Pharmacokinetics and distributions of bevacizumab by intravitreal injection of bevacizumab-PLGA microspheres in rabbits

AIM:To investigate the pharmacokinetics and distributions of bevacizumab by intravitreal injection of prepared bevacizumab-poly (L-lactic-co-glycolic acid) (PLGA) microspheres in rabbits, to provide evidence for clinical application of this kind of bevacizumab sustained release dosage form.METHODS:Bevacizumab was encapsulated into PLGA microsphere via the solid-in-oil-in-hydrophilic oil (S/O/hO) method. Fifteen healthy New Zealand albino-rabbits were used in experiments. The eyes of each rabbit received an intravitreal injection. The left eyes were injected with prepared bevacizumab-PLGA microspheres and the right eyes were injected with bevacizumab solution. After intravitreal injection, rabbits were randomly selected at days 3, 7, 14, 28 and 42 respectively, three animals each day. Then we used immunofluorescence staining to observe the distribution and duration of bevacizumab in rabbit eye tissues, and used the sandwich ELISA to quantify the concentration of free bevacizumab from the rabbit aqueous humor and vitreous after intravitreal injection.RESULTS:The results show that the concentration of bevacizumab in vitreous and aqueous humor after administration of PLGA formulation was higher than that of bevacizumab solution. The T1/2 of intravitreal injection of bevacizumab-PLGA microspheres is 9.6d in vitreous and 10.2d in aqueous humor, and the T1/2 of intravitreal injection of soluble bevacizumab is 3.91d in vitreous and 4.1d in aqueous humor. There were statistical significant difference for comparison the results of the bevacizumab in vitreous and aqueous humor between the left and right eyes (P<0.05). The AUC0-t of the sustained release dosage form was 1-fold higher than that of the soluble form. The relative bioavailability was raised significantly. The immunofluorescence staining of PLGA-encapsulated bevacizumab (b-PLGA) in rabbit eye tissues was still observed up to 42d. It was longer than that of the soluble form.CONCLUSION: The result of this study shows the beneficial effects of PLGA in prolonging the residency of bevacizumab in the vitreous. And the drug delivery system may have potential as a treatment modality for related disease.     

Safety and pharmacokinetics of a preservative-free triamcinolone acetonide formulation for intravitreal administration

PURPOSE: The safety and pharmacokinetics of a triamcinolone acetonide (TA) preservative-free (TA-PF) formulation were investigated after intravitreal administration in rabbits. METHODS: A TA-PF formulation was prepared as a sterile 40-mg/mL or 160-mg/mL suspension in single-use vials by adding TA powder to 0.5% hydroxypropyl methylcellulose in normal saline. TA-PF (4-mg and 16-mg doses) and Kenalog (Bristol-Myers-Squibb, Princeton, NJ) (4-mg dose) were injected into the vitreous of separate groups of rabbits, and drug levels were measured in the vitreous over time with HPLC. Ocular toxicology (clinical examination, serial electroretinography, and histopathologic analysis) was evaluated in a separate group of animals after intravitreal TA-PF injection. RESULTS: The half-lives of the injection amount in the vitreous, 4-mg TA-PF, 16-mg TA-PF, and 4-mg Kenalog, were found to be 24 days, 39 days, and 23 days, respectively. There were no signs of toxicities by clinical examination after TA-PF injection. Serial electroretinograms of rabbits receiving either 4-mg or 16-mg intravitreal TA-PF injections remained normal over time. Histopathologic analysis showed normal ocular tissues in animals receiving either 4-mg or 16-mg intravitreal TA-PF injections. CONCLUSION: The half-life of TA in the vitreous after a 4-mg injection of either TA-PF or Kenalog was comparable. A 16-mg dose of TA-PF produced a long vitreous half-life, and this may be of clinical benefit in patients requiring 6 months of drug exposure in the eye for a chronic disease.     

