Drug Eluting Baloon Coating Development
While the treatment of coronary and peripheral heart disease is still dominated by the drug eluting stent, there has been a growing interest in the use of Drug Eluting Balloons (DEB) as an alternative therapeutic approach. Due to the transient presence of the device within the body, the potential for delayed healing and late-stage thrombotic events is significantly reduced.
While DEBs offer significant promise, there are still a number of challenges that have fully been overcome. Controlling the drug dose, preventing excess drug loss during delivery and maximising adhesion of the drug to the vessel wall remains a challenge. Manufacturers have attempted to optimise this process by adjusting balloon expansion time, formulating drug mixtures and varying excipient levels.
At present, paclitaxel is the preferred drug in many DEB systems, but there is on-going interest in alternative drugs such as sirolimus, zotarolimus or everolimus and preliminary clinical data has suggested that these are as effective as paclitaxel. Hydrophilic excipients are generally added to increase the solubility and transfer of these lipophilic drugs. This combination of hydrophilic and lipophilic agents have been associated with crystal formation on the DEB surface, with resultant downstream issues as the crystalline particulates are known to cause vascular embolisms. Moving to a smoother external finish has also been shown to reduce drug loss and maximise performance. Careful control of the drug to excipient ratios, coating application methods and surface finish is critical to maximise drug stability, reduce microparticle formation and minimise blood scouring of the drug prior to delivery and this requires an optimised coating methodology.
While DEBs offer significant promise, there are still a number of challenges that have fully been overcome. Controlling the drug dose, preventing excess drug loss during delivery and maximising adhesion of the drug to the vessel wall remains a challenge. Manufacturers have attempted to optimise this process by adjusting balloon expansion time, formulating drug mixtures and varying excipient levels.
At present, paclitaxel is the preferred drug in many DEB systems, but there is on-going interest in alternative drugs such as sirolimus, zotarolimus or everolimus and preliminary clinical data has suggested that these are as effective as paclitaxel. Hydrophilic excipients are generally added to increase the solubility and transfer of these lipophilic drugs. This combination of hydrophilic and lipophilic agents have been associated with crystal formation on the DEB surface, with resultant downstream issues as the crystalline particulates are known to cause vascular embolisms. Moving to a smoother external finish has also been shown to reduce drug loss and maximise performance. Careful control of the drug to excipient ratios, coating application methods and surface finish is critical to maximise drug stability, reduce microparticle formation and minimise blood scouring of the drug prior to delivery and this requires an optimised coating methodology.
TheraDep has developed a novel coating process that allows drugs and excipients to be applied to both metal and polymer surfaces. The thin films are adherent, conformal and retain pharmaceutical efficacy. These coatings are compatible with a range of Drug Eluting Balloons materials including Nylon-12, Pebax elastomers and PET. The coatings can be adjusted to integrate numerous excipients and combine pharmaceutical efficacy with a smooth topography to maximise drug delivery.