Biomedical Engineering Reference
In-Depth Information
4.7
Conclusions
Poly(ortho ester) have been under development since 1970, and while it is a very
well-understood system, its commercialization has been slow in coming. This was
primarily due to the fact that much of the early poly(ortho ester) work was carried
in an academic setting at the former Stanford Research Institute, now SRI
International.
Beginning in 1985, serious attempts by the former Interx Laboratories of Merck
to develop a 6-month ivermectin delivery implant based on POE II to prevent
heart-worm infestation in dogs was initiated. However, even though desired iver-
mectin blood levels have been achieved for many months and in a clinical trial the
formulation was 100% effective in preventing heart-worm infestations in dogs, it
was not possible to prepare devices that had reproducible erosion times. This
irreproducibility problem eventually doomed commercialization.
Beginning in 1994, the fourth family of poly(ortho ester), POE IV, was devel-
oped at Advanced Polymer Systems, now AP Pharma. This polymer system is
currently under active development at AP Pharma for a number of applications,
and a Phase II clinical trial using mepivacaine for postoperative pain control was
completed. This trial demonstrated for the fi rst time that a specifi c family of
poly(ortho ester) has a benign toxicology and that it is a suitable system for use
in humans.
Based on the benign toxicology of this particular family of poly(ortho esters), the
development of a granisetron delivery system to control chemotherapy-induced
nausea and vomiting was initiated. This system has recently completed a Phase
III clinical trial and work preparatory to an NDA fi ling is underway.
In addition, a number of proprietary systems based on POE II are also under
development.
Thus, after a very long induction period, a number of delivery systems based on
poly(ortho esters) are on their way of becoming a commercial reality.
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