Comparative pharmacokinetics of intravenous ofloxacin and ciprofloxacin

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.

Allometric analysis of ciprofloxacin and enrofloxacin pharmacokinetics across species

The purpose of this study was to examine the allometric analysis of ciprofloxacin and enrofloxacin using pharmacokinetic data from the literature. The pharmacokinetic parameters used were half-life, clearance and volume of distribution. Relationships between body weight and the pharmacokinetic parameter were based on the empirical formula Y = aW(b), where Y is half-life, clearance or volume of distribution, W the body weight and a is an allometric coefficient (intercept) that is constant for a given drug. The exponential term b is a proportionality constant that describes the relationship between the pharmacokinetic parameter of interest and body weight. A total of 21 different species of animals were studied. Results of the allometric analyses indicated similarity between clearance and volume of distribution as they related to body weight for both drugs. Results of the current analyses indicate it is possible to use allometry to predict pharmacokinetic variables of enrofloxacin or ciprofloxacin based on body size of species. This could provide information on appropriate doses of ciprofloxacin and enrofloxacin for all species.

Pharmacokinetics of ciprofloxacin in patients with acute renal failure undergoing continuous venovenous haemofiltration: influence of concomitant liver cirrhosis

To determine an adequate dosage of ciprofloxacin in critically ill medical patients on continuous venovenous haemofiltration, we studied the pharmacokinetics of ciprofloxacin in eight critically ill medical patients with renal failure treated with continuous venovenous haemofiltration using polysulfone membranes. Three of those patients also presented with severe liver dysfunction. For comparison, three patients with approximately normal renal function and two patients with impaired renal function were included. During haemofiltration, plasma concentrations of ciprofloxacin were variable. In all critically ill patients ciprofloxacin elimination was significantly slowed; the mean half-life was similarly prolonged to about 14 h in patients on haemofiltration and those with approximately normal renal function. In critically ill patients with impaired renal function not on haemofiltration, the mean half-life was longest. Ciprofloxacin clearance by haemofiltration was a quarter of the total clearance. Although a unique dose recommendation can hardly be made because of the high variability of pharmacokinetics during haemofiltration, a daily dose of 800 mg (400 mg b.i.d.) in average can be regarded as appropriated for reaching a target plasma concentration of 2 to 3 micrograms/mL (mean concentration). Because the half-life of ciprofloxacin was further prolonged by the presence of liver cirrhosis, the dose should be reduced to 600 mg in patients on haemofiltration with concomitant severe liver dysfunction.

Pharmacodynamics of levofloxacin, ofloxacin, and ciprofloxacin, alone and in combination with rifampin, against methicillin-susceptible and -resistant Staphylococcus aureus in an in vitro infection model

