Journal of Radioanalytical and Nuclear Chemistry, Articles, Vol. 134, No. 2. (1989} 423-431 PREPARATION AND EVALUATION OF 99mTc-THIODIGLYCOLIC ACID (TDGA) FOR RENAL FUNCTION STUDIES* N. RAMAMOORTHY, 1** S. A. BALAKRISHNAN, 1 S. M. GAITONDE,1 P. M. PANDEY,' U. N. NAYAK,2 M. C. PATEL, 2 R. B. PATEL, 2 P. RAMANATHAN 2 Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Bombay - 400 085 (India) 2 Radiation Medicine Centre, Bhabha Atomic Research Centre, TMCAnnex Parel Bombay - 400 012 (India) (Received June 13, 1989) Methods for the preparation and analysis of a new renal radiopharmaceutieal, 99mTc- thiodiglycolic acid (TDGA), are reported. The kit for Tc-TDGA contains a lypophilized acidic (pH 2.5) mixture of 5 mg TDGA and 0.05 mg SnC12 9 2 Ha O. Acetate buffer has been found to be a suitable solvent for paper chromatography of 99mTc-TDGA. The results of the quantitative organ distribution studies in rats and rabbits indicated the characteristics of 99mTc-TDGA to be intermediate to the renal tubular agent 13~ I-Hippuran and the GFR agent 99mTc-DTPA. Introduction Hippuran labelled with 1311 has been in use for assessing the renal tubular func- tion; however, due to the poor physical characteristics of 131i, it is restricted to only probe renography. Because of the high cost and limited availability of ~alI-- Hippuran, it has been used only in selected centers in developed countries. Hence development of 99mTc-eompounds to replace Hippuran and to study renal tubular function has been the aim of many research workers in recent years) -a Many com- pounds, such as Tc-DADS derivatives,2'4's Tc-MAGa a'6 and 131I=lectins7 have *Parts of this work have been presented at the Indo-US Seminar on Radiopharmaceutieals-eum- 17th Ann. Conf. of Soc. Nucl. Med. (India) held at Bangalore in Jan. 1986 and at the 18th Ann. Conf. of Soc. Nucl. Med. (India) held at Madras in Dec. 1986. Also a part of this work has been included in the dissertation of N. Ramamoorthy submitted to the University of Bombay for the Ph.D. degree in chemistry. **Author for correspondence. Elsevier Sequoia S, A., Lausanne Akad~miai Kiad6, Budapest