Topical Solution for Retinal Delivery: Bevacizumab and Ranibizumab Eye Drops in Anti-Aggregation Formula (AAF) in Rabbits.

PURPOSE: Wet age-related macular degeneration (AMD) is a blinding retinal disease. Monthly intravitreal anti-VEGF antibody injections of bevacizumab (off-label) and ranibizumab (FDA approved) are the standard of care. Antibody aggregation may interfere with ocular absorption/distribution. This study assessed topical delivery of dilute antibodies to the posterior segment of rabbit eyes using a novel anti-aggregation formula (AAF). METHODS: Bevacizumab, or biosimilar ranibizumab was diluted to 5 mg/ml in AAF. All rabbits were dosed twice daily. Substudy 1 rabbits (bevacizumab, 100 µl eye drops): Group 1 (bevacizumab/AAF, n = 6); Group 2 (bevacizumab/PBS, n = 7) and Vehicle control (AAF, n = 1). Substudy 2 rabbits (ranibizumab biosimilar/AAF, 50 µl eye drops): (ranibizumab biosimilar/AAF, n = 8). At 14.5 days, serum was drawn from rabbits. Aqueous, vitreous and retina samples were recovered from eyes and placed into AAF aliquots. Tissue analyzed using AAF as diluent. RESULTS: Bevacizumab in AAF permeated/accumulated in rabbit aqueous, vitreous and retina 10 times more, than when diluted in PBS. AAF/0.1% hyaluronic acid eye drops, dosed twice daily, provided mean tissue concentrations (ng/g) in retina (29.50), aqueous (12.34), vitreous (3.46), and serum (0.28 ng/ml). Additionally, the highest concentration (ng/g) of ranibizumab biosimilar was present in the retina (18.0), followed by aqueous (7.82) and vitreous (1.47). Serum concentration was negligible (< 0.04 ng/ml). No irritation was observed throughout the studies. CONCLUSIONS: Bevacizumab and ranibizumab, in an AAF diluent eye drop, can be delivered to the retina, by the twice daily dosing of a low concentration mAb formulation. This may prove to be an adjunct to intravitreal injections.

Longitudinal Assessment of Alkali Injury on Mouse Cornea Using Anterior Segment Optical Coherence Tomography.

Purpose: Chemical burns due to alkalis cause extensive damage to the ocular surface leading to blindness. Assessment of ocular burn could be challenging due to severe opacity, inflammation, and angiogenesis. Anterior segment optical coherence tomography (AS-OCT) and OCT angiography (OCTA) may provide fast, non-invasive deep tissue visualization of pathology with high sensitivity in conjunction with slit-lamp analysis. Methods: C57-BL/6J mice were anesthetized with ketamine/dexmedetomidine, and corneal alkali burn was induced (n = 6) by placing filter paper soaked in 1-M sodium hydroxide for 30 seconds on the right eye while the left eye was kept as control. Longitudinal imaging was done with AS-OCT/OCTA and fluorescein angiography at various time intervals for 14 days. Results: AS-OCT showed characteristic pathological changes in alkali-burned eyes with high sensitivity. Although OCT/OCTA showed three-dimensional and cross-sectional views of the anterior chamber and angiogenesis, fluorescein angiography showed nascent vessels with active leakage. Corneal swelling progressively increased by 125.26% on day 12 with a high prevalence of epithelial bullae, stromal cysts, stromal splitting, and Descemet's membrane detachment. Neovascularization was noted as early as day 4 in the burned eyes by both methods. Severe corneal opacity and anterior chamber inflammation were also detected by AS-OCT/OCTA. Conclusions: AS-OCT/OCTA is a promising, noninvasive, high-resolution imaging modality that can provide both qualitative and quantitative information regarding deep tissue pathology at a structural level. Translational Relevance: Noninvasive AS-OCT/OCTA and fluorescein methods show promise in clinical pathology evaluation for ocular injury management and prognostic indications, as the early presence of Descemet's membrane detachment and corneal swelling appears to be correlated with the severity and localization of corneal neovascularization.

Spectral Evaluation of Eyeglass Blocking Efficiency of Ultraviolet/High-energy Visible Blue Light for Ocular Protection.

SIGNIFICANCE: We investigated, for safety and awareness, ultraviolet and high-energy violet light-blocking protection provided by assorted types of eyewear. Ultraviolet and high-energy violet light-filtering efficiency varied and did not correlate with price or advertised claims. Standardization of methods and specifications for lens spectral transmission evaluation is recommended. PURPOSE: Studies have linked exposure of high-energy visible blue light to effect and damage on retinal epithelial cells, photoreceptors, and ganglion cells. "Blue light" is more accurately differentiated into "high-energy visible blue-violet light" and "circadian rhythm blue-turquoise light." This study measured and compared spectral transmission of ultraviolet and high-energy violet light of low-, medium-, and high-priced sunglasses. METHODS: Sunglasses and lens blanks were obtained from the University of Texas Medical Branch Optical Shop and vendors. Groups were based on promotional, retail, designer sunglasses, or "blue blocker" lenses. The percent transmittance of ultraviolet/visible spectral scans (800 to 350 nm) was measured using an Agilent Cary 50 spectrophotometer. High-energy violet/blue light was defined as 400 to 450 nm. RESULTS: Promotional sunglasses (tinted polycarbonate) blocked 100% ultraviolet and 67 to 99.8% high-energy violet blue light. Retail sunglasses filtered out 95 to 100% ultraviolet A and 67% high-energy violet light. The tested designer sunglasses varied widely in their optical transmissibility with respect to their ultraviolet A and high-energy violet light-blocking properties, with some not blocking ultraviolet A. Clear and colorless Kodak Total Blue provided maximal high-energy violet protection, whereas clear Essilor Crizal Prevencia provided less high-energy violet blocking between 400 and 450 nm. CONCLUSIONS: The ultraviolet and high-energy violet (400 to 450 nm) light-filtering efficiency varied between sunglasses and clear lenses and did not correlate with price or advertised claims. Standardization of methods and specifications for lens spectral transmission evaluation is recommended.

