Pharmacobezoar Formation From HPMC-AS-Containing Spray-Dried Formulations in Nonclinical Safety Studies in Rats.

Changing the physical state from crystalline to amorphous is an elegant method to increase the bioavailability of poorly soluble new chemical entity (NCE) drug candidates. Subsequently, we report findings from repeat-dose toxicity studies of an NCE formulated as a spray-dried amorphous solid dispersion (SD-ASD) based on hydroxypropyl methylcellulose acetate succinate (HPMC-AS) in rats. At necropsy, agglomerates of SD-ASD were found in the stomach and small intestine, which in reference to literature were termed pharmacobezoars. We interpreted the pH-dependent insolubility of HPMC-AS in the acidic gastric environment to be a precondition for pharmacobezoar formation. Gastric pharmacobezoars were not associated with clinical signs or alterations of clinical pathology parameters. Pharmacobezoar-correlated histopathological findings were limited to the stomach and consisted of atrophy, erosion, ulcer, and inflammation, predominantly of the nonglandular mucosa. Pharmacobezoars in the small intestines induced obstructive ileus with overt clinical signs which required unscheduled euthanasia, prominent alterations of clinical pathology parameters indicative of hypotonic dehydration, degenerative and inflammatory processes in the gastrointestinal tract, and secondary renal findings. The incidence of pharmacobezoars increased with dose and duration of dosing. Besides the relevance of pharmacobezoars to animal welfare, they limit the non-observed adverse effect level in nonclinical testing programs and conclusively their informative value.

Exploring the potential of tianeptine matrix tablets: Synthesis, physico-chemical characterization and acute toxicity studies.

The main objective of the present study was to explore the potential of matrix tablets as extended release dosage form of tianeptine, using HMPC K100 as a polymer. HPMC K100 extended the release of the drug from formulation due to the gel-like structure. Direct compression method was adopted to compress the tablets using different concentrations of polymer. Tablets were evaluated for pre-compression and post-compression parameters. Drug release study showed that tablet extends the release of drug with the increasing concentration of polymer. Drug, polymers and tablets were analyzed and/or characterized for compatibility, degradation, thermal stability, amorphous or crystalline nature via FTIR, DSC, TGA, XRD studies. SEM study predicted that tablets had a uniform structure. HPMC K100 based tablets were similar to that of the reference product. Acute toxicity study conducted on Swiss albino mice showed that matrix tablets were safe and non-toxic, as no changes in physical activity and functions of organs were observed. Biochemical and histopathological study revealed lack of any kind of abnormality in liver and renal function. Moreover, necrotic changes were absent at organ level.

Repeated Intraperitoneal Administration of Low-Concentration Methylcellulose Leads to Systemic Histologic Lesions Without Loss of Preclinical Phenotype.

Methylcellulose (MC; 0.5% concentration) is commonly used when evaluating investigational agents for efficacy in preclinical models of disease. When administered by the oral (PO) route, MC is considered a Food and Drug Administration "generally recognized as safe" compound. Yet, there is limited data pertaining to the tolerability and impact on model fidelity of repeated intraperitoneal administration of 0.5% MC. Chronic administration of high-concentration MC (2%-2.5%) has been used to induce anemia, splenomegaly, and lesions in multiple organ systems in several preclinical species. Histopathological findings from a diagnostic pathologic analysis of a single mouse from our laboratory with experimentally induced chronic seizures that had received repeated intraperitoneal administration of antiseizure drugs delivered in MC revealed similar widespread lesions. This study thus tested the hypothesis that chronic administration of intraperitoneal, but not PO, MC incites histologic lesions without effects on preclinical phenotype. Male CF-1 mice (n = 2-14/group) were randomized to receive either 6 weeks of twice weekly 0.5% MC or saline (intraperitoneal or PO) following induction of chronic seizures. Histology of a subset of mice revealed lesions in kidney, liver, mediastinal lymph nodes, mesentery, aorta, and choroid plexus only in intraperitoneal MC-treated mice (n = 7/7). Kindled mice that received MC PO (n = 5) or saline (intraperitoneal n = 6, PO n = 3) had no lesions. There were no effects of intraperitoneal MC treatment on body weight, appearance, seizure stability, or behavior. Nonetheless, our findings suggest that repeated intraperitoneal, but not PO, MC elicits systemic organ damage without impacting the model phenotype, which may confound interpretation of investigational drug-induced histologic lesions. SIGNIFICANCE STATEMENT: Methylcellulose (0.5% concentration) is commonly used when evaluating investigational agents for efficacy in preclinical models of disease. Herein, we demonstrate that repeated administration of 0.5% methylcellulose by the intraperitoneal, but not oral, route results in systemic inflammation and presence of foam-laden macrophages but does not impact the behavioral phenotype of a rodent model of neurological disease.