Gantrez AN Nanoparticles for Ocular Delivery of Memantine: In vitro Release Evaluation in Albino Rabbits

Aim: To prepare and evaluate the in vitro release of memantine-loaded poly(anhydride) (Gantrez?) nanoparticles (NPs). The clinical safety and retinal toxicity caused by unloaded NPs after sub-Tenon and intravitreal ocular injections were also evaluated. Methods: Preparation and characterization of this type of NP as well as the in vitro release study are described. Twenty-three healthy New Zealand rabbits were used for clinical and histological assessment after sub-Tenon and intravitreal ocular injections of unloaded NPs. Results: The amount of drug associated with NPs was 55 μg of memantine/mg of NP. The release profile of memantine from this type of NPs was characterized by an initial burst effect, followed by continuous release of the drug for at least 15 days. No relevant complications were found during the clinical follow-up. The histological evaluation suggested that Gantrez NPs are well tolerated after sub-Tenon ocular injection and that signs of inflammation during the first days after intravitreal ocular injections can be considered a normal reaction of the eye's defence mechanism.     

Clearance of intravitreal voriconazole

Purpose To investigate the elimination rate of voriconazole after intravitreal injection in rabbits. METHODS: Intravitreal injections of 35 microg/0.1 mL voriconazole were administered to rabbits. Vitreous and aqueous humor levels of voriconazole were determined at selected time intervals (1, 2, 4, 8, 16, 24, and 48 hours), and the in vitreous half-life was calculated. Four to six eyes per time point after injection were enucleated and immediately stored at -80 degrees C. Aqueous humor samples were withdrawn before enucleation, and vitreous samples were obtained from ocular dissection and isolation at various time intervals. Voriconazole concentrations in vitreous and aqueous humor were assayed with high-performance liquid chromatography (HPLC). RESULTS: The concentration of intravitreal voriconazole at various time points exhibited exponential decay with a half-life of 2.5 hours. The mean vitreous concentration was 18.912 +/- 2.058 microg/mL 1 hour after intravitreal injection; this declined to 0.292 +/- 0.090 microg/mL at 16 hours. The mean aqueous concentration was much lower and showed a decline from 0.240 +/- 0.051 microg/mL at 1 hour to undetectable levels 8 hours after injection. CONCLUSIONS: Vitreous concentrations achieved during the first 8 hours were greater than the previously reported minimum inhibitory concentrations (MICs) of organisms most involved in fungal endophthalmitis. A rapid decline of intravitreal concentration suggests that supplementation of intraocular voriconazole to maintain therapeutic levels may therefore be required in clinical settings. Further studies are needed to determine the elimination rate of voriconazole after intravitreal injection in humans.     

The pathophysiology of the ocular microenvironment. II. Copper-induced ocular inflammation and hypotony

The ocular effects of intravitreally injected copper sulfate solutions were studied in New Zealand white rabbits. These injections resulted in uveitis characterized by prolonged ocular hypotony, increased protein concentrations and decreased ascorbic acid concentrations in both the vitreous and aqueous humors, and an apparent decrease in the transport function of the anterior uvea. The extent and the duration of these effects were dose-dependent. The lower doses used, 3 or 6 micrograms of Cu as CuSO4 per eye, produced reversible inflammation. The highest dose, 30 micrograms of Cu per eye, also produced some signs of ocular chalcosis: hemorrhage, vitreous liquefaction, prolonged hypotony and local iridial ischemia. Six hours after the intravitreal injection of 6 micrograms of Cu as CuSO4 per eye, the Cu concentration in the vitreous humor increased to approximately 100 times that in the vitreous of control eyes, and began to decline only 3 days later, with a half-time of approximately 8 days. The Cu concentration in the anterior chamber of these eyes never exceeded 1 ppm and returned close to control values within 3 days. Based on these findings, factors that affect ocular trace-metal distribution and kinetics are discussed, as are reasons for the apparent difficulty in diagnosing the presence of Cu-containing intraocular foreign bodies on the basis of the Cu concentration of the aqueous humor.     

