DETERMINATION OF DYSPROSIUM IN MONKEY SERUM BY INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY (ICP-AES) AFTER THE ADMINISTRATION OF SPRODIAMIDE INJECTION, A NEW CONTRAST-MEDIUM FOR MAGNETIC-RESONANCE-IMAGING

Sprodiamide Injection (S-043 Injection, Nycomed Salutar; WIN 59080, St erling Winthrop) is a magnetic susceptibility-based MRI contrast agent which contains 500 mM dysprosium diethyienetriaminepentaacetic acid b is(methylamide) (DyDTPA-BMA), and 25 mM caldiamide sodium (CaNaDTPA-BM A). A study was conducted to evaluate clearance of drug in cynomolgus monkeys. Eighteen cynomolgus monkeys, divided into three groups of six animals each, were administered Sprodiamide Injection intravenously a t dose levels of 0.25, 0.5 and 2.5 mmol kg(-1), respectively. The conc entration of dysprosium in serum was determined in a monkey serum-hydr ochloric acid matrix by inductively-coupled plasma atomic emission spe ctrometry (ICP-AES). The ICP-AES method was demonstrated to be valid f or sensitivity, precision, accuracy, and specificity. The dynamic rang e was linear from 0 to 50 mu g ml(-1) and the limit of quantification was 24 ng ml(-1). The measured dysprosium concentration in monkey seru m ranged from 0 to 339 mu g ml(-1) for the 0.25 mmol kg(-1) Sprodiamid e Injection dose group, from 0 to 633 mu g ml(-1) for the 0.5 mmol kg( -1) and from 0 to 2920 mu g ml(-1) for 2.5 mmol kg(-1) dose groups. Dy sprosium was not detected after 480 min in any of the serum samples fr om the 0.25 and 0.5 mmol kg(-1) dose groups after the administration o f Sprodiamide Injection. All the monkeys in the 2.5 mmol kg(-1) dose g roup, with one exception, required 720 min for clearance of the drug f rom the serum. The drug was completely cleared from serum in all monke ys within 24 h.