Nursabah E. Basci

Penetration of topically applied ciprofloxacin and ofloxacin into the aqueous humor and vitreous

Purpose: To determine the intraocular penetration of topical drops of 2 antibiotics, ciprofloxacin 0.3% and ofloxacin 0.3%, into the aqueous humor and vitreous and to relate these levels to the miminum inhibitory concentration (MIC90) for organisms associated with ocular bacterial infections. Setting: Department of Ophthalmology, Ankara Hospital, and Department of Pharmacology, Faculty of Medicine, Hacettepe University, Ankara, Turkey. Methods: This prospective randomized clinical trial comprised 18 patients having cataract surgery, all with an intact corneal epithelium. The patients were randomly assigned to receive topical ciprofloxacin 0.3% (n = 10) or topical ofloxacin 0.3% (n = 8) 1 drop every 15 minutes 5 times and every 30 minutes 3 times before surgery. Aqueous and vitreous samples (if vitreous loss occurred during the cataract surgery) were collected 30 minutes after the administration of the last dose. Drug concentrations were determined by high‐performance liquid chromatography (HPLC) fluorescence. Results: All patients had detectable drug concentrations in the aqueous humor and vitreous measurable by HPLC. The mean aqueous humor concentration of ciprofloxacin was 1.13 &mgr;g/mL ± 1.90 (SD) and the mean vitreous concentration, 0.23 ± 0.06 &mgr;g/mL. Topical administration of ciprofloxacin yielded 4.9 times more drug concentration in the anterior chamber than in the vitreous. The mean aqueous concentration of ofloxacin was 2.06 ± 1.06 &mgr;g/mL and the mean vitreous concentration, 0.46 ± 0.10 &mgr;g/mL. Topical administration of ofloxacin yielded 4.7 times more drug concentration in the anterior chamber than in the vitreous. Aqueous humor concentrations of ofloxacin and ciprofloxacin were not statistically significantly different (P = .353). Intravitreal concentrations of ofloxacin were statistically significantly higher than those of ciprofloxacin (P = .001). Conclusions: Topical ofloxacin 0.3% penetrated better than topical ciprofloxacin 0.3% into the anterior chamber and vitreous in noninflamed eyes. Both drugs were above the MIC90 for most ocular pathogens in the anterior chamber. The mean concentration in the vitreous of topically applied ofloxacin 0.3% was statistically significantly higher than that of ciprofloxacin 0.3%, but it was not sufficiently above the MIC90 for most ocular pathogens in terms of empirical endopthalmitis therapy.

Optimization of mobile phase in the separation of β-blockers by HPLC

Abstract β-blockers are generally determined using high-performance liquid chromatography (HPLC). Previous HPLC separations of β-blockers have often required a mobile phase containing three components; acetonitrile or methanol to control the retention; buffer to control the ionic strength and pH of the mobile phase; ion-pairing reagent to provide adequate retention of β-blockers or organic amines as masking agent to reduce peak tailing. Due to the complexity of the mobile phases employed, development of these assays can be a laborious process. Additionally, alkyl sulphonates and organic amines dramatically reduces the life-time reduction of silica based C18 columns. The results of this study demonstrated that the addition of tested alkyl sulphonates and organic amines is not essential for an adequate separation of β-blockers. In this study, we developed a simple HPLC method for the simultaneous separation of model β-blockers, atenolol, practolol, metoprolol, oxprenolol and propranolol. Atenolol, practolol, metoprolol, oxprenolol and propranolol adequately separated with high peak symmetries using a mobile phase consisted of methanol/acetonitrile/phosphate buffer (10 mM, pH 3.0) (15:15:70, v/v/v). By altering only the fraction of methanol with respect to acetonitrile, method development becomes a more efficient separation. Furthermore, atenolol, practolol, metoprolol, oxprenolol and propranolol can be detected up to 0.25, 5, 10, 50 and 10 ng ml−1. In this publication, we present the simultaneous separation of β-blockers having a wide range of polarity. It is proposed that this new mobile phase, consisting only acetonitrile, methanol and phosphate buffer can be used for the analysis of the several β-blockers presently in doping control analysis as well as others.

Determination of ofloxacin in human aqueous humour by high-performance liquid chromatography with fluorescence detection.

A reversed-phase high-performance liquid chromatographic method is described for the determination of ofloxacin in human aqueous humour; the method involves fluorescence detection (excitation at 290 nm; emission at 500 nm) after direct injection of samples. The method utilized a 100 mm x 8 mm i.d. cartridge column packed with 4 microns Novapak C18 with a mobile phase methanol-acetonitrile-0.4 M citric acid (3:1:10, v/v/v) and a flow rate of 1 ml min-1 at ambient temperature. The retention times for the internal standard pipemidic acid and for ofloxacin were 4.82 and 7.32 min respectively. The mean recovery (+/- ISD) from human aqueous humour was 103.24 +/- 4.45% for ofloxacin at 1 microgram ml-1 (n = 6). The within-day and day-to-day RSDs at 0.1 microgram ml-1 and 1 microgram ml-1 were less than 6.71% (n = 6) and the lower limit of reliable determination corresponding to a signal-to-noise ratio of 2.5:1 was 20 ng ml-1. The assay was shown to be suitable for measuring ofloxacin levels in human aqueous humour samples after topical, oral and intravenous administration.

