Distribution of topical ocular nepafenac and its active metabolite amfenac to the posterior segment of the eye.

Nepafenac ophthalmic suspensions, 0.1% (NEVANAC(®)) and 0.3% (ILEVRO™), are topical nonsteroidal anti-inflammatory drug (NSAID) products approved in the United States, Europe and various other countries to treat pain and inflammation associated with cataract surgery. NEVANAC is also approved in Europe for the reduction in the risk of postoperative macular edema (ME) associated with cataract surgery in diabetic patients. The efficacy against ME suggests that topical administration leads to distribution of nepafenac or its active metabolite amfenac to the posterior segment of the eye. This article evaluates the ocular distribution of nepafenac and amfenac and the extent of local delivery to the posterior segment of the eye, following topical ocular instillation in animal models. Nepafenac ophthalmic suspension was instilled unilaterally in New Zealand White rabbits as either a single dose (0.1%; one drop) or as multiple doses (0.3%, one drop, once-daily for 4 days, or 0.1% one drop, three-times daily for 3 days and one morning dose on day 4). Nepafenac (0.3%) was also instilled unilaterally in cynomolgus monkeys as multiple doses (one drop, three-times daily for 7 days). Nepafenac and amfenac concentrations in harvested ocular tissues were measured using high-performance liquid chromatography/mass spectrometry. Locally-distributed compound concentrations were determined as the difference in levels between dosed and undosed eyes. In single-dosed rabbit eyes, peak concentrations of locally-distributed nepafenac and amfenac showed a trend of sclera > choroid > retina. Nepafenac peak levels in sub-samples posterior to the eye equator and inclusive of the posterior pole (E-PP) were 55.1, 4.03 and 2.72 nM, respectively, at 0.25 or 0.50 h, with corresponding amfenac peak levels of 41.9, 3.10 and 0.705 nM at 1 or 4 h. By comparison, peak levels in sclera, choroid and retina sub-samples in a band between the ora serrata and the equator (OS-E) were 13- to 40-fold (nepafenac) or 11- to 23-fold (amfenac) higher, indicating an anterior-to-posterior directional concentration gradient. In multiple-dosed rabbit eyes, with 0.3% nepafenac instilled once-daily or 0.1% nepafenac instilled three-times daily, cumulative 24-h locally-distributed levels of nepafenac in E-PP retina were similar between these groups, whereas exposure to amfenac once-daily dosing nepafenac 0.3% was 51% of that achieved with three-times daily dosing of 0.1%. In single-dosed monkey eyes, concentration gradients showed similar directionality as observed in rabbit eyes. Peak concentrations of locally-distributed nepafenac were 1580, 386, 292 and 13.8 nM in E-PP sclera, choroid and retina, vitreous humor, respectively, at 1 or 2 h after drug instillation. Corresponding amfenac concentrations were 21.3, 11.8, 2.58 and 2.82 nM, observed 1 or 2 h post-instillation. The data indicate that topically administered nepafenac and its metabolite amfenac reach pharmacologically relevant concentrations in the posterior eye segment (choroid and retina) via local distribution, following an anterior-to-posterior concentration gradient. The proposed pathway involves a choroidal/suprachoroidal or periocular route, along with an inward movement of drug through the sclera, choroid and retina, with negligible vitreal compartment involvement. Sustained high nepafenac concentrations in posterior segment tissues may be a reservoir for hydrolysis to amfenac.

Intraocular distribution of melanin in human, monkey, rabbit, minipig and dog eyes.

The purpose of this study was to quantify the melanin pigment content in sclera, choroid-RPE, and retina, three tissues encountered during transscleral drug delivery to the vitreous, in human, rabbit, monkey, minipig, and dog models. Strain differences were assessed in NZW × NZR F1 and Dutch belted rabbits and Yucatan and Gottingen minipigs. The choroid-RPE and retina tissues were divided into central (posterior pole area) and peripheral (away from posterior pole) regions while the sclera was analyzed without such division. Melanin content in the tissues was analyzed using a colorimetric assay. In all species the rank order for pigment content was: choroid-RPE >retina ≥ sclera, except in humans, where scleral melanin levels were higher than retina and central choroid. The melanin content in a given tissue differed between species. Further, while the peripheral tissue pigment levels tended to be generally higher compared to the central regions, these differences were significant in human in the case of choroid-RPE and in human, monkey, and dogs in the case of retina. Strain difference was observed only in the central choroid-RPE region of rabbits (NZW × NZR F1 >Dutch Belted). Species, strain, and regional differences exist in the melanin pigment content in the tissues of the posterior segment of the eye, with Gottingen minipig being closest to humans among the animals assessed. These differences in melanin content might contribute to differences in drug binding, delivery, and toxicity.

