Safety assessment of astaxanthin from Haematococcus pluvialis: Acute toxicity, genotoxicity, distribution and repeat-dose toxicity studies in gestation mice.

Natural astaxanthin is the strongest antioxidant ever discovered, with many biological functions, and it is widely used in the fields of health food and biomedical research. In the present study, we aimed to investigate the plasma concentration, distribution and safety of astaxanthin from Haematococcus pluvialis in pregnant mice. In the acute studies, the oral LD50 of astaxanthin was greater than 20 g/kg·bw. In mouse bone marrow micronucleus test, 10 g/kg·bw astaxanthin did not cause damage to chromosomes and mitotic apparatus of pregnant mice. After treatment with a single dose of 500 mg/kg·bw astaxanthin, the concentration of astaxanthin in plasma reached the maximum at 8 h (55.7 µg/L), which was completely metabolized after 48 h. In the repeat-dose toxicity test, 100, 250 and 500 mg/kg·bw astaxanthin showed no abnormalities in terms of body and organ weight as well as hematological and biochemical parameters in clinical observation throughout the pregnancy. During pregnancy, the liver accumulated the highest content of astaxanthin, while the eye exhibited the least. The results indicated that administration of astaxanthin from H. pluvialis throughout pregnancy had no adverse effect on mice.

Preparation and evaluation of novel chitosan: gelrite ocular system containing besifloxacin for topical treatment of bacterial conjunctivitis: scintigraphy, ocular irritation and retention assessment.

This study was aimed to prepare, characterize and evaluate in situ gel formulations based on a blend of chitosan (CS), polyvinyl alcohol (PVA) and gellan gum (Gelrite™) for a sustained ocular delivery of besifloxacin (BSF). The developed formulations were evaluated for physicochemical properties, gelation time (Tsol-gel), rheological behaviour, antimicrobial efficacy, pharmacokinetic assessment, gamma scintigraphy study and ocular irritation. The results showed BSF sol-gel system were found to be sensitive enough which underwent instantaneous phase transition upon getting physiological stimulation. The ex vivo permeation experiments indicated that the developed formulation was able to enhance the retention of BSF at corneal surface. The HET-CAM confirmed the non-irritancy of developed formulation and also demonstrated the ability of ocular protection against strongly irritant substances. The results of gamma scintigraphy study revealed the higher concentration of drug retains at the corneal surface. In addition, optimized BSF sol-gel system showed enhanced anti-bacterial activity compared to BSF suspension.

Fabrication of novel ultradeformable bilosomes for enhanced ocular delivery of terconazole: In vitro characterization, ex vivo permeation and in vivo safety assessment.

The objective of this work was to encapsulate terconazole (TCZ), a water insoluble antifungal drug, into novel ultradeformable bilosomes (UBs) for achieving enhanced ocular delivery. In addition to the constituents of the conventional bilosomes; namely, Span 60, cholesterol, and the bile salts, UBs contain an edge activator which imparts extra elasticity to the vesicles and consequently hypothesized to result in improved corneal permeation. In this study, TCZ loaded UBs were prepared utilizing ethanol injection method according to 23 full factorial design. The investigation of the influence of different formulation variables on UBs properties and selection of the optimum formulation was done using Design-Expert® software. The selected UBs formulation (UB1; containing 10mg bile salt and 5mg Cremophor EL as an edge activator) showed nanosized spherical vesicles (273.15±2.90nm) and high entrapment efficiency percent (95.47±2.57%). Results also revealed that the optimum UBs formulation exhibited superior ex vivo drug flux through rabbit cornea when compared with conventional bilosomes, niosomes, and drug suspension. Furthermore, in vivo ocular tolerance and histopathological studies conducted using male albino rabbits proved the safety of the fabricated UBs after topical ocular application. Overall, the obtained results confirmed that UBs could be promising for ocular drug delivery.

Safety assessment of a traditionally used extract from leaves of Boldoa purpurascens.

