Non-Isotopic Detection of Osteoblastic Activity In Vivo Using Modified Bisphosphonates

Abstract

The present invention is directed to a non-isotopic methods for the in vitro and in vivo detection of hydroxyapatite-positive cells and structures.

1 . A contrast agent represented in the general formula [I] or pharmaceutically acceptable salts thereof: 
       
         
           
           
               
               
           
         
         wherein 
         D represents a fluorescent moiety; 
         R represents a linking group that covalently links the dye (D) and bisphosphonate moiety; 
         R 1  represents H, —OH, or a halogen; and 
         R 2  represents, independently for each occurrence, a free electron pair, hydrogen, or a pharmaceutically acceptable counterion. 
       
     
     
         2 .- 14 . (canceled) 
     
     
         15 . A contrast agent comprising a bisphosphonate covalently linked to a near-infrared fluorescent moiety, wherein the contrast agent (a) has an extinction coefficient of at least 100,000 M −1 cm −1  in aqueous medium, (b) has an LD 50  of at least 100 mg/Kg in humans, and (c) has a half-life in the human body of at least 10 minutes. 
     
     
         16 .- 18 . (canceled) 
     
     
         19 . A method for in vivo imaging of tissue with exposed hydroxyapatite, comprising,
 (i) administering to the animal a contrast agent of  claim 1  or  claim 15  in an amount sufficient to render hydroxyapatite-containing tissue detectable by a fluorescent detector;   (ii) obtaining a fluorescent image of the animal, or at least a portion thereof, at a wave length(s) which detects the contrast agent; and   (iii) constructing an image of the animal including the pattern of distribution of the contrast agent.   
     
     
         20 .- 28 . (canceled)