Coronary Angioplasty and Drug-Eluting Stents - Applications of Biotechnology in Cardiovascular Therapeutics - page 308

6 months, the scaffold design and manufacturing process of its polymer were
modified, which have substantially improved the medium-term performance of this
new generation of drug-eluting scaffold to become comparable to those of current
drug eluting stents (Serruys et al. 2010b ). Clinical trials with such devices are under
way and the initial results are encouraging. The advantages of biodegradable poly-
mers include high drug loading capacity, controlled long-term drug release, and full
degradation of the polymer over a certain time resulting in full release of the drug
during a well-controlled time interval.
DES Versus Drug-Eluting Balloons
Non-stent-based methods for local drug delivery enable restenosis inhibition with-
out the need for stent implantation. They do not permanently change the structure
of the vessel, are repeatable, and seems to be applicable where DES provide insuf-
ficient protection. Preclinical data indicate that short exposure of the vessel wall to
a lipophilic inhibitor of cell proliferation is sufficient for preventing restenosis.
Initial evidence to this effect emerged from an investigation of paclitaxel embedded
in a matrix that enhances the solubility and release of the agent from the balloon
coating as well as its transfer to the vessel wall (Schnorr et al. 2010 ). Further cor-
roborating data from preclinical and clinical studies demonstrating a reduction in
late lumen loss and lower restenosis rates led to the market introduction of a variety
of paclitaxel-coated angioplasty balloons. The effectiveness of restenosis inhibition
is not determined by the active agent alone. Other factors that are crucial for the
effectiveness and safety of drug-coated balloons (DEBs) for angioplasty are the
formulation containing the agent and the coating technique.
A preclinical study was done to optimize the use of DEB DIOR (second genera-
tion) by measurements of tissue and plasma paclitaxel concentrations in porcine
coronary artery overstretch and to prove efficacy in inhibition of neointimal growth
without complementary use of stent (Pósa et al. 2010 ). Paclitaxel penetrated up to
2 mm tissue deepness. Measurable plasma paclitaxel level was found only after
60 s balloon inflation time. At follow-up, the dilated arterial segment neointimal
area and maximal neointimal thickness were significantly smaller with DIOR
versus uncoated balloon use. Fluorescence images of DIOR showed a homogenous
distribution of the drug on the vessel, in contrast with DES. The study concluded
that using the DIOR(secondgeneration) DEB, a maximal balloon inflation time of
30-45 s is optimal, reducing effectively the neointimal hyperplasia.
References
Aoki J, Abizaid AC, Serruys PW, et al. Evaluation of four-year coronary artery response after
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