The potential use of quinolones in future ocular antimicrobial therapy

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.

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 (MIC(90)) 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 microg/mL +/- 1.90 (SD) and the mean vitreous concentration, 0.23 +/- 0.06 microg/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 microg/mL and the mean vitreous concentration, 0.46 +/- 0.10 microg/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 MIC(90) 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 MIC(90) for most ocular pathogens in terms of empirical endopthalmitis therapy.

Comparison of antibiotic drops placed in the conjunctival cul-de-sac to antibiotic ointment applied to the lid margin in reduction of bacterial colonization on the lid margin

PURPOSE

To compare the efficacy of antibiotic drops placed in the conjunctival cul-de-sac to antibiotic ointment applied to the lid margin in reduction of bacterial colonization on the lid margin.

METHODS

A randomized, prospective, single-masked study was conducted on 19 patients with culture-proven colonization of bacteria on the lid margins. Ophthalmic eligibility criteria included the presence of > or =50 colony-forming units/mL (CFU/mL) of bacteria on both right and left lids. Each patient received one drop of ofloxacin in one eye every night for one week, followed by one drop once a week for one month. In the same manner, each patient received bacitracin ointment (erythromycin or gentamicin ointment if lid margin bacteria were resistant to bacitracin) to the lid margin of the fellow eye. Quantitative lid cultures were taken at initial visit, one week, one month, and two months. Fifteen volunteers (30 lids) served as controls. Lid cultures were taken at initial visit, one week, and one month.

RESULTS

Both antibiotic drop and ointment reduced average bacterial CFU/mL at one week and one month. Average bacterial CFU/mL reestablished to baseline values at two months. There was no statistically significant difference between antibiotic drop and ointment in reducing bacterial colonization on the lid margin.

CONCLUSION

Antibiotic drops placed in the conjunctival cul-de-sac appear to be as effective as ointment applied to the lid margins in reducing bacterial colonization in patients with > or =50 CFU/mL of bacteria on the lid margins.

Management of infectious scleritis after pterygium excision

PURPOSE

We sought to describe the clinical features, responsible pathogens, management, and prognosis of infectious scleritis after pterygium excision.

METHODS

A retrospective study through review of medical records of patients diagnosed with infectious scleritis after pterygium excision over a 10-year period at our institution.

RESULTS

A total of 16 cases of infectious scleritis after pterygium excision was identified. Among them, eight were associated with sclerokeratitis, and six had multifocal scleral nodules with subconjunctival abscesses. Culture results were positive in 15 (93.8%) cases. Pseudomonas was isolated in 13 (81.3%) patients, fungus in three (18.8%), and two had a mixed growth (12.5%). Based on the in vitro susceptibility test, four (31%) Pseudomonas isolates were resistant to gentamicin, whereas all isolates were sensitive to amikacin. During the course of treatment, eight cases were complicated by vitreous opacity, four developed glaucoma, four had serous retinal or choroidal detachment, and two had secondary cataract. Scleral infection recurred in two patients after cessation of therapy. Among the nine patients treated with medical therapy, two eyes were enucleated, whereas only two attained a visual acuity of > or =2/200 at the end of the follow-up period. On the other hand, seven patients had combined antibiotic therapy and surgical debridement. The number of surgical debridement ranged from one to three, with an average of 1.4. In this combined-treatment group, only one patient required enucleation, and five cases attained a visual acuity of > or =2/200. The duration of hospitalization for patients with combined treatment was 21.2+/-4.8 days compared with the 28.4+/-5.0 days for those with medical treatment alone (p = 0.035).

CONCLUSION

Surgical debridement in combination with appropriate antimicrobial therapy shortens the course of treatment and improves the visual outcome of severe infectious scleritis after pterygium excision.

Comparison of topical 0.3% ofloxacin with fortified tobramycin plus cefazolin in the treatment of bacterial keratitis

PURPOSE

Ofloxacin is a broad spectrum fluoroquinolone antibiotic with good ocular penetration. We compared ofloxacin 3% solution with a combination of fortified tobramycin sulphate and cefazolin sodium solutions in the treatment of culture-proven bacterial keratitis.

METHODS

Thirty eyes with culture-proven bacterial corneal ulcers were enrolled in a prospective randomised, controlled, double-masked study for comparison. The ofloxacin drop and saline were decanted into two identical-looking bottles to the tobramycin and cefazolin. The cases were randomly allocated into treatment with 0.3% ofloxacin solution or a combination of fortified antibiotics (1.5% tobramycin and 10% cefazolin solutions; control group) along with supportive cycloplegic, vitamins and anti-glaucoma therapy. Student's t-test was used to compare the results.

