Formulation and evaluation of freeze-dried DOTMP kit for the preparation of clinical-scale 177Lu-DOTMP and 153Sm-DOTMP at the hospital radiopharmacy

Abstract

Abstract Objective: The objective of the present work is to develop and evaluate freeze-dried DOTMP kit, which could be utilized for the convenient and single-step preparation of clinical-scale 177Lu-DOTMP and 153Sm-DOTMP, both of which have shown potential as alternative agents for metastatic bone pain palliation. Experimental: Freeze-dried DOTMP kits, each comprising a lyophilized mixture of 20 mg DOTMP and 8.75 mg NaOH, were prepared. The kits were used for the preparation of clinical-scale 177Lu-DOTMP and 153Sm-DOTMP complexes. The agents were prepared by dissolving the lyophilized powder in 1 mL of normal saline and incubating with 177LuCl3 or 153SmCl3, produced in-house, for 15 min at room temperature. Pharmacokinetic behavior and biological distribution of the agents were studied by carrying out biodistribution as well as scintigraphic studies in normal male Wistar rats. Shelf-life of the freeze-dried kits was also ascertained. Results: Clinical-scale 177Lu-DOTMP and 153Sm-DOTMP complexes, comprising up to 3.7 GBq (100 mCi) of activity, were prepared with > 99% radiochemical purity using the freeze-dried kits. The complexes exhibited high in vitro stability when stored at room temperature. Biological studies showed selective skeletal accumulation and insignificant uptake of the radiotracers in any of the vital organs/tissue. The non-accumulated activity exhibited primary urinary clearance. The kits had a shelf-life of 2 years when stored at 4 ℃ temperature. Conclusion: Freeze-dried DOTMP kits, suitable for the preparation of clinical-scale 177Lu-DOTMP and 153Sm-DOTMP, have been developed and the radiochemical and biological behaviors of the radiolabeled agents have been studied. The use of the kit at the hospital radiopharmacy is expected to make the preparations easy and convenient. This in turn will enable the widespread dissemination of these promising agents towards their application for regular use.