Following the previous study, which investigated the pharmacological properties of the Technekitty injection (Tc-99m), the toxicity of a single intravenous administration of the Technekitty injection (Tc-99m) and the side effects that may occur at the diagnostic dose were confirmed. The Technekitty injection (Tc-99m) was administered intravenously once at a dose of 0, 0.67, 2.0, and 6.0 mCi/kg to 5 male and female rats per group. Mortality, general symptom observation, and weight measurement were performed for 2 weeks, followed by observation of autopsy findings. There were no deaths, and no statistically significant weight change was observed. No abnormal systemic signs related to the Technekitty injection (Tc-99m) were observed. These results confirmed that Technekitty injection (Tc-99m) can be safely administered intravenously at doses up to 6.0 mCi/kg. Additionally, technetium-99m at an average dose of 2 mCi (74 MBq) has been verified as a diagnostic dose without adverse effects, allowing the Technekitty injection (Tc-99m) to be used safely without side effects at this dosage. This study demonstrates that the Technekitty injection (Tc-99m) has a wide safety margin, supporting its potential for clinical application. Moreover, these findings align with the nonclinical safety standards for radiopharmaceuticals, reinforcing its utility in veterinary medicine. The Technekitty injection (Tc-99m) is expected to be applicable for clinical diagnosis as a veterinary drug in Korea.

Following the previous study, the toxicity of a single subcutaneous administration of the Thyrokitty injection (I-131) and the side effects that may occur at therapeutic doses were confirmed. The Thyrokitty injection (I-131) was administered subcutaneously once at a dose of 0, 2.0, 6.0, and 18.0 mCi/kg, 5 male and female rats per group, and mortality, general symptom observation, and weight measurement were performed for 2 weeks, followed by observation of autopsy findings. There were no deaths, and no statistically significant weight change was observed. Mild hair loss, fissures, and crusting were observed by general symptom observation, but it was not a toxic change related to the Thyrokitty injection (I-131). Gastric atrophy and a decrease in the size of the spleen were observed by the autopsy. As a results of single subcutaneous administration of the Thyrokitty Injection (I-131) to rats at a maximum dose of 18.0 mCi/kg, a decrease in the size of the spleen and gastric atrophy were observed as the dose of the Thyrokitty Injection (I-131) increased, which may be related to the test substance. No abnormal findings related to the Thyrokitty injection (I-131) were observed. Therefore, the approximate lethal dose of the Thyrokitty injection (I-131) was 18.0 mCi/kg or more. In addition, as reported for the treatment of feline hyperthyroidism with radioiodine (131I), side effects of the Thyrokitty injection (I-131) are expected to be extremely rare. Temporary dysphagia and fever may occur, but it will recover naturally. It should be administered with caution in cats with diseases such as urinary system, cardiovascular system, gastrointestinal system and endocrine system, especially with kidney disease. And it should not be used in cats who are pregnant, lactating, or likely. It is expected that the Thyrokitty injection (I-131) can be used for clinical treatment in Korea as a veterinary drug.