Hydrophilic Coating - Living tissue interaction

Transcription

1 Tailoring polymer friction, wear and hydrophilic lubricity of intermittent catheters Page 1

2 Content Introduction to hydrophilic coating technology Development and applications of hydrophilic coatings on urinary catheters Evaluation of lubricious coatings in contact with living tissue Conclusive remarks Page 2

3 Hydrophilic coating on medical device - benefits Low friction facilitates insertion & removal Improve the biocompatibility Low friction minimizes injury Minimize bacterial adhesion Drug delivery Antimicrobial delivery system Reduce biofilm formation Reduce formation of encrustations Page 3

4 Device, Substrate- and Coating Materials Medical devices Urinary catheters Guide wires Heart valves Contact lenses Endotracheal tubes Gastroenteric feed tube Etc. Substrate materials PVC Polyurethane Natural Rubber Silicone Polyolefin and Vinyl rubber Metals Ceramics Etc. Coating Polymers Synthetic: Poly(vinylpyrrolidone) - PVP Poly(ethylenoxide) - PEO Poly(acrylic acid) - PAA Poly(vinylalkohol) - PVA Hydrophilic polyurethanes Etc. Biopolymers: Hyaluronic acid Chondroitin sulphate Heparin CMC Etc. Page 4

5 Coloplast Ready to Use SpeediCath platform N n O + Photoinitiator N n O + Photoinitiator-H N O n Hydrophilic coating PVP PVP N n O cross-linked PVP Water with 0,9% NaCl and PVP Catheter tip Catheter wall Tube lumen Swelled crosslinked PVP coating Catheter eyelets Catheter SpeediCath Ready to use intermittent catheter product range so far: Page 5

6 Self catheterization with intermittent catheters Male intermittent catheterization Female intermittent catheterization User groups: Spinal cord injury (SCI) Spina Bifida Multiple Sclerosis (MS) Stress and/or Urge Incontinence Lubricious coating facilitates ease of insertion Page 6

7 Characterization of frictional properties of urinary catheters Friction force tested on fully hydrated coating using dry silicone gripper pads Friction force and wear tested in aqueous solution at constant temperature - mucous membrane or tissue an option Page 7

8 In vivo friction test - coating versus living tissue Configuration of the rabbit urethra and bladder Size CH8 coated catheter inserted in the rabbit urethra and bladder Finding the rabbit penis Histology cross section of the rabbit urethra Page 8

9 Friction force against rabbit urethra mucosa Withdrawal force measured as Static- and Dynamic friction force of coating swelled in sterile water or -saline solution T-peak Dynamic T-peak, Static friction 3 2 2,5 2 1,5 Dynamic friction 1,5 1 0,5 5 minutes 15 minutes 1 0,5 5 minutes 15 minutes 0-0,5 Sterile water Water w. 0,9% NaCl 0 Sterile water Water w. 0,9% NaCl -1-0,5 Withdrawal force [mn] of the coating from the rabbit urethra Static friction force [N] or adhesion of the coating to rabbit urethra measured after 5 and 15 minutes of insertion time Dynamic friction force [N] between coating and rabbit urethra measured after 5 and 15 minutes of insertion time Osmolality (osmotic pressure) plays an important role on the withdrawal force Page 9

10 Osmolarity-driven mass transport of water Impact on the lubricity and adhesiveness of hydrophilic polymers Coating swelled in sterile water Coating swelled in sterile isotonic water, 0.9% NaCl Hydrophilic coating Hydrophilic coating Water movement Water movement Mucous membrane of the rabbit urethra Mucous membrane of the rabbit urethra The coating system must not dry out during use The effect of osmolarity on the friction force of a catheter against the urethra mucosa wall is examined in the paper by Lundgren et al The importance of osmolality for intermittent catheterization of the urethra; Spinal Cord, 38, pp Page 10

11 Lubricity and adhesiveness of hydrophilic polymers depends on hydration! The Diffusion-Interpenetration Theory of Mucoadhesion Commonly used mucoadhesive polymers Rank order of mucoadhesive force a. Top layer (Polymer) - Bottom layer mucous membrane before contact b. Top and bottom layer mucous membrane immediately after contact c. Top and bottom layer mucous membrane after contact for a period of time HUANG, Y.; LEOBANDUNG, W.; FOSS, A.; PEPPAS, N.A. Molecular aspects of muco- and bioadhesion: Tetheres structures and site-specific surfaces. J. Control. Release,v.65, n.1, p.63-71, Chen J, Cyr GN. Compositions producing adhesion through hydration. In: Manly RS, editor. Adhesion in biological systems. NewYork: Academic;1970. pp Page 11

12 From test in rabbit to validation on humans Man and machine: Stensballe J, Looms D, Nielsen PN, Tvede M.: Hydrophilic-coated catheters for intermittent catheterisation reduce urethral micro trauma: a prospective, randomised, participant-blinded, crossover study of three different types of catheters. Eur Urol Dec;48(6): Page 12

13 Conclusive remarks Demonstrated: It is possible to design a superior hydrophilic lubricious coating system for intermittent catherization The hydrophilic coating is highly affected by osmotic driven water transport in contact with living tissue Fully hydrated hydrophilic polymers are extremely lubricious Partially hydrated hydrophilic polymers may form a strong mucoadhesive gel Preclinical trials are crucial for tailoring polymer systems for high lubricity of intermittent catheters Page 13