Safe and effective inhibition of renal uptake of radiolabelled octreotide by a combination of XXXX and @entity369 .

@entity1 @entity5 @entity535 @entity391 @entity413 @entity376 @entity972 @entity39259 @entity1943 @entity369
As scintigraphy with @entity39259 has become a standard technique in analysing @entity1943 receptor-receptor positive lesions such as @entity5 , a logical next step is peptide receptor radionuclide therapy (PRRT). Initial studies on PRRT were performed with high doses of @entity39259 , and recently other radionuclides coupled to other @entity1943 analogues have been used for this purpose. However, the dose delivered to the kidney is a major dose-limiting factor. @entity535 solutions have previously been used to reduce renal uptake of radioactivity, but these solutions have some disadvantages, i.e. their hyperosmolarity and their propensity to cause @entity391 and metabolic changes. In this study we tested various @entity535 solutions in @entity1 receiving @entity39259 PRRT in order to assess their safety and their capacity to inhibit the renal uptake of radioactivity. @entity1 served as their own non-infused control. Renal radioactivity at 24 h following the injection of @entity39259 was inhibited by (1) a commercially available @entity535 solution (AA) (21%+/-14%, P<0.02), (2) by 25 g (17%+/-9%, P<0.04), 50 g (15%+/-13%, P<0.04) or 75 g of @entity376 (44%+/-11%, P<0.001) and (3) by a combination of 25 g of @entity376 plus 25 g of @entity369 (LysArg) (33%+/-23%, P<0.01). Fluid infusion alone (500, 1,000 or 2,000 ml of saline/ @entity413 ) did not change renal uptake of radioactivity. In @entity1 studied with 75 g of @entity376 (Lys75) and LysArg, serum @entity972 levels rose significantly. Maximal @entity972 levels were within the toxic range (6.3, 6.7 and 6.8 mmol/l) in three out of six @entity1 infused with Lys75, whereas with LysArg the highest concentration measured was 6.0 mmol/l. Electrocardiographic analysis did not reveal significant changes in any of the @entity1 . Vomiting occurred in 50% of @entity1 infused with AA, but in only 6% of @entity1 receiving no @entity535 infusion (controls) and 9% of @entity1 receiving LysArg. We conclude that co-infusion of Lys75 or LysArg results in a significant inhibition of renal radioactivity in PRRT, allowing higher treatment doses and thus resulting in higher @entity5 radiation doses. Because Lys75 produced serious hyperkalaemia, it is not suitable for clinical use. LysArg, however, is effective in offering renal protection in PRRT and is safe.
