title: Subcutaneous administration of superoxide dismutase entrapped in long circulating liposomes: in vivo fate and therapeutic activity in an inflammation model.
abstract: OBJECTIVE
  We are exploring liposomal delivery with the aim to change the pharmacokinetics and biodistribution of SOD to increase its therapeutic activity. From a practical point of view, a convenient route of administration would be the subcutaneous (s.c.) route. Liposomal size has been shown to be the most important factor influencing the rate and extent of drainage of liposomes from the s.c. injection site.
  
  
  METHODS
  To monitor the in vivo fate of the subcutaneous administered SOD-containing liposomes in rats with a chronic arthritis inflammation, the liposomes were labeled by the co-encapsulation of the 111In-DTPA complex in the internal water space.
  
  
  RESULTS
  Over the initial 10h-observation period post-injection, the small-sized poly(ethyleneglycol)-liposomes (mean size about 110 nm) left the site of injection to a 2-fold higher extent (45% of the injected dose) as compared to large-sized poly(ethyleneglycol)-liposomes (mean size about 450 nm). Small-sized liposomes gave a 17-fold higher uptake in the inflamed foot than the large-sized liposomes. Comparing the localization in the inflamed foot with the non-inflamed foot, uptake was more than 15-fold higher for the small-sized liposomes as compared to the large-sized liposomes. After s.c. administration, small-sized SOD-liposomes showed substantial higher activity than large-sized SOD-liposomes. S.C. administration of small-sized SOD-liposomes is equally effective as i.v. administration of the same liposomes. I.V. administration of the large-sized SOD-liposomes yielded a significantly higher activity as compared to s.c. administration.
  
  
  CONCLUSIONS
  These results indicate that small-sized poly(ethyleneglycol)-liposomes can be used for the targeting of SOD to arthritic sites after subcutaneous administration.
authors.affiliation: Unidade de Novas Formas de Agentes Bioactivos - DB - IBQTA - INETI, Lisboa, Portugal. luisa.corvo@ibqta.ineti.pt
authors.forename: M L
authors.initials: ML
authors.lastname: Corvo
authors.forename: O C
authors.initials: OC
authors.lastname: Boerman
authors.forename: W J
authors.initials: WJ
authors.lastname: Oyen
authors.forename: J C
authors.initials: JC
authors.lastname: Jorge
authors.forename: M E
authors.initials: ME
authors.lastname: Cruz
authors.forename: D J
authors.initials: DJ
authors.lastname: Crommelin
authors.forename: G
authors.initials: G
authors.lastname: Storm
mesh_terms: D000818:Animals; D004337:Drug Carriers; D004339:Drug Compounding; D004355:Drug Stability; D005620:Freund's Adjuvant; D007249:Inflammation / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology; D007279:Injections, Subcutaneous; D008081:Liposomes; D008297:Male; D009161:Mycobacterium / Q000276:immunology; D010316:Particle Size; D011092:Polyethylene Glycols; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000008:administration & dosage* / Q000493:pharmacokinetics / Q000627:therapeutic use; D014018:Tissue Distribution
chemical_list: D004337:Drug Carriers; D008081:Liposomes; D011092:Polyethylene Glycols; D005620:Freund's Adjuvant; D013482:Superoxide Dismutase