title: Micro-patterned drug delivery device for light-activated drug release.
abstract: BACKGROUND
  The primary goal of this study was the fabrication, long-term stability, and measured release of a marker dye from a micro-patterned drug delivery device using (i) mechanical puncture and (ii) photodisruption with an ophthalmic Nd:YAG laser.
  
  
  METHODS
  A drug delivery device was made from a transparent bio-compatible polymer. The device consisted of two 2.6 mm diameter reservoirs containing 10% Na fluorescein dye. The device was implanted in the rabbit's eye (n = 2) with the cap of the device facing toward the exterior of the eye. Once the animals recovered from the implant surgery, 100% anhydrous glycerol was topically applied to the eye at the implantation site to decrease light scattering in the conjunctiva and sclera. The dye was released from one of the reservoir either using a 28 G ½ needle or an ophthalmic Q-switched Nd:YAG laser. A fluorescence spectrophotometer (FS) with fiber optic probe was used to measure the half-life of the dye in the eye. Measurements of fluorescence intensity were collected until the measurements return to baseline and histology was done on the tissue surrounded the device.
  
  
  RESULTS
  None of the devices leaked of 10% Na fluorescein dye after implant. The ablation threshold of the drug delivery device was between 6 and 10 mJ to create 100-500 µm holes. The half-life measurement of the dye was found to be 13 days at the vitreous chamber after measuring the fluorescence intensity through the dilated cornea. Histology study showed minimal immune and foreign body response such as mild inflammation.
  
  
  CONCLUSIONS
  This study established that the drug delivery device seemed to elicit minimal inflammatory response and retained its fluidic content until it was released with relatively longer retention time (half-life). Thus, similar device could be used for controlled release of drugs for certain ocular diseases.
authors: Stanford University School of Medicine, Stanford, California 94305, USA. rtzaman@stanford.edu
authors: Raiyan T
authors: RT
authors: Zaman
authors: Ashwini
authors: A
authors: Gopal
authors: Kathryn
authors: K
authors: Starr
authors: Xiaojing
authors: X
authors: Zhang
authors: Sharon
authors: S
authors: Thomsen
authors: James W
authors: JW
authors: Tunnell
authors: Ashley J
authors: AJ
authors: Welch
authors: Henry G
authors: HG
authors: Rylander
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D016503:Drug Delivery Systems / Q000295:instrumentation*; D004343:Drug Implants; D004867:Equipment Design; D004869:Equipment Safety; D005123:Eye / Q000187:drug effects; D005260:Female; D019793:Fluorescein / Q000494:pharmacology*; D009010:Monte Carlo Method; D011817:Rabbits; D011897:Random Allocation; D014055:Tomography, Emission-Computed
chemical_list: D004343:Drug Implants; D019793:Fluorescein