title: Evidencing the modulation of P-glycoprotein at blood-ocular barriers using gamma scintigraphy.
abstract: OBJECTIVE
  To evaluate the effect of P-glycoprotein modulation at blood-ocular barriers using gamma scintigraphy.
  
  
  METHODS
  Ofloxacin, a fluoroquinolone, was selected as a substrate to study the drug efflux transporter (P-glycoprotein) modulation after labeling with Technetium ((99m)Tc) in rabbits. New Zealand albino rabbits were randomized into two groups of 4 each. Group I received labeled ofloxacin intravitreally (100 micro Ci) and Group II animals were given verapamil intravitreally 15 min before the labeled ofloxacin. Static imaging was done at predetermined time, and dynamic images were also taken after 30 min of intravitreal injection.
  
  
  RESULTS
  The radio-chemical purity of labeled ofloxacin was found to be 90-95% with the labeling efficiency of 90%. The static anterior planar images of verapamil pre-treated group showed marginal increase in the uptake of labeled ofloxacin, and dynamic images showed less systemic pool as compared to its control.
  
  
  CONCLUSIONS
  This study further confirms the findings of our laboratory regarding the involvement of P-glycoprotein in the intraocular disposition of susceptible drugs.
authors.affiliation: Department of Ocular Pharmacology and Pharmacy, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Senthilkumari
authors.forename: Thirumurthy
authors.initials: T
authors.lastname: Velpandian
authors.forename: Nihar Ranjan
authors.initials: NR
authors.lastname: Biswas
authors.forename: Assem
authors.initials: A
authors.lastname: Bhatnagar
authors.forename: Gaurav
authors.initials: G
authors.lastname: Mittal
authors.forename: Supriyo
authors.initials: S
authors.lastname: Ghose
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics; D018916:Blood-Aqueous Barrier / Q000000981:diagnostic imaging / Q000502:physiology*; D001813:Blood-Retinal Barrier / Q000000981:diagnostic imaging / Q000502:physiology*; D015902:Gamma Cameras; D008297:Male; D015242:Ofloxacin / Q000493:pharmacokinetics; D011817:Rabbits; D013667:Technetium; D015899:Tomography, Emission-Computed, Single-Photon; D014665:Vasodilator Agents / Q000008:administration & dosage; D014700:Verapamil / Q000008:administration & dosage; D014822:Vitreous Body / Q000000981:diagnostic imaging / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000900:Anti-Bacterial Agents; D014665:Vasodilator Agents; D013667:Technetium; D015242:Ofloxacin; D014700:Verapamil