兔玻璃体内注射聚N-异丙基丙烯酰胺-聚氧化乙烯纳米粒的眼内毒理学效应

目的:评估玻璃体腔内注射新型缓释给药载体聚N-异丙基丙烯酰胺-聚氧化乙烯(PNIPAAm-PEO)纳米粒的眼内毒理学效应。方法:玻璃体腔注射不同浓度(1mg/0.1mL,2mg/0.1mL,3mg/0.1mL,4mg/0.1mL)的PNIPAAm-PEO纳米稀释液后于不同时间点行裂隙灯、检眼镜、视网膜电图以及组织病理学检测。对照组注射0.1mL无菌生理盐水。将所用不同浓度稀释液局部点眼,观察局部组织的刺激反应。结果:兔眼角结膜对检测浓度范围内的PNIPAAm-PEO有良好耐受性,眼部无刺激症状。玻璃体腔内注射1mg和2mg组未见明显视网膜毒性反应。3mg组眼底检查无异常,ERG-b波1~3d下降幅度>30%,第7~14d略有恢复;第14d光镜下视网膜部分感光细胞外节间隙增宽,外丛状层以内结构空泡变性,细胞排列正常;电镜下各层均有较明显的结构改变,广泛的细胞水肿和空泡变性,细胞间隙增宽,感光细胞膜盘结构基本正常。4mg组ERG-b波波幅下降>30%;第1~14d组织病理学观察均有明显视网膜结构破坏,广泛空泡变性,部分感光细胞的盘膜崩解,层状结构紊乱、模糊不清。结论:PNIPAAm-PEO纳米粒的眼部耐受性良好,具有用作眼部给药载体的潜力,但大剂量使用时应注意眼部安全性问题。     

Ocular pharmacokinetics of bevacizumab in vitrectomized eyes with silicone oil tamponade

Purpose. We characterized the ocular pharmacokinetics of bevacizumab in vitrectomized eyes with silicone oil tamponade. Methods. A total of 18 pigmented rabbits underwent vitrectomy and silicone oil tamponade before an intra-silicone oil injection of 1.25 mg bevacizumab. At post-injection days 1, 7, 14, 28, 42, and 56, 3 rabbits were sacrificed and enucleated, and bevacizumab concentrations were measured in various ocular tissues and plasma. Results. The bevacizumab peak concentration was reached at day 14 in the aqueous humor (4030.70 ng/mL), retina (42,171.7 ng/g), and choroid (56,243.33 ng/g). In the iris/ciliary body and plasma, the peak concentration was reached at day 7 with 52,648.30 ng/g and 197.70 ng/mL, respectively. The choroid had the maximum exposure to bevacizumab with an area under the curve calculated from time zero to the last observed time (AUC(last)) of 1,151,633.40 ng/day/g and the aqueous humor had the minimum exposure (AUC(last) = 74,611.28 ng/day/g) among the ocular tissues, while the drug exposure to the plasma was the smallest of all tissues studied (AUC(last) = 3795.17 ng/day/g). The terminal half-lives and the mean residence time of bevacizumab in the ocular tissues ranged from 3-5 and 10-13 days, respectively. Conclusions. The peak concentration of bevacizumab in various ocular tissues and plasma was delayed and lower than that found in normal rabbit eyes; however, the terminal half-lives were similar to those found in the eyes with native vitreous following an intravitreal injection. Oil may have impacted the distribution of bevacizumab and led to an altered profile of drug level in the ocular tissues.     

