Synthesis, radiochemistry and biological evaluation of a new somatostatin analogue (SDZ 219-387) labelled with technetium-99m.
A new derivative of octreotide SDZ 219-387 [PnAO-(D)Phe(1)-octreotide] was synthesized, which binds specifically and with high affinity to somatostatin receptors in vitro (pKi = 9.79 +/- 0.16). This new somatostatin analogue chelates technetium-99m under mild labelling conditions in good yields. The resulting [99mTc]SDZ 219-387 was stable up to 6 h after labelling and could be isolated in a pure radiochemical and chemical form by high-performance liquid chromatographic purification. The intravenous administration of purified [99mTc]SDZ 219-387 revealed that the radioligand was rapidly cleared from circulation, and tumour uptake of 0.38% ID/g was observed at 1.5 h post injection. [99mTc]SDZ 219-387 specifically interacted with somatostatin binding sites on the tumour. However, the radioligand is highly lipophilic and excreted mainly through the hepatobiliary system. As a consequence, [99mTc]SDZ 219-387 exhibits increased background activity and therefore is not appropriate for the in vivo visualization of somatostatin receptor-positive tumours and/or their metastases in the abdomen.
Maina
T
T
Institut für Nuklearmedizin, Universitätskliniken, Kantonsspital Basel, Switzerland.
Stolz
B
B
Albert
R
R
Bruns
C
C
Koch
P
P
Mäcke
H
H
D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism; D008297:Male; D008956:Models, Chemical; D015282:Octreotide / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics; D015609:Organotechnetium Compounds / Q000737:chemistry / Q000493:pharmacokinetics; D011869:Radioligand Assay; D051381:Rats; D011917:Rats, Inbred Lew; D017207:Rats, Sprague-Dawley
C088857:(PnAO-(D)Phe(1))octreotide; D015609:Organotechnetium Compounds; D015282:Octreotide