Ranibizumab Population Pharmacokinetics and Free VEGF Pharmacodynamics in Preterm Infants With Retinopathy of Prematurity in the RAINBOW Trial.

Purpose: To develop a population pharmacokinetic (PK) model for intravitreal ranibizumab in infants with retinopathy of prematurity (ROP) and assess plasma free vascular endothelial growth factor (VEGF) pharmacodynamics (PD). Methods: The RAnibizumab compared with laser therapy for the treatment of INfants BOrn prematurely With retinopathy of prematurity (RAINBOW) trial enrolled 225 infants to receive a bilateral intravitreal injection of ranibizumab 0.1 mg, ranibizumab 0.2 mg, or laser in a 1:1:1 ratio and included sparse sampling of blood for population PK and PD analysis. An adult PK model using infant body weight as a fixed allometric covariate was re-estimated using the ranibizumab concentrations in the preterm population. Different variability, assumptions, and covariate relationships were explored. Model-based individual predicted concentrations of ranibizumab were plotted against observed free VEGF concentrations. Results: Elimination of ranibizumab had a median half-life of 5.6 days from the eye and 0.3 days from serum, resulting in an apparent serum half-life of 5.6 days. Time to reach maximum concentration was rapid (median: 1.3 days). Maximum concentration (median 24.3 ng/mL with ranibizumab 0.2 mg) was higher than that reported in adults. No differences in plasma free VEGF concentrations were apparent between the groups or over time. Plotted individual predicted concentrations of ranibizumab against observed free VEGF concentrations showed no relationship. Conclusions: In preterm infants with ROP, elimination of ranibizumab from the eye was the rate-limiting step and was faster compared with adults. No reduction in plasma free VEGF was observed. The five-year clinical safety follow-up from RAINBOW is ongoing. Translational Relevance: Our population PK and VEGF PD findings suggest a favorable ocular efficacy: systemic safety profile for ranibizumab in preterm infants.

Ocular pharmacokinetics comparison between 0.2% olopatadine and 0.77% olopatadine hydrochloride ophthalmic solutions administered to male New Zealand white rabbits.

PURPOSE: The primary objective of this study was to compare uptake and distribution of the commercially available formulation of 0.2% olopatadine and the newly developed 0.77% olopatadine hydrochloride ophthalmic solution formulation with improved solubility following a single (30 µL), bilateral topical ocular dose in male New Zealand white rabbits. METHODS: Each animal received a single 30-µL topical ocular dose (0.2% olopatadine or 0.77% olopatadine hydrochloride ophthalmic solution) to the right (OD) eye followed by the left (OS) eye for a total dose of 60 µL. Olopatadine concentrations were measured in ocular tissues (cornea, bulbar, conjunctiva, choroid, iris-ciliary body, whole lens, retina), aqueous humor, and plasma at prespecified time points over 24 h using a qualified liquid chromatography coupled with mass spectrometry (LC-MS/MS) analytical method. RESULTS: Olopatadine was absorbed into the eye and reached maximal levels (Cmax) within 30 min (0.5 h) to 2 h (Tmax) in ocular tissues and plasma for both treatment groups, except for the lens in which the Tmax was 4 h in the 0.2% olopatadine group and 8 h in the 0.77% olopatadine hydrochloride group, respectively. Tissues associated with the site of dosing, that is, the conjunctiva and cornea, had the highest concentrations of olopatadine in both the 0.2% olopatadine (609 and 720 ng/g) and 0.77% olopatadine hydrochloride (3,000 and 2,230 ng/g) dose groups. The greatest differences between 0.2% olopatadine and 0.77% olopatadine hydrochloride were associated with the overall duration and level of ocular exposures. CONCLUSIONS: The newly developed 0.77% olopatadine hydrochloride ophthalmic solution formulation resulted in a higher and more prolonged olopatadine concentration in the target tissue, that is, conjunctiva compared to the commercial formulation of 0.2% olopatadine ophthalmic solution.