NITRIC OXIDE AND CHLORHEXIDINE RELEASING CATHETER FOR ANTI-PLATELET AND ANTIMICROBIAL DUAL FUNCTIONALITY

Abstract

A catheter configured to release nitric oxide and chlorhexidine providing anti-platelet and antimicrobial properties is manufactured by impregnating a thermoplastic polyurethane catheter extrusion with a nitric oxide releasing compound and with chlorhexidine. Thereafter, the impregnated catheter extrusion is coated with a polyurethane coating comprising chlorhexidine and/or a nitric oxide releasing compound. In the impregnating step, the catheter extrusion may be exposed to a solvent having the nitric oxide releasing compound and chlorhexidine dissolved therein. The solvent is removed from the catheter extrusion. In the coating step, the impregnated catheter extrusion may be dip coated in a polymer solution comprising polyurethane and chlorhexidine and/or a nitric oxide releasing compound in a suitable solvent. The nitric oxide releasing compound, impregnated and/or coated, may be selected from s-nitroso-n-acetylpenicillamine (SNAP), s-nitrosoglutathione (GSNO), and mixtures thereof. The chlorhexidine, impregnated and/or coated, may be selected from chlorhexidine diacetate, chlorhexidine base, chlorhexidine gluconate, and mixtures thereof.

Claims

1. A method of manufacturing a catheter configured to release nitric oxide and chlorhexidine to provide anti-platelet and antimicrobial properties, comprising: impregnating a thermoplastic polyurethane catheter extrusion with a nitric oxide releasing compound and with chlorhexidine; and coating the impregnated catheter extrusion with a polyurethane coating comprising chlorhexidine.

2. The method of claim 1, wherein the impregnated nitric oxide releasing compound is selected from s-nitroso-n-acetylpenicillamine (SNAP), s-nitrosoglutathione (GSNO), and mixtures thereof.

3. The method of claim 1, wherein the impregnating step comprises: obtaining the nitric oxide releasing compound and chlorhexidine dissolved in a solvent; and exposing the thermoplastic polyurethane catheter extrusion to the nitric oxide releasing compound and chlorhexidine dissolved in a solvent; and evaporating the solvent from the catheter extrusion.

4. The method of claim 3, wherein the chlorhexidine dissolved in a solvent is selected from chlorhexidine diacetate, chlorhexidine base, chlorhexidine gluconate, and mixtures thereof.

5. The method of claim 3, wherein the solvent comprises methanol, acetone, and methyl ethyl ketone (MEK).

6. The method of claim 5, wherein the solvent comprises from 20 to 25 vol. % methanol, from 17.5 to 77.5 vol. % acetone, and the balance vol. % methyl ethyl ketone (MEK).

7. The method of claim 1, wherein the polyurethane coating further comprises a nitric oxide releasing compound.

8. The method of claim 1, wherein the coating step comprises dipping the catheter extrusion into a polymer solution comprising polyurethane and chlorhexidine dissolved in a solvent.

9. The method of claim 8, wherein the polymer solution further comprises a nitric oxide releasing compound

10. The method of claim 9, wherein the nitric oxide releasing compound is selected from s-nitroso-n-acetylpenicillamine (SNAP), s-nitrosoglutathione (GSNO), and mixtures thereof.

11. The method of claim 8, wherein the polyurethane comprises an aliphatic polyurethane.

12. The method of claim 8, wherein the polyurethane comprises an aromatic polyurethane.

13. The method of claim 8, wherein the chlorhexidine concentration in the dip-coating solution ranges from 0.5 wt. % to 20 wt. %.

14. The method of claim 8, wherein the solvent comprises methanol and dioxolane.

15. The method of claim 14, wherein solvent comprises from 10 vol. % to 25 vol. %, methanol and from 75 vol. % to 90 vol. % dioxolane.

16. A catheter configured to release nitric oxide and chlorhexidine to provide anti-platelet and antimicrobial properties, comprising: an extruded thermoplastic polyurethane catheter body impregnated with a nitric oxide releasing compound and with chlorhexidine; and a polyurethane coating on the polyurethane catheter body comprising chlorhexidine.

17. The catheter of claim 16, wherein the nitric oxide releasing compound impregnated in the catheter body is selected from s-nitroso-n-acetylpenicillamine (SNAP), s-nitrosoglutathione (GSNO), and mixtures thereof.

