DTPA Liposomes in
Diagnostic Imaging
Meliha KORKMAZ*,**, A. Yekta ÖZER**,°
* Sakarya University, Faculty of Arts and Science,
Department of Chemistry, 54187, Sakarya, TURKEY
**
Ataturk University, Faculty of
Pharmacy, Department of Analytical Chemistry, 25240, Erzurum,
TURKEY
oCorresponding Author
Summary
Diethylene triamine penta-acetic acid (DTPA) is used as the
active chelator substance in some solutions and in therapy
of heavy metal toxication. The commercial Tc-99m-DTPA kit is
used for renal, brain and blood flow imaging.Film method
followed by sonication was used for the preparation of DTPA-containing
vesicles. Bilayer molar concentrations of (10:1:4) for gel
state liposomes were used. DSPC (distearoylphosphatidyl
choline) was used as the phospholipid, SA (stearylamine) and
cholesterol (Chol) were incorporated into bilayers, both as
positive charge inducer and bilayer condenser. The amounts
of free and encapsulated drug, liposomal phospholipid
content, particle size and lamellarity were determined for
all vesicles. DTPA-containing liposomes were radiolabelled
by different methods and compared with empty vesicles and
commercial Tc-99m-DTPA kits. It was found that
radiolabelling of liposomes was as successful as the
commercial kit. Sterilization studies were performed with
three methods, namely aseptic, heat and gamma irradiation,
and heat sterilization was found to be the most effective.
Scintigraphic imaging findings were found in accordance with
in vivo biodistribution studies. It was observed that
DTPAcontaining liposomes were cleared from the circulation
and accumulated in the liver and spleen. Tc-99m-DTPA
liposomes accumulated in the kidneys. The organ/background
ratios were higher in liposomes. When the biodistribution
and scintigraphic imaging studies were evaluated, the L1
formulation was determined to be the optimum formulation.
For diagnostic and therapeutic purposes, L1 formulation (DSPC:SA:Chol)
(10:1:4) was found to be the most meaningful formulation for
diagnostic imaging of the liver.
Key Words :
DTPA (diethylene triamine penta-acetic acid)
(pentatate), diagnostic imaging, Tc-99m-DTPA liposomes,
scintigraphic imaging, biodistribution.
