Structural investigations of stereoselective profen binding by equine and leporine serum albumins.

Serum albumin, the most abundant transport protein of mammalian blood, interacts with various nonsteroidal anti-inflammatory drugs (NSAIDs) affecting their disposition, metabolism, and excretion. A big group of chiral NSAIDs transported by albumin, profens, is created by derivatives of 2-arylpropionic acid. The chiral center in the structures of profens is adjacent to the carboxylate moiety and often determines different pharmacological properties of profen enantiomers. This study describes crystal structures of two albumins, isolated from equine and leporine serum, in complexes with three profens: ibuprofen, ketoprofen, and suprofen. Based on three-dimensional structures, the stereoselectivity of albumin is discussed and referred to the previously published albumin complexes with drugs. Drug Site 2 (DS2) of albumin, the bulky hydrophobic pocket of subdomain IIIA with a patch of polar residues, preferentially binds (S)-enantiomers of all investigated profens. Almost identical binding mode of all these drugs clearly indicates the stereoselectivity of DS2 towards (S)-profens in different albumin species. Also, the affinity studies show that DS2 is the major site that presents high affinity towards investigated drugs. Additionally, crystallographic data reveal the secondary binding sites of ketoprofen in leporine serum albumin and ibuprofen in equine serum albumin, both overlapping with previously identified naproxen binding sites: the cleft formed between subdomains IIIA and IIIB close to the fatty acid binding site 5 and the niche created between subdomains IIA and IIIA, called fatty acid site 6.

Enantioseparations in nonaqueous capillary electrophoresis using charged cyclodextrins.

The enantioseparation of acidic and basic compounds can be successfully achieved in nonaqueous capillary electrophoresis using single-isomer charged ß-cyclodextrin (ß-CD) derivatives of opposite charge to that of the analytes. This chapter describes how to separate the enantiomers of three basic substances selected as model compounds, i.e., alprenolol, bupranolol, and terbutaline, using the negatively charged heptakis(2,3-di-O-acetyl-6-O-sulfo)-ß-CD. The enantiomers of three acidic drugs (tiaprofenic acid, suprofen, and flurbiprofen) are resolved using a monosubstituted amino ß-CD derivative, namely, 6-monodeoxy-6-mono(3-hydroxy)propylamino-ß-CD.

Photodegradation mechanism of nonsteroidal anti-inflammatory drugs containing thiophene moieties: suprofen and tiaprofenic acid.

The photodegradation of nonsteroid anti-inflammatory drugs suprofen, 2-[4-(2-thienoyl)phenyl]propionic acid, and tiaprofenic acid, 2-(5-benzoyl-2-thienyl)propanoic acid, is studied by means of density functional theory. Besides the redox properties of the neutral species, we report on absorption spectra and degradation pathways involving excitation, intersystem crossing to the T(1) state, and spontaneous decarboxylation of the deprotonated species of each drug. The energetics and properties of the suprofen and tiaprofenic acid systems are found to be very similar to those of the highly photolabile benzyl analogue ketoprofen. Mechanisms leading to the formation of a closed-shell decarboxylated ethyl species, as well as peroxyl radicals capable of initiating lipid peroxidation reactions, are discussed.

Enantiomeric separation of acidic compounds by nano-liquid chromatography with methylated-beta-cyclodextrin as a mobile phase additive.

Some racemic nonsteroidal anti-inflammatory drugs, namely naproxen, indoprofen, ketoprofen, flurbiprofen, carprofen, cicloprofen, flunoxaprofen and suprofen were separated into their enantiomers by nano-LC. Chiral recognition was achieved adding to the mobile phase heptakis (2,3,6-tri-O-methyl)-beta-cyclodextrin (TM-beta-CD). Capillary columns of 100 microm id, packed with different RP particles were used for experiments. Effect of experimental parameters such as mobile phase composition, stationary phase type and length of packed capillary column on retention factor and chiral resolution of analytes were studied. The stationary phase type played a very important role in the enantiorecognition process. Best results in terms of highest enantioresolution factor and largest number of separated enantiomers were obtained reducing the particles size to 3 microm with RP(18) stationary phase. Most favourable mobile phase for enantiodiscrimination was obtained using relatively low concentrations of ACN (30%, v/v), 30 mM of TM-beta-CD and pH value of 3.0. The retention time of all studied enantiomers decreased by increasing the CD derivative concentration. The retention factors of selected studied compounds, specifically flurbiprofen, naproxen and suprofen, were measured employing TM-beta-CD concentrations in the range 0-40 mM. Assuming a 1:1 enantiomer/CD ratio, the apparent association constants of the studied enantiomers were calculated.