Cationic methylcellulose derivative with serum-compatibility and endosome buffering ability for gene delivery systems.

In this work, methylcellulose was employed as a template polymer with graft of polyethylenimine 0.8 kDa (PEI0.8k) for gene delivery systems. Synthesized PEI-grafted oxidized methylcellulose (MC-PEI) could condense pDNA into positively charged and nano-sized particles, which could protect pDNA from serum nuclease. The cytotoxicity of MC-PEI was minimal in both serum-free and serum condition due to the biocompatibility of methylcellulose and low cytotoxicity of PEI0.8k. MC-PEI polyplex also showed low cytotoxicity in serum condition. In serum condition, MC-PEI showed less decreased transfection efficiency than PEI25k, meaning good serum-compatibility of MC-PEI. Bafilomycin A1-treated transfection results indicate that the transfection of MC-PEI is mediated via endosomal escape by endosome buffering ability. Flow cytometry results suggest that MC-PEI polyplex could be internalized into cells and efficiently deliver pDNA to cells due to its serum-compatibility. These results demonstrate that MC-PEI possesses a potential for efficient gene delivery systems.

Development and optimization of controlled release bioerodable anti infective ophthalmic insert.

The present investigation was carried out to formulate and optimize the bioerodable insert of Azithromycin in order to prolong the release time and improve the ocular availability in ophthalmic infections. A modified solvent casting method was used for the preparation of azithromycin insert in which hydroxyl propyl methyl cellulose (HPMC) and Eudragit RL100 were used as drug reservoir and rate controlling membrane respectively. Thereafter the, formulations were evaluated for the uniformity of thickness and weight, surface pH, folding endurance, percentage moisture loss, percentage moisture absorption, drug content, in-vitro release, kinetics studies (zero order, first order, Higuchi and Korsmeyer - Peppas model) and stability studies. The Formulation H8 (amongst the range of H1-H10), comprising of 1.5% HPMC and 3% Eudragit RL100, was found to be optimized formulation on the basis of uniformity of thickness (0.26±0.004 mm) and weight (24.9±0.27 mg), surface pH (7.1±0.063), folding endurance (18.3±0.81), percentage moisture loss (7.49±0.30%), percentage moisture absorption (5.7%), drug content (1.98 mg), in-vitro release (99%), AUC for in vitro and in vivo release is 38828.33 and 39783.33 g min/ml respectively and higher than pure drug (1190 g min/ml), (Shelf life- 622 days) and further better occular tolerablity found. The formulation H8 showed a steady and controlled release of the drug over a 12 hour period with non-Fickian diffusion release mechanism, compared to a normal release period of 2-3 hours. The optimized insert showed promising results and can be used to treat a wide range of ocular infections.

Rabbit intraocular reactivity to endotoxin measured by slit-lamp biomicroscopy and laser flare photometry.

OBJECTIVE: To evaluate the ocular reactivity of the rabbit to an intracameral injection of a dispersive ophthalmic viscosurgical device (OVD) containing various levels of bacterial endotoxin using slit-lamp biomicroscopy and laser flare photometry. DESIGN: Experimental, randomized, masked animal study. PARTICIPANTS: Thirty Dutch-Belted rabbits. METHODS: The rabbits were randomized into 6 groups to receive 0.05 ml of a hydroxypropyl methylcellulose-based dispersive OVD to which had been added one of 5 different doses of bacterial endotoxin ranging from 0.02 to 1.4 endotoxin units (EUs) or a vehicle control to both eyes. The eyes were evaluated for anterior segment inflammation at baseline and 3, 6, 9, 24, 48, and 72 hours after injection using slit-lamp biomicroscopy and laser flare photometry. MAIN OUTCOME MEASURES: Corneal clarity and anterior chamber (AC) inflammation. RESULTS: All the corneas remained clear throughout the study. Anterior chamber cells were seen at 6, 9, and 24 hours in 60% to 100% of the eyes intracamerally injected with endotoxin-containing OVD, and the response declined rapidly after 24 hours. A dose-response effect was seen between the concentration of endotoxin and the AC cell response. The aqueous flare response in eyes injected with the 2 highest doses of endotoxin was significantly greater (P<0.05) than that of controls. The amounts of fibrin observed in the AC were random, with no apparent dose-response effect seen. The flare values as obtained by laser flare photometry were consistent with the slit-lamp biomicroscopy flare findings up to grade 3+. However, the increase in laser flare value seemed to level off in eyes with more than 3+ flare. Neither measure of flare correlated with endotoxin level. CONCLUSIONS: Among the parameters evaluated in this study, the AC cell response, evaluated by slit-lamp biomicroscopy and graded using a standard grading system, was found to be the most reliable indicator of the amount of endotoxin in the dispersive OVD. The use of laser flare photometry alone does not seem to be useful in detecting an ocular response to endotoxin contamination in OVDs.