RESULTS

Staphylococcus aureus and coagulase-negative staphylococci were the two most common organisms isolated. Resolution of the ulcer was achieved in 93% and 87% of cases in the ofloxacin and control groups respectively. The mean time required for symptomatic relief was 7.8 +/- 1.54 days and for epithelial healing 15.0 +/- 3.86 days in ofloxacin group, compared with 8.33 +/- 1.54 days for symptomatic relief and 15.46 +/- 3.86 days for epithelial healing in the control group. Post-resolution best corrected visual acuity of 20/200 or better was achieved in all but one eye in both groups.

CONCLUSIONS

Ofloxacin and combined fortified tobramycin and cefazolin topical drops were comparable for treating cases of bacterial corneal ulcer. However, considering its easy availability and cost-effectiveness, monotherapy with ofloxacin is preferred over the combined fortified tobramycin and cefazolin therapy.

Penetration of topically applied ciprofloxacin, norfloxacin and ofloxacin into the aqueous humor of the uninflamed human eye

This study was undertaken to compare aqueous humor penetration of topical 0.3% ciprofloxacin, 0.3% norfloxacin and 0.3% ofloxacin in 63 patients undergoing cataract surgery. The patients were divided into two groups. Group 1 (long-term treatment) involved 30 patients undergoing cataract extraction who received either 0.3% ciprofloxacin, 0.3% norfloxacin or 0.3% ofloxacin topical drops. Each patient was preoperatively given a single drop per hour six times. At the time of surgery, 0.1 ml aqueous fluid was aspirated from the anterior chamber and immediately stored at -70 degrees C. Topically applied ciprofloxacin, ofloxacin and norfloxacin achieved mean aqueous humor levels of 2.80 +/- 1.07, 2.95 +/- 1.19 and 1.50 +/- 0.48 micrograms/ml respectively. There was no statistically significant difference in intraocular mean aqueous levels of ciprofloxacin versus ofloxacin. Topical ciprofloxacin and ofloxacin achieved mean aqueous humor levels significantly higher than norfloxacin (p < 0.001 and p < 0.0008 respectively). Group 2 (short-term treatment) involved 33 patients undergoing cataract extraction who received 0.3% ciprofloxacin, 0.3% ofloxacin and 0.3% norfloxacin topical drops. These patients were given one drop at 90 minutes and one drop 30 minutes preoperatively. At the time of surgery, 0.1 ml aqueous fluid was aspirated from the anterior chamber and immediately stored at -70 degrees C. Topically applied ciprofloxacin, ofloxacin and norfloxacin achieved mean aqueous humor levels of 1.11 +/- 0.50, 1.50 +/- 0.62 and 1.20 +/- 0.43 micrograms/ml respectively. There was no statistically significant difference in intraocular mean aqueous humor levels of ofloxacin versus norfloxacin and ciprofloxacin versus norfloxacin. Topical ofloxacin achieved a significantly higher mean aqueous humor level than ciprofloxacin (p < 0.03). All levels were above the minimum inhibitory concentrations of ciprofloxacin, ofloxacin and norfloxacin for most of the sensitive organisms.

Comparison of ciprofloxacin ophthalmic solution 0.3% to fortified tobramycin-cefazolin in treating bacterial corneal ulcers. Ciprofloxacin Bacterial Keratitis Study Group

PURPOSE

The purpose of the study is to compare the clinical efficacy and safety of ciprofloxacin ophthalmic solution 0.3% (Ciloxan) with a standard therapy regimen (fortified tobramycin, 1.3%-cefazolin, 5.0%) for treating bacterial corneal ulcers.

