Efficacy and Safety of Antofloxacin-Based Triple Therapy for Helicobacter pylori Eradication Failure in China

AIMS

Quinolone-containing triple therapy has been considered as the second-line therapy for eradication of Helicobacter pylori (H. pylori). At present, there are no data to show the efficacy and safety of antofloxacin-based rescue therapy for the eradication of H. pylori, and this pilot clinical trial was designed.

METHODS

A total of 196 patients who failed H. pylori eradication using the clarithromycin-based or metronidazole-based triple or bismuth quadruple therapy were randomly allocated to one of the following rescue eradication therapy groups: AEA group (antofloxacin 200 mg once daily, esomeprazole 20 mg + amoxicillin 1000 mg twice daily) for 14 days, or LEA group (levofloxacin 500 mg once daily, esomeprazole 20 mg + amoxicillin 1000 mg twice daily) for 14 days. The minimal inhibitory concentrations were tested by the E-test method. The gyrA mutation was analyzed by sequencing. Follow-up ^13/14C-urea breath test was examined at 1 month after discontinuation.

RESULTS

A total of 178 eligible patients were included in this study. The eradication rate was significantly higher in AEA group than in LEA group according to both ITT (87.6% vs. 68.5%; P = 0.002) and PP analyses (90.7% vs. 70.1%; P = 0.001). ITT analyses indicated that the eradication rate was significantly higher in AEA group than in LEA group with Asn87 mutation (78.9% vs. 31.3%; P = 0.005) and levofloxacin-resistant strains (76.9% vs. 44.2%; P = 0.003). Two groups exhibited similar adverse event rates (AEA 14.6% vs. LEA 20.2%, P = 0.323).

CONCLUSIONS

The findings showed that antofloxacin may be a promising candidate in rescue therapy for H. pylori eradication failure in China.

Antofloxacin-based bismuth quadruple therapy is safe and effective in Helicobacter pylori eradication: A prospective, open-label, randomized trial

BACKGROUND AND STUDY AIMS

The present study was designed to evaluate the safety, efficacy, and tolerability of antofloxacin-based bismuth quadruple therapy in Chinese patients with Helicobacter pylori infection.

PATIENTS AND METHODS

Total 290 patients with H. pylori infection were randomly and equally divided into two groups as per different bismuth quadruple therapies for 14 d: colloidal bismuth pectin 200 mg thrice a day, lansoprazole 30 mg twice a day, amoxicillin 1 g twice a day, and antofloxacin 200 mg once a day (ACLA group) or levofloxacin 500 mg once a day (LCLA group). Eradication was assessed with ¹³C-urea breath test 6 wk after treatment completion; the primary endpoint was the eradication rate by intention-to-treat (ITT) and per-protocol (PP) analyses. The minimum inhibitory concentration was measured with the PDM epsilometer test to assess the susceptibility of H. pylori strains on gastric biopsy specimens to antofloxacin and levofloxacin.

RESULTS

The eradication rates of H. pylori in the ACLA group were 93.8% and 97.8% for the ITT and PP analysis, respectively; these rates were significantly higher than those in the LCLA group, at 86.2% and 92.6%, respectively (p = 0.031 and 0.041, respectively). The total incidence of adverse events during the eradication therapy did not significantly differ between the ACLA and LCLA groups (31.7% vs. 37.9%%, p = 0.267), and the two groups displayed similar severity of adverse events (p = 0.156) and compliance rate (100% by ACLA vs. 97.8% by LCLA, p = 0.080). The eradication rate with the antofloxacin susceptible strains in the ACLA group was significantly higher than that with the resistant strains (99.2% vs. 66.7%, p = 0.045). Moreover, the eradication rate with the levofloxacin susceptible strains in the LCLA group was significantly higher than that with the resistant strains (95.3% vs. 80.0%, p = 0.013).

CONCLUSION

Antofloxacin is safe and effective for H. pylori eradication. Antofloxacin-based bismuth quadruple therapy could be an alternative treatment for H. pylori eradication.