Assessment of hydroxypropyl methylcellulose, propylene glycol, polysorbate 80, and hydroxypropyl-ß-cyclodextrin for use in developmental and reproductive toxicology studies.

BACKGROUND: A series of studies were conducted to assess Polysorbate 80 (PS80), Propylene Glycol (PG), and Hydroxypropyl-ß-Cyclodextrin (HPßCD), when compared with Hydroxypropyl Methylcellulose (MC) in developmental and reproductive toxicology (DART) studies. METHODS: In the rat fertility study, 20 mg/kg MC, 10 mg/kg PS80, 1,000 mg/kg PG, 500 mg/kg HPßCD or 1,000 mg/kg HPßCD were administered orally before/during mating, and on gestation Day (GD) 0-7, followed by an assessment of embryonic development on GD 14. In the rat and rabbit teratology studies, the doses of MC, PS80, PG, and HPßCD were the same as those in the fertility study. In these teratology studies, pregnant females were dosed during the period of organogenesis, followed by an assessment of fetal external, visceral, and skeletal development. RESULTS: In the rat fertility and rat teratology studies, PS80, PG, and HPßCD did not exhibit toxicity, when compared with MC. Similarly, in the rabbit teratology study, there was no PS80 or PG-related toxicity, when compared with MC. However, individual rabbits in the 500 and 1,000 mg/kg HPßCD groups exhibited maternal toxicity, which included stool findings, decreased food consumption, and body weight gain. Furthermore, one rabbit each in the 500 and 1,000 mg/kg HPßCD groups exhibited evidence of abortion, which was considered secondary to maternal toxicity. CONCLUSIONS: Although HPßCD was not well tolerated in rabbits at doses of 500 and 1,000 mg/kg, PS80 and PG were comparable to MC and should be considered for use in developmental and reproductive toxicology studies.

Comprehensive investigation of hydroxypropyl methylcellulose, propylene glycol, polysorbate 80, and hydroxypropyl-beta-cyclodextrin for use in general toxicology studies.

This study was conducted to assess the safety and tolerability of the alternative formulation vehicles polysorbate 80 (PS80), propylene glycol (PG), and hydroxypropyl-beta-cyclodextrin (HPßCD) in general toxicology studies in the mouse, rat, dog, and monkey. Twenty (20) mg/kg of hydroxypropyl methylcellulose (MC, control), 10 mg/kg PS80, 1000 mg/kg PG, 500 mg/kg HPßCD, or 1000 mg/kg HPßCD were administered by oral gavage to mice, rats, dogs, and cynomolgus monkeys for approximately 90 days. The effects of these formulations on clinical observations, body weight and food consumption parameters, clinical pathology, and histopathology were evaluated across all species. The suitability of formulations containing up to 20 mg/kg MC, 10 mg/kg PS80, and 1000 mg/kg PG for use in preclinical safety studies was confirmed by a lack of effects on all parameters examined. However, formulations containing HPßCD produced elevated transaminase (aspartate and alanine aminotransferase) levels in rats and mice and fecal changes (loose and soft stool) in large animals. Although the etiology and toxicological significance of the transaminase elevations in rats and mice is uncertain, this finding could represent a significant liability for a preclinical formulation because of the critical importance of these biomarkers in the risk assessment of novel therapeutic agents. Based on these data, PS80 and PG are considered to be practical alternatives to MC in preclinical toxicology studies. However, formulations containing HPßCD should be used with caution because of the elevations in rodent transaminase levels.

