Development and characterization of a scalable microperforated device capable of long-term zero order drug release

Abstract

A drug delivery system that consists of microperforated polyimide microtubes was developed and characterized. Two groups of polyimide tubes were used. One set consisted of microtubes (I.D. = 125 microm) with 32.9 +/- 1.7 microm size holes. The second set consisted of larger tubes (I.D. = 1000 microm) with 362-542 microm holes. The number of holes was varied between 1 and 3. The small tubes were loaded with crystal violet (CV) and ethinyl estradiol (EE) and the drug release studies were performed in 0.01 M phosphate buffered saline (PBS) (pH 7.1-7.4) at 37.0 +/- 1.0 degrees C for upto 4 weeks. The large tubes were loaded with CV and the drug release was studied in vitro in PBS and also ex vivo in rabbit's vitreous humor. Linear release rates with R(2) > 0.9900 were obtained for all groups with CV and EE. Release rates of 7.8 +/- 2.5, 16.2 +/- 5.5, and 22.5 +/- 6.0 ng/day for CV and 30.1 +/- 5.8 ng/day for EE were obtained for small tubes. For large tubes, a release rate of 10.8 +/- 4.1, 15.8 +/- 4.8 and 22.1 +/- 6.7 microg/day was observed in vitro in PBS and a release rate of 5.8 +/- 1.8 microg/day was observed ex vivo in vitreous humor.