Mechanism-based inactivation of cytochrome P450 2C9 by tienilic acid and (+/-)-suprofen: a comparison of kinetics and probe substrate selection.

In vitro experiments were conducted to compare k(inact), K(I) and inactivation efficiency (k(inact)/K(I)) of cytochrome P450 (P450) 2C9 by tienilic acid and (+/-)-suprofen using (S)-flurbiprofen, diclofenac, and (S)-warfarin as reporter substrates. Although the inactivation of P450 2C9 by tienilic acid when (S)-flurbiprofen and diclofenac were used as substrates was similar (efficiency of approximately 9 ml/min/micromol), the inactivation kinetics were characterized by a sigmoidal profile. (+/-)-Suprofen inactivation of (S)-flurbiprofen and diclofenac hydroxylation was also described by a sigmoidal profile, although inactivation was markedly less efficient (approximately 1 ml/min/micromol). In contrast, inactivation of P450 2C9-mediated (S)-warfarin 7-hydroxylation by tienilic acid and (+/-)-suprofen was best fit to a hyperbolic equation, where inactivation efficiency was moderately higher (10 ml/min/micromol) and approximately 3-fold higher (3 ml/min/micromol), respectively, relative to that of the other probe substrates, which argues for careful consideration of reporter substrate when mechanism-based inactivation of P450 2C9 is assessed in vitro. Further investigations into the increased inactivation seen with tienilic acid relative to that with (+/-)-suprofen revealed that tienilic acid is a higher affinity substrate with a spectral binding affinity constant (K(s)) of 2 microM and an in vitro half-life of 5 min compared with a K(s) of 21 microM and a 50 min in vitro half-life for (+/-)-suprofen. Lastly, a close analog of tienilic acid with the carboxylate functionality replaced by an oxirane ring was devoid of inactivation properties, which suggests that an ionic binding interaction with a positively charged residue in the P450 2C9 active site is critical for recognition and mechanism-based inactivation by these close structural analogs.

Chemoenzymatic and microbial dynamic kinetic resolutions.

This review tracks a decade of dynamic kinetic resolution developments with a biocatalytic inclination using enzymatic/microbial means for the resolution part followed by the racemization reactions either by means of enzymatic or chemocatalyst. These fast developments are due to the ability of the biocatalysts to significantly reduce the number of synthetic steps which are common for conventional synthesis. Future developments in novel reactions and products of dynamic kinetic resolutions should consider factors that are needed to be extracted at the early synthetic stage to avoid inhibition at scale-up stage have been highlighted.

Differential suppression of menstrual fluid prostaglandin F2a, prostaglandin E2, 6-keto prostaglandin F1a and thromboxane B2 by suprofen in women with primary dysmenorrhea.

Eleven women with primary dysmenorrhea completed a randomized, double-blind, placebo-controlled, three-way cross-over study comparing 200 and 400mg suprofen. Menstrual fluid volume did not change. Mean+/-S.E.M. menstrual fluid PGF2a was significantly suppressed from 18.9+/-1.9 microg (placebo) to 10.9+/-1.7 and 9.3+/-2.1 microg with 200 and 400 mg suprofen, respectively (p=<0.005). PGE2 dropped from 7.8+/-0.9 to 4.6+/-0.8 and 4.6+/-1.1 microg (p=<0.05) and TxB2 from 17.5+/-4.3 to 7.5+/-2.9 and 3.6+/-1.3 microg (p=<0.01), respectively. 6-Keto PGF1a was significantly suppressed (2.7+/-0.4 to 1.9+/-0.5 microg, p=<0.025) with only 400 mg suprofen. Six subjects rated placebo poor and five fair to very good. In contrast, nine rated suprofen excellent to fair while two rated poor. Thus, suprofen was clinically effective but the differential suppression of prostanoids favors 200mg which spares 6-keto PGF1a.

Nonaqueous capillary electrophoretic behavior of 2-aryl propionic acids in the presence of an achiral ionic liquid. A chemometric approach.

