The effect of topical cyclosporin A on the rabbit cornea. A clinical and electron microscopic study

Physicochemical Stability of a Novel Tacrolimus Ophthalmic Formulation for the Treatment of Ophthalmic Inflammatory Diseases

Tacrolimus is an immunosuppressant used to treat a large variety of inflammatory or immunity-mediated ophthalmic diseases. However, there are currently no commercial industrial forms available that can provide relief to patients. Various ophthalmic formulations have been reported in the literature, but their stability has only been tested over short periods. The objective of this study was to evaluate the physicochemical stability of a preservative-free tacrolimus formulation (0.2 and 1 mg/mL) at three storage temperatures (5 °C, 25 °C and 35 °C) for up to nine months in a multidose eyedropper. Analyses performed were the following: visual inspection and chromaticity, turbidity, viscosity, size of micelles, osmolality and pH measurements, tacrolimus quantification by a stability-indicating liquid chromatography method, breakdown product research, and sterility assay. In an in-use study, tacrolimus quantification was also performed on the drops emitted from the eyedroppers. All tested parameters remained stable during the nine month period when the eyedrops were stored at 5 °C. However, during storage at 25 °C and 35 °C, several signs of chemical instability were detected. Furthermore, a leachable compound originating from a silicone part of the eyedropper was detected during the in-use assay. Overall, the 0.2 mg/mL and 1 mg/mL tacrolimus ophthalmic solutions were physicochemically stable for up to nine months when stored at 5 °C.

[Cyclosporine eye drops: A 4-year retrospective study (2009-2013)]

INTRODUCTION

The University Hospitals Paris Centre Pharmacy compounds three concentrations of cyclosporine eye drops: 20mg/mL (=2%); 5mg/mL (=0.5%) and 0.5mg/mL (=0.05%). Cyclosporine A 2% drops were developed in 1995 to prevent the rejection of high-risk cornea transplants after failure of topical steroids. The other concentrations of eye drops were developed for the treatment of various immune or inflammatory diseases of the cornea, conjunctiva and uvea. These eye drops are dispensed with a physician's prescription to hospitalized or ambulatory patients. A retrospective study over 4 years (2009-2013) was conducted to analyze the details of prescription and possible adverse events.

MATERIALS AND METHODS

Dispensations made from January 1st, 2009 through December 31st, 2013 were studied, including patient age, dose of cyclosporine and practice location of prescribing physician. We also recorded the indications for cyclosporine eye drops in a sample of ambulatory patients. The analysis of local tolerability and the effect on visual comfort was based on questionnaires sent to the patients on cyclosporine 2% over a period of 2 months.

RESULTS

Cyclosporine eye drops prescription grew continuously from 2009 through 2013 for all concentrations. In 2013, 5,859 patients were treated, among which 3,616 patients with topical cyclosporine 2%, 1,681 patients with 0.5%, and 562 patients with 0.05%. In total, this represents 62,621 eye drops. Treated patients ranged from 1 week to 100 years old. Topical 2% cyclosporine is indicated in 61% of cases to prevent high-risk corneal graft rejection. Other indications are corneal ulcer (6%), atopic keratoconjunctivitis (5%), vernal keratoconjunctivitis (5%) and herpetic keratitis (4%). Topical 0.5% cyclosporine is prescribed primarily for dry eye syndrome (20%) and to prevent rejection of high-risk corneal transplantation (11%), to treat ocular rosacea (10%), vernal keratoconjunctivitis (10%), atopic keratoconjunctivitis (8%) and Sjögren's syndrome (7%). Topical 0.05% cyclosporine is prescribed primarily for dry eye syndrome resistant to conventional treatment (47%) and Sjögren's syndrome (21%). Local tolerability of topical cyclosporine was evaluated in 388 patients. The majority of patients (63%) did not experience any adverse effects. The main side effects are redness, burning sensation and itching.

