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| FIG. 1 illustrates a protective welding hood 60 comprising essentially a helmet-like portion, ... |
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| Article for infants, forming pacifier and teething ring simultaneously |
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| Corneal holder |
| OF THE INVENTION The corneal holder of the present invention will be better understood by ... |
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| Blood transfusion connector assembly |
| OF THE INVENTION Referring first to FIG. 1, there is shown a container 10 constituting a source of ... |
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| Measuring probe |
| I claim: 1. An optical probe comprising: an outer sheath comprising a first end, a second end, and ... |
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| Process for determining parameters of interest in living organisms |
| It is an object of the invention to propose a simple method which should also be suitable for use ... |
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| Safety syringe |
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| Device or apparatus for manipulating matter having a elastic ring clip |
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Coating medical devices with cationic antibiotics
| Details |
Inventors: Lee, Clarence C.;
Assignee: C. R. Bard, Inc. (Murray Hill, NJ)
Primary Examiner: Rosenbaum; C. Fred
Assistant Examiner: Rose; Sharon
Attorney, Agent or Firm:
A medical device having long-lasting bactericidal properties and a method for making the same is provided. The material from which the medical device is made, the substrate, carries a negatively-charged group having a pKa of less than 6. A cationic antibiotic is ionically bonded to the negatively-charged group. The negatively-charged group may be a portion of a larger carrier molecule. The carrier molecule is bound to the substrate such that the negatively-charged group is exposed for ionic interaction with the cationic antibiotic. Heparin is an ideal carrier molecule because it has both anti-bacterial adhesion activity and anti-thrombogenic activity. |
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Medical devices according to the present invention may be fabricated from virtually any biocompatible substrate.
It is only necessary that the substrate be capable of carrying negatively-charged groups having pKa values of less than 6.
Dacron, latex, silicone, polyethylene and PVC have all been tested successfully.
Medical devices are provided with negatively-charged groups having a pKa of less than 6 and then are soaked in solutions of cationic antibiotics to ionically bind the cationic antibiotic to the medical device.
It has been found that the negatively-charged groups having a pKa value of less than 6 will bind cationic antibiotics more firmly than negatively-charged groups having pKa values of greater than 6.
This firmer bond does not impair the efficacy of the antibiotic's germicidal activity and holds the antibiotic on the medical device for an extended period of time.
In particular, it has been found that sulphate groups, sulfonate groups and phosphate groups, having pKa values of less than 1, about 1 and 2.
1 respectively, bind cationic antibiotic much more firmly than carboxyl groups (COOH) having a pKa value of greater than 6.
The negatively-charged groups may be manufactured into the surface of the medical device.
Sulfonated polystyrene, for example, may be manufactured to carry suitably charged surface groups.
Likewise, negatively charged groups may be attached directly to the surface of the medical device.
Suitable techniques include the immobilization of negative groups carried on polymers or biopolymers by radiation or chemical cross-linking.
Negatively-charged groups may also be coated onto the surface of the medical device.
In particular, a negatively-charged group may be a portion of a larger carrier molecule which is coated or otherwise attached onto the surface of the medical device.
For example, phospholipids include both a phosphate group and at least one long hydrophobic side chain.
A medical device manufactured from a hydrophobic substrate may be soaked in a solution containing the phospholipid
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