万古霉素在正常兔眼和细菌性眼内炎兔眼内的药代动力学研究

背景万古霉素近年来常被作为金黄色葡萄球菌性眼内炎治疗的首选药物,万古霉素在眼内药代动力学的研究报道较少。目的观察万古霉素在正常兔眼和细菌性眼内炎兔眼房水、玻璃体及血清中质量浓度的变化,并进行药代动力学参数比较。方法选取健康成年兔72只,采用随机数字表法分为正常组和眼内炎组,每组36只。眼内炎组兔右眼玻璃体腔内接种2000CFU／ml金黄色葡萄球菌建立眼内炎模型,注射后72h待出现典型的眼内炎表现时,兔眼玻璃体腔内注射10g／L万古霉素注射液0．1ml,分别于注射后0．5、2、4、6、12、24、48、72、84h经兔耳缘静脉采血2ml,之后以空气栓塞法处死动物,摘除眼球,收集房水和玻璃体,利用高效液相色谱仪紫外（HPLC—UV）法检测万古霉素在血液、房水和玻璃体内的质量浓度。3p97药代动力学软件拟合药代动力学参数。结果HPLC法的准确度和精确度符合生物样品的检测要求。玻璃体腔内注射万古霉素后,其在正常兔眼内的代谢呈二室模型,拟合曲线的高峰质量浓度Cmax分别为50．16mg／L和751．42mg／L,t1/2为51．04h和53．21h;其在金黄色葡萄球菌性眼内炎兔眼中代谢呈一室模型,高峰质量浓度Cmax分别为24．94mg／L和687．66mg／L,t1/2分别为11．42h和12．91h,2组动物血药质量浓度均较低,差异无统计学意义（P〉0．05）。正常组和眼内炎组玻璃体腔内注射万古霉素后随时间延长,玻璃体中万古霉素的质量浓度逐渐下降,而房水中出现先升高后下降的趋势。与正常组相应时间点比较,眼内炎组玻璃体和房水中万古霉素的质量浓度均明显下降,差异均有统计学意义（P〈0．05,P〈0．01）。结论HPLC能满足万古霉素药代动力学分析的需要;万古霉素在正常兔眼内的质量浓度较高,清除缓慢,而在细菌性眼内炎兔眼中质量浓度较低、清除较快。     

后Tenon囊下注射曲安奈德后玻璃体腔内药物质量浓度的测定

目的探讨后Tenon囊下注射曲安奈德（TA）后玻璃体腔内的药物质量浓度及代谢情况。方法32只健康成年有色家兔,右眼为实验眼,给予后Tenon囊下注射TA20mg（0.1mL）;左眼为对照眼,给予后Tenon囊下注射生理盐水0.1mL,依据注射后不同时间点分为第1、3、7天,2、3、4、6、8周8个亚组,于注药前及注药后各时间点行裂隙灯检查、眼压测量并处死1组家兔,取玻璃体样本,用高效液相色谱法测定药物质量浓度并行药物代谢动力学分析。结果所有家兔未见手术及药物所致的并发症。玻璃体腔内药物质量浓度于第2周达到最高,为（1.91±0.13）μg/mL,以后逐渐下降。结论后Tenon囊下注射TA,在玻璃体腔内可达到并维持一定的药物质量浓度。     

Release of slow reacting substance from rabbit ocular tissues

Investigations were carried out to determine whether any slow reacting substance (SRS) is released from the ocular tissues. The SRS activity was bioassayed using the guinea pig ileum in the presence of mepyramine and atropine. An SRS-specific antagonist, FPL55712, was also used to confirm SRS-induced ileum contraction. Incubation of the ocular tissue fragments of the rabbit with a Ca-ionophore A23187 resulted in a marked release of the SRS in the potency order of the choroid, ciliary body, conjunctiva and iris. The rabbit was sensitized with bovine serum albumin and complete Freund's adjuvant. Experimental uveitis was induced by injection of antigen into the vitreous body the sensitized rabbits. The SRS could not be detected in the aqueous humor 10-24 hours after the antigen injection but it was released markedly into the vitreous. The SRS from the vitreous humor of the rabbits with experimental uveitis was purified by high performance liquid chromatography, and leukotriene C4 and leukotriene D4 were identified. It was suggested that release of the SRS from the ocular tissues plays a role in allergic and nonallergic uveitis.     