Ionic liquids (ILs) appear really attractive as electrolyte additives in nonaqueous capillary electrophoresis (NACE). These salts may offer new possibilities of interactions to modulate analyte effective mobilities. The presence of 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMIM NTf2) in acetonitrile/alcohol background electrolytes (BGEs) was investigated in this work. The aim of this study was to elucidate the influence of the IL concentration on the electrophoretic behavior of four arylpropionic acids and to identify the interactions between the analytes and the IL cation. The influence on mobility of the IL concentration, the nature and the proportion of the organic solvents, and the concentration of the ionic components of the BGE was first studied by a univariate approach. A four-factor D-optimal experimental design was then applied to provide a deeper insight into analyte interaction with IL cation present both free in BGE and adsorbed onto the capillary wall.

Intramolecular electron transfer between tyrosine and tryptophan photosensitized by a chiral pi,pi* aromatic ketone.

The photochemical reaction of Trp and Tyr and related peptides with Suprofen (SUP) as sensitizer in H2O/CH3CN (28:1 v/v) solutions has been studied by time-resolved spectroscopy. The results show that SUP induces oxidation of both Trp and Tyr, as well as intramolecular-ET reactions in the related peptides. The influence of photosensitizer configuration on the involved processes has been studied by using the enantiomerically pure compounds. A significant chiral recognition is observed in which the concentration of the radicals formed after triplet quenching depends on the configuration of the chiral center; the quenching process is higher when using the (R)-SUP enantiomer.

In vitro effects of risperidone and 9-hydroxy-risperidone on human platelet function, plasma coagulation, and fibrinolysis.

BACKGROUND: Thrombotic events have been reported with the use of antipsychotic compounds, although the incidence, predisposing factors, and biological mechanisms associated with these events in psychiatric patients are subject to debate. OBJECTIVE: The in vitro actions of risperidone and its active metabolite 9-hydroxy-risperidone (9-OH-risperidone) on human platelet function, plasma coagulation, and fibrinolysis were examined to explore whether hematologic effects might be a mechanism for thrombotic events with these compounds. METHODS: Blood was donated by healthy white male subjects who were free of medications (particularly acetylsalicylic acid and nonsteroidal anti-inflammatory compounds). Platelet shape change and adhesion/aggregation reactions to risperidone and 9-OH-risperidone induced by adenosine diphosphate (ADP), collagen, epinephrine, and 5-hydroxytryptamine (5-HT) were tested in human platelet-rich plasma. Arachidonic acid metabolism was assessed in human platelets and rat aortic rings. Plasma coagulation was tested in human platelet-poor plasma. Fibrinolysis was measured in human whole blood. RESULTS: The 12 study subjects ranged in age from 20 to 40 years (median age 30 years). At concentrations of 1 x 10(-5) mol/L (approximately 4180 ng/mL), neither risperidone nor 9-OH-risperidone induced platelet shape change or aggregation, amplified reactions to ADP, or modified platelet adhesion/aggregation induced by collagen or ADP, but they did attenuate epinephrine-induced platelet aggregation (-50% in the case of 9-OH-risperidone; P < 0.05) and 5-HT-induced platelet aggregation (drug concentrations yielding 50% inhibition of 5-HT-induced platelet aggregation, 0.5 and 0.2 ng/mL, respectively). Cyclooxygenase, thromboxane A2 synthase, 12-lipoxygenase, prostacyclin synthase, plasma coagulation, and fibrinolysis were unaffected. CONCLUSIONS: Risperidone and 9-OH-risperidone reduced epinephrine- and 5-HT-induced human platelet aggregation but did not significantly alter other measures of platelet function, plasma coagulation, or fibrinolysis in vitro.

Synthesis of precursor of anti-inflammatory agents by using highly reactive zinc.

Highly reactive zinc metal was prepared by electrolysis of a N,N-dimethylformamide (DMF) solution containing naphthalene and a supporting electrolyte in a one-compartment cell fitted with a platinum cathode and a zinc anode. This highly reactive electrogenerated zinc (EGZn/Naph) was used for transformation of ethyl 2-bromoacrylate into the corresponding organozinc compound, which can not be achieved by the use of usual zinc metals. Reaction of the organozinc compounds thus prepared with various aryl halides in the presence of 5 mol% of palladium catalyst gave the corresponding cross-coupling products in high yields. These cross-coupling reactions were successfully applied to a synthesis of the precursor of anti-inflammatory agents such as ibuprofen, naproxen, cicloprofen and suprofen.