The pharmacodynamic properties of levofloxacin (an optically active isomer of ofloxacin), ofloxacin, and ciprofloxacin, alone and in combination with rifampin, were evaluated over 24 to 48 h against clinical isolates of methicillin-susceptible and -resistant Staphylococcus aureus (MSSA 1199 and MRSA 494, respectively) in an in vitro infection model. The incidence of the emergence of resistance among the test strains was also determined. The fluoroquinolones were administered to simulate dosage regimens of 200 mg, 400 mg given intravenously (i.v.) every 12 h (q12h), and 400 and 800 mg given i.v. q24h. Rifampin was dosed at 600 mg i.v. q24h. Although the MICs and MBCs of the quinolones were similar (< or = 0.49 microgram/ml), levofloxacin was the most potent agent in time-kill studies on the basis of the time required to achieve a 99.9% reduction in the number of log10 CFU per milliliter (e.g., with the regimen of levofloxacin [400 mg q24h, 6.5 h] versus ofloxacin [12.5 h], P < 0.024, and levofloxacin versus ciprofloxacin [6.5 versus 9.0 h], P < 0.0017) against MSSA 1199. The killing activity of levofloxacin was similar to that of ofloxacin against MRSA 494 (time to achieve a 99.9% reduction in the number of log10 CFU per milliliter, 11.1 versus 13.8 h, respectively). Levofloxacin and ofloxacin dosed once daily demonstrated greater bactericidal activity than when they were dosed twice daily against MSSA 1199. Resistance to levofloxacin or ofloxacin was not observed with any dosage regimen. Furthermore, resistance to ofloxacin was not detected when the half-life was reduced from 6 to 3 h. Regrowth and stable resistance (65-fold increase in the MIC for MSSA 1199; 16-fold increase in the MIC for MRSA 494) were noted within 24 h of exposure to ciprofloxacin at 200 mg q12h. Combination therapy with rifampin prevented the emergence of resistance to ciprofloxacin. Neither DNA gyrase alteration nor an energy-dependent efflux process mediated by the norA gene appeared to be responsible for the resistance observed. Our data suggest that with levofloxacin there is a more rapid onset of bactericidal activity than with ofloxacin or ciprofloxacin against MSSA 1199 and that the activity of levofloxacin is similar to that of ofloxacin but better than that of ciprofloxacin against MRSA 494. Resistance was noted only after exposure to the low dose of ciprofloxacin. Resistance to ofloxacin did not develop even when the pharmacokinetics of the drug were set to equal those of ciprofloxacin, suggesting that ofloxacin differs from ciprofloxacin irrespective of time of exposure. The resistance to ciprofloxacin that developed in our vitro model may be mediated by the cfx-ofx locus, which has been shown to be associated with low-level fluoroquinolone resistance. Overall, levofloxacin demonstrated potent bactericidal activity against S. aureus, without the emergence of resistance in our infection model. Quinolones dosed once daily were more effective than equivalent dosages administered twice daily. The addition of rifampin was not synergistic but prevented the emergence of ciprofloxacin resistance.

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.

Pharmacokinetic quantification of the exchange of drugs between blood and cerebrospinal fluid in man

Various parameters which may be useful in quantification of drug transit from blood into CSF and vice versa after a short duration infusion are compared here by recalculating previously published data from our group. Due to the slower entry into and elimination from the CSF compartment as compared to the central compartment, the ratio of drug concentrations in CSF and serum sampled at the same time increase with time after an infusion. Therefore, concentration quotients of simultaneously drawn blood and CSF are inadequate to characterise CSF penetration. The ratio of the areas under the concentration-time curves in a body fluid and serum (AUCbody fluid/AUCs) is an established measure to quantify overall penetration from the central into a peripheral compartment. AUCCSF/AUCs is closely correlated with the quotient of the maximum CSF and serum concentrations (CmaxCSF/CmaxS) (rs = 0.87, n = 42, P < 0.001) and with the rate constant of distribution in CSF (CLin/VCSF) (rs = 0.80, n = 42, P < 0.001). Since CmaxCSF/CmaxS depends on the mode of drug administration, it is suggested that AUCCSF/AUCs be used to quantify overall drug transit into CSF. CLin/VCSF is of use when CSF can only be sampled once, or when the velocity of the transit of a drug into CSF is to be described. The CSF exit rate constant (CLout/VCSF) characterises elimination from CSF independent of the elimination from serum and may be applied to estimate the formation rate of CSF; in the present study it averaged 20 ml/h.

Pharmacokinetics and serum bactericidal titers of ciprofloxacin and ofloxacin following multiple oral doses in healthy volunteers

