Preparation, characterization, and bioevaluation of 99mTc-famotidine as a selective radiotracer for peptic ulcer disorder detection in mice

This work focuses on tracking peptic ulcer localized in mice. The formation of a [99mTc]dithiocarbamate of famotidine complex at optimum conditions of reaction temperature (37 °C), reaction time (30 min), pH of the reaction mixture (5), amount of substrate (100 µg), amount of reducing agent (tin (II) content, 50 µg), was achieved using radioactive Tc-99m (250–400 MBq), with labelling yield of 98% and high radiochemical purity. The in-vitro stability of [99mTc]dithiocarbamate of famotidine complex was shown to be high in rat serum for up to 8 h. Normal and ulcerated mice were used in biodistribution studies. Famotidine works by blocking histamine-2-receptor antagonists (H2RAs). The high absorption of [99mTc]dithiocarbamate of famotidine complex in stomach in amount of 27.15% injected dose/g organ (ID/g) observed in ulcerated mice for up to 24 h demonstrated its usefulness as a novel radiotracer for stomach imaging.

Preparation and Quality Control of 99mTc-Calciumgluconate

A procedure for the labelling of lyophilised Sn-Ca-Gluconate by a 99mTc instant technique was developed. Paper and TLC chromatography and low-voltage electrophoresis were used for the determination of the labelling yield which reached between 95 to 98%. The biodistribution was followed in white (albino) rats. About 25 to 35% of the total activity of the compound was retained in the kidneys one hour after its i.v. injection.

99mTc-Labelled Cu(I)-EHDP, a Potential Skeletal Imaging Agent

99mTc-Cu-EHDP has been prepared with high labelling yield applying for the first time the method of instantly formed cuprous ions in the mixture. A gelchromatography column scanning technique has been used to study the 99mTc fractions in the preparation. The study of the influence of pH-value on the amount of 99mTc-Cu-EHDP fraction shows that pH 1.6 - 1.7 gave the best labelling results. The formation rate of 99mTc-Cu-EHDP complex with a high labelling yield was fast and achieved within a few mins. This suggests the reduction of 99mTc-pertechnetate to Tc (IV). The final preparation was found stable for at least 4 hrs after mixing the reactants with the 99mTc-eluate. Comparative biokinetic studies of 99mTc-Cu-EHDP and 99mTc-Sn-EHDP in rabbits and mice showed a high bone uptake and fast elimination of 99mTc-Cu-EHDP from the skeleton. No significant difference was found in the plasma protein binding of 99mTc-Cu-EHDP and 99mTc-Sn-EHDP in rats as assessed by the GCS-technique. Radionuclide imaging in rabbits, using a gamma camera, showed 99mTc-Cu-EHDP to be a good bone-imaging agent.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).