IOP spikes after Avastin therapy may be attributable to differences in how doses are prepared by compounding pharmacies
SAN FRANCISCO — How different compounding pharmacies prepare doses of Avastin may lead to differences in high molecular weight adducts that may plug outflow pathways or cause an immunologic response that leads to IOP spikes, a speaker said here.
Malik Y. Kahook
"By no means am I saying that Avastin is doing something to the trabecular meshwork or the eye cells," Malik Y. Kahook, MD, said during the joint meeting of the American Academy of Ophthalmology and Pan-American Association of Ophthalmology. "Certain compounding techniques are affecting the components that you're getting in the syringe, whether it's aggregation of proteins, formation of dimers and trimers, or other components that could be as large as 20 µm."
Dr. Kahook said that he has seen 16 cases in his clinic, but has seen reports of at least 74 additional cases in five states in the United States. Investigation is ongoing with Lucentis (ranibizumab, Genentech), but "cases are overwhelmingly in the Avastin corner," Dr. Kahook said.
Inflammation and toxicity related to delivery of Avastin (bevacizumab, Genentech) have been suggested as potentially causing IOP spikes. However, micro flow imaging showed significant differences in total particle number in samples of bevacizumab drawn directly from a multidose vial, from the vehicle and from a dose supplied by a compounding pharmacy, Dr. Kahook said. The compounding pharmacy was selected because it supplied doses to a Utah clinic that saw 42 postinjection IOP spikes.
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