Nourish and nurture: development of a nutrient ocular lubricant.

PURPOSE: The authors aimed to produce a new tear substitute capable of providing both lubrication and nutrition, based on a novel nutrient-containing therapeutic ocular surface medium (TOSM). METHODS: Viscous substances, including hypromellose (HPMC), carbopol, and sodium hyaluronate (SH) were added to the TOSM at various concentrations. Three commercial preservative-free artificial tear substitutes, Hypromellose (Pharmacy of Moorfields Eye Hospital, London, UK), Thilo-Tears (a carbomer; Alcon Pharma GmbH, Freiburg, Germany), and Vislube (a hyaluronate; Chemedica AG, Munich, Germany) were used as control preparations. Their viscosity and surface tension were measured. Human corneal (HCE-T) and conjunctival (IOBA-NHC) cell lines were used to investigate cell proliferation and viability in response to the formulations by means of a luminescence-based ATP assay and a calcein AM/EthD-1 assay. RESULTS: HPMC, carbopol, and SH increased the viscosity of TOSM significantly. The surface tension of TOSM was reduced by HPMC, but not by carbopol or SH. TOSM-HPMC supported cell proliferation and viability better than TOSM-carbopol and TOSM-SH. TOSM-HPMC and TOSM-carbopol supported cell proliferation significantly better than the corresponding commercial artificial tears. However, TOSM-Vislube supported cell growth significantly better than TOSM-SH. CONCLUSIONS: TOSM-HPMC showed superior lubricant and nutrient properties with moderate viscosity and little cytotoxicity. It thus could be an ideal nutrient and lubricant tear substitute for dry eyes and should be evaluated in a clinical study.

[Toxicity of a new moistening agent and preservative in vitro]. / Toxizität neuer Benetzungs- und Konservierungsmittel in vitro.

PURPOSE: The use of preservatives such as benzalkonium chloride (BAC) usually increases the toxicity of pharmaceutical tear substitutes. HP-guar has been recently introduced as a new artificial tear substitute and includes the preservative Polyquad (0.001%), which is considered to be non-toxic. We therefore examined the effect of preserved (cetrimide 0.01%) and unpreserved HPMC (hydroxypropylmethyl cellulose) and HP-guar in dose and time-response experiments in a human corneal and conjunctival epithelial cell culture model. METHODS: Immortalized human conjunctival and corneal epithelial cells were cultured in 96-well plates at 37 degrees C with 5% CO(2) and exposed to the test solutions. The ATP content was quantified by means of a luminescence-based ATP assay, intracellular esterase activity by double fluorescent viability staining (calcein AM/ethidium homodimer D-1) and cell migration by a colony dispersion assay. All experiments were performed in triplicate and repeated at least once. The significance of differences was determined with an unpaired two-sided t-test. RESULTS: HPMC with preservative severely reduced the ATP content at all concentrations tested. Unpreserved HPMC, however, showed an inhibition of ATP production only at 100% and good esterase activity. HP-guar with and without preservative were found to reduce ATP activity more than unpreserved HPMC, but the unpreserved solution was found to reduce cellular ATP levels significantly more than the preserved solution. CONCLUSIONS: The new preservative Polyquad induced significantly less cytotoxicity than cetrimide. However, even unpreserved HP-guar can induce cytotoxicity in vitro, while unpreserved HPMC remains a good alternative tear substitute with low cytotoxicity.

Safety assessment of hydroxypropyl methylcellulose as a food ingredient.

Hydroxypropyl methyl cellulose (HPMC; CAS No. 9004-65-3) is an odorless and tasteless, white to slightly off-white, fibrous or granular, free-flowing powder that is a synthetic modification of the natural polymer, cellulose. It is used in the food industry as a multipurpose food ingredient. HPMC is approved by FDA as both a direct and an indirect food additive, and is approved for use as a food additive by the EU. The JECFA has evaluated the food uses of HPMC and established an acceptable daily intake (ADI) of 'not specified' for such uses. Based on the no-observed-adverse-effect level (NOAEL) of 5000 mg/kg body weight/day from a 90-day feeding study in rats, a tolerable intake for ingestion of HPMC by humans of 5 mg/kg body weight/day is posited and, as such, is more than 100-fold greater than the estimated current consumption of 0.047 mg/kg body weight/day.