ETHNOPHARMACOLOGICAL RELEVANCE: Boldoa purpurascens Cav. (Nyctaginaceae) is a plant species used in traditional medicine in Cuba as a diuretic. AIM OF THE STUDY: The aim of the present investigation was to evaluate the safety profile of a hydroalcoholic extract from leaves of Boldoa purpurascens. MATERIALS AND METHODS: First, an experimental study to assess the oral acute toxicity at a dose of 2000mg/kg body weight of the extract was carried out. Potential genotoxicity of the extract was evaluated using the Ames test and the micronucleus induction assay in mouse bone marrow. In the Ames test a concentration range of 50, 100, 150, 300 and 500µg/plate was tested. In the micronucleus induction assay, doses of 500, 1000 and 2000mg/kg of body weight were tested. For completeness, since the extract contains saponins, the evaluation of the hemolytic activity, ocular and skin irritation were included. RESULTS: No signs or symptoms of toxicity were observed in the oral acute toxicity test (body weight at baseline, seven days and end of the experiment of 236.41±20.07, 256.81±30.44 and 240.02±26.16 respectively for the treated group). The hydroalcoholic extract from the leaves was not mutagenic in the Ames test, and no genotoxicity was observed in the micronucleus assay. A hemolysis test at concentration of 1mg/mL confirmed hemolytic activity, which is not a safety concern since saponins are not absorbed after oral administration. In order to evaluate the percentage of protein denaturation, the ocular irritability index was calculated. The extract was found to be irritating. Finally, skin irritability was evaluated and the irritation index was equal to zero. CONCLUSIONS: Based on the toxicological evaluation of a traditionally used hydroalcoholic extract from the leaves of Boldoa purpurascens we can confirm the safety of its oral use.

Assessment of 8-methosypsoralen, lomefloxacin, sparfloxacin, and Pirfenidone phototoxicity in Long-Evans rats.

Phototoxicity has a strong impact on drug development. Although several animal models have been developed to quantitatively assess human risks, none have been validated for standardized use. In this study, we validated an in vivo phototoxicity model using Long-Evans (LE) rats treated with 4 well-known phototoxic drugs, namely 8-methoxypsoralen, lomefloxacin, sparfloxacin, and pirfenidone. Daily macroscopic observations of skin and eyes, ophthalmological examinations 4 days after dosing, and blood sampling for toxicokinetics (TKs) were performed after exposure of treated animals to ultraviolet, and dose-dependent eye and/or skin reactions were noted for all compounds. Margins of safety were calculated when possible and correlated well with known relative phototoxicity of the 4 compounds. We conclude that the present in vivo phototoxicity assay using LE rats with TK analysis can be used to quantitatively predict the risk of pharmaceutical phototoxicity in humans.

Fish eyes and brain as primary targets for mercury accumulation - a new insight on environmental risk assessment.

Fish eyes and brain are highly susceptible to environmental Hg exposure but this issue is still scarcely investigated, mainly regarding methylmercury (MeHg) accumulation. Yet, Hg levels in fish lens have not been previously examined under field conditions. Total Hg (tHg), MeHg and inorganic Hg (iHg) levels were assessed in the brain, eye wall and lens of the golden grey mullet (Liza aurata) from an Hg contaminated area, both in winter and summer, together with water and sediment levels. Sampling was performed at Aveiro lagoon (Portugal) where a confined area (LAR) is severely contaminated by Hg. Fish brain, eye wall and lens accumulated higher levels of tHg, MeHg and iHg at LAR than the reference site, reflecting faithfully environmental spatial differences. The brain and eye wall responded also to the winter-summer changes found in water and sediment, accumulating higher levels of MeHg (and tHg) in winter. Contrarily, lens was unable to reflect seasonal changes, probably due to its composition and structural stability over time. The three neurosensory structures accumulated preferentially MeHg than iHg (MeHg was higher than 77% of tHg). Lens exhibited a higher retention capacity of MeHg (mean around 1 µg g(-1) at LAR), accumulating higher levels than the other two tissues. Interestingly, MeHg and iHg levels were significantly correlated for the brain and eye wall but poorly associated within the two analysed eye components. The high levels of MeHg found in the brain, eye wall and lens could compromise their functions and this needs further research.

Evaluation of pharmacological activities and assessment of intraocular penetration of an ayurvedic polyherbal eye drop (Itone™) in experimental models.