UV-induced drug release from photoactive REV sensitized by suprofen.

In order to achieve local administration of drugs, calcein (CAL) encapsulated reverse phase evaporation vesicles (REV) carrying photoactive destabilization agent suprofen (SPF) in the lipid bilayer were prepared. Effect of both UV-A and UV-B photoactivation of liposomal membrane incorporated SPF on the destabilization of the liposome bilayer and the release of encapsulated CAL was investigated. Standard REV of phosphatidylcholine (PC):cholesterol (CHOL) in 7:3 molar ratio, and photoactive REV of PC:CHOL:SPF, and DPPC:CHOL:SPF in 7:3:3 molar ratio were prepared. CAL encapsulation efficiency (EE (%)) and in situ release was studied. SPF incorporation in the PC REV membrane led to approximately 5% increase in the EE (34%) in comparison to standard REV (29%). EE decreased (21%) when DPPC was used to replace PC. Exposure to UV-B caused the highest CAL release. The lowest release was from the unexposed REV. DPPC led to a higher liposomal membrane stability (lower CAL release) than PC. A linear relationship was observed between UV-B exposure duration and REV permeability. This study revealed that membrane destabilization of SPF incorporated REV was best achieved upon photoactivation of the membrane-localized SPF by a 40 min exposure to UV-B.

Process modeling of the lipase-catalyzed dynamic kinetic resolution of (R, S)-suprofen 2,2,2-trifluoroethyl thioester in a hollow-fiber membrane.

A Candida rugosa lipase immobilized on polypropylene powder was employed as the biocatalyst for the enantioselective hydrolysis of (R, S)-suprofen 2,2,2-trifluorothioester in cyclohexane, in which trioctylamine was added as the catalyst to perform in situ racemization of the remaining (R)-thioester. A hollow-fiber membrane was also integrated with the dynamic kinetic resolution process in order to continuously extract the desired (S)-suprofen into an aqueous solution containing NaOH. A kinetic model for the whole process (operating in batch and feed-batch modes) was developed, in which enzymatic hydrolysis and deactivation, lipase activation, racemization and non-enantioselective hydrolysis of the substrate by trioctylamine, and reactive extraction of (R)- and (S)-suprofen into the aqueous phase in the membrane were considered. Theoretical predictions from the model for the time-course variations of substrate and product concentrations in each phase were compared with experimental data.

Synthesis of precursor of anti-inflammatory agents by using highly reactive zinc

Highly reactive zinc metal was prepared by electrolysis of a N,N-dimethylformamide (DMF) solution containing naphthalene and a supporting electrolyte in a one-compartment cell fitted with a platinum cathode and a zinc anode. This highly reactive electrogenerated zinc (EGZn/Naph) was used for transformation of ethyl 2-bromoacrylate into the corresponding organozinc compound, which can not be achieved by the use of usual zinc metals. Reaction of the organozinc compounds thus prepared with various aryl halides in the presence of 5 mol% of palladium catalyst gave the corresponding cross-coupling products in high yields. These cross-coupling reactions were successfully applied to a synthesis of the precursor of anti-inflammatory agents such as ibuprofen, naproxen, cicloprofen and suprofen.

Dextrans--potential polymeric drug carriers for suprofen.

Dextrans are clinically useful biodegradable polysaccharide macromolecules and have been utilized as carriers for suprofen. Conjugates of suprofen were synthesized by preparing their acylimidazol derivatives which were condensed in situ with dextrans of different molecular weights (40000, 60000, 110000 and 200000). The structures of the synthesized conjugates were confirmed by IR and NMR spectroscopy. The degrees of substitution obtained were between 7.5 and 9.0%. The molecular weight was determined by the Mark-Howin Sakurada viscosity equation. Hydrolysis was studied in different buffer solutions (pH 1.2, 7.4, 9.0) and 80% human plasma (pH 7.4) and followed first order kinetics. Much faster hydrolysis was observed at pH 9.0 compared to pH 7.4 buffer solution and 80% human plasma (pH 7.4). Biological evaluation for acute and chronic anti-inflammatory activity was performed and the results were found to be comparable with the parent drug. The ulcerogenic index of conjugates showed a remarkable reduction compared to the parent suprofen.

