Sustained mechanical release of dexamethasone sodium phosphate from a foldable capsular vitreous body.
OBJECTIVE
Since 300-nm-mili apertures were present in the capsule of the foldable capsular vitreous body (FCVB), the authors tested whether the FCVB could mechanically release dexamethasone sodium phosphate (DexP) from its capsule.


METHODS
In the in vitro study, DexP at concentrations of 0.25, 0.5, 1, 2, and 4 mg/mL in a balanced salt solution were injected into the capsules, which were immersed in cups of modified Franz diffusion cells. Two hundred microliters of liquid was aspirated at time intervals of 10, 20, 40, 60, 120, 180, 240, 300, and 360 minutes. In the in vivo study, the capsule was folded and implanted into the vitreous cavities of five rabbits. Approximately 0.6 mL DexP (2 mg/mL) was then injected into the capsule. An intravitreal injection with DexP was performed on another five rabbits as the control group. Aqueous humor was aspirated on days 1, 3, 7, 14, 28, and 42 after implantation. The DexP contents in the cups and aqueous humor were detected by HPLC-MS/MS.


RESULTS
FCVB released DexP in a time-dependent and dose-dependent manner in vitro with five dosages from 10 to 360 minutes. Especially in the 0.25 mg/mL DexP group, the content (y) had good linear relationships with time (x), as shown by y = 0.7635x + 10.205. The DexP contents in the aqueous humor were detected until day 28 and were undetectable on day 42. However, the DexP contents were detected only before day 3 in the controls.


CONCLUSIONS
FCVB can sustainably and mechanically release DexP by capsule apertures in a time-dependent and dose-dependent manner in addition to serving as a vitreous substitute.
Liu
Yaqin
Y
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, School of Pharmaceutical Sciences, Sun Yatsen University, Guangzhou, China.
Ke
Qicheng
Q
Chen
Jiajia
J
Wang
Zhichong
Z
Xie
Zhiyong
Z
Jiang
Zhaoxin
Z
Ge
Jian
J
Gao
Qianying
Q
D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003907:Dexamethasone / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D004305:Dose-Response Relationship, Drug; D005938:Glucocorticoids / Q000493:pharmacokinetics*; D008855:Microscopy, Electron, Scanning; D011817:Rabbits; D053719:Tandem Mass Spectrometry; D013997:Time Factors; D014822:Vitreous Body / Q000378:metabolism* / Q000648:ultrastructure
D005938:Glucocorticoids; C004180:dexamethasone 21-phosphate; D003907:Dexamethasone