Abstract
Age-related macular degeneration (AMD) is a leading cause of blindness in the modern world. The standard treatment regimen for neovascular AMD is the monthly/bimonthly intravitreal injection of anti-VEGF agents such as ranibizumab or aflibercept. However, these repeated invasive injections can lead to sight-threatening complications. Sustained delivery by encapsulation of the drug in carriers is a way to reduce the frequency of these injections. Liposomes are biocompatible, non-toxic vesicular nanocarriers, which can be used to encapsulate therapeutic agents to provide sustained release. The protein encapsulation was performed by a modified dehydration-rehydration (DRV) method. The liposomes formed were characterized for size, zeta potential, encapsulation efficiency, stability, in vitro release, and ex vivo release profiles. In addition, the localization of the liposomes themselves was studied ex vivo. Entrapment-efficiency of ranibizumab into 100-nm liposomes varied from 14.7 to 57.0%. Negatively-charged liposomes prepared from DPPC-DPPG were found to have the slowest release with a low initial burst release compared to the rest of liposomal formulations. The ex vivo protein release was found to slower than the in vitro protein release for all samples. In conclusion, the DPPC-DPPG liposomes significantly improved the encapsulation and release profile of ranibizumab.
Highlights
For several proliferative vitreoretinal diseases in the eye, intravitreal injection of anti-VEGF drugs is the current standard of treatment
Ambati et al have studied the transport of several small molecules across the sclera in an ex vivo setup to determine the size effect of these molecules on trans-scleral transport[5]
We investigated the effect of cholesterol on DPPC using differential scanning calorimetry (DSC)
Summary
For several proliferative vitreoretinal diseases in the eye, intravitreal injection of anti-VEGF drugs is the current standard of treatment. Various attempts have been made to improve therapeutic effect of drugs to the posterior segment, by the use of inserts, implants, micro- and nano-particulate systems, etc.[12,13] Most of these formulations only focused on intravitreal sustained drug release[14,15,16,17,18,19,20]. Our group has demonstrated sustained duration of action for an anti-glaucoma drug via the sub-conjunctival route using nanoliposomes[22,23], even though the drug target is in the anterior segment in this case Nanocarriers such as liposomes are attractive owing to their biocompatibility, ability to deliver both hydrophobic and hydrophilic drugs as well as their non-toxic nature. Liposomal Formulation DPPC DPPC-Chol (4:1 mol/mol) DPPC-DPTAP (4:1 mol/mol) DPPC-DPPG (4:1 mol/mol) nanoliposomes, our group has demonstrated that it is achievable with partition-controlled release[22] for lipophilic drugs and another group has demonstrated it for a soluble drug such as gentamicin[24]
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