Formulation Stabilization and Disaggregation of Bevacizumab, Ranibizumab and Aflibercept in Dilute Solutions.

PURPOSE: Studies were conducted to investigate dilute solutions of the monoclonal antibody (mAb) bevacizumab, mAb fragment ranibizumab and fusion protein aflibercept, develop common procedures for formulation of low concentration mAbs and identify a stabilizing formulation for anti-VEGF mAbs for use in in vitro permeation studies. METHODS: Excipient substitutions were screened. The most stabilizing formulation was chosen. Standard dilutions of bevacizumab, ranibizumab and aflibercept were prepared in PBS, manufacturer's formulation, and the new formulation. Analysis was by SE-HPLC and ELISA. Stability, disaggregation and pre-exposure tests were studied. RESULTS: When Avastin, Lucentis and Eylea are diluted in PBS or manufacturer's formulation, there is a 40-50% loss of monomer concentration and drug activity. A formulation containing 0.3% NaCl, 7.5% trehalose, 10 mM arginine and 0.04% Tween 80 at a pH of 6.78 stabilized the mAbs and minimized the drug loss. The formulation also disaggregates mAb aggregation while preserving the activity. Degassing the formulation increases recovery. CONCLUSIONS: We developed a novel formulation that significantly stabilizes mAbs under unfavorable conditions such as low concentration or body temperature. The formulation allows for tissue permeation experimentation. The formulation also exhibits a disaggregating effect on mAbs, which can be applied to the manufacture/packaging of mAbs and bioassay reagents.

Photokinetic Drug Delivery: Near infrared (NIR) Induced Permeation Enhancement of Bevacizumab, Ranibizumab and Aflibercept through Human Sclera.

PURPOSE: Permeation studies, with near infrared (NIR) light and anti-aggregation antibody formulation, were used to investigate the in vitro permeation of bevacizumab, ranibizumab and aflibercept through human sclera. METHODS: A vertical, spherical Franz cell diffusion apparatus was used for this scleral tissue permeation model. A photokinetic ocular drug delivery (PODD) testing device accommodated the placement of NIR LEDs above the donor chambers. An adjustable LED driver/square wave generator provided electrical energy with a variable pulse rate and pulse width modulation (duty cycle). RESULTS: Exposure to non-thermal NIR light had no effect on mAbs with regard to monomer concentration or antibody binding potential, as determined by SE-HPLC and ELISA. The optimal LED wavelength was found to be 950 nm. Duty cycle power of 5% vs 20% showed no difference in permeation. When compared to controls, the combination of non-aggregating antibody formulation and NIR illumination provided an average transscleral drug flux enhancement factor of 3X. CONCLUSION: Narrow wavelength incoherent (non-laser) light from an NIR LED source is not harmful to mAbs and can be used to enhance drug permeation through scleral tissue. The topical formulation, combined with pulsed NIR light irradiation, significantly improved scleral permeation of three anti-VEGF antibody drugs.

Identifying present challenges to reliable future transdermal drug delivery products.

Transdermal systems have become an accepted means of drug delivery, offering clinical benefits over other dosage forms. Although transdermal delivery has been very successful as a controlled release technology platform, there are a number of challenges that prevent this delivery route from achieving its fullest commercial potential. Additionally, beginning in 1997, transdermal drug delivery companies aligned with life science industries to deliver large molecules, peptides and proteins through the skin, which is difficult due to the skin barrier properties. A number of methods and technologies have been conceived to overcome the skin barrier. Among these are mechanical, chemical and thermal permeation enhancement techniques. These methods are briefly discussed as well as future directions for transdermal therapies.

Photokinetic Drug Delivery: Light-Enhanced Permeation in an In Vitro Eye Model.

PURPOSE: To investigate light-enhanced molecular movement as a potential technology for drug delivery. To do this, we developed an in vitro eye model while representing similar concentration gradient conditions and compositions found in the eye. METHODS: The eye model unit was fabricated by inserting a cross-linked type I collagen membrane in a spectrophotometer cuvette with 1% hyaluronic acid as the drug recipient medium. Photokinetic delivery was studied by illuminating 1 mg/mL methotrexate (MTX) placed in the drug donor compartment on top of the membrane, with noncoherent 450 nm light at 8.2 mW from an LED source pulsed at 25 cycles per second, placed in contact with the solution. A modified UV-visual spectrophotometer was employed to rapidly determine the concentration of MTX, at progressive 1 mm distances away from the membrane, within the viscous recipient medium of the model eye after 1 h. RESULTS: A defined, progressive concentration gradient was observed within the nonagitated drug recipient media, diminishing with greater distances from the membrane. Transport of MTX through the membrane was significantly enhanced (ranging from 2 to 3 times, P < 0.05 to P ≤ 0.001) by photokinetic methods compared with control conditions by determining drug concentrations at 4 defined distances from the membrane. According to scanning electron microscopy images, no structural damage or shunts were created on the surface of the cross-linked gelatin membrane. CONCLUSION: The application of pulsed noncoherent visible light significantly enhances the permeation of MTX through a cross-linked collagen membrane and hyaluronic acid recipient medium without causing structural damage to the membrane.