METHODS

This randomized, parallel group, double-masked, multicenter study was conducted in 324 patients at 28 centers in the United States, Europe, and India. Patients were randomized into 2 treatment groups: 160 to ciprofloxacin and 164 to fortified tobramycin-cefazolin. Positive microbiologic cultures were obtained in 188 (58%) of 324 patients. Of these, 176 patients met protocol criteria and were evaluated for treatment efficacy: 82 in the ciprofloxacin group and 94 in the standard therapy group. The dosing schedule for both treatment groups was 1 to 2 drops of the first study medication (ciprofloxacin or fortified tobramycin) every 30 minutes for 6 hours, then hourly for the remainder of day 1; 1 to 2 drops every hour on days 2 and 3; 1 to 2 drops every 2 hours on days 4 and 5, followed by 1 to 2 drops every 4 hours on days 6 to 14. The second medication (ciprofloxacin or cefazolin) was instilled 5 to 15 minutes after the first drug, following the same dosing frequency. Physician's judgment of clinical success, cure rate, changes in ocular sings, and symptoms and the rate of treatment failures were the primary efficacy criteria.

RESULTS

Topical ciprofloxacin monotherapy is equivalent clinically and statistically to the standard therapy regimen of fortified antibiotics. No statistically significant treatment differences were found between ciprofloxacin (91.5%) and standard therapy (86.2%) in terms of overall clinical efficacy (P = 0.34). Similarly, no differences were noted in resolution of the clinical signs and symptoms (P > 0.08) or the time to cure (P = 0.55). The incidence of treatment failures was less in the ciprofloxacin group (8.5%) compared with the standard therapy group (13.8%). Significantly fewer patients treated with ciprofloxacin reported discomfort than did patients treated with the standard therapy regimen (P = 0.01).

CONCLUSION

Ciprofloxacin ophthalmic solution 0.3% monotherapy is equivalent clinically and statistically to standard therapy (fortified tobramycin-cefazolin) for the treatment of bacterial corneal ulcers and produces significantly less discomfort.

Distribution kinetics of enoxacin and its metabolite oxoenoxacin in excretory fluids of healthy volunteers

The distribution kinetics of enoxacin and its main metabolite oxoenoxacin in excretory fluids was investigated in 11 healthy volunteers. A single intravenous dose of 428 mg of enoxacin was given as a 1-h infusion. Serial samples of plasma, urine, saliva, nasal secretions, tears, and sweat were drawn and analyzed for enoxacin and oxoenoxacin by reversed-phase high-pressure liquid chromatography. Large differences in the concentration-time profiles of the excretory fluids analyzed were observed. Nasal secretions exhibited the highest enoxacin exposure, as assessed by the area under the concentration-time curve. Excretory fluid/plasma area under the concentration-time curve ratios were found to be 1.67 +/- 0.36 for nasal secretions, 0.76 +/- 0.28 for saliva, 0.25 +/- 0.07 for sweat, and 0.23 +/- 0.11 for tears. The elimination half-life of enoxacin from sweat (8.27 +/- 2.63 h) was significantly longer than that for plasma (5.10 +/- 0.46 h). Oxoenoxacin was detected in urine and saliva and exhibited a higher renal clearance and a lower saliva exposure than the parent compound. In contrast to that of the metabolite, distribution of enoxacin in saliva was found to be time and pH dependent. In conclusion, our study revealed considerable differences in the distribution kinetics of enoxacin among various excretory sites. Because of distinct acidic and basic properties, the anionic oxometabolite significantly differs from the zwitterionic parent compound in its distribution characteristics.

Effect of inflammation on intraocular penetration of intravenous ofloxacin in albino rabbits

The effect of inflammation on the intraocular penetration of ofloxacin was studied in 20 albino rabbits (New Zealand White). Inflammation was induced in the left eye by inoculation of a suspension of 10(9) CFU of heat-killed Staphyloccus epidermidis per 0.1 ml of saline solution (0.9%) in the midvitreous cavity. The other eye was kept as a control. Twenty-four hours following inoculation, ofloxacin was administered in the marginal ear vein at a dose of 15 mg/kg over 20 min with an infusion pump. Animals were sacrificed at different times up to 24 h following drug administration. Ofloxacin levels were determined in aqueous humor, vitreous humor, and serum by a bioassay. Inflammation was scored on the basis of perilimbal and corneal reactions and vitreoretinal statuses. Inflammation had a relevant effect on intraocular penetration of ofloxacin, with levels in the ocular fluids of the inflamed eye markedly exceeding the ones of the control eye. In the uninflamed eye, the levels were rapidly decaying below assay sensitivity and were no longer detectable at approximately 5 h following drug administration while they were still detectable in both ocular fluids of the inflamed eye at 24 h. Ofloxacin levels in the ocular fluids of the inflamed eye were superior to the MIC for several of the bacteria which commonly cause endophthalmitis, including Staphylococcus epidermidis, Staphylococcus aureus, most members of the family Enterobacteriaceae, Haemophilus influenzae, and strains of Pseudomonas aeruginosa.