Mechanism-based inactivation of human recombinant P450 2C9 by the nonsteroidal anti-inflammatory drug suprofen.

The nonsteroidal anti-inflammatory agent (+ or -)-suprofen [alpha-methyl-4-(2-thienylcarbonyl)benzeneacetic acid] was evaluated as a P450 2C9 inactivator. (+ or -)-Suprofen inactivated the diclofenac-4-hydroxylase activity of baculovirus-expressed P450 2C9 in a time- and concentration-dependent manner, which was consistent with mechanism-based inactivation. The loss of activity followed pseudo-first-order kinetics and was suprofen- and NADPH-dependent. The kinetic parameters for inactivation kinact and KI were 0.091 min-1 and 3.7 microM, respectively, and the partition ratio was 101. Although P450 2C9 substrate S-warfarin partially protected against inactivation, reactive oxygen scavengers such as superoxide dismutase and catalase did not prevent inactivation. Extensive dialysis did not regenerate enzyme activity, suggesting that inactivation proceeded via covalent modification. Inactivated P450 2C9 lost <10% of its ability to form a CO-reduced complex, suggesting that inactivation may have resulted from covalent modification of apoprotein. Addition of exogenous nucleophiles such as glutathione and semicarbazide partially protected against inactivation. Apart from the metabolism of suprofen to 5-hydroxysuprofen, the formation of a suprofen-glutathione conjugate was also discernible in microsomal mixtures containing glutathione. Time of flight mass spectrometry revealed a protonated monoisotopic mass of 566.1304 for this conjugate, consistent with an elemental composition of C24H28N3O9S2. The mass spectrum indicated that conjugation had occurred on the intact thiophene ring, presumably via a thioether linkage. Further evidence for the formation of an electrophilic intermediate in suprofen-P450 2C9 incubations was obtained via the characterization of a novel pyridazine adduct upon addition of semicarbazide to the microsomal mixtures. The pyridazine derivative had a protonated monoisotopic mass of 257.0895 that was consistent with an elemental composition of C14H13O3N2. The formation of the stable pyridazine adduct suggested the generation of an electrophilic gamma-thioketo-alpha, beta-unsaturated aldehyde, analogous to that observed during the cytochrome P450-mediated bioactivation of furan. This electrophilic alpha, beta-unsaturated aldehyde represents a possible reactive intermediate that bioalkylates P450 2C9.

Topically applied vitamin C and cysteine derivatives protect against UVA-induced photodegradation of suprofen in ex vivo pigskin.

Exposure of the nonsteroidal anti-inflammatory drug suprofen (SUP) to UV-radiation results in the formation of radicals, reactive oxygen species (ROS), photodecarboxylated products and photoadducts with biomacromolecules. Using an ex vivo pigskin explant model, we investigated whether topical coapplication of the water-soluble antioxidants vitamin C (Lascorbic acid, ASC), N-acetyl-L-cysteine (NAC) or L-cysteine ethylester (CYSET) with SUP reduced ultraviolet A (UVA)-induced decomposition of SUP. UVA-induced changes in antioxidant bioavailability in the stratum corneum and epidermis were also studied. Epidermal bioavailability of SUP in sham-irradiated pigskin increased 2.2- to 4.1-fold after the lowest antioxidant doses (P < 0.05). As compared with no applied antioxidant, increasing doses of all tested antioxidants resulted in increased levels of SUP and decreased levels of photoproducts (P < 0.05). A maximal protection against SUP photodegradation of 70% was found after an ASC dose of 1 micromol/cm2; these values were 60% for a NAC dose of 10 micromol/cm2 and 50% for a CYSET dose of 5 micromol/cm2. Skin antioxidant levels increased with increasing applied dose (P < 0.05); the bioavailability of CYSET was approximately three-fold lower than that of ASC and NAC. UVA exposure resulted in 30-50% consumption of the topically applied ASC or NAC in the stratum corneum, whereas CYSET was not consumed. In conclusion, the topically applied water-soluble antioxidants ASC, NAC and CYSET protect against UVA-induced decomposition of SUP by scavenging radicals and ROS. Coapplication of these antioxidants may therefore be an effective way to reduce or prevent the phototoxic effects of SUP in vivo.

Experimental study on phototoxicity and the photosensitization potential of ketoprofen, suprofen, tiaprofenic acid and benzophenone and the photocross-reactivity in guinea pigs.