BACKGROUND: The polyherbal eye drop (Itone™) is a mixture of aqueous distillates of nineteen traditionally used ingredients that sum up to impart potency to the formulation and make it a useful adjunct in various ocular pathologies. However, as there have been no controlled experimental studies accounting to the above claim, therefore, the present study was designed to evaluate the polyherbal formulation (PHF) for antiangiogenic, anti-inflammatory, anticataract, antioxidant and cytotoxicity in addition to the evaluation of intraocular penetration of PHF in rabbit eyes using LC-MS/MS. MATERIALS AND METHODS: Antiangiogenic activity of the PHF was evaluated using in ovo chick chorio-allantoic membrane (CAM) assay and in vivo cautery induced corneal neovascularization assay in rats. Anticataract potential was evaluated using steroid induced cataract in developing chick embryos, sodium selenite induced cataract in rat pups and galactose induced cataract in rats. The antioxidant activity was evaluated using di-phenyl picryl hydrazyl (DPPH) radical scavenging assay. Anti-inflammatory activity was evaluated in vitro using inhibition of LTB4 formation in human WBCs and in vivo using carrageenan induced paw edema assay in rats. The cytotoxicity was evaluated against HeLa cancer cell lines using (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Furthermore evaluation of the intraocular penetration of the PHF was carried out in rabbit eyes via aqueous humor paracentesis and further analysis using LC-MS/MS. RESULTS: PHF significantly inhibited VEGF induced proliferation of new blood vessels in CAM assay and inhibited the cautery induced corneal neovascularization in rats. Additionally, PHF showed noticeable delay in the progression of cataract in the selenite and galactose induced cataract models whereby the PHF treated lenses were graded for stages II and III respectively. However, the PHF did not show any anticataract activity in the hydrocortisone induced cataract model. Moreover, PHF exhibited anti-inflammatory activity whereby it showed 39.34% inhibition of LTB4 formation and significantly inhibited carrageenan induced paw edema in rats. Eight compounds of PHF viz. camphor, casticin, curcumin-II, quercetin, rosmarinic acid, γ-terpinene, ß-pinene and dipentene exhibited transcorneal penetration in rabbit eyes. CONCLUSION: The significant antiangiogenic and anti-inflammatory activities evinced by the PHF merits further investigation for ocular neovascular and inflammatory diseases in humans.

Assessment of the association of matrix metalloproteinases with myopia, refractive error and ocular biometric measures in an Australian cohort.

Extracellular matrix proteins have been implicated in protein remodelling of the sclera in refractive error. The matrix metalloproteinases (MMPs) falling into the collagenase (MMP1, MMP8, MMP13), gelatinase (MMP2, MMP9) and stromelysin (MMP3, MMP10, MMP11) functional groups are particularly important. We wished to assess their association with myopia, refractive error and ocular biometric measures in an Australian cohort. A total of 543 unrelated individuals of Caucasian ethnicity were genotyped including 269 myopes (≤-1.0D) and 274 controls (>-1.0D). Tag single nucleotide polymorphisms (SNPs) (n = 53) were chosen to encompass these eight MMPs. Association tests were performed using linear and logistic regression analysis with age and gender as covariates. Spherical equivalent, myopia, axial length, anterior chamber depth and corneal curvature were the phenotypes of interest. Initial findings indicated that the best p values for each trait were 0.02 for myopia at rs2274755 (MMP9), 0.02 for SE at both rs3740938 (MMP8) and rs131451 (MMP11), 0.01 for axial length at rs11225395 (MMP8), 0.01 for anterior chamber depth at rs498186 (MMP1) and 0.02 at rs10488 (MMP1). However, following correction for multiple testing, none of these SNPs remained statistically significant. Our data suggests that the MMPs in the collagenase, gelatinase and stromelysin categories do not appear to be associated with myopia, refractive error or ocular biometric measures in this cohort.

Proteomics of Drosophila compound eyes: early studies, now, and the future--light-induced protein phosphorylation as an example.

In the past three decades, efforts to understand the molecular mechanisms underlying photoreceptor transduction of the fruit fly Drosophila melanogaster experienced drastic waves of technological development that involve multiple areas of scientific disciplines; the multidisciplinary approach includes a classical genetic manipulation in which random mutations are created and phenotypes are screened, a modern genetics maneuver in which a specific gene relevant to a hypothesis is molecularly cloned and manipulated, and, more recently, direct studies of proteins by proteomics technologies in combination with modern molecular biology and electrophysiology. This paper will review efforts that originated three decades ago in Professor William L. Pak's laboratory at Purdue University to study proteins involved in the Drosophila photoreceptor transduction process and show the power of such multidisciplinary approach that involves collaboration between molecular genetics, electrophysiology, and proteomics.

Recent overview of ocular patents.

