Urotech Ureteric Stents

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    U R E T E R I C S T E N T S

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    Medi-Globe-Straße 1-5 · D-83101 Achenmühle, Germany 

     +49 (0) 80 32 / 973-200 · Fax: +49 (0) 80 32 / 973-211 info@urotech.com · www.urotech.com

    UROTECH  The worldwide only Manufacturer  of PC coated Urological Devices

     What is Phosphorylcholine?

    Phosphorylcholine is a biocompatible and durable

    sealing of the inner and outer surface of implants to prevent biofilm formation and subsequent

    encrustation. It is successfully used not only in urology

    but also in other medical fields (coronary stents,

    contact lenses).

    Mechanism

    PC technology is based on the observation that the

    ouside leaflet of a red blood cell membrane is

    haemocompatible, while the inner leaflet is throm-

    bogenic. The inner, thrombogenic surface contains

    negatively charged phospholipids while the outer bi-layer is composed of zwitteronic phospholipids.

    These have both

    positive and ne-

    gative charges in

    close proximity

    but are overall

    e l e c t r i c a l l y

    neutral (Fig 1).

     A zwitteron (bi-

    pol) consists in

    equal parts of positive and negative charged ions in one molecule.

    So it is to the outside electrically neutral. 80 % of

    the outer cell membrance of a erythrocite consists

    of Phosphorylcholine, the rest consists of other not

    zwitteronic phospholipids. An equal coating with

    Phosphorylcholine applied to coronary stents, contact

    lenses and urological implants therefore mimics the

    bi-pol character of the physiological membrane and

    increases the bio- and haemocompatibility. Water

    molecules show also a zwitteronic structure and

    therefore many water molecules bind losely on thePhosphorylcholine surface (Fig 2).

     The Effect 

    Phosphorylcholine is according to the described effec-

    tiveness highly suitable for the application in the urology. The water molecules on the surface of the implants

    stop the binding of other molecules and materials on

    the PC surface and reduces at the same time the coeffi-

    cient of friction,

     which results in

    a better implan-

    tation behavior.

    Even a short

    time after im-

    plantation a bi-ofilm formation

    on the surface

    of uncoated ca-

    theters is obser-

     ved, containing multiple microorganism and extracel-

    lular matrices. This biofilm can be seen as a permanent

    reservoir of these bacteria, protected them against

    antibiotic therapy and maintaining a catheter associa-

    ted urinary tract infection (CAUTI). Most of these micro-

    organism are forming ureasplitting enzymes (urease)

    resulting in an increasing ph-level of urine and in the

    biofilm. If the ph-level exceed the neutral point (ph=7),

    different soluted molecules precipitate and cristalize

    on the surface of the implant. An encrustation is for-

    med and the inner lumen of the catheter is narrowed

    down and the implant is not functioning (Fig. 3a).

    Phosphorylcholine (PC):

    Modern Technology for high Requirements

    Since 10 years now Urotech is successfully using Phosphorylcholine coating (PC) on

    urological devices. Phosphorylcholine lowers proven  the risk of encrustations  and

    infections, which results in prolonging the indwelling time  of ureteral stents and

    nephrostomy catheters.

    Below, we would like to show the effectiveness of the PC coating and its advantage.

    Fig. 1: Distribution of electrical charges in the cell

    membrane of a red blood cell

    Fig. 2: Phosphorylcholine binds many water 

    molecules on its surface

    1.40.2.

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    UROTECH  The worldwide only Manufacturer  of PC coated Urological Devices

    Due to the

     waterfilm on

    its surface

    Posphorylcho-

    line reduces

    the adhesion

    of bacteria

    and proteins,

    resulting in

    a decreased

    biofilm and

    therefore signi- ficantly lowers

    encrustation.

    (Fig. 3b).

    Effectiveness

    Multiple in vitro and clinical studies show theeffectiveness of Phosphorylcholine on urological

    devices. Fig. 4 shows the adsorption of E.coli at

    different coated materials used for such devices

    compared to uncoated (controls after 18 h incubation).