18. The catheter of claim 16, wherein the polyurethane coating further comprises a nitric oxide releasing compound.

19. The catheter of claim 18, wherein the nitric oxide releasing compound in the polyurethane coating is selected from s-nitroso-n-acetylpenicillamine (SNAP), s-nitrosoglutathione (GSNO), and mixtures thereof.

20. The catheter of claim 16, wherein the chlorhexidine impregnated in the catheter body is selected from chlorhexidine diacetate, chlorhexidine base, chlorhexidine gluconate, and mixtures thereof.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0026] Example embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0027] FIG. 1 is cross-sectional representation of portion of a catheter body fabricated to contain a nitric oxide (NO) releasing compound and chlorhexidine to provide dual anti-platelet and antimicrobial functionality.

DESCRIPTION OF EMBODIMENTS

[0028] The disclosure relates to a catheter impregnated and coated with nitric oxide (NO) releasing compound(s) and chlorhexidine. The combination of nitric oxide and chlorhexidine provides a dual anti-platelet and antimicrobial functionality. Furthermore, nitric oxide in combination with other antimicrobials enhances the overall antimicrobial effects and imparts biofilm penetration and eradication mechanisms. The disclosure further relates to methods of manufacturing a catheter configured to release nitric oxide and chlorhexidine to provide anti-platelet and antimicrobial properties.

[0029] Nitric oxide (NO) is a natural platelet activation inhibitor produced by endothelial cells within the body, which also exhibits antimicrobial and biofilm eradication abilities. Nitric oxide is produced by a Nitric Oxide Synthase in endothelial, neural, and other cells within the human body.

[0030] NO mediates platelet activation through the soluble guanylate cylase (sGC) pathway: NO binds to the heme iron moeity of sGC, increasing intracellular concentrations of cyclic guanosine monophosphate, which increases concentrations of cyclic adenosine monophasphate, and eventually decreases concentrations of calcium ions—a prominent component of the coagulation responses.

[0031] Ultimately, NO activated sGC leads to calcium ion concentration decrease. Additionally, it inhibits phosphoinositide 3-kinase, reduces affinity of platelets towards fibrinogen, and reduces number of fibrinogen binding sites on surface of platelets.

[0032] As an antimicrobial agent, NO reacts with physiological concentrations of superoxide to create peroxynitrite which induces oxidative stress, nitrosates amino acids of bacterial cells, oxidizes and breaks their DNA strands, and causes cell membrane damage via lipid peroxidation. Additionally, NO reacts with oxidators to form N.sub.2O.sub.3 which reacts with sulfhydryl groups of cysteine residues on bacteria membrane proteins and alters or inhibits their functionality.

[0033] An important aspect of the present disclosure is incorporating both a nitric oxide releasing compound and chlorhexidine into a thermoplastic polyurethane catheter extrusion.

[0034] By incorporating a nitric oxide releasing compound into the catheter device, the NO releasing compound will degrade over time and release NO in the gaseous phase at physiologically relevant levels to exert the above described physiological mechanisms on the blood stream or infecting bacteria.

[0035] The disclosed catheter configured to release nitric oxide and chlorhexidine to provide anti-platelet and antimicrobial properties is manufactured by first impregnating a thermoplastic polyurethane catheter extrusion with a nitric oxide releasing compound and with chlorhexidine. Thereafter, the impregnated catheter extrusion is coated with a polyurethane coating comprising chlorhexidine and/or a nitric oxide releasing compound.

[0036] The impregnating step may be accomplished in one step by exposing the catheter extrusion to a solvent having the nitric oxide releasing compound and chlorhexidine dissolved therein. The catheter extrusion is exposed to the solvent solution for sufficient time to permit the nitric oxide releasing compound and chlorhexidine to penetrate the catheter extrusion. The impregnating step may be accomplished in two steps by exposing the catheter extrusion a solvent having the nitric oxide releasing compound dissolved therein and to another solvent having the chlorhexidine dissolved therein. The catheter extrusion is exposed to each of the solvent solutions for sufficient time to permit the nitric oxide releasing compound and chlorhexidine to penetrate the catheter extrusion. The exposure time may range from about 25 minutes to about 240 minutes. The sufficient exposure time is inversely related to the concentration of the nitric oxide releasing compound and chlorhexidine in the solvent. The solvent is then removed from the catheter extrusion by evaporation.

