Biodistribution and clearance of liposomal gadolinium-DTPA.
Gadolinium-DTPA (Gd-DTPA) liposomes have been studied previously as liver contrast agents and have been shown to improve the detection of hepatic metastases in rats. We synthesized 100-nm and 50-nm liposomes that encapsulated Gd-DTPA and did biodistribution and clearance studies in rats. Parallel magnetic resonance imaging (MRI) studies were also done. Biodistribution showed a prolonged blood pool phase for Gd-DTPA liposomes with a blood pool half-life of approximately 4 hours for the 100-nm liposomes. The highest uptake per gram of tissue was achieved by the spleen. Clearance of gadolinium from the liver and spleen showed a half-life of 3 to 4 days. The smaller 50-nm Gd-DTPA liposomes resulted in a longer blood pool phase and a higher delivery of gadolinium to the liver, bone marrow, and spleen. Imaging studies after intravenous (IV) administration of liposomal Gd-DTPA showed organ enhancement that paralleled the data on biodistribution studies, with appreciable hepatic enhancement at doses as low as 0.025 mm/kg of liposomal Gd-DTPA.
Unger
E
E
University of Arizona, Department of Radiology, Tucson, Arizona 85724.
Cardenas
D
D
Zerella
A
A
Fajardo
L L
LL
Tilcock
C
C
D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage*; D004337:Drug Carriers; D005682:Gadolinium; D019786:Gadolinium DTPA; D008081:Liposomes / Q000493:pharmacokinetics*; D008279:Magnetic Resonance Imaging; D008297:Male; D009942:Organometallic Compounds / Q000008:administration & dosage*; D004369:Pentetic Acid / Q000008:administration & dosage*; D051381:Rats; D011916:Rats, Inbred F344; D014018:Tissue Distribution
D003287:Contrast Media; D004337:Drug Carriers; D008081:Liposomes; D009942:Organometallic Compounds; D004369:Pentetic Acid; D005682:Gadolinium; D019786:Gadolinium DTPA