CONCLUSION

Prescription of various formulations of topical cyclosporine is current practice for surgical indications: rejection of high-risk corneal transplantation; or medical indications: vernal or atopic keratoconjunctivitis and dry eye syndrome. Further prospective randomized studies would be necessary to validate formulations, doses and indications of cyclosporine eye drops.

Intravitreal injection of therapeutic agents

BACKGROUND

Intravitreal injection (IVI) with administration of various pharmacological agents is a mainstay of treatment in ophthalmology for endopthalmitis, viral retinitis, age-related macular degeneration, cystoid macular edema, diabetic retinopathy, uveitis, vascular occlusions, and retinal detachment. The indications and therapeutic agents are reviewed in this study.

METHODS

A search of the English, German, and Spanish language MEDLINE database was conducted. A total of 654 references spanning the period through early 2008 were individually evaluated.

RESULTS

The advantage of the IVI technique is the ability to maximize intraocular levels of medications and to avoid the toxicities associated with systemic treatment. Intravitreal injection has been used to deliver several types of pharmacological agents into the vitreous cavity: antiinfective and antiinflammatory medications, immunomodulators, anticancer agents, gas, antivascular endothelial growth factor, and several others. The goal of this review is to provide a detailed description of the properties of numerous therapeutic agents that can be delivered through IVI, potential complications of the technique, and recommendations to avoid side effects.

CONCLUSION

The IVI technique is a valuable tool that can be tailored to the disease process of interest based on the pharmacological agent selected. This review provides the reader with a comprehensive summary of the IVI technique and its multitude of uses.

Quantitative Analysis of Ring-Shaped (Crater-Like) Features at the Tear Film–Epithelial Interface of the Rabbit Cornea as Assessed by Scanning Electron Microscopy

PURPOSE

To develop a method for the quantitative analyses of the ring-shaped features usually observed on the surface of mammalian corneal epithelial cells.

METHODS

The corneas of 10 young adult female albino rabbits were prepared for scanning electron microscopy (SEM) by fixation in 2% glutaraldehyde in 80 mM cacodylate buffer (pH 7.2 to 7.4, 320 to 340 mOsm/kg) and single images taken at 1000x of the central region of the corneal epithelial surface. On enlarged prints at 5000x final magnification, cell-cell borders were marked as were the outlines of the ring-shaped features. Cell areas and the dimensions of the ring-shaped features were measured and the cell characteristics in terms of electron reflex (light, medium, and dark) as well as the number of apices (sides) also noted.

RESULTS

The ring-shaped features had an overall density of 2.5/100 microm2, or an average of 6.5/cell. With the corneal epithelial cells being small and light in appearance (median area 36 microm2), medium in size and appearance (median area 151 microm2), or larger and darker (median area 476 microm2), the number of features/cell was very strongly associated with both the cell type (p < 0.001) and the cell area (p < 0.001). The ring-shaped features could be between 0.65 and 5.5 microm in diameter, but sizes more than 3 microm were most unusual. Ring-shaped features of light cells were smallest (median diameter 1.35 microm), slightly larger on medium cells (1.55 microm), and largest on the dark cells (1.90 microm).

CONCLUSIONS

The ring-like features seen on SEM photomicrographs of rabbits (also known as craters or holes) are reproducible in terms of their overall density per unit surface area as well as their diameter. Such methods should be useful for objective analysis of these features after various treatments of the ocular surface.

An Ex-Vivo, Whole-Globe Porcine Model of Corneoepithelial Wound Healing Tested Using Immunomodulatory Drugs

BACKGROUND

An efficient epithelial wound healing is essential for the preservation of vision. Hence, the effects of novel topical drugs on the ocular surface must be ascertained before clinical use. We have tested the utility of an ex vivo, whole-globe porcine screening model to serve as a partial substitute for resource- and time-consuming animal experiments.