Availability of 0.3% ofloxacin ointment and solution in human conjunctiva and aqueous humor

Ofloxacin 0.3% ophthalmic solution or ointment was administered preoperatively to 13 patients undergoing cataract surgery. Mean drug concentrations in conjunctival biopsies were 2.62 and 6.55 micrograms/gm and in aqueous humor samples were 0.36 micrograms/mL and 0.43 micrograms/mL, for ointment and solution respectively. Mean conjunctival concentrations of ofloxacin achieved MIC90 values for 419 gram-positive and gram-negative organisms previously analyzed.

The ocular penetration of oral sparfloxacin in humans

The penetration of sparfloxacin into the aqueous humor after oral administration was studied in 28 patients undergoing cataract surgery. Each patient received a single, oral dose of 400 mg of sparfloxacin. In eight other patients scheduled to undergo vitreal surgery, multiple daily oral doses were administered for a total amount of 1,000 mg. The aqueous levels were (mean +/- SEM) 0.127 +/- 0.036 microgram/ml to 0.404 +/- 0.159 microgram/ml from two to 24 hours after ingestion. In the vitreous, the mean drug level was 0.840 microgram/ml (range, 0.480 to 2.060 microgram/ml), from 4.3 to 8.0 hours after the most recent oral dose. Blood samples obtained at the same time as vitreous and aqueous taps were assayed by high-performance liquid chromatography. These data demonstrate that therapeutic levels of sparfloxacin may be achieved in noninflamed, noninfected eyes undergoing cataract or vitreous surgery.

Aqueous humor penetration of ofloxacin given by various routes

We studied the aqueous humor penetration of ofloxacin after topical, oral, and intravenous administration in 51 consecutive patients undergoing cataract surgery. Aqueous humor concentration (mean +/- SD) was 0.53 +/- 0.35 mg/l when ofloxacin 0.3% eyedrops were instilled topically six times, one drop every three hours, until 90 minutes preoperatively, and 0.63 +/- 0.29 mg/l (P = .45) when two additional instillations were made, one drop every 30 minutes, until 30 minutes before aqueous humor aspiration. Aqueous humor concentration two hours after a single 200-mg oral dose (0.38 +/- 0.15 mg/l) was significantly lower (P = .048) than that 12 hours after the same oral dose (0.58 +/- 0.24 mg/l). Two hours following an intravenous infusion of 200 mg of ofloxacin, aqueous humor concentration was 0.33 +/- 0.19 mg/l. Our results suggest that therapeutic levels above the minimum inhibitory concentration for many bacteria cultured in endophthalmitis can be achieved in aqueous humor after either topical or oral administration, which indicates that this antibiotic passes easily through the corneal and the blood aqueous barriers.

Gentamicin, norfloxacin and lysozyme concentration in human tears: in vivo and in vitro study

Hen's egg lysozyme (HEL) activity was measured in vitro with gentamicin and norfloxacin by a turbidimetric technique. Gentamicin at the concentration of 10(-3) M inhibited HEL activity by 39%, while 10(-3) M norfloxacin did not affect HEL activity. However, an in vivo study in healthy persons did not show any significant statistical difference in tear lysozyme activity when 0.3% gentamicin or 0.3% norfloxacin were topically applied.

Topically administered norfloxacin compared with topically administered gentamicin for the treatment of external ocular bacterial infections. The Worldwide Norfloxacin Ophthalmic Study Group

In this double-masked study, we randomly assigned 488 patients with clinical signs of acute bacterial conjunctivitis or blepharitis, or both, to treatment with either norfloxacin ophthalmic solution 0.3% (245) or gentamicin ophthalmic solution 0.3% (243) for one week. Of the patients with positive cultures, 71% (85 of 120) of the norfloxacin-treated patients and 65% (86 of 133) of the gentamicin-treated patients were clinically cured. An additional 25% (30 of 120) of norfloxacin-treated patients and 32% (43 of 133) of gentamicin-treated patients were clinically improved. On the basis of posttreatment cultures, 89% of all cultured bacteria were eradicated (146 of 179 organisms) or suppressed (14 of 179 organisms) after treatment with norfloxacin. The condition of five norfloxacin-treated patients did not clinically improve, compared with the condition of eight gentamicin-treated patients. Both antibiotics had similar efficacy against gram-positive and against gram-negative organisms. One norfloxacin-treated patient and two gentamicin-treated patients withdrew from the study because of local intolerance. Norfloxacin appears to be an effective and relatively safe agent for the treatment of bacterial infections of the eyelids or conjunctiva, or both. In this study, norfloxacin was clinically and microbiologically similar in activity to gentamicin.

