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The in vitro stability of monoclonal antibodies used for age-related macular degeneration, ranibizumab and bevacizumab, was investigated. The aggregation profile of the antibodies was compared, alone and after association with dexamethasone sodium phosphate or triamcinolone acetonide. Commercial formulations of ranibizumab and bevacizumab were dialysed into three different buffers. After dialysis, samples were stored at 4°C, 25°C and 40°C during 35 days, alone and in combination with dexamethasone sodium phosphate, triamcinolone acetonide phosphate solution or triamcinolone acetonide suspension. Combined formulations based on both commercial formulations were investigated as well. The aggregation state of the antibodies was measured by multi-angle light scattering (MALS) after separation by asymmetrical flow field-flow fractionation (AFFF) or size-exclusion chromatography (SEC). Ranibizumab results to be more stable than bevacizumab, alone and in combination with dexamethasone sodium phosphate or triamcinolone acetonide. Elevation in concentration, pH and temperature causes a decrease in stability of both antibodies. The association of triamcinolone acetonide phosphate solution with either ranibizumab or bevacizumab is observed to be the least stable combination of all samples tested. Dexamethasone sodium phosphate was shown to have a stabilizing effect on bevacizumab, although this is not the case for its combination with the commercial formulation Avastin®. The results demonstrate that the in vitro association of either ranibizumab or bevacizumab with dexamethasone sodium phosphate or triamcinolone acetonide suspension does not decrease the stability of these antibodies. Although ranibizumab is more stable than bevacizumab in vitro, further research has to point out how this affects their mechanism of action in vivo., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Purpose: To report results and complications of 23-gauge transconjunctival sutureless pars plana vitrectomy for a variety of vitreoretinal diseases., Methods: A prospective consecutive case series study was performed in 66 eyes of 66 patients. Indications for surgery were epiretinal membrane (n = 20), rhegmatogenous retinal detachment (n = 19: 14 pseudophakic, 5 phakic), macular hole (n = 16), vitreous hemorrhage (n = 5), cyclodialysis (n = 1), intraocular lens luxation (n = 1), asteroid hyalosis (n = 1), congenital retinoschisis (n = 1), and endophtalmitis (n = 2). Main outcome measures included visual acuity, intraocular pressure, and intra- and post-operative complications., Results: Mean patient age at time of operation was 68 ± 12 years. Overall, visual acuity improved from 1.03 ± 1.00 logMAR preoperatively to 0.32 ± 0.33 logMAR postoperatively (p < 0.01) after a mean follow-up time of 9.3 ± 4.7 months. Mean preoperative intraocular pressure was 13.9 ± 3.5 mmHg, and mean postoperative intraocular pressure was 17.9 ± 9.6 mmHg on day 1 (p < 0.01) and 14.7 ± 2.8 mmHg (p = 0.05) at final visit. Concerning complications, 2 cases of hypotony and 7 of hypertony occurred on day 1, a macular hole reopened some weeks later, and a retinal detachment recurred in one case., Conclusion: 23-gauge transconjunctival sutureless vitrectomy is an effective and safe technique for a variety of vitreoretinal diseases.

The biocompatibility of autocatalyzed poly(ortho ester) (POE(70)LA(30)), a viscous, hydrophobic, bioerodible polymer, was investigated. POE(70)LA(30) was synthesized, sterilized by gamma irradiation, and injected in rabbit eyes at adequate volumes through subconjunctival, intracameral, intravitreal, and suprachoroidal routes. Clinical examinations were performed postoperatively at regular time points for 6 mo, and histopathologic analysis was carried out to confirm tissular biocompatibility. After subconjunctival injection, the polymer was well tolerated and persisted in the subconjunctival space for about 5 weeks. In the case of intracameral injections, polymer biocompatibility was good; the POE(70)LA(30) bubble was still present in the anterior chamber for up to 6 mo after injection. No major histopathologic anomalies were detected, with the exception of a localized Descemet membrane thickening. After intravitreal administration, POE(70)LA(30) biocompatibility was excellent, and no inflammatory reaction could be detected during the observation period. The polymer was degraded in approximately 3 mo. Suprachoroidal injections of POE(70)LA(30) were reproducible and well tolerated. POE(70)LA(30) triggered a slight elevation of the retina and choroid upon clinical observation. The polymer was detectable in the suprachoroidal space for about 6 mo. No inflammatory reaction and no major retinal anomalies could be detected by histology. In conclusion, POE(70)LA(30) appears to be a promising biomaterial for intraocular application, potentially providing sustained drug delivery over an extended period of time, with a good tolerance., (Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 44-53, 2003)

