Permeability of the Cornea to Topically Applied Drugs

Benson, Harriet

doi:10.1001/archopht.1974.03900060323017

Cited by 88 publications

(20 citation statements)

References 58 publications

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“…To pass through both the epithelium and the stroma, a molecule must have good solubility in both lipid and aqueous phases [6, 7]. Elimination of the hydrophilic component of this barrier, the epithelium and anterior stroma, will facilitate penetration of low-molecular-weight polar substances into the corneal stroma [8]. PRK, which involves removal and ablation of the corneal epithelium, Bowman’s layer and anterior stroma, which are crucial elements of the corneal barrier, will thus be expected to alter corneal permeability.…”

Section: Discussionmentioning

confidence: 99%

Does Photorefractive Keratectomy Alter the Effect of Topical Medications?

Nemet

Morad

2002

Ophthalmologica

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Introduction: The influence of photorefractive keratectomy (PRK) on drug penetration into the eye is not yet established, as this procedure may alter the barrier function of the cornea as well as the blood ocular barrier. Pupillary response to topical tropicamide depends on its penetration into the anterior chamber. The purpose of this study was to examine the influence of PRK on pupillary response to topical tropicamide, and hence to evaluate whether PRK alters drug penetration into the eye. Methods: Pupillary diameter was measured using infrared pupillometer at 0, 15 and 30 min after instillation of 0.1% tropicamide to both eyes of 28 patients 4 weeks after PRK in one eye. The untreated eye served as control. Results: Pupillary diameter before and 30 min after dilation was 7.4 ± 1.2 and 8.0 ± 1.0 mm in the treated eyes and 7.5 ± 1.2 and 8.1 ± 1.0 mm in the untreated eyes, respectively (p = 0.45). Percentage of pupillary dilation (Δ pupillary diameter/pupillary diameter at 0 min ×100) was also similar in treated and untreated eyes for the entire study group (12.5 and 10.5%, respectively, p = 0.17). A trend for greater dilation was seen in patients with myopia above 6 diopters (13.7 and 10.5% in treated and untreated eyes, respectively, p = 0.11) and cornea thinner than 540 µm (14.2 and 10.1% in treated and untreated eyes, respectively, p = 0.1). Discussion: Our results confirm animal and human studies that found restoration of the ocular drug barrier at 4 weeks following PRK. The trend for greater penetration in patients with high myopia and thin corneas warrants further study on a larger cohort of this subgroup.

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Section: Discussionmentioning

confidence: 99%

Does Photorefractive Keratectomy Alter the Effect of Topical Medications?

Nemet

Morad

2002

Ophthalmologica

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“…When significant aqueous humor levels of an antibiotic are desired, the preferred route of administration is either topical fortified application or subconjunctival injections [1, 14]. Aqueous humor concentrations of 1.0 µg/ml of amikacin are expected to be bactericidal for most gram-negative bacterial pathogens, whereas levels of 3.5 µg/ml would inhibit most strains of Staphylococcus aureus and many strains of Pseudomonas aeruginosa [15].…”

Section: Discussionmentioning

confidence: 99%

Penetration of Amikacin into Aqueous Humor of Rabbits

et al. 2001

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Amikacin is an aminoglycoside antibiotic that has poor corneal penetration due to its hydrophilic properties. The purpose of this study was to compare and evaluate the penetration of amikacin sulfate into aqueous humor of the rabbit eye when applied by different routes and concentrations, namely 100 or 250 mg/ml topical fortified amikacin eye drops, 100 or 250 mg/ml amikacin-embedded soft contact lenses and 25 mg subconjunctival amikacin injection. One hour after application, amikacin was not detectable in any of the 100 mg/ml concentration groups. High levels of amikacin above the minimum inhibitory concentration for susceptible bacteria were detected when applied subconjunctivally and by 250 mg/ml topical fortified routes. Topical fortified amikacin 250 mg/ml reached the highest value in the aqueous (p < 0.05). Our results point out the poor corneal penetration of amikacin in standard concentrations from the intact rabbit cornea and that subconjunctival injections might provide satisfactory penetration.

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“…Therefore, local delivery is preferred especially when the in¯ammatory disease is limited to the eye (Stanbury and Graham, 1998). Frequent topical administration of eye drops or subconjunctival injections may induce suf®cient concentrations of drugs within the anterior segment of the eye (Mc Catney et al, 1965;Benson, 1974;Demailly, Hamard and Luton, 1976;Leibowitz and Kupferman, 1977). However, to achieve effective tissue concentrations in the posterior segment of the eye, systemic administration, intravitreal or periocular injections are necessary (Barry, Rousseau and Babineau, 1969;Demailly et al, 1976;Bodker et al, 1993;Weijtens et al, 1997Weijtens et al, , 1998.…”

Section: Introductionmentioning

confidence: 99%