Radiometric
Detection of Effects of Antirheumatoid Drugs on SH Groups in Blood
By Ngo Manh Tran, Thomas Ntundulu
(1), and Etienne LeBel, Department of Nuclear Medicine and Radiobiology,
Centre Hospitalier Universitaire, Sherbrooke, Quebec
Radiometric measurement of non-enzymatic oxidation of DOPA in the presence of isolated tissues was considered as a possible means for detection of SH groups in these tissues (J. Nucl. Med. 15: 539, 1974). We demonstrate here that both salicylate and indomethacin can interfere with SH groups in blood, which can be useful for rapid quantification of these drugs in clinical applications.
An automated indicator system (Bactec) was used for measurement of 14CO2 release from 0.1 µCi DOPA-1-14C incubated with 0.1-2.0 ml human blood, with and without various amounts of indomethacin and salicylate in 20 ml 0.1 M phosphate buffer, pH 7.0, at 37ºC, for 90 min.
Results and conclusions show that: 1) Non-enzymatic oxidation of DOPA inhibited by human whole blood (n=10; p< 0 .001) was significantly prevented 9.4 mg salicylate (n=10; p < 0.001), 4.7 mg indomethacin (n=10; p< 0 .02), respectively.; 2) Non-oxidation of DOPA without blood was however unchanged in the presence of 4.7-9.4 mg salicylate (p> 0.05) and 4.7-9.4 mg indomethacin (p> 0.05), respectively.
Results obtained from 1) and 2) show that effects of antirheumatoid drugs, i.e. salicylate and indomethacin in blood were specific, and these drugs were probably bound to blood SH groups which might subsequently prevent the non-enzymatic oxidation of DOPA; 3) A reversed 14CO2 production from DOPA-1-14C by salicylate and indomethacin in blood may be considered as a sensitive index of radiometric detection of antirheumatoid drugs in blood; and 4) The method may be useful for rapid detection of SH metabolism in blood of connective disorders, subsequent to administration of antirheumatoid drugs. Abnormality in SH metabolism was known in these disorders.
Journal of Nuclear Medicine, 16: 576-577, 1975
(1) T. Ntundulu was a graduate student for Master degree of Sciences in Nuclear Medicine and Radiobiology at the University of Sherbrooke , Quebec, Canada