METHODS

Standardized corneoepithelial lesions, 5.0 mm in diameter and 40 microm in depth, were created with an Excimer laser in freshly enucleated porcine eyes. These were then exposed to control solutions (physiological saline (baseline), tissue-culture medium (positive control) and NH4 + (toxicity control)) and to three test agents (cyclosporin A, dexamethasone, and mitomycin C). The wound-healing response and toxic effects were monitored after 20-26 h by comparing lesion sizes.

RESULTS

According to baseline data obtained using physiological saline, tissue-culture medium improved wound healing. The highest doses of NH4 + (1 M) and mitomycin C (1.0 mg/mL) elicited toxic effects (confidence interval according to Scheffé's post hoc test: -0.65 to -0.07 and -0.99 to -0.60, respectively). Under the same test conditions, cyclosporin A (0.1 to 10 mg/mL) and dexamethasone (0.1 to 10 mg/mL) had no influence on corneoepithelial wound healing.

CONCLUSIONS

Drug screening with this ex vivo porcine model permits a reproducibly quantitative and time- and dose-dependent assessment of corneoepithelial wound healing. This model corresponds more closely to the clinical situation than cell culturing and may, therefore, be useful in evaluating novel pharmaceutical agents, thereby helping to cut down on the number of animal experiments performed prior to the instigation of clinical trials.

Préparation d’un collyre de ciclosporine à 2 %

PURPOSE

Cyclosporine administration is very effective in the case of immunological diseases of the cornea, conjunctive or uvea. Moreover, it is widely used in the case of high-risk rejection corneal transplantation. We present a preparation of cyclosporine 2% eye drops.

METHODS

Cyclosporine 2% eye drops are prepared following a particular formulation including one part commercially available cyclosporine oral solution (Sandimmun) diluted in four parts of sterile castor oil. Manufacturing procedures maintain the sterile state of the preparation with a laminar airflow hood placed in a particulate controlled room, with pharmacists, technicians and clerical personnel wearing sterile clothes. Physical and chemical monitoring during and after manufacture for each batch guarantees the process and minimizes the risk of batch rejection. Chemical analysis of cyclosporine is conducted using a validated stability-indicating high-performance liquid chromatographic assay (reverse-phase). Blood dosages taken after the first administration at the 24th hour (after administration of the 6th drop) check for systemic integration.

RESULTS

Cyclosporine 2% eye drops are fairly stable: 12 months after manufacturing, concentrations result in levels not statistically different from concentrations measured the day of preparation. After a daily regimen of six drops in the eye, cyclosporine 2% eye drops have a very low systemic bioavailability, because the blood concentrations only reach the detection limit of the fluorescence polarization immunoassay used for cyclosporine drug monitoring. This explains the absence of systemic toxicity.

CONCLUSION

Cyclosporine 2% eye drops can be available in the hospital pharmacy. The eye drops are stable at room temperature and can be delivered up to 12 months after manufacture. No local adverse effects have been noted, probably in relation with the very low concentration of ethanol in the ocular preparation.

Iontophoresis of lecithin vesicles of cyclosporin A

Site-specific immunosuppression with topical cyclosporin A (CsA) has broad clinical implications in the treatment of skin disorders like psoriasis, pyoderma gangrenosum, lichen planus, cutaneous graft-versus-host disease and contact hypersensitivity and the temporary treatment of skin allografts on burn wounds. However, like any other peptide drug, its skin delivery is hindered by the barrier property of stratum corneum and the physicochemical properties of CsA. We have attempted to deliver CsA across human cadaver epidermis in vitro using colloidal systems like microemulsion and lecithin vesicles and iontophoresis. Although, passive diffusion did not result in permeation of quantifiable amounts of CsA, anodal iontophoresis of the negatively charged colloidal systems facilitated the permeation. Electroosmosis and compromised epidermis might have contributed to the higher skin flux. Lecithin vesicles were better than microemulsion for the iontophoretic delivery of CsA and appear to have potential in site-specific immunosuppression.

Prolongation of corneal allograft survival using cyclosporine in a polylactide-co-glycolide polymer

PURPOSE

To test for prolongation of corneal transplant survival with cyclosporine in a polymer placed in the anterior chamber of corneal allograft recipients.