Purpose: Drug delivery to treat diseases of the posterior segment of the eye, such as choroidal neovascularization and its complications, is hampered by poor intraocular penetration and rapid elimination of the drug from the eye. The purpose of this study was to investigate the feasibility and tolerance of suprachoroidal injections of poly(ortho ester) (POE), a bioerodible and biocompatible polymer, as a biomaterial potentially useful for development of sustained drug delivery systems., Methods: After tunnelization of the sclera, different formulations based on POE were injected (100 microL) into the suprachoroidal space of pigmented rabbits and compared with 1% sodium hyaluronate. Follow-up consisted of fundus observations, echography, fluorescein angiography, and histologic analysis over 3 weeks., Results: After injection, POE spread in the suprachoroidal space at the posterior pole. It was well tolerated and progressively disappeared from the site of injection without sequelae. No bleeding or retinal detachment occurred. Echographic pictures showed that the material was present in the suprachoroidal space for 3 weeks. Angiography revealed minor pigment irregularities at the site of injection, but no retinal edema or necrosis. Histology showed that POE was well tolerated in the choroid., Conclusions: POE suprachoroidal injections, an easy, controllable, and reproducible procedure, were well tolerated in the rabbit eye. POE appears to be a promising biomaterial to deliver drugs focally to the choroid and the retina.

Purpose: Pharmacologic modulation of wound healing after glaucoma filtering surgery remains a major clinical challenge in ophthalmology. Poly(ortho ester) (POE) is a bioerodible and biocompatible viscous polymer potentially useful as a sustained drug delivery system that allows the frequency of intraocular injections to be reduced. The purpose of this study was to determine the efficacy of POE containing a precise amount of 5-fluorouracil (5-FU) in an experimental model of filtering surgery in the rabbit., Methods: Trabeculectomy was performed in pigmented rabbit eyes. An ointmentlike formulation of POE containing 1% wt/wt 5-FU was injected subconjunctivally at the site of surgery, during the procedure. Intraocular pressure (IOP), bleb persistence, and ocular inflammatory reaction were monitored until postoperative day 30. Quantitative analysis of 5-FU was performed in the anterior chamber. Histologic analysis was used to assess the appearance of the filtering fistula and the polymer's biocompatibility., Results: The decrease in IOP from baseline and the persistence of the filtering bleb were significantly more marked in the 5-FU-treated eyes during postoperative days 9 through 28. Corneal toxicity triggered by 5-FU was significantly lower in the group that received 5-FU in POE compared with a 5-FU tamponade. Histopathologic evaluation showed that POE was well tolerated, and no fibrosis occurred in eyes treated with POE containing 5-FU., Conclusions: In this rabbit model of trabeculectomy, the formulation based on POE and containing a precise amount of 5-FU reduced IOP and prolonged bleb persistence in a way similar to the conventional method of a 5-FU tamponade, while significantly reducing 5-FU toxicity.

