Improved targeting of antimony to the bone marrow of dogs using liposomes of reduced size.
A novel liposomal formulation of meglumine antimoniate (MA), consisting of vesicles of reduced size, has been evaluated in dogs with visceral leishmaniasis to determine its pharmacokinetics as well as the impact of vesicle size on the targeting of antimony to the bone marrow. Encapsulation of MA in liposomes was achieved through freeze-drying of empty liposomes in the presence of sucrose and rehydration with a solution of MA. The resulting formulation, with a mean vesicle diameter of about 400 nm, was given to mongrel dogs with visceral leishmaniasis as an i.v. bolus injection at 4.2 mgSb/kg of body weight. The pharmacokinetics of antimony were assessed in the blood and in organs of the mononuclear phagocyte system and compared to those achieved with the free drug and the drug encapsulated in large sized liposomes (mean diameter of 1200 nm). The targeting of antimony to the bone marrow was improved (approximately three-fold) with the novel liposomal formulation, when compared to the formulation of MA in large sized liposomes. This study provides the first direct experimental evidence that passive targeting of liposomes to the bone marrow of dogs is improved by the reduction of vesicle size from the micron to the nanometer scale.
Schettini
Dante A
DA
Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Av. Antônio Carlos 6627, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, Minas Gerais, Brazil.
Ribeiro
Raul R
RR
Demicheli
Cynthia
C
Rocha
Olguita G F
OG
Melo
Maria N
MN
Michalick
Marilene S M
MS
Frézard
Frédéric
F
D000818:Animals; D000965:Antimony / Q000008:administration & dosage* / Q000493:pharmacokinetics; D001853:Bone Marrow; D004285:Dogs; D016503:Drug Delivery Systems; D008081:Liposomes; D008536:Meglumine / Q000008:administration & dosage; D000077485:Meglumine Antimoniate; D009942:Organometallic Compounds / Q000008:administration & dosage; D010316:Particle Size; D014018:Tissue Distribution
D008081:Liposomes; D009942:Organometallic Compounds; D008536:Meglumine; D000077485:Meglumine Antimoniate; D000965:Antimony