[Treatment of trophic ulsers of different etiology]

The research included 40 patients with chronic trophic ulcers of lower extremities of different etiology (arterial insufficiency - 14 patients, venous insufficiency - 20 patients, diabetic foot syndrome - 6 people). According to the data of prime bacteriological inoculation, the main pathogens were: gram-positive coccus (Staphylococcus spp., Staphylococcus aureus - 75%, Staphylococcus epidermidis - 7,5%) and yeast-like fungi (Candida albicans - 7,5%). Microbial semination in plentiful quantity (more than 106 KOE) was detected at first inoculation in 85% of the patients. The ointment <Oflomelid> was applied for the patients. After 20 days, the lack of growth and the decrease of contamination level (lower than critical (less than 102 KOE) were noted. A visual analog scale estimated an intensity of pain in patients and it consisted of 39,8% before the treatment, 27,1% - after 10 days, 14,6% - after 20 days. The "Oflomelid" application allowed the reduction of the terms of wound cleansing from nonviable tissues in majority of patients and gained the fast transition from the granulation to epithelization phase. The principle of wound management with the application of ointment "Oflomelid" should be followed in a moist environment. A modern wound dressing must be used after the ointment. This shortened the terms of separate-phase wound repair and decreased the terms of the whole period of trophic ulcers repair in patients with vascular and endocrine pathology.

[A multi-center, randomized, controlled, double blind and double dummy clinical trial of antofloxacin hydrochloride tablet versus levofloxacin tablet for the treatment of acute bacterial infections]

OBJECTIVE

To evaluate the clinical efficacy and safety of antofloxacin hydrochloride tablet for the treatment of acute bacterial infections.

METHODS

A multi-center randomized control, double blind and double dummy clinical trial was conducted; levofloxacin tablet was closed as controlled drug. The duration of treatment was 7-14 days in both groups.

RESULTS

A total of 719 patients were enrolled in the study, in which 359 patients treated with antofloxacin and 360 patients treated with levofloxacin were included. Three hundred and thirty and 337 patients completed the study and met with all the criteria for per-protocol analysis, respectively. By the end of chemotherapy, the cured rates in per protocol set (PPS) population were 79.7% and 77.4%, the effective rates were 95.2% and 96.7%, and the bacterial clearance were 96.7% and 97.5% for the treating and control group, respectively. The clinical and bacterial efficacy of antofloxacin and levofloxacin was comparable by the analysis of infectious sites. Three hundred and fifty-seven and 356 patients in antofloxacin and levofloxacin groups were evaluated the safety. The drug adverse events occurred both in 10.1%, and drug adverse reactions occurred in 7.8% and 7.9% patients in the two groups. The most common drug adverse reactions were mild gastroenteric symptoms. No QTc prolongation was detected in all the patients. One patient in each group had mild blood glucose increase at the end of therapy, but the glucose returned to normal level without any intervention. No statistic significant difference between the two groups in clinical efficacy and safety was detected (P > 0.05).

CONCLUSIONS

Antofloxacin hydrochloride tablet was effective and safe for the treatment of acute bacterial infections.

Pharmacokinetic study of single and multiple oral dose administration of antofloxacin hydrochloride in healthy male volunteers

BACKGROUND

A new fluroquinolone antibacterial agent, antofloxacin hydrochloride, developed in China, is an 8-NH(2) derivant of levofloxacin. The purpose of the study was to evaluate the pharmacokinetic characteristics of single and multiple oral doses of antofloxacin hydrochloride in Chinese healthy male volunteers.

METHODS

An open-label, non-randomized, single and multiple dose clinical trial was conducted. In single dose study, 12 subjects took 200 mg antofloxacin hydrochloride. In multiple dose study, 12 subjects took antofloxacin hydrochloride 400 mg once on day 1 and 200 mg once daily from day 2 to day 7. HPLC was used to assay the serum and urinary concentrations of antofloxacin.

RESULTS

In single dose study, the maximum concentration of drug in serum (C(max)), the time to reach C(max) (T(max)), and the area under the serum concentration-time curve (AUC (0-∞)) of antofloxacin were (1.89 ± 0.65) mg/L, (1.29 ± 0.26) hours, and (25.24 ± 7.26) mg×h(-1)×L(-1), respectively. Accumulating elimination rate of antoflocaxin from urine within 120 hours was 39.1%. In multiple dose study, blood concentration of antofloxiacin achieved stable state on day 2 after dosing. The minimum concentration drug in serum (C(min)), AUCss, mean concentration of drug in serum (C(av)), and degree of fluctuation (DF) were (0.73 ± 0.18) mg/L, (47.59 ± 7.85) mg×h(-1)×L(-1), (1.98 ± 0.33) mg/L, and 1.74 ± 0.60, respectively. On day 7 after dosing, T(max), C(max), and AUC (0-∞) was (1.14 ± 0.50) hours, (2.52 ± 0.38) mg/L, and (48.77 ± 8.44) mg×h(-1)×L(-1), respectively. Accumulating elimination rate of antofloxaxin from urine within 120 hours after the last dosing was 60.06%.

