COX-1 (IC50 = 64.3 μM); COX-2

Nepafenac shows significantly greater ocular bioavailability and amfenac demonstrated greater potency at COX-2 inhibition than ketorolac or bromfenac. Nepafenac exhibits only weak COX-1 inhibitory activity with IC50 of 64.3 mM. Nepafenac inhibits prostaglandin synthesis in the iris/ciliary body (85-95%) and the retina/choroid (55%) in rabbits. Nepafenac (0.5%) produces 65% reduction in retinal edema which is correlated with 62% inhibition of blood-retinal barrier breakdown. Nepafenac (0.5%) significantly inhibits (46%) blood-retinal barrier breakdown concomitant with near total suppression of PGE2 synthesis (96%). Nepafenac significantly inhibits retinal prostaglandin E(2), superoxide, cyclooxygenase-2, and leukostasis within retinal microvessels in insulin-deficient diabetic rats, without affecting vascular endothelial growth factor (VEGF) and nitric oxide (NO). Nepafenac significantly inhibits the number of transferase-mediated dUTP nick-end labeling-positive capillary cells, acellular capillaries, and pericyte ghosts in diabetic rats. Nepafenac results in significantly less choroidal neovascularization and significant less ischemia-induced retinal neovascularization in mice compare to control. Nepafenac also blunts the increase in VEGF mRNA in the retina induced by ischemia. Nepafenac delays the progression of malignancy as well as reduces weight in an ocular and metastatic animal model of uveal melanoma.

In contrast to diclofenac (IC50 = 0.12 microM), nepafenac exhibited only weak COX-1 inhibitory activity (IC50 = 64.3 microM). However, amfenac was a potent inhibitor of both COX-1 (IC50 = 0.25 microM) and COX-2 activity (IC50 = 0.15 microM)[1].

Human uveal melanoma cell lines were transfected to constitutively express COX-2 and the proliferative rate of these cells using two different methods, with and without the addition of Amfenac, was measured. Nitric oxide production by macrophages was measured after exposure to melanoma-conditioned medium from both groups of cells as well as with and without Amfenac, the active metabolite of Nepafenac .
Results: Cells transfected to express COX-2 had a higher proliferation rate than those that did not. The addition of Amfenac significantly decreased the proliferation rate of all cell lines. Nitric oxide production by macrophages was inhibited by the addition of melanoma conditioned medium, the addition of Amfenac partially overcame this inhibition.
Conclusion: Amfenac affected both COX-2 transfected and non-transfected uveal melanoma cells in terms of their proliferation rates as well as their suppressive effects on macrophage cytotoxic activity.https://pubmed.ncbi.nlm.nih.gov/18042295/

Methods: A masked trial was performed to compare the topical effects of vehicle with one of several concentrations of nepafenac (0.01%, 0.03%, 0.1%, or 0.5%), 0.1% diclofenac, or 0.5% ketorolac tromethamine in mice with oxygen-induced ischemic retinopathy, mice with choroidal NV (CNV) due to laser-induced rupture of Bruch's membrane, or transgenic mice with increased expression of vascular endothelial growth factor (VEGF) in photoreceptors (rho/VEGF transgenic mice).
Results: Mice treated with 0.1% or 0.5% nepafenac had significantly less CNV and significant less ischemia-induced retinal NV than did vehicle-treated mice. Nepafenac also blunted the increase in VEGF mRNA in the retina induced by ischemia. In rho/VEGF transgenic mice, nepafenac failed to inhibit neovascularization. In additional studies, compared with vehicle-treated mice, mice treated with 0.1% or 0.03% nepafenac had significantly less CNV, whereas eyes treated with 0.1% diclofenac showed no significant difference. Mice treated with 0.5% ketorolac tromethamine for 14 days had high mortality, but when evaluated after 7 days of treatment showed no difference from mice treated with vehicle for 7 days.[3]

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The purpose of this study was to evaluate the ability of the nonsteroidal anti-inflammatory drug nepafenac to prevent development of mitogen-induced pan-retinal edema following topical ocular application in the rabbit. Anesthetized Dutch Belted rabbits were injected intravitreally (30 microg/20 microL) with the mitogen concanavalin A to induce posterior segment inflammation and thickening (edema) of the retina. The Heidelberg Retina Tomograph was used to generate edema maps using custom software. Blood-retinal barrier breakdown was assessed by determining the protein concentration in vitreous humor, whereas analysis of PGE2 in vitreous humor was performed by radioimmunoassay. Inhibition of concanavalin A-induced retinal edema was assessed 72 h after initiation of topical treatment with nepafenac (0.1-1.0%, w/v), dexamethasone (0.1%), VOLTAREN (0.1%), or ACULAR (0.5%). Concanavalin A elicited marked increases in vitreal protein and PGE2 synthesis at 72 h postinjection. Retinal thickness was also increased by 32%, concomitant with the inflammatory response. Topical application of 0.5% nepafenac produced 65% reduction in retinal edema which was correlated with 62% inhibition of blood-retinal barrier breakdown. In a subsequent study, 0.5% nepafenac significantly inhibited (46%) blood-retinal barrier breakdown concomitant with near total suppression of PGE2 synthesis (96%). Neither Voltaren nor Acular inhibited accumulation of these markers of inflammation in the vitreous when tested in parallel. This study demonstrates that nepafenac exhibits superior pharmacodynamic properties in the posterior segment following topical ocular dosing, suggesting a unique therapeutic potential for a variety of conditions associated with retinal edema.[2]

