Mini drug pump for ophthalmic use

• Published in: Transactions of the American Ophthalmological Society 2009-12, Vol.107, p.60-70
• Main Authors: Saati, Saloomeh, Lo, Ronalee, Li, Po-Ying, Meng, Ellis, Varma, Rohit, Humayun, Mark S
• Format: Article
• Language: English
• Subjects: Animals; Anterior Chamber - surgery; Coloring Agents - administration & dosage; Cornea - pathology; Drug Delivery Systems - instrumentation; Electrolysis - instrumentation; Equipment Design; Feasibility Studies; Fluorescein Angiography; In Vitro Techniques; Microscopy, Electron; Ophthalmic Solutions - administration & dosage; Ophthalmologic Surgical Procedures; Prostheses and Implants; Rabbits; Swine; Trypan Blue - administration & dosage
• ISSN: 0065-9533; 1545-6110

To evaluate the feasibility of developing a novel mini drug pump for ophthalmic use. 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 benchtop 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 seton. To determine the ability to refill and also the patency of the cannula, at intervals of 4 to 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 up by slit-lamp examination, photography, and fluorescein angiography. Benchtop 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 mm Hg. All implanted devices refilled at 4- to 6-week intervals for 4 to 6 months. No infection was seen. No devices extruded. No filtering bleb formed over the implant. 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 pharmacologic agents is needed to determine its ultimate potential for ophthalmic use.