Penetration of ofloxacin in human aqueous and vitreous humors following oral and topical administration.

Purpose: To determine aqueous and vitreous humor ofloxacin levels following oral and topical application of ofloxacin in patients with noninflamed cornea and intact crystalline lens, and to compare the drug levels provided by each route. Materials and Methods: Twenty‐six patients undergoing pars plana vitrectomy for various ocular pathologies were divided into two groups. Fourteen patients received two drops of 0.3% ophthalmic solution of ofloxacin every 30 minutes for 3 hours and every 60 minutes for the next 3 hours, and 12 patients received a single oral dose of 400 mg ofloxacin 8 hours before surgery. The aqueous and vitreous humor samples were simultaneously collected after oral or topical administration during pars plana vitrectomy to assess penetration of the drug. Samples were assayed for ofloxacin concentrations by a previously described method using high‐performance liquid chromatography. Results: The aqueous and vitreous humor levels of ofloxacin were 1.54 ± 0.27 μg/mL (mean ± standard error) and 1.77 ± 0.24 μg/mL after oral and 1.44 ± 0.24 μg/mL and 0.37 ± 0.05 μg/mL after topical ofloxacin administration, respectively. Aqueous humor levels were not statistically different following oral or topical administration (P > 0.8). However, vitreous level of the drug after oral administration was significantly higher than that after topical administration (P < 0.001). Conclusion: Ocular bioavailability of ofloxacin in aqueous humor after oral and topical administration is similar when the drug is applied as described. Penetration of ofloxacin into vitreous humor is less than that into aqueous humor following topical application. The aqueous humor levels of ofloxacin via both routes and the vitreous level of the drug after oral route exceed the minimum inhibitory concentrations for certain bacterial species that frequently cause intraocular infection.

Human aqueous and vitreous humour levels of ciprofloxacin following oral and topical administration

Purpose To assess aqueous and vitreous humour ciprofloxacin concentrations following oral and topical administration of ciprofloxacin in patients with non-inflamed cornea and an intact crystalline lens, and to compare the concentrations of the drug given by either route.Methods In this prospective study, 34 patients undergoing pars plana vitrectomy for various ocular pathologies were divided into two groups. Eighteen patients received 2 drops of 0.3% ophthalmic solution of ciprofloxacin every 30 min for 3 h and then every 60 min for the next 3 h, and 16 patients received a single oral dose of 1000 mg ciprofloxacin 6 h before surgery. The aqueous and vitreous humour samples were simultaneously harvested after oral or topical administration during pars plana vitrectomy to assess penetration of the drug. These samples were assayed for ciprofloxacin concentrations by a method described previously by us using high-performance liquid chromatography.Results The aqueous and vitreous humour levels of ciprofloxacin were 0.59 ± 0.06 μg/ml (mean ± SEM) and 0.64 ± 0.06 μg/ml after oral and 0.44 ± 0.07 μg/ml and 0.22 ± 0.04 μg/ml after topical ciprofloxacin administration, respectively. Aqueous humour levels were not statistically significantly different following oral and topical administration (p = 0.069). However, the vitreous level of the drug after oral administration was significantly higher than that after topical administration (p<0.001).Conclusion Ocular bioavailability of ciprofloxacin in aqueous humour following oral and topical administration is found to be similar when the drug was applied as described above. Penetration of ciprofloxacin into vitreous humour is less than that into aqueous humour after topical administration.

Rapid liquid chromatographic assay of ciprofloxacin in human aqueous humor

A simple, selective and sensitive method has been developed to determine ciprofloxacin in human aqueous humor. Separation of ciprofloxacin was carried out with pipemidic acid as internal standard using a Novapak C18 reversed-phase cartridge column (100 x 8 mm i.d., particle size 4 microns) and a mobile phase consisting of methanol-acetonitrile-citric acid (0.4 M) (3:1:10, v/v/v) at a flow rate of 1 ml min-1. The column effluent was monitored with fluorescence detection at 278 nm (excitation) and 450 nm (emission) after direct injection. The retention times were 4.88 min for pipemidic acid and 7.52 min for ciprofloxacin. The within-day and day-to-day reproducibilities were less than 7% for ciprofloxacin at 0.1 and 1 microgram ml-1 (n = 6). The mean recovery from aqueous humor was found to be 101.37 +/- 6.7% for ciprofloxacin at 0.1 micrograms ml-1 (n = 6 and the detection limit corresponding to a signal-to-noise ratio of 2.5:1 was 250 pg ml-1. The method was shown to be suitable for determining ciprofloxacin levels in human aqueous humor samples.