两种不同注射方法眼局部注射鼠神经生长因子后兔眼内药物分布

目的 观察兔玻璃体腔注射与球周注射~(125)I-神经生长因子(NGF)后眼部各组织药物含量分布.方法 45只家兔分别于左眼玻璃体腔(A组)和右眼球周(B组)注射~(125)I-NGF 30 μg/100μl.于注药后15、30 min,1、3、6、8、12、24、48 h取眼房水、玻璃体等眼内容物,角膜、巩膜等眼球外壁组织,虹膜睫状体、视网膜、脉络膜等眼球内壁组织进行γ-计数,计算~(125)I-NGF的含量.结果 A组药物在眼内容物及眼球内壁各组织弥散较快,玻璃体内含量呈梯度下降,其它眼内组织含量呈正态曲线变化;房水、虹膜睫状体、视网膜、脉络膜达峰值时间均为给药后3 h,巩膜、角膜分别为6、8 h;B组眼内各组织药物含量呈正态曲线变化,药物达眼内峰值时间较慢,除房水在给药后3 h达峰值,其他组织均在6 h达峰值;A组各组织~(125)I-NGF峰值含量也明显高于B组;A组除玻璃体直接注射导致高药物含量外,视网膜药物含量最高.结论 玻璃体腔注射~(125)I-NGF较球周注射更能在眼内各组织达到高药物含量.     

Intraocular use of rituximab

PURPOSE: To evaluate the toxicity of 1 mg of intraocular rituximab and to present a small case-series of patients treated with intravitreal rituximab. METHODS: Rituximab (1 mg/0.1 ml) was injected in the vitreous of one eye of three Dutch-belted rabbits. Two animals were injected with balanced salt solution as controls. At 1 month the rabbits were killed and the eyes examined by light microscopy. Three patients (five eyes) with intraocular lymphoma were also treated with a 1 mg injection of rituximab. RESULTS: The treated rabbit eyes and the control eyes showed no light microscopic evidence of ocular toxicity at 1 month following injection. The five human eyes of three patients have shown no evidence of intraocular toxicity with a median follow-up time of 3.6 months (range 2.0-6.4 months). One patient received a total of four injections in the right eye and three injections in the left eye. CONCLUSION: Intravitreal rituximab at a dose of 1 mg does not appear to cause toxicity in rabbit eyes and in the five eyes of three patients.     

Antioxidant activity of aqueous and vitreous humor from the inflamed rabbit eye

The effects of aqueous and vitreous humors and plasma on the rate of auto-oxidation of a rabbit brain homogenate were measured. Both aqueous and vitreous humors from normal eyes increased, while plasma decreased the rate of oxidation in the homogenate. During endotoxin-induced ocular inflammation the copper (Cu) and iron (Fe) concentrations of both the aqueous and vitreous humors increased, most likely due to the influx of their plasma binding proteins, ceruloplasmin (Cu) and transferrin (Fe). As both proteins are known to be antioxidants, it was not surprising to find that the aqueous and vitreous humor from the inflamed eyes had significant antioxidant activity. This antioxidant activity correlated well with the concentrations of Cu and Fe in aqueous humor and Cu but not Fe in the vitreous humor throughout the time course of the inflammatory response. Thus, entry of plasma proteins through disrupted blood ocular barriers may function in protecting ocular tissues against the increased oxidation which occurs during inflammation.     

