquids outside of the sphere are generally not attacking the material in question (See also “
Environmental Stress Cracking In Plastics
,” Hansen and Just, Pharmaceutical and Medical Packaging (1999), Vol. 9, 7.1 to 7.7, ISBN 87-89753-26-7. Hansen also noted that higher stress/temperature levels will enlarge the sphere (increase the radius) as well as the size and shape of the liquid molecules. Generally, the larger the molecule, the harder it is for the molecule to attack the material in question. Thus, as discussed further below, the molecular weights of the components are also important to prevent interaction. The assignee of this application has noted material interactions under ambient conditions, but material interaction is found more frequently at elevated temperatures, such as during autoclaving and annealing. As set forth above, however, the problems associated with material interaction between cyclic olefin polymers and the polymers conventionally used for components of medical devices has severely limited the use of cyclic olefin polymers in medical transfer and storage devices.
The distance between the HSP coordinate of polymer A to HSP coordinates of another material (liquid or Polymer B) is defined as Ra. The radius of the Polymer A sphere is defined as Ro. Ra/Ro is now defined by Hansen as the Relative Energy Distance (RED). Hansen reports that if Ra/Ro is less than 1, the two materials may stress crack or dissolve each other. If Ra/Ro is greater than or equal to 1, the materials do not have an affinity to one another under standard conditions. Ro is determined through experimentation described by Hansen, and the 3D distance, Ra, is defined by the equation:
(
Ra
)
2
=4(Delta-
D
1
−Delta-
D
2
)
2
+(Delta-
P
1
−Delta-
P
2
)
2
+(Delta-
H
1
−Delta-
H
2
)
2
1=polymer
2=liquid (2
nd
solid in this disclosure)
and
RED=Relative Energy Distance=Ra/Ro
Ra/Ro is inside the polymer sphere if it is less than 1
Ra/Ro is on the surface of the sphere if it is 1
Ra/Ro is outside the polymer sphere if it is greater than 1.
For Ticona Topas® cyclic olefin copolymers, the Hansen Solubility Parameters have been reported by Hansen to be:
Delta-D=18.0, Delta-P=3.0 and Delta-H=2.0 and Ro=5.0
For Ticona Topas, a cyclic olefin, which has seen cracking the Hansen Solubility Parameters have been reported by Hansen to be:
Delta-D=17.3, Delta-P=3.1 and Delta-H=2.1 and Ro=6.4.
The stress cracked Ticona resin has a bigger sphere, more easily attacked than non-stress cracked Topas material.
Thus, the larger the Hansen solubility difference between two polymers, the less likely the polymers will destructively in
Hetzler Kevin George
Lubrecht Thea
Becton Dickinson and Company
Fortunato David M.
Fristoe, Jr. John K
LandOfFree
Sterilizable transfer or storage device for medicaments,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sterilizable transfer or storage device for medicaments,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sterilizable transfer or storage device for medicaments,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3039782