[0037] Any physiologically compatible nitric oxide releasing compound may be used. Non-limiting examples of nitric oxide releasing compounds include s-nitroso-n-acetylpenicillamine (SNAP), s-nitrosoglutathione (GSNO), and mixtures thereof. The s-nitroso-n-acetylpenicillamine (SNAP) may have a concentration in the solvent from 0 to 20 wt./vol. %. The s-nitrosoglutathione (GSNO) may have a concentration in the solvent from 0 to 20 wt./vol. %. The combination of SNAP and GSNO must have a concentration in the solvent greater than 0 wt./vol. %.

[0038] Chlorhexidine is characterized as being a strong base with cationic properties. It is commercially available in both the free base and stable salt forms. Non-limiting examples of chlorhexidine include chlorhexidine diacetate, chlorhexidine base, chlorhexidine gluconate, and mixtures thereof. The chlorhexidine diacetate may have a concentration in the solvent from 0.5 to 6.5 wt./vol. %. The chlorhexidine base may have a concentration in the solvent from 0 to 2.5 wt./vol. %.

[0039] Any solvent that is compatible with the polyurethane catheter extrusion may be used. The solvent should not cause polymer degradation. The solvent should also be effectively removed by evaporation. Unevaporated solvent should be avoided.

[0040] The solvent may include methanol. The solvent may include acetone. The solvent may include methyl ethyl ketone (MEK). The solvent may include a mixture of solvents. The solvent may include a mixture of methanol, acetone, and MEK. In a non-limiting embodiment, the solvent may comprise from 20 to 25 vol. % methanol, from 17.5 to 77.5 vol. % acetone, and the balance vol. % MEK.

[0041] The impregnating step may occur at room temperature. The impregnating step may occur at a temperature in the range from about 25 to 55° C.

[0042] The coating step may be accomplished by dip coating the impregnated catheter extrusion in a polymer solution comprising polyurethane and chlorhexidine and/or a nitric oxide releasing compound in a suitable solvent.

[0043] The dwell time of the impregnated catheter in the polymer solution may range from about 1 minute to about 120 minutes.

[0044] The polyurethane in the dip coating polymer solution may comprise an aliphatic or aromatic polyurethane. The polyurethane may be a solution grade aliphatic polyurethane, such as commercially available Tecoflex® aliphatic polyether-based thermoplastic polyurethane manufactured by Lubrizol. The polyurethane may be a thermoplastic silicone-polycarbonate-urethane (TSPCU), such as commercially available CarboSil® TSPCU manufactured by DSM Biomedical.

[0045] The practical polymer concentration in the dip coating polymer solution is related to its molecular weight. For instance, a low molecular weight thermoplastic polyurethane (TPU) having a molecular weight of about 50 kDa may be present at a higher concentration, up to 5 wt. % and provide a usable viscosity. A high molecular weight TPU having a molecular weight of about 240 kDa may be present at a lower concentration, 0.5 wt. % to 1 wt. %.

[0046] The chlorhexidine in the polymer solution may comprises chlorhexidine base. The chlorhexidine concentration in the dip-coating solution may range from 0.5 wt. % to 7.5 wt. %.

[0047] The nitric oxide releasing compound in the polymer solution may be any physiologically compatible nitric oxide releasing compound. Non-limiting examples of nitric oxide releasing compounds include s-nitroso-n-acetylpenicillamine (SNAP), s-nitrosoglutathione (GSNO), and mixtures thereof. The s-nitroso-n-acetylpenicillamine (SNAP) may have a concentration in the solvent from 1 to 20 wt./vol. %.

[0048] The solvent for the dip coating polymer solution may comprise methanol, dioxolane, and mixtures thereof. In a non-limiting embodiment, the solvent comprises from 10 vol. % to 25 vol. %, methanol and from 75 vol. % to 90 vol. % dioxolane.

[0049] The coating step may occur at room temperature. The coating step may occur at a temperature in the range from about 25 to 50° C.

[0050] The resulting catheter manufactured as described above is configured to release nitric oxide and chlorhexidine to provide anti-platelet and antimicrobial properties. FIG. 1 is cross-sectional representation of portion of a catheter 100 fabricated to contain a nitric oxide (NO) releasing compound and chlorhexidine to provide dual anti-platelet and antimicrobial functionality. The catheter 100 includes an extruded thermoplastic polyurethane catheter body 110 impregnated with a nitric oxide releasing compound and with chlorhexidine. The catheter 100 further includes a polyurethane coating 120 on the polyurethane catheter body 110 comprising chlorhexidine. The polymer coating 120 may further comprise a nitric oxide releasing compound.

[0051] All examples and conditional language recited herein are intended for pedagogical objects to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Although embodiments of the present inventions have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention. It should be understood that the embodiments may be combined.