Ocular drug therapy has always been considered as a major challenge in the field of drug delivery. The presence of blood ocular barriers and efflux pumps has imposed a great concern as well. Various vision threatening disorders require a long term therapy of drug molecules, especially for the diseases that affect the posterior segment. Pharmaceutical companies and other research institutes have adopted a multidisciplinary approach to meet the current challenges which is evidenced by the trends seen in the published and filed U.S. patents. Various strategies have been employed to achieve long term sustained and targeted delivery for both the anterior and the posterior segments of the ocular diseases. These strategies include formulating drugs into implant, micro or nanoparticulate systems and hydrogel-based systems. Transporter targeted approach has also allowed scientists to deliver drugs to both the segments of the eye. Recent developments such as delivery of drugs utilizing ultrasound, iontophoresis and microneedle based devices have been promising. Genebased therapeutics has opened a new avenue for vision threatening disorders. In all, the current developments in the entire field have been very exciting for finding out new strategies to treat vision threatening disorders.

Opposing interactions between homothorax and Lobe define the ventral eye margin of Drosophila eye.

Patterning in multi-cellular organisms involves progressive restriction of cell fates by generation of boundaries to divide an organ primordium into smaller fields. We have employed the Drosophila eye model to understand the genetic circuitry responsible for defining the boundary between the eye and the head cuticle on the ventral margin. The default state of the early eye is ventral and depends on the function of Lobe (L) and the Notch ligand Serrate (Ser). We identified homothorax (hth) as a strong enhancer of the L mutant phenotype of loss of ventral eye. Hth is a MEIS class gene with a highly conserved Meis-Hth (MH) domain and a homeodomain (HD). Hth is known to bind Extradenticle (Exd) via its MH domain for its nuclear translocation. Loss-of-function of hth, a negative regulator of eye, results in ectopic ventral eye enlargements. This phenotype is complementary to the L mutant phenotype of loss-of-ventral eye. However, if L and hth interact during ventral eye development remains unknown. Here we show that (i) L acts antagonistically to hth, (ii) Hth is upregulated in the L mutant background, and (iii) MH domain of Hth is required for its genetic interaction with L, while its homeodomain is not, (iv) in L mutant background ventral eye suppression function of Hth involves novel MH domain-dependent factor(s), and (v) nuclear localization of Exd is not sufficient to mediate the Hth function in the L mutant background. Further, Exd is not a critical rate-limiting factor for the Hth function. Thus, optimum levels of L and Hth are required to define the boundary between the developing eye and head cuticle on the ventral margin.

Utility of quantitative whole-body autoradiography (QWBA) and imaging mass spectrometry (IMS) by matrix-assisted laser desorption/ionization (MALDI) in the assessment of ocular distribution of drugs.

INTRODUCTION: Assessment of drug candidate properties and potential liabilities can greatly benefit from issue driven studies that are designed to address specific toxicological effects such as ocular phototoxicity. If a compound absorbs light in the wavelength range of 290-700 nm (UV-A, UV-B, and visible light) and generates a positive response in a standard in vitro neutral red uptake phototoxicity assay in Balb/c 3T3 mouse fibroblasts, a single-dose in vivo study may be conducted to assess the potential for drug-induced phototoxicity in the eyes and skin of pigmented Long-Evans rats. Critical to ocular phototoxicity assessment is the hypothesis that the drug or drug-related material must be present in the affected substructures such as the uveal tract, retina, lens, or cornea. For compounds that induce a positive ocular response in the in vivo phototoxicity assay, data on distribution patterns to substructures of the eye can inform decisions regarding the nature of the ocular findings and possibly influence compound advancement. METHODS: Quantitative whole-body autoradiography (QWBA) and imaging mass spectrometry (IMS) by matrix-assisted laser desorption ionization (MALDI) on an ion trap mass spectrometer employing higher order mass spectrometric scanning functions were utilized for localization of dosed drug or metabolites in eye substructures. RESULTS: In investigative studies designed to simulate an in vivo phototoxicity study, rats were administered radio-labeled test article for QWBA analysis and un-labeled test article for IMS analysis. Autoradiograms from the QWBA study indicated that the radio-labeled analyte(s) preferentially distributed to the uveal tract and not the cornea. However, QWBA did not provide information on the nature of the detected analyte(s); i.e. intact parent drug versus potential metabolites or degradants. Multistage MS experiments performed directly on tissue sections demonstrated semi-quantitative localization in the uveal tract and unequivocal identification of the analyte as the dosed parent drug; no potential metabolites were detected. DISCUSSION: Image analysis by QWBA and IMS by MALDI proved complementary in the localization and identification of small molecule drug distribution within the eye.