Radiation sterilization is becoming increasingly popular for the sterilization of many pharmaceutical products. Although this technique is not limited to the sterilization of polymers, it is probably the most suitable method for such materials. This method however suffers several drawbacks. The sterilization of a product must lead to a safety level of 10(-6), i.e. one chance in a million to find a contaminated sample. In many cases, this assurance of sterility can be achieved by using a uniform treatment dose of 2.5 Mrad, recommended by the pharmacopeia. We investigated the possibility of using doses of radiation inferior to 2.5 Mrad to sterilize a semi-solid poly(ortho ester) (POE) developed for use as carrier in controlled drug delivery. After determination of the initial bioburden, the polymer was intentionally contaminated with the bioindicator Bacillus pumilus E 601. Following exposure to gamma irradiation, the D10 value of the radio resistant bioindicator was determined. Using the initial contamination value, the reduction factor D10 and the safety level, it is possible to calculate an optimal sterilizing dose for POE. All polymers are affected by ionizing radiation and the amount of radiation which produces a significant change in properties may vary from one polymer to the other. A molecular weight and dynamic viscosity decrease resulting from backbone cleavage was observed for this POE at a dose lower than 2.0 Mrad. Evaluation of the structure using 1H-NMR, 13C-NMR and IR analysis shows that for doses higher than 2.0 Mrad, another degredation process takes place.(ABSTRACT TRUNCATED AT 250 WORDS)

The biocompatibility of a new semisolid, hydrophobic poly(ortho ester) (POE) intended for controlled drug delivery to the eye was evaluated. The polymer was injected subconjunctivally in rabbits, and clinical and histologic examinations were performed 3, 10, 15, and 21 days after injection. Polymers injected as controls were an aqueous gel of sodium hyaluronate (SH), 1% in phosphate buffer, and medical grade silicone oil. After injection, the POE emulsified into small droplets and a focal eosinophilic reaction was noted at 3 days' implantation. At 10 days' implantation, the POE was not identified in the implantation site and the inflammatory reaction had resolved, with fibroblasts being the predominant cell type. At 15 and 21 days, no POE was identified and normal appearing tissue was present in the injection site. Sodium hyaluronate was not inflammatory over the period of the implantations. Silicone oil induced a slight inflammation at 3 days, with the presence of eosinophils and limited necrosis with cellular debris. Silicone oil was present in the implantation site at 3, 10, 15, and 21 days. The inflammatory response to the respective polymers was evaluated in the subconjunctival tissue. The inflammatory reaction was quantified at the implant site, adjacent subconjunctival tissues, and scleral and corneal stroma. The inflammatory cell densities in these respective tissue zones were determined, and the ratio of eosinophils over total inflammatory cells was calculated. POE did not become encapsulated with fibrous tissue, but biodegraded in a short time, indicating its potential for use after glaucoma filtration surgery.

We evaluated the biotolerance of a new semisolid poly(ortho ester) (POE) intended for controlled drug delivery. Two different investigations were carried out in rats: subcutaneous injections and the cage-implant system. Sodium hyaluronate (SH), 1%, in phosphate buffer was used as a noninflammatory control. When injected subcutaneously in rats, the POE induced a mild and local inflammation at 3 and 7 days followed by a minimal chronic inflammation at 14 and 21 days. When using the cage-implant system, we quantified the inflammatory components of the exudate surrounding the implanted material within the cage system at 3, 7, 14, and 21 days. The total leukocyte and macrophage concentrations were higher only at 7 days for both SH and POE compared to the control (empty cage). The other parameters were not significantly different from the control. These results show that POE is well-tolerated by rats when used subcutaneously.

Sodium hyaluronate (SH) solutions have a longer precorneal residence time than isotonic saline solution in rabbits and in humans. The present study investigates the effect of a 0.25% SH vehicle, compared with a phosphate buffer solution (PBS), on the tear concentration after topical administration of gentamicin sulfate (GS) in humans. Eight volunteers received 25 microliters 0.5% GS in PBS in the left eye and 25 microliters 0.5% GS in 0.25% SH in the right eye. Tear samples of 1 microliters were taken from the inferior sulcus using a capillary before instillation and 5, 10, 20, and 40 min after instillation. The tear concentration of GS was determined by radioimmunoassay. There was a statistically significantly higher concentration of GS in the inferior conjunctival sulcus of the SH-instilled eye at 5 min (P < 0.01) and at 10 min (P < 0.05) after instillation (paired t-test, n = 9). At 20 min the concentration of GS in the SH-instilled eye was only slightly higher, and at 40 min GS concentrations in left and right eyes were comparable. SH 0.25% used as a vehicle therefore increases the availability of GS at the ocular surface for at least 10 min. This effect could be due to the prolonged precorneal residence time of SH.

