title: Cellular uptake and concentrations of tamoxifen upon administration in poly(epsilon-caprolactone) nanoparticles.
abstract: OBJECTIVE
  In an attempt to increase the local concentration of tamoxifen in estrogen receptor positive breast cancer cells, we have prepared and characterized poly(epsilon-caprolactone) (PCL) nanoparticle formulation.
  
  
  METHODS
  PCL (mol wt 14,800 daltons) nanoparticles were prepared by the solvent displacement method in acetone-water system in the presence of Pluronic F- 68. PCL nanoparticles, labeled with rhodamine123, were incubated with MCF-7 estrogen receptor positive breast cancer cells to determine uptake, intracellular distribution, and localization as a function of time. Intracellular drug concentrations over a specified period of time using different initial doses were examined using tritiated [3H]-tamoxifen.
  
  
  RESULTS
  A significant fraction of the administered rhodamine123-loaded PCL nanoparticles was found in the perinuclear region of the MCF-7 cells, where estrogen receptors are also localized, after 1 hour of incubation. Measurements of the intracellular concentrations revealed that most of the administered nanoparticle dose was internalized within the first 30 minutes of incubation, and the uptake followed saturable transport kinetics.
  
  
  CONCLUSIONS
  Results of this study show that PCL nanoparticles were rapidly internalized in MCF-7 cells and intracellular tamoxifen concentrations followed a saturable process. This approach may provide better therapeutic benefit by delivering the drug locally, near the tumor cells, for a longer period of time.
authors.affiliation: Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, Boston, MA 02115, USA.
authors.forename: Jugminder S
authors.initials: JS
authors.lastname: Chawla
authors.forename: Mansoor M
authors.initials: MM
authors.lastname: Amiji
mesh_terms: D000284:Administration, Oral; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000096:biosynthesis; D001943:Breast Neoplasms / Q000737:chemistry* / Q000378:metabolism* / Q000473:pathology; D002208:Caproates / Q000008:administration & dosage*; D016503:Drug Delivery Systems / Q000379:methods; D005456:Fluorescent Dyes / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000096:biosynthesis; D006801:Humans; D007783:Lactones / Q000008:administration & dosage*; D008863:Microspheres; D036103:Nanotechnology / Q000379:methods; D010316:Particle Size; D011108:Polymers / Q000008:administration & dosage*; D011960:Receptors, Estrogen / Q000096:biosynthesis; D012235:Rhodamines / Q000378:metabolism; D013629:Tamoxifen / Q000008:administration & dosage* / Q000378:metabolism*; D013678:Technology, Pharmaceutical; D014407:Tumor Cells, Cultured
chemical_list: D018931:Antineoplastic Agents, Hormonal; D014408:Biomarkers, Tumor; D002208:Caproates; D005456:Fluorescent Dyes; D006360:Heat-Shock Proteins; D007783:Lactones; D011108:Polymers; D011960:Receptors, Estrogen; D012235:Rhodamines; D013629:Tamoxifen; C121056:caprolactone