Assessment of acetylcholinesterase activity in Clarias gariepinus as a biomarker of organophosphate and carbamate exposure.

The objective of this study was to investigate the response of acetylcholinesterase (AChE) activities in Clarias gariepinus in response to Organophosphates (Ops) and carbamate exposure. The AChE activities were determined in plasma, and eye and brain homogenates of unexposed and exposed fish using Ellman's method and 5,5'-dithiobis-2-nitrobenzoic acid (DTNB) chromophore. The baseline AChE activities in plasma, eyes and brain tissues in unexposed fish were comparable between males and females (P > 0.05). Concentrations of pesticides that inhibited 50% (IC(50)) of AChE activities in brain homogenates following in vitro exposures were 0.003, 0.03, 0.15, 190, 0.2, 0.003 and 0.002 microM for carbaryl, chlorfenvinphos, diazinon, dimethoate, fenitrothion, pirimiphosmethyl and profenofos, respectively. The in vivo dose-effect relationships were assessed using chlorfenvinphos and carbaryl at different concentrations that ranged from 0.0003 to 0.06 microM and 0.0005 to 0.05 microM, respectively. Acetylcholinesterase activities were comparable in plasma, and eye and brain homogenates from control and carbaryl-exposed fish. Following exposure of fish to chlorfenvinphos at concentrations above 0.03 microM, a significant inhibition of AChE activities in plasma (84%) and eye homogenate (50%) was observed. The AChE activities in brain homogenate were comparable between chlorfenvinphos-exposed fish and controls. Because carbaryl cause reversible inhibition of AChE activities was found to be more potent than chlorfenvinphos that cause irreversible inhibition following in vitro exposure. Contrary, carbaryl was less potent than chlorfenvinphos after in vivo exposure possibly due to more rapid biotransformation of carbaryl than chlorfenvinphos. Findings from this study have demonstrated that inhibition of AChE activity in C. gariepinus is a useful biomarker in assessing aquatic environment contaminated by anticholinesterases.

Assessment of methylsulfonylmethane as a permeability enhancer for regional EDTA chelation therapy.

Pharmacologic chelators do not effectively penetrate cell membranes and blood-brain barrier. This study assesses methylsulfonylmethane (MSM) as a permeability enhancer and an excipient to facilitate EDTA transport across biologic membranes, and to make possible localized, regional chelation. Topical application of MSM with C(14)EDTA onto the rat cornea led to uptake of the C(14)EDTA in all tested ocular tissues. Without MSM, EDTA did not penetrate the eye. The ability of MSM to deliver EDTA into an eye provides an opportunity for regional chelation therapy. Additionally, these studies suggest that MSM could also be an adjuvant for delivering ciprofloxacin and other chemical compounds to specific, local tissue sites.

An assessment of the ocular safety of inactive excipients following sub-tenon injection in rabbits.

PURPOSE: This work characterized the safety and toleration of inactive excipients following sub-Tenon (ST) administration. METHODS: Rabbits were anesthetized and eyes received an ST injection of the following test excipients: carboxy methylcellulose (CMC; low [90 kDa], mid [250 kDa], and high [700 kDa] molecular weight [MW], 0.25%-1.0% w/v), polysorbate 80 (0.02 and 0.2% w/v), polyethylene glycol 3350 (PEG; 0.2 and 1.0% w/v), poloxamer 188 (0.01 and 0.25% w/v), poloxamer 182 (2% w/v), benzyl alcohol (BA; 4% w/v), benzalkonium chloride (BAC; 0.02%, 0.04%, and 0.05% w/v), and methylcellulose (MC; 0.25% w/v). After a 1-week observation period for clinical signs of ocular tolerability, the animals were euthanized and eyes were collected for histologic examination. RESULTS: The ocular tolerability of the tested excipients were ranked as follows from the innocuous to most deleterious: saline approximately PEG (1% w/v) approximately polysorbate 80 (0.2% w/v) > CMC (0.25% w/v, 90 kDa) > MC (0.25% w/v) approximately poloxomer 188 (0.25% w/v) approximately sodium citrate (pH 9) BAC (0.05% w/v) > CMC (0.5% w/v, 700 kDa) > poloxomer 182 (2% w/v) > BA (4% w/v). Clinical signs of ocular irritation were limited to redness and chemosis observed with most test excipients. The BA excipient also produced corneal opacity. Microscopic findings included histiocytic infiltration (BAC, BA, CMC, MC, and poloxamer 188), heterophilic inflammation (BA, CMC, and poloxamer 182), and edema (BAC, BA, CMC, and poloxamer 182) in episcleral tissue. The severity of the clinical and hisopathologic effects increased with the concentration of the test excipients administered. CONCLUSIONS: This research has evaluated the safety profile of inactive excipients that may be used to formulate new chemical entities for the treatment of ocular disease following a ST injection.

