Abstract: Natural or synthetic drugs can alter the bioavailability of radiopharmaceuticals used in diagnostic imaging in nuclear medicine. The knowledge of such altered bioavailability is important in making diagnostic of diseases and to try to understand biological effect of drugs in specific organs. The use of natural products has been increasing in the world. Echinacea is a natural product widely used for the treatment of respiratory tract infections. The aim of this study was to evaluate the effect of the echinacea on the bioavailability of the radiopharmaceutical 99mTc-sodium pertechnetate (Na99mTcO4) and on the mass of organs to try to verify possible undesirable actions of the studied natural product. An extract of Echinacea was daily administered by intragastric via into Wistar rats during 10 days. Na99mTcO4 (3.7MBq) was administered by ocular plexus via and 10 minutes after the animals were sacrificed. Blood and various organs were removed, their mass determined, their radioactivity counted in a well counter and the percentages of the injected dose per gram of organ (%ID/g) calculated. The results showed that in the treated animals: (i) the mass of the organs was not modified; (ii) the %ID/g decreased in lungs. The effect of echinacea on the Na99mTcO4 bioavailability in the lung was statistically significant (Student test, p<0.05) and it could be explained by the metabolization or therapeutic action of this herb in this organ.
M.L. Gomes , E.A.C. Lima , S.M.S. Souza , L.C. Bernardo , M.E. Penas , R.L. Jales , M.T.J.A. Catanho and M. Bernardo Filho , 2004. Evaluation of the Effect of an Echinacea Extract in Rats: Study of the Mass of Organs And of the Bioavailability of the Radiopharmaceutical Sodium Pertechnetate (Tc-99m) . Journal of Food Technology, 2: 148-152.