Effects of miglyol 812 on rats after 4 weeks of gavage as compared with methylcellulose/tween 80.

Miglyol 812 is a medium-chain triglyceride used in toxicology studies as an excipient to improve test compound solubility/absorption. As part of a larger toxicology study, 15 Wistar Han IGS rats/sex/group were dosed by oral gavage for 4 weeks with 10 mL kg(-1) day(-1) of 100% Miglyol 812 or 0.5% methylcellulose/0.1% Tween 80 in water (MC-T) followed by 4 weeks without treatment to evaluate the potential effects of this excipient in long-term toxicology studies relative to a traditional excipient such as MC-T. Clinical signs evident during the dosing phase included soft and/or mucoid stool in 12/15 males and 11/15 females treated with Miglyol 812 but in no animals treated with MC-T. Animals treated with Miglyol 812 had a 6-7% statistically significant reduction in body weight gain as compared to MC-T-treated animals. Statistically significant changes in clinical chemistry parameters as compared to MC-T included decreased blood urea nitrogen (50% and 29% in males and females, respectively), increased cholesterol (1.6-fold and 1.5-fold in males and females, respectively), decreased total protein (6% and 8% in males and females, respectively), decreased globulins (15% and 11% in males and females, respectively), and increased triglycerides (2.8-fold and 1.7-fold in males and females, respectively). Absolute and relative thymic weights decreased 28% and 24%, respectively, in males, and 18% and 17%, respectively, in females without histological alterations. Histopathology revealed increased alveolar histiocytosis with focal interstitial inflammation in lungs in 5/10 males and 7/10 females treated with Miglyol 812 compared to only 1/10 males and 1/10 females treated with MC-T. All effects were reversible during the recovery period. Results of this study indicate that 100% miglyol 812 produces reversible gastrointestinal effects and decreases in body weight gains along with changes in several serum chemistry parameters. Therefore, it should not be considered innocuous when delivered by oral gavage in long-term rodent toxicology studies.

Use of proteomic methods to identify serum biomarkers associated with rat liver toxicity or hypertrophy.

BACKGROUND: Our objectives were to identify serum marker proteins in rats that might serve as sensitive indicators of hepatomegaly, hepatocellular necrosis, or hepatobiliary injury and to use them to analyze data from a collaborative proteomics project. METHODS: In each of 4 studies comprising the collaborative project, rats were given 1 of 4 compounds that target the liver through different mechanisms. Sera and liver samples were collected by terminal bleeds at 1 of 3 postdose time points. Sera were depleted of major secretory proteins and then separated into protein features by 2-dimensional gel electrophoresis (2DGE). Liver specimens were also processed and subjected to 2DGE. Protein spots that significantly increased or decreased in quantity after drug treatment were recovered, digested, analyzed by mass spectroscopy, and compared with available databases for identification. Criteria for further consideration were (a) temporal expression (i.e., increase or decrease at early, fulminant, or recovery periods), (b) known biological function, (c) probable hepatic origin, and (d) any previous association with toxicity in published studies. Markers that changed significantly at the early time point were important because of their potential sensitivity for signaling minimal damage. RESULTS: Vitamin D-binding protein, paraoxonase, cellular retinol-binding protein, malate dehydrogenase, F-protein, and purine nucleoside phosphorylase were identified as empirically confirmed serum markers for hepatic effects in drug-treated rats. CONCLUSION: Proteomics can be applied for the identification and confirmation of peripheral biomarkers for altered liver function after toxicant exposure.

Embryo/fetal development studies with hydroxypropyl methylcellulose acetate succinate (HPMCAS) in rats and rabbits.