CONCLUSIONS

The regimen of 400 mg loading dose given on the first treatment day and then 200 mg dose once daily results in satisfactory serum drug concentration.

Determination of the inhibitory potential of 6 fluoroquinolones on CYP1A2 and CYP2C9 in human liver microsomes

AIM

To determine the inhibitory potential of 2 new fluoroquinolones, caderofloxacin and antofloxacin, together with 4 marketed fluoroquinolones, moxifloxacin, gatifloxacin, levofloxacin, and ciprofloxacin, on the activity of cytochrome P450 isoforms 1A2 (CYP1A2) and 2C9 (CYP2C9).

METHODS

Probe substrates, phenacetin (CYP1A2), and tolbutamide (CYP2C9) were incubated with human liver microsomes and the metabolites were analyzed by liquid chromatography/mass spectrometry using electrospray ionization in positive or negative mode. Glipizide was used as the internal standard in both modes. The inhibitory potential of fluoroquinolones on CYP1A2 and CYP2C9 was investigated.

RESULTS

The IC50 values (micromol/L) determined with the cocktail were in agreement with individual probe substrates (alpha-naphthoflavone: 0.27 vs 0.26; sulfaphenazole: 0.49 vs 0.37). Ciprofloxacin showed weak inhibition on both the activity of CYP1A2 (IC50 135 micromol/L) and CYP2C9 (IC50 180 micromol/L), whereas levofloxacin inhibited only CYP2C9 (IC50 210 micromol/L). Caderofloxacin, antofloxacin, moxifloxacin, and gatifloxacin showed little or no inhibition on the activity of CYP1A2 or CYP2C9 when tested at comparable concentrations (0-200 mg/L).

CONCLUSION

Caderofloxacin, antofloxacin, moxifloxacin, and gatifloxacin are negligible inhibitors to CYP1A2 and CYP2C9. The in vitro system can be used as a high-throughput model to screen similar compounds for the early identification of drug-drug interaction potential.

Pharmacokinetics/pharmacodynamics of antofloxacin hydrochloride in a neutropenic murine thigh model of Staphylococcus aureus infection

AIM

Antofloxacin hydrochloride is a new fluoroquinolone antibiotic with broad-spectrum in vitro activity. Using the neutropenic murine thigh infection model, we defined the pharmacodynamic profile and property of antofloxacin hydrochloride against Staphylococcus aureus.

METHODS

Single-dose pharmacokinetic studies of antofloxacin hydrochloride were carried out in thigh infected mice. Therapy was initiated at 2 h postinoculation with 5-640 mg/kg per d fractionated for different dosing regimens. The thighs were removed for bacterial measurement after 24 h of therapy, the best pharmacokinetic/ pharmacodynamic (PK/PD) index correlated with the efficacy was determined by nonlinear regression analysis. A sigmoid E(max) dose-response model was used to estimate the daily dose and AUC(24 h)/MIC (minimal inhibitory concentration) required to achieve a static effect.

RESULTS

The PK was linear with similar elimination half-life over the dose range studied. The AUC(24 h)/MIC ratio was the PK/PD parameter that best correlated with efficacy (R(2)=92.3%, 90.8% for the two organisms, compared with C(max)/MIC and T>MIC [%], respectively). The 24 h static dose ranged from 34.3 to 153.7 mg/kg per d for all S aureus strains, the total AUC(24 h)/MIC ratio to achieve bacteriostatic effect varied from 31.7 to 122.5 (mean, 65.7+/-30.6).

CONCLUSION

Antofloxacin hydrochloride showed powerful antibacterial activity against the S aureus isolates used in our neutropenic infected mice model. Our data suggested that the AUC/MIC ratio appeared to be most closely linked to the bacterial outcome (R(2)>90%), and a total AUC(24 h)/MIC ratio of 65.7 appears to be the target value to achieve a net bactericidal activity against S aureus, similar to the results of other fluoroquinolones.