Ocular effects of exposure to industrial chemicals: clinical management and proteomic approaches to damage assessment.

Industrial chemicals in a variety of applications are often found in highly populated areas and their presence carries risks. The threat of serious consequences from inadvertent or intentional events involving hazardous chemicals is a possibility. Extremism and/or other illicit activities pose environmental threats from chemical exposures. We present here a review of the threat of ocular injury in small-and large-scale chemical releases and discuss mechanisms of damage and repair to the eyes. The emerging field of proteomics has been described in relation to its potential role in the assessment of ocular changes following chemical exposures and management of ocular trauma.

Comparative assessment of distribution of blackcurrant anthocyanins in rabbit and rat ocular tissues.

Anthocyanins (ACs) are phenolic compounds that are distributed widely in fruits and vegetables. Although consumption of these compounds has been shown to improve visual function, the distribution of ACs in ocular tissue has not been examined in detail. The aim of this study was therefore to evaluate the ocular distribution of blackcurrant anthocyanins (BCAs) in rats and rabbits after oral, intravenous (i.v.) and intraperitoneal (i.p.) administration. Identification and quantification of ACs were carried out using high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) and high-performance liquid chromatography (HPLC) with UV-visible detection, respectively. BCAs were identified in the plasma and whole eye after oral and i.p. administration in rats. No other peaks were detected in either plasma or ocular tissues after administration when the absorbance of the eluate was monitored at 520 nm. This finding indicates that intact forms of ACs were present in rats after administration of BCA. In rats given i.p. administration, the concentration of total ACs in the whole eye and some ocular tissues was higher than that measured in plasma. These results suggested that ACs detected in the ocular tissues were not due to residual blood. Following i.v. administration in rabbits, four ACs were identified in the plasma and several ocular tissues including the aqueous humor, cornea, sclera, choroid, ciliary body, iris and retina. A small amount of ACs was also detected in the vitreous and lens. In conclusion, this study demonstrated that BCAs were absorbed and distributed in ocular tissues as intact forms. Our data show clearly that intact forms of BCAs pass thorough the blood-aqueous barrier and blood-retinal barrier in both rats and rabbits.

Iontophoretic drug delivery using the IOMED Phoresor system.

Iontophoresis, or electromotive drug administration, is a process that enhances the delivery of drugs through a biological membrane via the application of low-intensity electrical current. This technology offers several advantages over oral and injection drug delivery. Key advantages of iontophoretic drug delivery include the avoidance of pain and potential for infection associated with needle injection, the ability to control the rate of drug delivery, the ability to programme the drug-delivery profile and the minimisation of local tissue trauma. Research using iontophoresis has shown delivery of a number of drug classes. By controlling the applied electric current one can tailor a dosage regimen with a drug delivery profile specific for an indication and the needs of the patient. Advances in iontophoretic electrode design, microelectronics and methods to optimise iontophoretic drug delivery have improved the ability to safely deliver both older, off-patent drugs, as well as new chemical entities being developed to treat a variety of diseases. In addition to transdermal applications, current research indicates that iontophoresis may prove to be a viable noninvasive drug delivery method for treating conditions that affect the back of the eye.

[Assessment of retention and drug-release of ophthalmic ointment on the ocular surface].

PURPOSE: The dynamics of ophthalmic ointment on the ocular surface were investigated using a fluorescent ointment. METHODS: Ten healthy volunteers were enrolled. Ointment (1.0 cm length, 0.05 g) containing 0.1% flavin adenine dinucleotide sodium was squeezed out from the tube and placed in the left lower conjunctival sac. The eyes were then closed for 30 seconds and permitted to blink naturally. Two examinations including observation of tear film lipid layer interference pattern and fluorophotometric measurement of fluorescence intensity, both at the center of the cornea, were performed before examination and at 1, 3, 6, 9, 12, 15, 30, 60 minutes after instillation. RESULTS: In all cases, even 1 hour after instillation, tear film interference patterns were observed, and fluorescence intensity greater than before instillation, was present. CONCLUSION: Ointment placed in the conjunctival sac is thought to remain and release agents on the ocular surface for at least one hour.