An improved synthesis of [125I]N-(diethylaminoethyl)-4-iodobenzamide: a potential ligand for imaging malignant melanoma.
To improve the radiolabeling yield and the specific activity of [125I]N-(2-diethylaminoethyl)-4-iodobenzamide (DAB), the aryltributyltin precursor was synthesized from the N-(2-diethylaminoethyl)-4-bromobenzamide derivative by palladium catalyzed stannylation using bis(tributyltin). The radiolabeled product, [125I]DAB, was obtained by an iododestannylation reaction in high radiochemical yields (85-94%, radiochemical purity, > 98%) using chloramine-T as an oxidizing agent. The specific activity was greater than 1600 Ci/mmol. The biodistribution studies in nude mice implanted with human malignant melanoma xenograft showed a good tumor uptake (6.14% ID/g at 1 h, 2.81% ID/g at 6 h and 0.42% ID/g at 24 h) of [125I]DAB. Unfortunately, a high uptake in the non-target organs, such as liver and lung, was found. At 1 h post-injection the activity level in liver and lung was 11.76 and 7.58% ID/g, respectively. A slow clearance of activity from liver and lung was observed at 6 h (3.43 and 0.49% ID/g). These results demonstrate that iodinated IDAB is a potential radiopharmaceutical for the management of patients with malignant melanoma.
John
C S
CS
Division of Nuclear Medicine, George Washington University Medical Center, Washington, DC 20037.
Saga
T
T
Kinuya
S
S
Le
N
N
Jeong
J M
JM
Paik
C H
CH
Reba
R C
RC
Varma
V M
VM
McAfee
J G
JG
D000818:Animals; D001549:Benzamides / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D003287:Contrast Media / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D006801:Humans; D008545:Melanoma / Q000000981:diagnostic imaging* / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D011877:Radionuclide Imaging; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured
D001549:Benzamides; D003287:Contrast Media; C066918:N-(2-(diethylamino)ethyl)-4-iodobenzamide