Vitreous concentrations of triamcinolone acetonide in human eyes after intravitreal or subtenon injection

PURPOSE: To compare vitreous concentrations of triamcinolone acetonide (TA) achieved by prior therapeutic intravitreal and subtenon injections. DESIGN: Interventional case series. METHODS: Vitreous samples were collected from patients who required vitreous surgery, six having received a subtenon injection of TA and another six, an intravitreal injection. Vitreous concentrations of TA were measured by high-performance liquid chromatography. RESULTS: Vitreous concentrations of TA after intravitreal injection were 1.22 +/- 0.24 mug/ml, significantly higher than those after subtenon injection (<0.001 mug/ml, P = .003). Vitreous concentrations of TA after subtenon injection and TA-assisted vitrectomy performed in a few patients to visualize the transparent vitreous gel were 0.20 +/- 0.11 mug/ml, an intermediate amount between these two groups. CONCLUSION: Much higher vitreous concentrations of TA after intravitreal injection than subtenon injection may accelerate therapeutic effect when intravitreal injections are given to reduce macular edema. Subtenon injections of TA may act via the sclera as opposed to the vitreous.     

Intraocular penetration kinetics of prednisolone after subconjunctival injection in rabbits

Prednisolone concentrations in cornea, aqueous humor, and vitreous humor and the residual amount in conjunctival tissue were assayed by high-performance liquid chromatography during a 14-hour period after subconjunctival injection of prednisolone sodium succinate in rabbits. Prednisolone was concentrated in the corneal epithelium and reached a peak within 5 min, whereas the peak level of prednisolone in stroma-endothelium was achieved 1 h after the injection. There was an apparent linear binding of prednisolone with the ocular tissue homogenates and fluids except for the vitreous humor. However, the protein binding of prednisolone with vitreous humor showed marked concentration dependency. A pharmacokinetic model involving a rapid conversion to prednisolone from its ester prodrug, first-order transfer to various tissues, and first-order elimination of unbound prednisolone from vitreous humor succeeded in predicting the observed concentration-time profiles of prednisolone in various ocular tissues and fluids after subconjunctival injection at three different doses: 0.1, 1.0, and 10.0 mg/kg. The present model predicted that absorption into precorneal area and epithelium and direct penetration into aqueous humor and vitreous humor are 1.7, 0.1, and 0.2% of the applied dose, respectively, and that almost the entire dose (98%) is absorbed into the systemic circulation, with a half-life of 38 min.     

Transscleral iontophoretic and intravitreal delivery of a macromolecule: Study of ocular distribution in vivo and postmortem with MRI

The distribution and clearance of macromolecules in ocular delivery are not well understood. It has been hypothesized that iontophoresis can enhance transscleral delivery of macromolecules. The objective of this study was to investigate the ocular distribution of a macromolecule after transscleral iontophoretic delivery and intravitreal injection in vivo using nuclear magnetic resonance imaging (MRI) and to compare these results. Experiments of constant current transscleral iontophoresis of 4 mA or intravitreal injection were performed on New Zealand white rabbits in vivo. Iontophoresis experiments were also performed on rabbits postmortem. Galbumin™ (Gd-labeled albumin) was the model permeant surrogate to clinical therapeutic agents. MRI was used to monitor the distribution of the molecule in the eye after ocular iontophoresis and intravitreal injection. In addition, the conjunctiva, sclera, choroid, and retina were extracted in the transscleral iontophoresis study to determine the amounts of Galbumin™ in these tissues using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The results show that iontophoresis enhanced the ocular delivery of Galbumin™. The macromolecule was mainly delivered into the conjunctiva and sclera in microgram quantities and then diffused towards the posterior section in the upper hemisphere of the eye in vivo. Both in vivo and postmortem studies show that the iontophoretic delivery of Galbumin™ into the vitreous was below the detection limit. In the intravitreal injection study, the diffusion coefficient of Galbumin™ in the vitreous humor was estimated to be close to that of free aqueous diffusion.     