Intravitreal penetration of oral ciprofloxacin in humans

Nineteen patients about to undergo elective vitreous surgery received 1 oral dose of 750 mg of ciprofloxacin before surgery. Specimens of serum and vitreous were collected 90 minutes to 18 hours after drug administration and were assayed for antibiotic content with a microbiologic disk agar technique. From 4 hours and 50 minutes to 16 hours and 50 minutes after a single oral dose, ciprofloxacin reached intravitreal levels above its minimal inhibitory concentration for 90% of Staphylococcus epidermidis, Bacillus species, and Enterobacteriaceae. However, intravitreal levels never exceeded the MIC90 for Staphylococcus aureus and Pseudomonas.

Ocular penetration of topically applied norfloxacin 0.3% in the rabbits and in humans

The kinetics of topically applied norfloxacin 0.3 percent were studied in rabbit and man. All measurements were performed by high-pressure liquid chromatography. Norfloxacin concentrations were investigated five to 120 minutes in rabbit ocular tissues after instillation of a single drop. In normal eyes, after 30 minutes, mean +/- SEM levels were 14.3 +/- 3.7 micrograms/g in cornea, 3.3 +/- 0.7 micrograms/g in conjunctiva, 0.2 +/- 0.1 microgram/g in aqueous humor. After removal of the corneal epithelium concentrations were as follows: 84.2 +/- 15.8 micrograms/g, 7.3 +/- 2.3 micrograms/g, 8.6 +/- 1.9 micrograms/g respectively. Penetration in posterior ocular tissues were rather poor. In human eyes, the intracorneal concentrations were assessed in patients being operated on corneal grafts. After instillation of 5 drops, the concentration in cornea was 15.5 +/- 2.1 micrograms/g. These data show that therapeutic levels of norfloxacin can be achieved in anterior ocular tissues, which may be of help in superficial infections of the eye.

The safety and efficacy of topical norfloxacin compared with chloramphenicol for the treatment of external ocular bacterial infections. The Norfloxacin-Chloramphenicol Ophthalmic Study Group

Two hundred and forty-six patients with signs of acute bacterial conjunctivitis and/or blepharitis were randomised to receive either norfloxacin or chloramphenicol for one week in this double-masked parallel group study. Ninety-two per cent of the norfloxacin-treated patients and 93% of the chloramphenicol-treated patients were rated as either clinically improved or cured at the end of the treatment period. Based upon pre-treatment bacteriological cultures, 31.3% of the patients had significant bacterial infection of the lids and/or conjunctiva. All of these culture-positive patients were rated as either clinically improved or cured. Based upon post-treatment cultures, 72 of 82 strains of Gram-positive and Gram-negative bacteria were eradicated or suppressed following treatment with either norfloxacin or chloramphenicol. However six of 41 strains persisted for norfloxacin and four of 41 for chloramphenicol. Two norfloxacin-treated patients and three chloramphenicol-treated patients had adverse experiences, predominantly ocular discomfort, which required cessation of drug therapy. Norfloxacin appears to be an effective and relatively safe agent for the treatment of bacterial infections of the lids and/or conjunctiva. In this study, norfloxacin was clinically and microbiologically similar in activity to chloramphenicol.

Ofloxacin compared with chloramphenicol in the management of external ocular infection

The safety and efficacy of 0.3% ofloxacin in treating bacterial ocular infections was compared with that of 0.5% chloramphenicol in a parallel-group, randomised clinical trial at five sites. Clinical and microbiological improvement rates were studied in 84 culture-positive patients. Patients with suspected bacterial ocular infections were evaluated for clinical improvement and were included in drug safety and comfort analyses. Clinical improvement did not differ significantly between drug treatments. All patients completing the study (79 assigned ofloxacin, and 74 chloramphenicol) showed clinical improvement. Clinical improvement in the culture-positive groups was 100% (41/41) after ofloxacin treatment, and 95% (41/43) after chloramphenicol treatment. Microbiological improvement rates were similar for the two drugs: 85% (33/39) improved with ofloxacin, and 88% (38/43) improved with chloramphenicol. Both drugs were well tolerated. Adverse reactions possibly due to the study medication occurred in 1% (1/89) of those who received ofloxacin, and in 4% (4/93) of those who received chloramphenicol.

