Intraocular Penetration of Bacitracin and Polymixin B after Administration by Means of Hydrophilic gel Contact Lenses

Abstract

Hydrophilic contact lenses made of poly(hydroxyethylmethacrylate) gel were saturated with 1-percent [¹⁴C]-glycyl-bacitracin or 0.1 -percent[¹⁴C]-glycyl-polymixinBand then applied to the eye of rabbits for 1, 3 and 5 h. The rabbits were afterwards killed, the eyes enucleated and radioactivity was measured in the contact lenses, the corneas and in an aliquot of aqueous. It was found that in the 1st hour bacitracin was freed from the contact lenses somewhat more rapidly than polymixin B, after 5 h, however, the content of both antibiotics in the contact lenses was approximately the same, about 40% of the original amount contained in the saturated lenses. Penetration of bacitracin into the cornea and aqueous was also higher than that of polymixin B, on an average six times as high in the 1st hour, four times as high after 3 h and twice as high after 5 h application of the contact lenses. The results show that these antibiotics are easily released from the hydrophilic gel, but that penetration into the eye depends upon the structure and size of the molecule.

Intraocular Penetration of Cysteine from Hydrophilic Gel Contact Lenses through the Intact, Epithelium-Denuded and Lime-Burned Cornea

“…For a successful treatment of some ocular disorders the possibility of drug pene tration from hydrophilic contact lens through the cornea seems to be most important. This fact was studied in our other papers dealing with the applica tion of glucose and sulfate , antibiotics [Brettschneider et al, 1975], and ethylenediaminetetraacetate [Praus et al, 1976], The penetration of a medication is not only a matter of simple diffusion. The epi thelium and endothelium are relatively impermeable to electrolytes, but are readily penetrated by fat-soluble substances.…”

“…As in our other studies Brettschneider et al, 1975], hydrophilic gel contact lenses made of poly(hydroxyethylmethacrylate), 13.5 mm in diameter and 0.5 mm thick (Spofa Lens, Ergon, Prague) were used in all experiments. Before application they were rinsed with distilled water, dried in vacuo and then incubated in a solution of cysteine hydrochloride at normal temperature overnight.…”

Yellow-Brown Cornea: A Complication of Topical Use of Tetracycline

“…1974;Brettschneider et at., 1975;K rejci et al, 1976], hydrophylic contact lenses (HGCL) made of poly(hydroxyethylmethacrylate), 13.5 mm in diameter and 0.5 mm thick (Spofa Lens, Ergon, Prague) were used in all ex periments. Before application they were rinsed with distilled water, dried in vacuo and then immersed in a 1% solution of TTC hydrochloride (Biotika, Czechoslovakia) at normal temperature over-night.…”