Chemical structure and pharmacokinetics of 99mTc-labelled aminomethane diphosphonic acid derivatives

99mTc-labelled derivatives of aminomethane diphosphonic acid, general formula: R1R2N-CR3 [PO(OH)2]2, as well as hydroxyethane diphosphonic acid and hydroxypropane monophosphonic acid were investigated with regard to their suitability for skeleton scintigraphy. Bone accumulation was related to chemical structure. It was concluded from the experiments that compounds able to form enols are accumulated to a higher degree and that big substituents influence the affinity to bone negatively by steric hindrance.