METHODS

Wistar inbred rats with vascularized corneas were recipients of corneal allografts from Sprague-Dawley donor rats. Grafted rats were randomized into six groups: untreated control animals, cyclosporine-polymer anterior chamber recipients, cyclosporine-polymer subconjunctival recipients, cyclosporine-olive oil drop recipients, polymer-only anterior chamber recipients, and autografted Wistar rats. Grafts were examined by slit lamp every 3 days and the clinical condition scored. The cyclosporine concentration in the aqueous humor was assayed at 1, 2, and 4 weeks. At 2 and 4 weeks after transplantation, the eyes were collected for histopathologic evaluation of the grafts.

RESULTS

The median survival time of untreated corneal allografts was 8.2 +/- 1.48 days for grafts treated with topical cyclosporine, 8.5 +/- 1.50 days for polymer-only anterior chamber implants, 10.6 +/- 1.90 days for 1% cyclosporine drops, 11.4 +/- 2.50 days for grafts given subconjunctival cyclosporine-polymer, 17 +/- 3.05 days for grafts given cyclosporine-polymer implants in the anterior chamber, and more than 3 months in autografted rats. There was a statistically significant difference ( p < 0.05) between the survival time of the allografts in the animals treated with the cyclosporine-polymer in the anterior chamber compared with the other groups of graft recipients. Significantly higher concentrations of cyclosporine were found in the eyes given an anterior chamber implant of cyclosporine-polymer than in the other treatment groups or the untreated rats. The cyclosporine-polymer implants placed in the anterior chamber induced a transient inflammatory response in transplanted eyes.

CONCLUSIONS

Cyclosporine-polymer placed in the anterior chamber significantly prolongs corneal allograft survival in a high-risk corneal graft rejection. This intraocular delivery system may be a valuable adjunct for the suppression of immune graft rejection in high-risk recipients of corneal transplants.

Site-specific immunosuppression using a new formulation of topical cyclosporine A with polyethylene glycol-8 glyceryl caprylate/caprate

PURPOSE

Dermal application of immunosuppressants can be an effective means of achieving site-specific immunosuppression (SITE) on skin allografts in burn wound management and in the treatment of various immune skin disorders. We have previously reported success with topical cyclosporine A (tCsA) in the treatment of skin allograft rejection in rats. Using a new tCsA formulation with a penetration enhancer (PE), polyethylene glycol-8 (PEG-8) glyceryl caprylate/caprate (Labrasol, Gattefossé, St. Priest, France), in a trinary drug delivery system, we hypothesized that we would induce SITE and significantly delay rejection of dual skin allografts in rats.

METHODS

Dual rat skin allografts from Lewis x Brown-Norway (LBN) donors were grafted to Lewis (Lew) recipients. Experimental animals (EXP, n = 7) received a 10-day course of systemic cyclosporine (sCsA, 8 mg/kg/day) followed by topical application. One of the two allografts on each experimental animal received tCsA/PE application (5 mg/kg/day) until sacrifice (tCsA/PE-treated). The other allograft received vehicle only (vehicle-treated). Allogeneic controls (ALLO-CON, n = 9) received no sCsA or tCsA. First signs of rejection were determined based on the initial observation of erythema, hair loss, flakiness, and/or scabs.

RESULTS

The mean time to rejection for ALLO-CON allografts was 6.3 +/- 0.7 days (t test, P = 0.0013); for vehicle-treated allografts, 12.3 +/- 3.8 days (paired t test, P = 0.0146); and for tCsA/PE-treated allografts, 25.6 +/- 5.4 days. The disparity of days to rejection between dual allografts in the ALLO-CON group was 0.0 +/- 0.0 day and that between the tCsA/PE- and vehicle-treated dual allografts was 13.3 +/- 3.9 days (t test, P = 0.0016).