BACKGROUND: Ketoprofen, suprofen and tiaprofenic acid are arylpropionic anti-inflammatories. Their chemical structures share the same elements as the benzoyl radical and the tiophene ring. We experienced nine cases of ketoprofen photoallergy, seven cases of suprofen photoallergy and three cases of tiaprofenic photoallergy. PURPOSE: To find the key structure of photosensitivity and photocross-reactivity to ketoprofen, suprofen and tiaprofenic acid. METHODS: : Three animals were tested for phototoxicity and six animals for the photosensitization potentials of ketoprofen, suprofen, tiaprofenic acid and benzophenone, and the photocross-reactivity of the above chemicals. Test substances were applied symmetrically on both sides of the animals' backs. The animals were irradiated with 180 mJ/cm2 UVB ((1/2) MED) and 10 J/cm2 UVA on the left side. The reactions were read on days 2, 3 and 4. The photosensitization potentials of ketoprofen, suprofen, tiaprofenic acid and benzophenone were determined using the Adjuvant-Strip method. Six animals were assigned to each test group and to a control group. RESULTS: Ketoprofen, suprofen, tiaprofenic acid and propionic acid showed negative reactions with the phototoxic test. Benzophenone showed phototoxic reactions to 40% acetone (ac.), 20% ac. and 10% ac. Therefore, we used 5% aq. benzophenone with the photosensitization test. Ketoprofen was the strongest photosensitizer (6/6) and showed photocross-reactivities to suprofen (2/6), tiaprofenic acid (3/6) and benzophenone (6/6). Suprofen was a strong photosensitizer (4/6) and showed photocross-reactivities to ketoprofen (1/4) and tiaprofenic acid (2/4), but not to benzophenone. Tiaprofenic acid was also a photosensitizer (2/6) but showed a photocross-reactivity only to benzophenone (2/2). Benzophenone was also the strongest photosensitizer (6/6), but did not photocross-react to the above three chemicals. CONCLUSION: From the test results, it appears that benzoyl radical is the key structure for photosensitivity and the photocross-reactivity of ketoprofen, suprofen and tiaprofenic acid. The whole structure of benzophenone was needed to induce photosensitization of benzophenone. The animals that were photosensitized from the entire structure of benzophenone did not photocross-react to ketoprofen, suprofen or tiaprofenic acid.

Effects of anti-inflammatory drugs and preservatives on morphologic characteristics and migration of canine corneal epithelial cells in tissue culture.

OBJECTIVE: To determine the effects of commonly used ophthalmic corticosteroids, suprofen, polysulfated glycosaminoglycan and preservatives on morphologic characteristics and migration of canine corneal epithelium grown in cell culture. ANIMALS STUDIED: Corneal epithelial cells harvested from the corneas of euthanized dogs were propagated in cell culture. PROCEDURES: Canine corneal epithelium was grown in tissue culture. The cells were treated with different corticosteroids, polysulfated glycosaminoglycan, suprofen or preservatives at different concentrations after a defect was created in the monolayer. Cellular morphologic characteristics and closure of the defect were compared between test drugs and controls. RESULTS: Morphologically the cells treated with dexamethasone were essentially the same as controls. Prednisolone and hydrocortisone caused rounding and shrinkage of the cells. Both suprofen and polysulfated glycosaminoglycan caused no apparent changes in morphologic characteristics at the lowest concentrations tested, but at higher concentrations there was a concentration-dependent degree of rounding and shrinkage. Benzylkonium chloride and thimerosal caused rounding and shrinkage of all the cells at all concentrations tested. Dexamethasone, hydrocortisone, and suprofen did not inhibit epithelial migration over the defects at the lowest concentrations tested. All other drugs and concentrations inhibited cellular migration. CONCLUSION: Dexamethasone affected the morphologic characteristics and migration of corneal epithelial cells less than hydrocortisone and prednisolone; therefore, dexamethasone may be the drug of choice when a corticosteroid is indicated and an epithelial defect is present. Suprofen and polysulfated glycosaminoglycan caused a concentration-dependent effect on morphologic characteristics and migration. The preservatives caused severe changes and inhibited migration of the canine corneal epithelial cells at all concentrations and may therefore contribute to poor epithelialization of ulcers treated with preservative-containing drugs.