Possible multiple transporters were involved in hepatobiliary excretion of antofloxacin in rats

1. The aim of the current study was to investigate the characteristics of biliary excretion of antofloxacin (ATFX) in rats. Rats received a bolus intravenous injection followed by a constant-rate infusion of ATFX. When plasma concentrations of ATFX reached steady state, cyclosporin A, erythromycin, probenecid, cimetidine and diclofenac were administered intravenously to the rats. Samples of blood and bile were collected and the concentrations of ATFX were measured and the corresponding pharmacokinetic parameters were estimated. 2. Biliary excretion of ATFX was observed in rats subjected to CCl(4)-induced experimental hepatic injury for 24 h (CCl(4)-EHI(24h)). Steady state concentrations of ATFX were attained at 60 min following infusion. 3. A slight increase in concentration of ATFX in plasma was observed after cyclosporin A, erythromycin, probenecid and cimetidine treatment. Significant increases in ATFX plasma levels were found in rats treated with diclofenac. Cyclosporin A, erythromycin, probenecid, cimetidine and diclofenac treatment significantly decreased the steady state biliary clearance of ATFX to 55, 68, 54, 53 and 56% of control values, respectively. 4. Cyclosprin A, probenecid, erythromycin and cimetidine also inhibited the biliary excretion of ATFX glucuronide. Significant decrease in the steady state biliary clearance of ATFX and its glucuronide was observed in CCl(4)-EHI(24h) rats. 5. These results indicate that multiple transporters are possibly involved in the biliary excretion of ATFX.

Synthesis and antibacterial activity of levofloxacin derivatives with certain bulky residues on piperazine ring

A number of levofloxacin analogues carrying a 2-aryl-2-oxoethyl or a 2-aryl-2-oxyiminoethyl moiety attached to the piperazine ring at C-10 position have been prepared and evaluated as antibacterial agents against a series of Gram-positive and Gram-negative bacteria. Some of them exhibited significant inhibitory activity against Gram-positive bacteria.

Synthesis and Antibacterial Activity of Nitroaryl Thiadiazole-Levofloxacin Hybrids

Novel levofloxacin-containing hybrids carrying a 5-(nitroaryl)-1,3,4-thiadiazol-2-yl group were synthesized and evaluated in vitro against Gram-positive and Gram-negative bacteria. Preliminary data indicated that levofloxacin-nitrofuran and levofloxacin-nitroimidazole hybrids have a potent activity against Gram-positive organisms with enhanced anti-staphylococcal activity compared with the parent quinolone (N-desmethyl levofloxacin).

Investigation of chromatographic conditions for the separation of ofloxacin and its degradation products

A sensitive, precise, and accurate reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for simultaneous determination of fluoroquinolone antibacterial ofloxacin and its degradation products: decarboxy ofloxacin, 9-piperazino ofloxacin, des-methyl ofloxacin, and ofloxacin-N-oxide. The proposed RP-HPLC method allowed separation of all five compounds simultaneously with the total time of the analysis not more than 15 min. The relative standard deviation (RSD) values for quantification of DOF, POF, MOF, OF, and NOF were of 0.77, 0.58, 0.51, 0.10, and 0.70%, respectively, indicating a good precision of the method. The limits of detection for DOF, POF, MOF, OF, and NOF were 0.10, 0.13, 0.06, 0.03, and 0.03 microg mL(-1), respectively. The described method can be used for simultaneous identification and quantification of all analysed compounds in different pharmaceutical formulations.

An ionizable chromophoric reagent for the analysis of primary amine-containing drugs by capillary electrophoresis

We found that ofloxacin acyl chloride is a potential chromophoric reagent for labeling amino analytes for capillary electrophoresis. Ofloxacin acyl chloride has a tertiary amino function in its structure and the derivatives from ofloxacin acyl chloride reacting with amino analytes can be ionized by an acid treatment and analyzed by simple capillary zone electrophoresis. Ofloxacin acyl chloride was used to derivatize model analytes (without chromophore) of amantadine (amino drug), tranexamic acid (non-protein amino carboxylic acid), glycine, and methionine (protein amino acids). The resulting derivatives were analyzed by capillary zone electrophoresis with ultraviolet detection (300 nm). The detection limits of the analytes studied were in the range of 1.0-2.5 microM (S/N = 3, injection 3 s). The precision (relative standard deviation) and accuracy (relative error) of the method for intra- and inter-day analyses of the analytes were respectively below 4.5% and 3.9%. Application of the method to the analysis of tranexamic acid in plasma proved feasible.

Synthesis and biological testing of non-fluorinated analogues of levofloxacin

Quinolones without the usual 6-fluorine substituent have been recently described as potent antibacterial agents. A series of non-fluorinated analogues of the antibacterial quinolone Levofloxacin were synthesized and tested.