Fourteen adult males participated in a randomized three-way crossover study to compare the pharmacokinetics and serum bactericidal titers (SBTs) of 500 mg of ciprofloxacin (regimen A), 750 mg of ciprofloxacin (regimen B), and 400 mg of ofloxacin (regimen C) administered every 12 h for seven doses. Mean steady-state peak concentrations in serum for regimens A, B, and C were 3.0, 4.4, and 6.5 micrograms/ml, respectively (P < 0.01, all comparisons) and mean half-lives were 4.5, 4.3, and 6.5 h, respectively (P < 0.05, C versus A and B). Mean steady-state areas under the concentration-time curve were 14.1, 21.1, and 48.1 micrograms/h/ml for regimens A, B, and C, respectively (P < 0.05, all comparisons). SBTs were determined at different times postdose for three isolates each of Streptococcus pneumoniae, Staphylococcus aureus, Escherichia coli, Enterobacter cloacae, and Pseudomonas aeruginosa. Mean steady-state peak SBTs for regimens A, B, and C, respectively, were as follows: S. pneumoniae, < 1:2, 1:8, 1:8, S. aureus, 1:16, 1:16, 1:16; E. coli, 1: > or = 128, 1: > or = 128, 1:64; E. cloacae, 1: > or = 128, 1: > or = 128, 1:64; P. aeruginosa, 1:8, 1:8, 1:2. These differences in SBTs within each genus were statistically significant. The majority of predicted SBTs were within one dilution of measured SBTs. Areas under the serum bactericidal time curves for E. coli, E. cloacae, and P. aeruginosa were significantly higher for ciprofloxacin; areas under the serum bactericidal time curves for S. pneumoniae and S. aureus were significantly greater for ofloxacin. Ofloxacin achieved higher concentrations in serum than ciprofloxacin, but differences in in vitro activity were a more important determinant of SBTs.

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.

The bioavailability of ofloxacin from several formulations

The bioavailability of ofloxacin after a single dose of one of two tablet formulations (200 or 400 mg) or a liquid formulation (1.67 mg/ml) was investigated in 24 healthy male volunteers in an open randomized, crossover design study with a 5-day wash-out period between doses. Plasma concentrations of ofloxacin were determined at various times after administration by a sensitive and specific High Pressure Liquid Chromatography (HPLC) method. Ofloxacin was well absorbed after each administration, although somewhat more slowly after the tablet formulations than the solution. Mean AUC values of 31.8, 31.3, and 31.3 micrograms.hr/ml were calculated after administration of the solution, 2 x 200 mg tablets and a 400 mg tablet, respectively. Thus, the bioavailability of the tablets was in excess of 98% that of the liquid reference. Mean Cmax values of 4.4, 3.7 and 3.7 micrograms/ml were observed at Tmax values of 0.8, 1.6 and 1.8 hours after administration of the solution, 2 x 200 mg tablets and a 400 mg tablet, respectively. The drug was well tolerated and no adverse effects necessitating subject withdrawal were noted during the study.

Safety and efficacy of intravenous ciprofloxacin in the treatment of selected infections

A prospective study of the efficacy and safety of intravenous ciprofloxacin in the treatment of selected infections was conducted at the Ochsner Medical Institutions from October 1986 through March 1987. Thirty-three patients were treated with intravenous ciprofloxacin at dosages of either 200 mg or 300 mg every 12 hours. The mean duration of therapy was 12 days. Various infection sites were treated and included urinary tract, respiratory tract, skin and skin structure, bone, intra-abdominal, blood, and heart. Clinical improvement was noted in 20 of the 26 evaluable patients (77 percent). Fifty-two bacterial pathogens were isolated with eradication of 37 (71 percent). There was bacteriologic persistence in seven patients (13 percent). Superinfection occurred in one patient; however, no recurring or reinfecting organisms were isolated. Adverse events related to ciprofloxacin occurred in six patients and were primarily mild. Overall, ciprofloxacin was useful in the treatment of a variety of infections, and adverse events were minimal.

Ofloxacin: a review

Ofloxacin is a new fluorinated quinolone antibiotic with a broad spectrum of activity against a variety of gram-positive and -negative bacteria including Enterobacteriaceae, Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus. In addition, ofloxacin has significant activity against Neisseria gonorrhoeae, Chlamydia trachomatis, and Mycobacterium tuberculosis and this may give rise to new indications for the class of quinolone antibiotics. Clinical trials to date have demonstrated the efficacy of ofloxacin in the treatment of lower respiratory tract infections, urinary tract infections, and sexually transmitted diseases. Adverse effects to ofloxacin are usually mild and include gastrointestinal, central nervous system, and hypersensitivity reactions. Significant drug interactions with ofloxacin have not been reported.