CONCLUSIONS

A new formulation of tCsA in a trinary drug delivery system is successful at delaying the onset of rejection in dual skin allografts in rats by SITE, and PEG-8 glyceryl caprylate/caprate may represent a potentially effective transdermal penetration enhancer.

Safety and tolerability of two percent cyclosporine (Sandimmune) ophthalmic ointment in normal volunteers

Thirty-six healthy male volunteers were enrolled in two sequential double-masked, placebo-controlled trials with the objective of assessing the safety and local tolerability of 2% cyclosporine ophthalmic ointment. Subjects were randomly assigned to active or placebo groups and dosed once, twice, or thrice daily for 14 days. Safety and tolerability were assessed through patient interviews, ophthalmologic examinations, routine laboratory testing, and blood cyclosporine assays. Relative to placebo, cyclosporine ointment was associated with higher frequencies of ocular burning, tearing, redness, itching, and headache. These intolerances were dose-related and reported predominantly in the TID group; QD and BID cyclosporine ophthalmic ointment were better tolerated than the placebo control. Symptoms were usually mild, were reported only once beyond Day 2 in the QD-BID groups, and never required interruption of the study. Transitory, asymptomatic, and unexplained elevations of serum transaminases were seen in five subjects in the first study, but were not confirmed in the second and are not felt to be drug-related. Cyclosporine blood levels were uniformly below the limits of detection. We conclude that the tolerability profile of 2% cyclosporine ointment, dosed once or twice daily in normal volunteers, is acceptable and supportive of trials in patient populations.

Site-specific suppression of cell-mediated immunity by cyclosporine

In this study, it was demonstrated that site-specific suppression of T-cell-mediated immune responsiveness could indeed be achieved by topical application of cyclosporine. Evidence for site-specific immune suppression was obtained from a dual skin allograft model in rats. These animals were given an initial 10-d systemic treatment of CsA. Subsequently, one allograft was treated with topical CsA and the other was treated with the vehicle alone. Anti-inflammatory efficacy and prolonged skin allograft survival were observed both grossly and histopathologically in the presence of topically administered CsA, while contralateral vehicle-treated control grafts underwent vigorous rejection. Systemic lymphocyte DNA synthesis following Con-A and PHA stimulation was normal to elevated. Therefore, systemic T-cell-mediated immunity appeared unaffected or possibly activated even with concomitant topical CsA treatment. CsA levels were low systemically, and showed relative site-specificity in terms of tissue concentration. In conclusion, this study indicates that topical CsA is capable of locally suppressing a strong T-cell-mediated immune response after an initial short-term systemic dose of CsA. Furthermore, certain putative autoimmune and inflammatory diseases of the skin, such as psoriasis and eczematous dermatitis, which may share common mechanisms of action compared to skin allograft rejection should likewise benefit from topical CsA treatment.

Actions of ricinoleic acid and structurally related fatty acids on the gastrointestinal tract. II. Effects on water and electrolyte absorption in vitro

Ricinoleic acid, the active component of castor oil, and related fatty acids were studied to determine their relative inhibitory effects on water and electrolyte absorption using everted hamster jejunal and ileal segments. Differences were found between hydroxylated and nonhydroxylated congeners as well as between cis and trans geometric isomers. At a mucosal concentration of 2.0 mM, the unsaturated fatty acids had the following rank order of potency on inhibition of water absorption: ricionoleate greater than or equal to ricinelaidate- greater than equal to linoleate greater than oleate greater than linelaidate greater than elaidate. Ricinoleyl alcohol was effective at 2.0 mM but the methyl ester of ricinoleic acid was ineffective at this concentration. Among a series of saturated fatty acids including palmitate, stearate, a mixture of 9- and 10-hydroxystearate, and 12-hydroxystearate, only the last compound had any inhibitory effect on water absorption. The results define those portions of the ricinoleic acid molecule required for its effect on water and electrolyte absorption and suggest that classification of this cathartic as an "irritant" or "stimulant" should be re-evlauated.