J Biomed Transl Res.  2022 Dec;23(4):163-177. 10.12729/jbtr.2022.23.4.163.

Pharmacological properties of the Thyrokitty injection (I-131) for the treatment of the feline hyperthyroidism

• Lim JC
• Kim DM
• Nam SS
• Cho EH
• Lee SY
• Chung HK
• Lee I

• KMID: 2538509
• DOI: http://doi.org/10.12729/jbtr.2022.23.4.163

Abstract

Radioiodine (¹³¹I) has been used for the treatment of feline hyperthyroidism since the 1990s in the USA and Europe, and it is recommended as the most effective treatment for feline hyper-thyroidism because it has a high therapeutic effect, small side effects, and does not require anesthesia. In this study, the pharmacological properties of the Thyrokitty injection (I-131), which is being developed as a treatment for feline hyperthyroidism, using radioiodine (¹³¹I) as an active ingredient, was tested. The %cell uptake of the Thyrokitty injection (I-131) in FRTL-5 thyroid cells was 0.410 ± 0.016%, which was about 18 times higher compared to Clone 9 hepatocytes, and it was decreased by 30.7% due to the competitive reaction with iodine (so-dium iodide). In addition, the %cell growth of the FRTL-5 thyroid cells was reduced by 25.0% by treatment with the Thyrokitty injection (I-131). As a result of the tissue distribution test, the Thyrokitty injection (I-131) was distributed at the highest concentration at 0.083 hours (5 min-utes) after subcutaneous administration to animals in most organs except the stomach, small intestine, large intestine, muscle and thyroid gland, and it was excreted mainly through the kidneys. The stomach and thyroid gland showed a typical distribution pattern observed when radioiodine (¹³¹I) was administered. In addition, about 78.45% of the total amount of excretion was excreted within 48 hours, of which more than 85% was excreted in urine. In conclusion, the Thyrokitty injection (I-131) has the same mechanism of action, potency, absorption, distribution, metabolism and excretion characteristics as radioiodine (¹³¹I) reported in connection with the treatment of feline hyperthyroidism. In the future, using the results of this study, it is expected that the Thyrokitty (I-131) could be safely used in the clinical treatment of feline hyperthyroidism.

Keyword

feline hyperthyroidism; radioactive iodine; sodium iodide I 131; Thyrokitty injec-tion (I-131); pharmacology