PHARMACOLOGICAL APPLICATIONS OF aAPIO ISOTOPES Thomas J. Haley, Ph.D. Chief of the Pharmacolory-Toxicology Division Atomic ifnerzgy Project University of California st Los Anreles This @iscussion will concern itself primarily with pharmacology | and toxicology seeking to point out practical spplications or radioisotopes to problems in these fields. Not all the tsotop-s ere useful in such studies becsuse of not only the Lleneth of tire involved inthe study itself but siso the short helf-life of the required element and the difficulties encountered in orgenic synthesis. . From a phermacologicsal end toxicolopiesl] viewpoint much is known concerning emphetamine (Bephenylisorhopyl amine) and its Hemethyl derivative. Both compounés have been shown to be potent stimulants of the motor cortez causing inereased sctivity in both man and animals. In men this activity may heve a Ccurstion of from siz to eight hours depending upon the individual. is not completed even 46 heurs loxever, the excretion of either compound .fter the finul dose. This is of par- ticulsr interest in as much as it hss been shown that derivatives of B-phenylisopropyl amine are inhibitors of amine oxida Further, phenol cxiésase has no effect upon the metabalism of thesse drurs teesuse ther a body catcxication mechenisms. one of the is no phenolic hy- éroxyl group in the molecule. . The only enzyme system thus far shown to attack these drugs is the escorbic-dchydroascorbic acid system. Asorbiec scid itself has also been found to ettack amphetamine causing deamination, In the course of further studies on amphetamine excretion it was found that the drug is quantitatively excreted by dogs poisoned with either carbon-tetrachloride or hydrazine. This might indicate that