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Sustained-release triamcinolone promising in animal studies
WAIKOLOA, Hawaii — A large-crystal non-micronized triamcinolone preparation “may be worthwhile pursuing,” according to an investigator of the formulation.
Donald R. Sanders, MD, PhD, said the beneficial effects of the usual dose of intravitreal triamcinolone (4 mg) tend to diminish after about 3 months. He said investigators have attempted to prolong the effectiveness of intravitreal triamcinolone, but increased dosages of the steroid tend to cause IOP to increase.
Dr. Sanders said that larger crystal sizes of triamcinolone have a decreased surface-area-to-volume relationship, resulting in a slower dissolution time in lab studies. Therefore, these larger crystal formulations may not cause IOP to increase, he suggested.
In animal studies, Dr. Sanders said, this new composition differs in shape and porosity from that of non-micronized triamcinolone. He said the studies also showed a “significant difference in the dissolution rate” between micronized and non-micronized samples of triamcinolone.
He added that the larger particle size can still be injected through a 22-gauge needle, which is the same size used for traditional triamcinolone preparations.
Dr. Sanders presented this information here at Retina 2005, as part of Hawaii 2005, The Royal Hawaiian Eye Meeting.