    E.coli is known as one of the main responsible bacteria

    for urinary tract infections. The PC coated surfaces

    show, independent from the material, significant less

    adsorptions of bacteria.

    In another in vitro trial catheters of different materials

    and coatings (latex and silicone, uncoated, hydrogel

    Russel JC. ; Bacteria, Biofilm and Devices: The Possible Protective Role of Phosphorylcholine Materials; J. Endourology 2000; 14(1): 39-42

    Stickler DJ, Evans A. et al.; Strategies for the control of catheter encrustation; Int. J. of Antimicrobial Agents 2002; 19(6): 499-506

    Heidenreich A., Becker T. et al.; Morbidity of internal Ureteral Stents: Prospective randomized Trial of Polyurethane versus Phosphorylcholine

    Coated Stents; Poster # 139 XVIIth Congress of European Association of Urology (EAU) Birmingham 2002

    and PC coated) were incubated in urine contaminated

     with proteus mirabilis until encrustation occured.

    The positive effect of Phoshorylcholine was here

    also confirmed: Phosphorylcholine coated silicone

    catheters remained open for the longest time.

    These experimental results have been in vivo confirmed

    from the authors. In a clinical study, 44 PC coated

    ureteral stents were examined for encrustation after

    12 weeks implantation, in comparison to 28 uncoated

    ureteral stents from the same patient which were

    implanted before. 61 % of the uncoated and 36 % of the PC coated showed a visual noticeable biofilm.

    The encrustation was evaluated with a standardized

    procedure. The encrustation index of the uncoated

    ureteral stents tested in all sections of the stent was

    higher than the PC coated stents.

    In a prospective randomised comparison study of

    uncoated and PC coated ureteral stents Heidenreich

    et al. found significant differences with different

    parameters: He examined the ureteral stents of 80

    patients with mostly stone removal treatments

    (40 uncoated/40 PC coated) with an indwelling

    time of 34-37 days. Patients with PC coated stents

    showed significant less pain and urge incontinence,

    less urinary tract infections and needed less

    anticholinergic medication. The authors conclude that

    Phosphorylcholine coated ureteral stents minimize

    - significant stent associated morbidity 

    - frequency of urinary tract infections, and therefore

    - less cost for accompanying medication

      (anticholinergics, antibiotics)

     We can send you further literature on request!

    Fig.3: cross-section of a catheter after three month

    implantation in the same patient

    a. uncoated b. PC coated

    Fig.4: Significant reduction of bacterial adsorption on PC coated surfaces

    a

    b

    1.40.2.

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    Medi-Globe-Straße 1-5 · D-83101 Achenmühle, Germany 

     +49 (0) 80 32 / 973-200 · Fax: +49 (0) 80 32 / 973-211 info@urotech.com · www.urotech.com

    URETERAL STENTS Introduction and general Information

    Introduction

    On the following pages we would like to give you

    a complete overview of our wide range of ureteral

    stents. Regardless of the indication, here you will find

    the appropriate solution. Since we have our own

    production premisis in house we are also capable of

    providing special designs to suit your needs for the

    not daily application.

    Material

    aliphatic Polyurethane (PUR)  All ureteral stents manufactured by Urotech are

    fabricated from aliphatic polyurethane which was

    especially developed for medical applications.

     Aliphatic polyurethane’s physical and chemical

    characteristics make it the optimal material for catheter

    application. When compared to other materials,

    aliphatic polyurethane exhibits minimal adhesion

    of blood components and significantly lower tissue

    irritation, in short or long term use.

     An additional beneficial characteristic of PUR is that

    the material softens as it reaches body temperature

    in an aqueous environment, which reduces the risk

    of traumas of stiff devices, pressing against the vessel

     wall.

    Through testing and actual use, aliphatic polyurethane

    has proven that it is one of the most tissue compatible,

    and one of the least thrombogenic materials for

    indwelling medical devices. As aliphatic polyurethane

    is manufactured exclusively for medical applications,

    the manufacturing process is performed under strict

    quality assurance requirements, which assures a

    constant equal quality and highest possible safety.

    Indwelling Time

     All ureteral stents from Urotech are approved for

    long term indwelling time and can remain in the