Determination and pharmacokinetic profile of liposomal foscarnet in rabbit ocular tissues after intravitreal administration

The treatment of ocular diseases affecting the posterior segment of the eye, such as cytomegalovirus (CMV) retinitis, requires the access of the drugs to the vitreous humor. Foscarnet inhibits replication of herpesviruses, including CMV. The drug's encapsulation in liposomes is meant not only to increase activity and to prolong the effect of the drug, but also to reduce its toxicity. The aims of the present study were to evaluate foscarnet levels and its pharmacokinetic parameters in vitreous humor and retinal tissue of rabbits after the administration of an intravitreal injection of both liposomal foscarnet and foscarnet commercial solution. Liposomes were prepared by the reverse-phase evaporation method. The amount of encapsulated foscarnet (F) was 63% wt. The in vitro diffusion assays showed that F was released more slowly when formulated in liposomes than in the commercial solution. The in vivo studies showed that, as opposed to commercial solution F, liposomal F achieves stable and durable therapeutic levels in retina, going beyond 72 h, reaching the vitreous humor with adequate levels to accomplish the aims of intravitreal therapy. Lyophilization also increased stability and dispersion of liposomes in aqueous medium, although not improving the pharmacokinetic results over those from non-lyophilized liposomes.     

Intravitreal delivery of oligonucleotides by sterically stabilized liposomes.

PURPOSE: The efficacy of sterically stabilized liposomes for delivering a model phosphodiester oligonucleotide intravitreally was investigated in the rabbit. METHODS: Ocular distribution and clearance from the vitreous humor of a model 16-mer oligothymidylate (pdT16) were evaluated in the rabbit by radioactivity measurements after intravitreal injection of either a solution or liposomes containing the [33P]pdT16 oligonucleotide. The integrity of pdT16 was investigated using a competitive hybridization assay. RESULTS: The residual concentration of the [33P]pdT16 oligonucleotide within the ocular tissues was significantly increased after intravitreal administration of the liposomal suspension compared with a simple solution. Administration of liposome-encapsulated pdT16 oligonucleotide resulted in sustained release into the vitreous and the retina-choroid compared with release from the solution and in a reduced distribution to nontarget tissues (sclera, lens). In addition, liposomes protected the phosphodiester oligonucleotide against degradation. This was not observed after administration of the free oligonucleotide. CONCLUSIONS: The intravitreal injection of a phosphodiester oligonucleotide encapsulated within liposomes is a new way of delivering intact oligonucleotide to the eye in a controlled manner. This offers interesting prospects for the treatment of retinal diseases.     

Time course for prostaglandin synthesis by rabbit lens during endotoxin-induced ocular inflammation

Three hours to 14 days following the intravitreal injection of 10 ng of E. coli endotoxin into the vitreal chamber of one eye of the New Zealand white rabbit, ocular inflammation was evaluated by clinical and biochemical criteria and prostaglandins were measured in the intraocular fluids and in the incubation medium of the intact lens. Increased synthesis of PGE2 was detected for lenses from inflamed eyes beginning at 18 h post-endotoxin injection. Lenticular PGE2 synthesis remained above control levels for the duration of the time course. Lenses also exhibited increased PGF2 alpha synthesis, which began at 18 h and returned to control levels by day 7. At the times of peak production, aqueous humor PGE2 concentration correlated with lenticular PGE2 synthesis and with aqueous humor leukocyte number. No correlations were found for lenticular PGE2 vs. cell number, or vitreous humor PGE2 vs. aqueous humor PGE2. These results suggest that during ocular inflammation, aqueous humor PGE2 may be derived, at least in part, from the lens and leukocytes.     

Intraocular lysozyme in experimental uveitis in rabbits: aqueous and vitreous assay.

We determined normal aqueous and vitreous lysozyme levels in rabbit eyes and induced experimental uveitis to record the uppermost aqueous and vitreous lysozyme levels. The normal aqueous humor of the rabbit eye contained 1.05 mug per milliliter lysozyme and the normal vitreous humor contained 0.45 mug per milliliter. After the intravitreal administration of a foreign protein, the aqueous and vitreous lysozyme levels rose within one day, reaching maximum values of 38.4 mug per milliliter and 114 mug per milliliter, respectively, at 14 days, and subsequently declining to minimal values by 28 days after injection.