title: Mini drug pump for ophthalmic use.
abstract: OBJECTIVE
  To evaluate the feasibility of developing a novel mini drug pump for ophthalmic use.
  
  
  METHODS
  Using principles of microelectromechanical systems engineering, a mini drug pump was fabricated. The pumping mechanism is based on electrolysis and the pump includes a drug refill port as well as a check valve to control drug delivery. Drug pumps were tested first on the bench-top and then after implantation in rabbits. For the latter, we implanted 4 elliptical (9.9 x 7.7 x 1.8 mm) non-electrically active pumps into 4 rabbits. The procedure is similar to implantation of a glaucoma aqueous drainage device. To determine the ability to refill and also the patency of the cannula, at intervals of 4-6 weeks after implantation, we accessed the drug reservoir with a transconjunctival needle and delivered approximately as low as 1 microL of trypan blue solution (0.06%) into the anterior chamber. Animals were followed by slit lamp examination, photography, and fluorescein angiography.
  
  
  RESULTS
  Bench-top testing showed 2.0 microL/min delivery when using 0.4 mW of power for electrolysis. One-way valves showed reliable opening pressures of 470 mmHg. All implanted devices refilled at 4-6 weeks intervals for 4-6 months. No infection was seen. No devices extruded. No filtering bleb formed over the implant.
  
  
  CONCLUSIONS
  A prototype ocular mini drug pump was built, implanted, and refilled. Such a platform needs more testing to determine the long term biocompatibility of an electrically-controlled implanted pump. Testing with various pharmacological agents is needed to determine its ultimate potential for ophthalmic use.
authors.affiliation: Doheny Eye Institute, University of Southern California Keck School of Medicine, Los Angeles, California 90033, USA.
authors.forename: Saloomeh
authors.initials: S
authors.lastname: Saati
authors.forename: Ronalee
authors.initials: R
authors.lastname: Lo
authors.forename: Po-Ying
authors.initials: PY
authors.lastname: Li
authors.forename: Ellis
authors.initials: E
authors.lastname: Meng
authors.forename: Rohit
authors.initials: R
authors.lastname: Varma
authors.forename: Mark S
authors.initials: MS
authors.lastname: Humayun
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D016503:Drug Delivery Systems / Q000295:instrumentation*; D005451:Fluorescein Angiography; D015918:Infusion Pumps, Implantable; D008422:Materials Testing; D009184:Mydriatics / Q000008:administration & dosage*; D010656:Phenylephrine / Q000008:administration & dosage*; D011680:Pupil / Q000187:drug effects; D011817:Rabbits; D014343:Trypan Blue / Q000008:administration & dosage
chemical_list: D001672:Biocompatible Materials; D009184:Mydriatics; D010656:Phenylephrine; D014343:Trypan Blue