BACKGROUND: Hoshi et al. [Hoshi et al. J Toxicol Sci 10(Suppl):187-255, 1985a,b,c,d] evaluated the potential for hydroxypropyl methylcellulose acetate succinate (HPMCAS) to produce developmental and reproductive toxicity in a series of studies that included rat and rabbit teratology studies, a rat fertility study, and a rat peri- and postnatal study. The authors concluded that there were no compound-related findings. In the cesarean-section phase of the rat teratology study, however, clubfoot was reported for 0.8, 2.1, 5.5, and 4.1% of fetuses in the control, 625, 1250, and 2500 mg/kg groups, respectively. There were no significant increases in external anomalies, but the apparent dose-related increase in clubfoot was not specifically addressed. In the rabbit teratology study, the number of litters evaluated (12-13 per group) was not consistent with current regulatory guidelines. Therefore, to definitively establish the potential of HPMCAS to produce developmental toxicity, embryo/fetal development studies were carried out in rats and rabbits. METHODS: Groups of 20 pregnant Sprague-Dawley rats and New Zealand White rabbits were dosed with 0, 50, 150, 625, or 2500 mg/kg HPMCAS from gestational day (GD) 6-17 or GD 7-19 for rats and rabbits, respectively. Fetuses were collected by cesarean section and examined for external, visceral and skeletal development. RESULTS: No developmental toxicity was observed as a result of HPMCAS exposure demonstrating that maternal HPMCAS exposure during gestation does not induce developmental anomalies. There were no findings of clubfoot or other limb anomalies in these studies at dose levels equivalent to those that were previously associated with a possible increase in clubfoot. CONCLUSIONS: The conclusion of the earlier study indicating that treatment with HPMCAS at doses up to and including 2500 mg/kg did not produce developmental toxicity was confirmed with these studies. It is likely that the clubfoot noted in the earlier rat teratology study was a misdiagnosis or artifact.

Toxicity of natural tear substitutes in a fully defined culture model of human corneal epithelial cells.

PURPOSE: Serum and saliva have recently been advocated as natural tear substitutes for intractable aqueous-deficient dry eyes, but the effects of these fluids on corneal epithelium have not been well characterized. A laboratory study was performed in a defined test model to compare the toxicity of natural and pharmaceutical tear substitutes and to identify potentially toxic factors in natural tear substitutes, such as amylase, hypotonicity, and variations in preparation. METHODS: Primary human corneal epithelial cells were cultured with defined keratinocyte serum-free medium. The cells were incubated with hypromellose (hydroxypropylmethylcellulose 0.3%) with and without benzalkonium chloride 0.01%, saliva with differing osmolalities, 100% serum, and 50% serum (1:1 vol/vol with chloramphenicol 0.5%) for varying times and concentrations. Toxicity was examined in four ways. Microvillous density was assessed with scanning electron microscopy. Cell membrane permeability and intracellular esterase activity were analyzed after staining with fluorescent calcein-AM/ethidium homodimer and cellular adenosine triphosphate (ATP) was quantified using a luciferin-luciferase-based assay. RESULTS: The toxicity ranking of the tear substitutes correlated in all assays. The ATP assay was the most sensitive, followed by ethidium cell permeability, and finally the esterase activity. Preserved hypromellose was more toxic than the unpreserved preparation. Among natural tear substitutes, natural saliva was most toxic. Isotonic saliva and 50% serum were of similar toxicity, and 100% serum was least toxic. Natural tear substitutes were-except for natural saliva-less toxic than unpreserved hypromellose. Hypotonicity, but not amylase, was the major toxic effect associated with saliva. The dilution of serum with chloramphenicol induced toxicity. CONCLUSIONS: This is the first toxicity study using human primary corneal epithelial cells cultured under fully defined conditions as an in vitro model. Cellular ATP is a sensitive parameter for quantifying toxicity. Isotonic saliva and serum offer greater therapeutic potential for severely aqueous-deficient dry eyes than do pharmaceutical tear substitutes.

[Cytotoxicity evaluation of three tear substitutes used in the treatment of dry eye syndromes]. / Evaluation de la cytotoxicité de trois substituts lacrymaux utilisés dans le traitement des syndromes secs.

PURPOSE: To investigate cell tolerance of three tear substitutes used in the treatment of dry eye syndromes. METHODS: Cytotoxicity tests were done on a continuous human conjunctival cell line using microplate cold light cytofluorimetry. Membrane integrity, DNA condensation and reactive oxygen species (ROS) production (hydrogen peroxyde and superoxide anion) were evaluated after 15 minutes of treatment or 15 minutes and 24 hours of cell recovery. Hyaluronic acid, hydroxypropyl methylcellulose associated with sodium perborate (HPMC) and carbomer 934P were tested at their commercial concentrations (respectively 0.18%, 0.3% and 0.3%) and after a 1/10 dilution. RESULTS: Cell viability and chromatin condensation were not altered by hyaluronic acid for all concentrations and times tested. A decrease in membrane integrity was observed with 0.3% carbomer 934P after 24 hours of cell recovery and with 0.3% HPMC after 15 minutes. This decrease was amplified after 24 hours and associated with an apoptotic phenomenon. A H(2)O(2) production was observed with HPMC associated with sodium perborate and an O(2) production was found with hyaluronic acid diluted at 1/10. CONCLUSION: Hyaluronic acid, carbomer and HPMC are in vitro well-tolerated even if HPMC induces a more important decrease of cell viability compared to the other drugs. Hyaluronic acid, with its rheologic properties, with no in vitro toxicity, seems to be efficient for dry eye patients.

