Title:Brimonidine Imprinted Hydrogels and Evaluation of Their Binding and Releasing Properties as New Ocular Drug Delivery Systems
Volume: 12
Issue: 6
Author(s): Hediye Moghadam Omranipour, Sayyed Abolghasem Sajadi Tabassi, Reza Kowsari, Maryam Shayani Rad and Seyed Ahmad Mohajeri
Affiliation:
Keywords:
Brimonidine tartrate; Hydrogels; Molecular imprinting; Ocular drug delivery systems; Poly (hydroxyethyl methacrylate)
Abstract: Molecular imprinting is a technique for preparation of specific polymeric receptors for recognition
and selective binding of chemicals. Recently, molecularly imprinted soft contact lenses have
been studied as novel ocular drug delivery systems. The aim of this work was to prepare, for the first
time, a brimonidine (BRN) imprinted soft contact lens material and study of its binding and releasing
properties in aqueous media. The hydrogels were prepared using hydroxyethyl methacrylate (HEMA)
as a backbone monomer, methacrylic acid (MAA), methacrylamide (MAAM) and 4-vinylpyridine
(4VP) as the functional monomers and ethylene glycol dimethacrylate (EGDMA) as a cross linker monomer. Different
BRN: MAA molar ratios were also applied in feed composition of monomers to study the influence of molecular imprinting
technique on their binding properties. The hydrogels were characterized by determination of their swelling and binding
properties in water. Their loading and release properties were also studied using Korsmeyer-Peppas equation in normal
saline (NaCl 0.9%) and artificial tear solution. Poly (HEMA-co-MAA) showed superior binding properties compared
to other copolymers. Also molecular imprinting technique significantly increased the hydrogel affinity to drug. It was
found that all molecularly imprinted polymers (MIPs) had higher affinity to BRN in comparison with nonimprinted polymers
(NIPs). The optimized MIP hydrogel with BRN: MAA molar ratio of 1: 8 showed greater ability to drug loading and
controlled release compared to other MIPs. The results of the present work indicated that molecular imprinting technique
had a significant effect on improving loading capacity and sustaining drug release from hydrogels.
