Figure 1. Intranasal I-125 radiolabeled ST266 accumulated at high levels in optic nerve and vitreous.

60 μl of I-125 radiolabeled ST266 was administered intranasally over 18 minutes as 6 μl drops given to alternating nares every 2 min. Animals (N = 4 Sprague Dawley rats) were euthanized 30 minutes later, tissues were removed, and levels of I-125 were measured. Significant accumulation of I-125 was detected in optic nerves (1100 ng/g of tissue) and vitreous (885 ng/g of tissue). Some radiolabeled ST266 material was also detectable in the blood, olfactory bulbs, trigeminal nerves, and across the brain, all at lower levels, less than 100 ng/g of tissue. Data represent the mean ± SD concentration measured as ng/g of tissue.