title: Transdermal delivery of CaCO3-nanoparticles containing insulin.
abstract: BACKGROUND
  This study evaluates the pharmacokinetic and pharmacodynamic effects of a transdermally delivered insulin using novel CaCO(3)-nanoparticles in normal mice and those with diabetes.
  
  
  METHODS
  CaCO3-nanoparticles encapsulating insulin (nanoinsulin) were transdermally applied to the back skin of normal ddY mice and dB/dB and kkAy mice with diabetes after fasting for 1 h. Serum insulin levels of ddY mice were analyzed by enzyme immunoassay, and blood glucose of normal mice and those with diabetes was monitored.
  
  
  RESULTS
  Maximum serum insulin was 67.1 +/- 25.9 microIU/mL at 4 h with 200 microg of transdermal nanoinsulin in ddY mice, whereas that after subcutaneous injection of 3 microg of monomer insulin was 462 +/- 20.9 microIU/mL at 20 min. Transdermal nanoinsulin decreased glucose levels in a dose-dependent manner. A maximum decrease in blood glucose of 48.3 +/- 3.9% (ddY), 32.5 +/- 9.8% (dB/dB), and 26.2 +/- 7.6% (kkAy) after 6 h was observed with 200 microg of transdermal nanoinsulin, compared with 64.1+/-1.0% (ddY), 57.9 +/-3.4% (dB/dB), and 24.1 +/- 6.7% (kkAy) after 1 h with 3 microg of subcutaneous monomer insulin. Insulin bioavailability until 6 h with transdermal nanoinsulin in ddY mice was 0.9% based on serum insulin level and 2.0% on pharmacodynamic blood glucose-lowering effects.
  
  
  CONCLUSIONS
  This CaCO(3)-nanoparticle system successfully delivered insulin transdermally, as evidenced by a significant sustained decrease in blood glucose in normal mice and those with diabetes. These results support the feasibility of developing transdermal nanoinsulin for human applications.
authors.affiliation: Institute of Drug Delivery System, Jikei University School of Medicine, Tokyo, Japan. mh0402@jikei.ac.jp
authors.forename: Megumu
authors.initials: M
authors.lastname: Higaki
authors.forename: Mieko
authors.initials: M
authors.lastname: Kameyama
authors.forename: Masae
authors.initials: M
authors.lastname: Udagawa
authors.forename: Yukio
authors.initials: Y
authors.lastname: Ueno
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Rie
authors.initials: R
authors.lastname: Igarashi
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Ishihara
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Mizushima
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D002119:Calcium Carbonate / Q000008:administration & dosage*; D007328:Insulin / Q000008:administration & dosage* / Q000097:blood* / Q000493:pharmacokinetics; D051379:Mice; D008815:Mice, Inbred Strains; D049329:Nanostructures; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000097:blood
chemical_list: D007328:Insulin; D011994:Recombinant Proteins; D002119:Calcium Carbonate