Penetration of ofloxacin and ciprofloxacin in Aqueous humor after topical administration

BACKGROUND AND OBJECTIVE To compare the aqueous humor levels of 0.3% ofloxacin and 0.3% ciprofloxacin containing eyedrops in patients with healthy cornea. PATIENTS AND METHODS Fifty patients with cataract were randomly assigned to have 0.3% ofloxacin containing eyedrop (25 patients) or 0.3% ciprofloxacin containing eyedrop (25 patients). Both drugs were repetitively instilled to each patient for 6 hours before the surgery. Aqueous samples were collected after penetrating the anterior chamber during cataract extraction and assayed by high-performance liquid chromatography method. RESULTS The aqueous humor level of ofloxacin (1.43 +/- 0.26 microg/ml, mean +/- SEM) was significantly higher than that of ciprofloxacin (0.35 +/- 0.07 microg/ml) following the topical application (P < .0002). CONCLUSION Aqueous humor penetration of topical ofloxacin is about 4 times higher than that of topical ciprofloxacin when the drugs are applied as described above.

Penetration of topical and oral ofloxacin into the aqueous and vitreous humor of inflamed rabbit eyes.

PURPOSE This study aimed to investigate the penetration of topical and oral ofloxacin into aqueous humor and vitreous humor in post-traumatic endophthalmitis model in rabbits. METHODS A standardized intraocular infection after penetrating injury was made in the right eyes of 16 rabbits. Intraocular infection was induced by intravitreal injection of a suspension of Staphylococcus aureus. The intact left eyes were maintained as controls. The animals were divided randomly into two groups. (1) In the topical group, two drops of ofloxacin 0.3% eyedrops were instilled to both eyes every 30 min for 4 h. (2) In the topical-oral group, two doses of 25 mg/kg of ofloxacin at 12-h intervals were given orally, then the protocol of the first group was applied. Aqueous and vitreous humor samples were taken 30 min after the last drop. Ofloxacin concentrations were measured by using HPLC. RESULTS Mean aqueous levels of ofloxacin in control eyes were: 3.25 +/- 2.55 microg/ml in topical group. 4.58 +/- 5.39 microg/ml in topical-oral group. Mean aqueous levels in inflamed eyes were: 5.21 +/- 4.55 microg/ml in topical group, 10.34 +/- 8.88 microg/ml in topical-oral group. Mean vitreous levels of ofloxacin in control eyes were: 0.17 +/- 0.07 microg/ml in topical group, 1.30 +/- 1.23 microg/ml in topical-oral group. Mean vitreous levels in inflamed eyes were: 0.35 +/- 0.22 microg/ml in topical group, 3.48 +/- 2.69 microg/ml in topical-oral group. There was no significant difference among the groups (P > 0.05), however. CONCLUSIONS The result of this study suggests that oral supplementation of ofloxacin to topical instillation increased the ocular levels of ofloxacin in the post-traumatic endophthalmitis model. Mean drug concentrations in aqueous and vitreous humors were above the 90% minimum inhibitory concentrations (MIC90) for most of the common microorganisms causing endophthalmitis in all eyes, except in the vitreous humors of the intact eyes instilled topically.

The penetration of ofloxacin into human aqueous humor given by various routes.

This study was designed to measure the concentration of ofloxacin in aqueous humor after topical, oral and intravenous administration in 50 patients undergoing cataract extraction. In Group 1, ofloxacin 0.3% eyedrops were topically instilled ten times and the aqueous humor concentration was 2.73 ± 0.88 μg/ml. In Group 2, ofloxacin 0.3% eyedrops were topically instilled six times and the aqueous humor concentration was 0.84 ± 0.61 μg/ml. Aqueous humor concentration 12 hours after 200 mg oral dose in Group 3, was 0.38 ± 0.12 μg/ml. In Group 4, patients were given ofloxacin as a single intravenous 200 mg dose and the aqueous humor concentration 2 hours after the end of infusion was 0.45 ± 0.11 μg/ml. Concentrations were determined by high performance liquid chromatography (HPLC) with fluorescence detection. There was a significant difference between Group 1 and the other groups, but not between Group 2 and Groups 3, 4. It was concluded that ofloxacin penetrates the corneal and the blood-aqueous barriers and can achieve good aqueous levels when given topically and systematically. Ofloxacin can be applied topically for external bacterial infections such as conjunctivitis and keratitis. Systematically administered ofloxacin reached higher levels than the MIC for some bacteria which cause endophthalmitis.

Aqueous humour levels of topically applied ciprofloxacin and ofloxacin in the same subjects

Purpose To evaluate aqueous humour levels of topical 0.3% ciprofloxacin and 0.3% ofloxacin in the same subjects.Methods Thirty-two bilateral cataractous patients received topical 0.3% ciprofloxacin in one eye and 0.3% ofloxacin in the other eye before each cataract extraction. Eyedrops were repetitively instilled for 6 h. Aqueous humour samples were collected and assayed for drug concentrations by a method described originally by us using high-performance liquid chromatography.Results Mean aqueous ciprofloxacin and ofloxacin levels were 0.33 ± 0.04 μg/ml (mean ± SEM) and 1.34 ± 0.14 μg/ml respectively (p<0.0001).Conclusion Ofloxacin level in the aqueous humour is 4 times higher than that of ciprofloxacin in the same subjects.