Successful treatment of methicillin-resistant Staphylococcus aureus Keratitis with topical ciprofloxacin

Ciprofloxacin is a new quinolone antibiotic with a broad spectrum of activity against most aerobic gram-positive and gram-negative bacteria. Topical ciprofloxacin (3 mg/ml) was used to treat bacterial keratitis caused by methicillin-resistant strains of Staphylococcus aureus in two patients. Both corneal ulcers had been previously treated with other antibiotics without success. Topical ciprofloxacin was curative in both cases. The authors recommend the use of topical ciprofloxacin for methicillin-resistant S. aureus keratitis.

Ofloxacin. A reappraisal of its antimicrobial activity, pharmacology and therapeutic use

Ofloxacin is a fluoroquinolone whose primary mechanism of action is inhibition of bacterial DNA gyrase. In vitro it has a broad spectrum of activity against aerobic Gram-negative and Gram-positive bacteria, although it is poorly active against anaerobes. Ofloxacin, unlike most other broad spectrum antibacterial drugs, can be administered orally as well as intravenously. Penetration into body tissues and fluids is highly efficient. Clinical trials with orally and intravenously administered ofloxacin have confirmed its potential for use in a wide range of infections, where it has generally proved as effective as standard treatments. Ofloxacin in well tolerated, and in comparison with other available fluoroquinolones is less likely to cause clinically relevant drug interactions. Ofloxacin thus offers a valuable oral treatment (with an option for intravenous administration if necessary) for use in a wide range of clinical infections, but with a particular advantage in more severe or chronic infections when recourse to parenteral broad spectrum agents would normally be required, thereby providing cost savings and additionally allowing outpatient treatment.

Topical fluoroquinolones: antimicrobial activity and in vitro corneal epithelial toxicity

To assess the potential of fluoroquinolones as topical antimicrobial agents, we evaluated in vitro the antimicrobial activity of five fluoroquinolones (ciprofloxacin, norfloxacin, ofloxacin, pefloxacin, and temafloxacin), as well as gentamicin, tobramycin, and cefazolin against 96 isolates of common bacterial corneal pathogens. Ciprofloxacin and temafloxacin were the most active quinolones [minimal inhibitory concentration inhibiting 90% of stains (MIC90) of 1 microgram/ml], followed by ofloxacin (MIC90 2 micrograms/ml), and norfloxacin and pefloxacin (MIC90s 4 micrograms/ml). In contrast, gentamicin and tobramycin MIC90s were 32 and 64 micrograms/ml, respectively; cefazolin MIC90 was greater than 2048 micrograms/ml. The corneal epithelial cytotoxicity of the fluoroquinolones also was evaluated utilizing an in vitro assay of 3H-thymidine uptake of rabbit corneal epithelial cell cultures. The least to greatest toxicity of the fluoroquinolones were as follows: ciprofloxacin and temafloxacin less than norfloxacin less than ofloxacin less than pefloxacin. Our study suggests that the fluoroquinolones, especially ciprofloxacin and temafloxacin, possess excellent in vitro activity against common bacterial corneal pathogens and are less toxic to the corneal epithelium than the aminoglycosides.

Comparison of ofloxacin, gentamicin, and tobramycin concentrations in tears and in vitro MICs for 90% of test organisms

Concentrations of three anti-infective agents in tear film were monitored after one topical application in rabbits. Ofloxacin concentrations exceeded the MIC for 90% of the organisms tested (MIC90) (gram-negative and gram-positive organisms) for 240 min. Tobramycin concentrations exceeded the MIC90 for 10 min. Gentamicin concentrations exceeded the MIC90 for 20 min for gram-positive organisms and 120 min for gram-negative organisms.

Reversible visual loss in a patient receiving high-dose ciprofloxacin hydrochloride (Cipro)

Bilateral acute visual loss characterized by cecocentral scotomas and acquired dyschromatopsia developed in a patient receiving large oral doses of ciprofloxacin hydrochloride (Cipro). The visual defects improved after cessation of this antibiotic. To our knowledge, this association has not been described previously. The use of this medication in high doses must be accompanied by careful monitoring of optic nerve function.