All-trans-retinoic acid loaded ocular microspheres: preparation and in-vitro characterization
ALL-TRANS-RETINOIC ACID LOADED OCULAR MICROSPHERES: PREPARATION AND IN-VITRO CHARACTERIZATION
Y. Çirpanli1, N. Ünlü1, S. Çalis1, A.A. Hincal1
1 Hacettepe University, Faculty of Pharmacy, Department of Pharmaceutical Technology,
ABSTRACT Preparation of PLGA (50:50)
with solvent evaporation technique. In-vitro
Microspheres
technique. For this purpose, 10 mg retinoic
average particle size was measured to be
microspheres were determined to be 1,65%
microspheres were continued for 11 days.
polyvinylalcohol and sodium oleat (4:1).
INTRODUCTION
Ultraturrax (T25 basic, IKA, Labortechnik,
ocular surfaces connected with reduction or
instability of the precorneal tear film. The
conjunctival goblet cell regression is one of
the important consequence of eye dryness.
centrifugation at 15.000 rpm for 15 min;
differentiation including goblet cell loss,
temperature. All procedure was carried out
keratinization occured as a result of KCS
and this is called squamous metaplasia (1). Conventional non-surgical treatments are
Drug Loading
not directed specificaly to reversing the
properly and added into 10 ml of ethanol :
acid (tretinoin) has been reported to be
phosphate buffer solution (pH 7,4) (7:3).
effective in reversing the epithelial changes
They were kept in an ultrasonic bath for 3
in dry eye disorders (2). Different dosage
min. After the removal of supernatant by
forms of retinoic acid including ophthalmic
centrifugation, the remaining microparticles
were dissolved in 5 ml of dichloromethane
have been attempted (3,4). The objective of
and this solution was extracted with 10 ml
of ethanol : phosphate buffer (pH 7,4) (7:3)
microparticles of retinoic acid. The rationale
for 1 hr in order to transfer retinoic acid
of retinoic acid microparticulate system is
from dichloromethane. When the extraction
formulation of poorly soluble and chemically
evaporated and the resulting solution was
labil drug (retinoic acid), and improvement
filtered through a membrane filter with a
2003 Controlled Release Society 30th Annual Meeting PROCEEDINGS
microspheres released retinoic acid during
1100–USA) equipped with a C18 column (5
µm, 250x4,6 mm, Phenomenex-USA) was used. The mobile phase was a mixture of methanol : acetonitrile : water : acetic acid (80:10:10:0,5). The flow rate was set to 1 mL/min, the detection was performed at 356 nm. Total drug content was calculated as the sum of retinoic acid amounts both on the surface and inside of the microspheres.
Particle Size Distribution Figure 1. SEM photographs of retinoic acid
microspheres containing retinoic acid was
measured using laser diffraction particle
sizer (Malvern Mastersizer 2000, UK). For
Time (day) Surface Morphology Figure2. Dissolution profiles of retinoic acid CONCLUSION
In this preliminary part of the study, in
vitro release of retinoic acid from PLGA
stubs with conductive silver paint and then
sputted with a 150 Aº thick layer of gold in a
Furthermore, stability assessment and in
vivo evaluation of the formulation will be
In Vitro Release
performed. REFERENCES
(50:50) microspheres were investigated in
ethanol : phosphate buffer solution (pH 7,4)
(7:3). Given amount of microspheres were
2. Tseng, S.C., Maumenee, A.E., Stark, W.J.
suspended in the release medium at 37 ±
Topical retinoid treatment for various dry-
3. Choi, Y., Kim, S.Y., Kim, S.H., Lee, K.S.,
Kim, C., Byun, Y. Long-term delivery of all-
RESULTS AND DISCUSSION
trans-retinoic acid using biodegradable PLLA/PEG-PLLA blended microspheres.
acid were prepared by a yield of 42,79 %.
4. Selek, H., Ünlü, N., Orhan, M., Irkeç, M.
The average particle size was measured to
emulsion in dry eye. Eur. J. Ophthalmol.
2003 Controlled Release Society 30th Annual Meeting PROCEEDINGS
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microspheres released retinoic acid during
1100–USA) equipped with a C18 column (5
µm, 250x4,6 mm, Phenomenex-USA) was used. The mobile phase was a mixture of methanol : acetonitrile : water : acetic acid (80:10:10:0,5). The flow rate was set to 1 mL/min, the detection was performed at 356 nm. Total drug content was calculated as the sum of retinoic acid amounts both on the surface and inside of the microspheres.
Particle Size Distribution