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Boston Scientific Corporation Message Board

  • Lkbum Lkbum Aug 28, 2000 6:15 AM Flag

    Taxol coatings

    Per previous posts, Taxol caotings are being
    pursued by BSC for their stents. The following was
    presented this weekened at a conference in Holland. I think
    this supports BSC efforts, but also points out short
    comings in polymer encapsulation. Since Bio already has
    CE mark approval for this procedure, does this put
    BSC behind in this area? Bio. is working towards FDA
    approval of this method of drug delivery.

    Session:
    (244 ) Poster Display III:Restenosis: mechanisms and
    new
    technologies
    Chair: S. Nitter-Hauge (Oslo, NO), F. B�r (Maastricht,
    NL)
    Monday, August 28, 2000 RAI Poster Hall

    Citation:
    European Heart Journal Vol 21, Abstr.
    Suppl.
    August/September 2000, page 285

    N. Swanson, K. Hogrefe, Q.
    Javed, A.H. Gershlick

    Cardiology Clinical
    Sciences, Glenfield Hospital, Leicester, United Kingdom



    Background: Stent based delivery of drugs is a rapidly
    expanding field as a means of
    delivering agents locally
    to prevent the complications of
    angioplasty/stenting. The choice
    of stent polymer has also been
    widely investigated as many polymers used to coat
    stents
    have proven to be pro-inflammatory or pro-coagulant.
    Phosphorylcholine-coated (PC)
    stents may overcome these dificulties
    since they have not been shown to suffer from
    these
    adverse qualities.Paclitaxel(Taxol) is a drug that
    profoundly suppresses of smooth muscle
    cell migration and
    proliferation, by interfering with microtubule function.Other
    groups
    have shown that PC stents can absorb and release a
    variety of agents. We report the use
    of
    paclitaxel-loaded stents.

    Results: Adsorption - A maximum of
    127 � 29�g of paclitaxel was adsorbed to the
    stents
    when immersed in 12mg/ml solutions. No difference in
    adsorption was seen with
    adsorption times over 5
    minutes.Elution - 13.4� 9% of the original paclitaxel was left
    on
    the stent after 24 hours perfusion. By 48 hours this
    had reduced to 3.8 � 1.7%.

    Discussion:
    Paclitaxel was rapidly adsorbed by the stents. The drug was
    then released
    more slowly over 24-48 hours, which
    is approximately the timescale required to
    suppress
    cell growth.This stent, which may be superior to
    others with more inflammatory polymers,
    could
    realistically be loaded with desired drug (e.g. paclitaxel) at
    the time of the
    procedure.

    SortNewest  |  Oldest  |  Most Replied Expand all replies
    • If BSX bought Medinol then Richter would be out,
      and eventually the operation would be moved to Galway
      in Ireland. They wouldn't want to leave the
      operation in hostile territory for too long.

      Woody

    • Same goes for Medtronic.

    • continues to show the way in interventional
      cardiology. In the Fortune issue of September 4, 2000, they
      are described as the number 99 fastest growing
      company. The reasons stated are three:
      Working on an
      implantable CHF device; reinvesting 15% into R&D which
      translates into a healthy pipeline and last but not least,
      management has a strong record in making good on their
      promises. Maybe someone should look in the mirror.....

    • Kind of shows you where BSX heads at when it
      comes to R & D. They can't even develope their own
      stent, and have to rely on Medinol. Like I said before,
      paying 2B for Medinol is way to much for old stent
      technology IMHO.

    • I love your post, they are so informative. If BSX bought Medinol who would manage and who would leave? Or would BSX move the plant?

    • The delay was caused by incompetence and a total
      breakdown in communication and cooperation with
      Medinol.
      Kobi R is an impossible guy to deal with.
      The whole
      thing has been mishandled by BSX management - many
      people told them so at the time and warned them this
      would happen.
      This was coupled with Scimed's
      inability to come up with a next generation stent, and also
      the fact that even though the Medinol relationship
      was difficult, BSX were unable to look at other
      technologies that were available, for fear of upsetting the
      Medinol folks - this has gone on for years now, and the
      bottom line is that Kobi Richter and his wife have
      turned themselves into billionaires at the expense of
      BSX (assuming the company is acquired for $2 billion
      as reports suggest).
      Kobi has always wanted to be
      able to afford a better private jet than Peter
      Nicholas - now Peter might have to give him his as part of
      the deal.
      BSX created the monster - and it's now
      consumed them.