A three-month repeated oral administration study of a low viscosity grade of hydroxypropyl methylcellulose in rats.

The toxicity of the lowest viscosity grade of hydroxypropyl methylcellulose (HPMC) that is currently commercially available was investigated by means of a three-month repeated oral administration study in male and female Crj:CD (SD) IGS rats at doses of 505, 1,020 and 2,100 mg/kg/day. Body weights of males and females in the 2,100 mg/kg group were lower than those of the control group on and after day 28 of administration, but the differences were not statistically significant. The degree of suppression of body weight gain in males was higher than that in females. This tendency was similar to the results in other toxicity studies of HPMC that have been reported. Males in the 2,100 mg/kg group showed a tendency (not significant) for decreased food consumption and urine volume. Examinations of general signs, hematology, blood chemistry, ophthalmology, absolute and relative organ weights, autopsy and histopathology revealed only a few, apparently coincidental, statistically significant differences from the control, and no evidence of any dose-dependent changes was found. It was concluded that the lowest viscosity grade of HPMC showed extremely low toxicity under the conditions of this study, as has been found for higher viscosity grades.

Skin sensitization and photosensitization studies of hydrophobically modified hydroxypropyl methylcellulose in guinea pigs.

Skin sensitization and photosensitization tests of hydrophobically modified hydroxypropyl methylcellulose (HM-HPMC), a new cellulose derivative used as a thickener for topical pharmaceuticals, were conducted using guinea pigs. An aqueous dispersion of HM-HPMC (3 w/v %) was applied in the tests. Skin reaction was not observed in any animal in the HM-HPMC-treated group or control group. In the photosensitization test, no skin reaction was found in any animal in the test-preparation group or the control group. It was concluded that HM-HPMC dispersion does not exhibit skin sensitizing or photosensitizing activity under the condition of this test.

A repeated-dose dermal toxicity study of hydrophobically modified hydroxypropyl methylcellulose in rats.

A six-month repeated-dose dermal toxicity study followed by a 30-day recovery test of hydrophobically modified hydroxypropyl methylcellulose (HM-HPMC), a new cellulose derivative used as a thickener for topical pharmaceuticals, was conducted using rats. Aqueous paste of HM-HPMC was applied to the skin of rats once daily at dose levels up to 60 mg/kg/day, which was the highest dose that could be administered. Items checked included general signs, urinalysis, hematology, ophthalmology, and histopathology. One rat died during the administration period owing to a malignant tumor in the hemopoietic system, which was not attributed to the test substance. Statistically significant differences were found in some test results, but those were not dose-dependent and were considered to be incidental or spontaneous. It was concluded that the test substance was not toxic upon chronic dermal administration at dose levels up to 60 mg/kg/day.

Effects of viscoelastics on bovine corneal endothelial cells in vitro.

PURPOSE: To evaluate the possible toxic effects of sodium hyaluronate and hydroxypropyl methylcellulose on corneal endothelium. METHODS: Cultured bovine corneal endothelial cells (BCEC) were treated with either original Healon (10 mg/ml) or Methocel (20 mg/ml) for 1 h, or with various dilutions of these substances in culture medium for up to one week. The toxicity of the viscoelastics was assessed in terms of lactate dehydrogenase (LDH) release into the supernatant and of cell density. RESULTS: Neither Healon nor Methocel in a dilution of 2 mg/ml enhanced LDH release after 72 h incubation, when compared with the control in a confluent model. In a proliferation model neither diluted Healon nor Methocel showed apparent inhibitory or stimulatory effects on the growth of BCEC up to the highest concentration we tested. When a BCEC monolayer was covered for 1 h with either undiluted Healon or undiluted Methocel, a significant, though transient, higher LDH release was induced. CONCLUSION: The results indicate that the diluted viscoelastics are safe for long time contact with BCEC, but undiluted they may temporarily interfere with the metabolism of the cytoplasm membranes of BCEC.