Influencia do metimazol na distribuicao dos radionuclideos 131I E 99m Tc em ratos / Influence of methimazole in distribution of radionuclides131I E 99m Tc in laboratorial rats

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Radionuclides, such as 99mTc and 131I, being administered as radiopharmaceuticals have been used in Nuclear Medicine to diagnose and treat many diseases in humans. Syntheticâs drugs as methymazole are used in treatment of hiperthyroidism so as to reduces hormones before the radioactive treatment. Interaction between medicines and radionuclides can modify radiopharmac activity, biasing the linking between the radionuclides and organs/tissues. This alteraction can lead to wrong diagnoses and expose the patients to excessive doses. The aim of this study is to evaluate biodistribution process of 99mTc and 131I radionuclides in Wistar rats treated with methymazole for 1 and 14 days, to find possible changes in linking ability of radionuclides with organs and tissues. Wistar rats with age 90 days were subjected to 99mTc (through the orbital plexus) or 131I (through gavage) at activities of 370 kBq and 555kBq, respectively. They were observed at different times, being 30 and 120 minutes for 99mTc and 2 and 48 hours to 131I. The results show that both radionuclides had the best linking capacity after 2 hours. Following this conclusion, 99mTc and 131I biodistribution, after 2 hours, was studied in rats treated by methymazole, through gavage, at concentration of 1mg/mL, during 1 and 14 days. The results show that after 1 day of treatment the methymazole alters the ability of 99mTc to link the organs, increasing the captation in stomach and decresing the capitation of the others organs studied. However, collection of 131I in rats, treated with methymazole for one day, decreased in all studied organs. In rats treated for 14 days an increase in 99mTc collection was found the thyroid, esophagus and stomach, while 131I in all organs, except liver showed significant decreasing trends. Therefore, the study in vivo with animal model shows that best rate of captation for radionuclides occured 2 hours after the treatment with methymazole and 14 days treatment changed 131I collection more than 99mTc. Showing that methymazole can promote a radioprotective effect mainly in thyroid

ASSUNTO(S)

tecnetium 99m metimazol engenharia nuclear methymazole thyroid tirÃide tecnÃcio 99m iodo 131 iodine 131

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