      Woody

    • I too remember being at the Rotterdam convention
      4 years ago. I remember seeing an impressive
      presentation of the niroyal stent-a stent that was only
      approved to market this year. Do you know what caused the
      delay? Does anyone in BSC know?

    • I hear U2 cath_man.

      Woody

    • The nature of these two polymers are very similar
      - polyester. They are more stable than other
      polyesters, but how about a few years down the road. This is
      something different from contact lense, the inviroment and
      the length of deployment.
      PET problem is real. PC
      potential problem is my best guess. Check out the following
      article.

      Title
      Comparison of self-expanding polyethylene
      terephthalate and metallic stents implanted in porcine iliac
      arteries.
      Author
      Wilczek K ; Scheerder ID ; Wang K
      ; Verbeken E ; Piessens J
      Address

      Department of Cardiology, University Hospital Gasthuisberg,
      49 Herestraat, 3000 Leuven, Belgium.
      Source

      Cardiovasc Intervent Radiol, 19(3):176-80 1996 May-Jun

      Abstract
      PURPOSE: Comparison of the biocompatibility
      of self-expanding polyethylene terephthalate (PET)
      stents with self-expanding metallic stents (Wallstents).
      METHODS: Diameter- and length-matched PET stents and
      Wallstents were symmetrically implanted in the paired iliac
      arteries of 13 crossbred domestic swine. Stent deployment
      was studied angiographically and with intravascular
      ultrasound immediately after stent implantation. The
      angiographic stented lumen diameter was measured using
      quantitative vessel analysis before, immediately after
      stenting, and at 6-week follow-up. Cross-section
      histopathology and area morphometry were performed. RESULTS:
      Immediately poststenting, intravascular ultrasound revealed
      proximal dislocation of 5 of the 13 PET stents, whereas
      all metal stents were firmly embedded at the
      implantation site. At 6-week follow-up, three of the remaining
      PET stents were totally or subtotally occluded by
      organized thrombus, whereas all metal stents were patent.
      Compared with immediately poststenting, the angiographic
      lumen diameter within the five remaining PET stents was
      reduced by 30%, and that of the metallic stents was
      virtually unaltered (p < 0.02). This observation was
      confirmed by postmortem morphometry, wherein the
      PET-stented vessel segments a diameter stenosis of 40% was
      measured vs only 9% in the metallic stents (p <
      0.0001). CONCLUSION: PET-stent deployment is difficult to
      control due to the lack of radiopacity of this stent. PET
      stents seem to be more thrombogenic and lead to
      significantly more neointimal proliferation than metallic
      stents.


      -------------------------------------

      I don't have any information on "The BSC taxol
      stent may solve the restenosis problem but could have
      late stage thrombus problems due to the exposed bare
      stent in the artery." So, I have no comment on that.

    • "Thrombus and restenosis are different things, I
      believe"

      Correct. If the drug delivering biodivYsio stent can
      succesfully reduce the rate of restenosis then the non
      thrombogenic PC coating will prevent any late stage thrombus
      formation. Cure two problems with one stent. Can you show me
      another stent combination that could potentially do that?


      The BSC taxol stent may solve the restenosis problem
      but could have late stage thrombus problems due to
      the exposed bare stent in the artery. This is JMHO
      and I have no evidence to back it up
      yet.

      "Furthermore these two polymers will degrade in the long run
      which may cause severe problem"

      Tests results
      for the PC coating suggest otherwise. Do you know
      different or are you guessing?

      [Just for your
      information and off topic but just to demonstrate that the PC
      coating is versatile. PC is used in Biocompatibles
      Proclear contact lenses which are FDA approved for "dry
      eyes". The only contact lenses able to make this
      claim.]

      Cheers
      2Bob

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