Cellular cytotoxicity of antiglaucoma drugs in cultured corneal endothelial cells

In this study, the various antiglaucoma drugs including betaxolol, timolol, levobunolol, carteolol, brimonidine, dipivefrin, dorzolamide, brinzolamide, latanoprost, unoprostone, and pilocarpine were used to investigate the effects of cellular cytotoxicity in cultured bovine corneal endothelial cells. After exposure to the drugs in three dilutions, 1/100, 1/1,000, and 1/10,000, for 100 minutes, cells were estimated based on the release assay of lactate dehydrogenase (LDH) enzyme. It was found that cellular LDH was significantly released in the medium only at 1/100th dilution of betaxolol, brimonidine, dorzolamide, dipivefrin, latanoprost and unoprostone to 130%, 123%, 145%, 157%, 128% and 237%, respectively, compared with controls upon exposure to drugs for 100 minutes. Moreover, benzalkonium chloride preservative at the concentrations ranging from 0.001 to 0.00001 mg/mL did not affect cellular LDH release in bovine corneal endothelial cells. These results indicate that high concentrations of antiglaucoma drugs may induce cytotoxicity in corneal endothelial cells.

[The effect of carteolol. Prolonged and increased effect by liposome suspension]

Liposomes are small lipid vesicles capable of trapping beta-blockers such as carteolol within their bilayer structure, the advantage being improved drug action, prolonged action time, and a reduction in drug concentration. In a prospective, randomized double-blind trial, carteolol 2%, liposomes (frozen and thawed multilamellar vesicles, FAT-MLVs), or carteolol 2% suspended with FAT-MLVs was applied to 25 eyes of 25 patients per group in a single 20 microliters dose. Intraocular pressure was measured for 3 days. A significant reduction in the IOP was observed in the patient groups receiving carteolol and carteolol suspended with liposomes. Moreover, improved action and prolongation of drug action was noted in the carteolol/MLV group as compared to carteolol treatment alone. Hence, carteolol 2% is suitable for reduction of IOP, but a reduction of drug concentration can be achieved by suspension with liposomes, thus reducing the side effects.

A comparison of the opacifying effects of carteolol.HCl and 8-hydroxycarteolol.HCl in the isolated porcine cornea

Using an in vitro method the authors have investigated whether 8-hydroxycarteolol.HCl(8-OH carteolol) and 8-OH carteolol with benzalkonium chloride affected intact isolated porcine corneas to the same or to a different degree as carteolol.HCl (carteolol) or carteolol with benzalkonium chloride. These ophthalmically used drugs were applied as solutions of varying concentrations to the epithelial surface only, to the endothelial surface only, or to both surfaces of porcine corneas. The resultant opacities were determined using an opacitometer. In general, 8-OH carteolol and 8-OH carteolol with benzalkonium chloride caused less opacity to develop than carteolol and carteolol with benzalkonium chloride. This suggests that 8-OH carteolol may be a safer drug than carteolol for ophthalmic use. It is very interesting to note that compounds with two nitrogens, e.g., 8-OH carteolol, caused greater opacity in the intact cornea when applied to the endothelial surface than when applied to both the epithelial and endothelial surfaces; however, compounds with none or one nitrogen caused greater opacity in the intact cornea when applied to both surfaces than when applied to the endothelial surface.

Evaluation of ocular toxicity of two beta blocking drugs, carteolol and practolol, in beagle dogs

The ocular effects of two beta blocking drugs, carteolol and practolol, were assessed in beagle dogs. Practolol-treated dogs showed a tear flow reduction: histopathological examination showed lymphocytic infiltration in the lacrymal glands and electroretinogram showed a decrease in the amplitudes of the A + B-wave. By contrast, no drug-related abnormal changes were observed in carteolol-treated dogs. These results were thought to indicate that a tear flow measurement and electroretinogram examination should be used in the evaluation of the safety of beta blocking drugs.

Reproduction study of carteolol hydrochloride in mice. Part 2. Peri -and postnatal toxicity

Carteolol was orally administered to mice once a day at doses of 3, 30 and 150 mg/kg/day during the perinatal and lactation periods and evaluated on its adverse effects on pregnant animals and their offspring. No appreciably abnormal findings related to the drug administration were revealed. Therefore, it was concluded that carteolol have no serious toxic potential on parturition and lactation by mother animals, no adverse effects on growth and development, and behavioral and reproductive performance of offspring and no carcinogenic action through placental and milk transfer.