Since the late 1970s, three families of poly(ortho esters) (POE) were synthesized to provide bioerodible carriers for drug delivery devices. The most recent POE is a semi-solid polymer with a viscous behavior at room temperature. Polymer synthesis by a transesterification reaction between a triol and a trialkyl ortho ester is described. The structure of the polymer was confirmed by conventional methods such as 1H-NMR, 13C-NMR and FT-IR. Information concerning average molecular weight and intrinsic viscosity was obtained respectively by GPC and viscosimetry. Residual solvents in the polymer were determined using gas chromatography. The chromatographic conditions were optimized to enable the quantification of the solvents in concentrations of a few percent. The mechanical behavior of the semi-solid POE was determined by rheometric measurements. Hydrolysis of the polymer leads to the formation of the original triol and the carboxylic acid derived from the trialkyl ortho ester used in the transesterification step. No toxicological problems associated with these compounds are anticipated.

In the anterior segment of the eye, fibrin clots must be rapidly resorbed to prevent further fibrosis and scarring. The aqueous humor of patients undergoing cataract surgery was analyzed for the presence of components of the fibrinolytic cascade. In 30 patients, aqueous humor and plasma were compared for their content of urokinase-type plasminogen activator (uPA), tissue-type plasminogen activator (tPA), plasminogen activators inhibitors (PAIs), plasminogen, and total proteins. With gel electrophoresis and zymographic assays of serial dilutions of plasma and aqueous humor, all these components were found to be present at lower concentrations in aqueous humor than in plasma. For total proteins, the aqueous/plasma ratio was approximately 0.003, and for plasminogen it was 0.001. Interestingly, the aqueous/plasma ratio for uPA was not as low and varied from 0.01 to 0.03. A significant proportion of the uPA in aqueous humor was present in the two-chain active form. In addition to uPA, aqueous humor contained lower levels of tPA, but no detectable levels of reactive plasminogen activators inhibitors (PAIs). The presence of a relatively high concentration of active uPA shows that the proteolytic balance of the aqueous humor in the anterior chamber of the eye is shifted toward fibrinolysis.

A standardized interview was undertaken in twenty patients, mean age of 70, suffering from cataract fifteen days following extra-capsular extraction of the cataract, and implantation of a lens in the posterior chamber. The patients were selected on the basis that they had no risk factors of socio-psychological complications either during the illness or post-operatively. The study investigated retrospectively the impact of cataract on different aspects of personality and life-style in these patients. We also studied the degree of reactive depression in the postoperative period, as measured by the Hamilton depression scale. Although the precise psychological correlation between the two time periods was not possible, half of the patients suffered from a major affective disorder, as classified by DSM-III, 15 days before the operation and a quarter of these were depressed after the operation. Our results show this condition to be associated with considerable but non specific socio-affective upheaval in these patients.

The localization of gentamicin in the retina after a single intravitreal injection in the rabbit eye was examined by indirect immunofluorescent staining with goat antigentamicin antiserum. Eight hours after the injection of 400 micrograms of gentamicin, staining was observed in the ganglion cell layer, the inner plexiform layer, the inner nuclear layer, and the photoreceptors. By 12 hours, the staining was also observed in the retinal pigment epithelium. Howeever, by 24 hours the staining was predominantly found in the retinal pigment epithelium and choriocapillaris, and only occasional staining was seen scattered in the neurosensory retina. At 36 to 48 hours, the labeling was confined to the retinal pigment epithelium and choriocapillaris. Electron microscopy confirmed the cytoplasmic localization of gentamicin in the retina.

14 eyes with a pterygium, including one eye from which a pterygium had previously been removed by a simple excision, underwent a conjunctival autograft. During an average follow-up of 13 months, we observed a recurrence in 5 eyes (35%). The visual acuity stayed unchanged in 10 eyes, worsened in 1 eye and improved in 3 eyes. The corneal astigmatism measured with a Javal keratometer showed a modification in 12 eyes. This method should not be used as a standard primary surgery for pterygium in view of the high recurrence rate observed.