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N/A

Nepafenac showed to significantly decrease the retinal levels of PGE2 in LPS-induced rats when administrated topically. However, nepafenac has revealed no significant effect on BRB permeability in LPS-induced rat model

Absorption, Distribution and Excretion
Nepafenac rapidly cross the cornea (6 times faster than diclofenac in vitro).
After oral administration of 14C-nepafenac to healthy volunteers, urinary excretion was found to be the major route of radioactivity elimination, accounting for approximately 85% of the dose, while fecal excretion represented approximately 6% of the dose. Nepafenac (prodrug) and amfenac (active compound) were not quantifiable in the urine.

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Metabolism / Metabolites
Nepafenac (prodrug) is deaminated to amfenac (active compound) in the ciliary body epithelium, retina, and choroid by intraocular hydrolases. Subsequently, amfenac undergoes extensive metabolism to more polar metabolites involving hydroxylation of the aromatic ring leading to glucuronide conjugate formation.

Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
No information is available on the clinical use of nepafenac during breastfeeding. Maternal use of nepafenac eye drops would not be expected to cause any adverse effects in breastfed infants. To substantially diminish the amount of drug that reaches the breastmilk after using eye drops, place pressure over the tear duct by the corner of the eye for 1 minute or more, then remove the excess solution with an absorbent tissue.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
Amfenac has high affinity toward serum albumin proteins. In vitro, the percent bound to human albumin and human serum was 95.4% and 99.1% respectively.

[1]. Inflammation.2000 Aug;24(4):357-70;
[2]. Inflammation.2003 Oct;27(5):281-91;
[3]. Invest Ophthalmol Vis Sci.2003 Jan;44(1):409-15.

Nepafenac is a monocarboxylic acid amide that is amfenac in which the carboxylic acid group has been converted into the corresponding carboxamide. It is a prodrug for amfenac, used in eye drops to treat pain and inflammation following cataract surgery. It has a role as a prodrug, a cyclooxygenase 2 inhibitor, a cyclooxygenase 1 inhibitor, a non-steroidal anti-inflammatory drug and a non-narcotic analgesic.
Nepafenac is a non-steroidal anti-inflammatory prodrug (NSAID) usually sold as a prescription eye drop. It is used to treat pain and inflammation associated with cataract surgery.
Nepafenac is a Nonsteroidal Anti-inflammatory Drug. The mechanism of action of nepafenac is as a Cyclooxygenase Inhibitor.
Nepafenac is a topical nonsteroidal anti-inflammatory drug that is used in eye drops for the treatment of eye pain and swelling.

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Drug Indication
For the treatment of pain and inflammation associated with cataract surgery.
FDA Label
Nevanac is indicated for: , , , prevention and treatment of postoperative pain and inflammation associated with cataract surgery; , reduction in the risk of postoperative macular oedema associated with cataract surgery in diabetic patients. , ,
Prevention of post operative pain and inflammation associated with cataract surgery

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Mechanism of Action
Nepafenac is a prodrug. After penetrating the cornea, nepafenac undergoes rapid bioactivation to amfenac, which is a potent NSAID that uniformly inhibits the COX1 and COX2 activity.

C15H14N2O2

254.28

254.105

C, 70.85; H, 5.55; N, 11.02; O, 12.58

78281-72-8

Nepafenac-d5;1246814-53-8

151075

Light yellow to yellow solid powder

1.3±0.1 g/cm3

562.5±50.0 °C at 760 mmHg

177-181ºC

294.0±30.1 °C

0.0±1.5 mmHg at 25°C

1.641

0.73

2

3

4

19

337

0

QEFAQIPZVLVERP-UHFFFAOYSA-N

InChI=1S/C15H14N2O2/c16-13(18)9-11-7-4-8-12(14(11)17)15(19)10-5-2-1-3-6-10/h1-8H,9,17H2,(H2,16,18)

2-(2-amino-3-benzoylphenyl)acetamide

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)