Structure and antimicrobial activity of some new norfloxacin and ofloxacin divalent metal ion complexes

The paper presents the studies of some new complexes of norfloxacin (Nf) and ofloxacin (Of) with Cd(II) and Hg(II). The synthesis, purification and the elemental chemical analysis of the Nf and Of compounds have been performed in order to obtain the chemical formulas. These formulas are confirmed by molecular mass determinations. IR, UV-VIS reflectance spectra were recorded, as well as electric conductometric measurements. These techniques confirm that the obtained compounds are electrolytes and give some hints about their molecular structures. The antimicrobial activity was tested using plates containing Muller-Hinton cultures as well as Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. All compounds and their Nf and Of ligands exert an obvious antimicrobial activity.

Stereoselective determination of ofloxacin and its metabolites in human urine by capillary electrophoresis using laser-induced fluorescence detection

A capillary electrophoresis method for the simultaneous separation and enantioseparation of the antibacterial drug ofloxacin and its metabolites desmethyl ofloxacin and ofloxacin N-oxide in human urine has been developed and validated. Enantioseparation was achieved by adding sulfobutyl beta-cyclodextrin to the running buffer. The detection of the analytes was performed by laser-induced fluorescence (LIF) detection using a HeCd-laser with an excitation wavelength of 325 nm. In comparison with conventional UV detection, LIF detection provides higher sensitivity and selectivity. The separation can be performed after direct injection of urine into the capillary without any sample preparation, because no matrix compounds interfere with the assay. Additionally, the high sensitivity of this method allows the quantification of the very low concentrations of enantiomers of both metabolites. The limit of quantification was 250 ng/ml for ofloxacin enantiomers and 100 ng/ml for each metabolites' enantiomers. This method was applied to the analysis of human urine samples collected from a volunteer after oral administration of 200 mg of (+/-)-ofloxacin to elucidate stereoselective differences in the formation and excretion of the metabolites. It could be demonstrated that the renal excretion of the S-configured metabolites, especially S-desmethyl ofloxacin, within the first 20 h after dosage, is significantly lower than that of the R-enantiomers.

Antimycobacterial activities of novel levofloxacin analogues

In order to investigate structure-activity relationships between antimycobacterial activities and basic substituents at the C-10 position of levofloxacin (LVFX), we synthesized a series of pyridobenzoxazine derivatives by replacement of the N-methylpiperazinyl group of LVFX with various basic substituents. A compound with a 3-aminopyrrolidinyl group had one-half the activity of LVFX against Mycobacterium avium, M. intracellulare, and M. tuberculosis. Mono- and dimethylation of the 3-amino moiety of the pyrrolidinyl group increased the activities against M. avium and M. intracellulare but not those against M. tuberculosis. On the other hand, dialkylation at the C-4 position of the 3-aminopyrrolidinyl group enhanced the activities against M. avium, M. intracellulare, and M. tuberculosis. Thus, introduction of an N-alkyl or a C-alkyl group(s) into the 3-aminopyrrolidinyl group may contribute to an increase in potency against M. avium, M. intracellulare, and/or M. tuberculosis, probably through elevation of the lipophilicity. However, among the compounds synthesized, compound VII, which was a 2,8-diazabicyclo[4.3.0]nonanyl derivative with relatively low lipophilicity, showed the most potent activity against mycobacterial species: the activity was 4- to 32-fold more potent than that of LVFX and two to four times as potent as that of gatifloxacin. These results suggested that an increase in the lipophilicity of LVFX analogues in part contributed to enhancement of antimycobacterial activities but that lipophilicity of the compound was not a critical factor affecting the potency.

Synthesis and anti-HIV activity of arylpiperazinyl fluoroquinolones: a new class of anti-HIV agents

Synthesis and anti-HIV activity of a series of novel arylpiperazinyl fluoroquinolones are reported. In the SAR study, the aryl substituents on the piperazine nitrogen were found to play an important role for the anti-HIV-1 activity. A few of the compounds exhibited potent anti-HIV activity: IC50=0.06 microM in chronically infected cells.

A new fluoroquinolone derivative exhibits inhibitory activity against human immunodeficiency virus type 1 replication

The inhibitory activity of several fluoroquinolone antibiotics against human immunodeficiency virus type 1 (HIV-1) replication was investigated. R-71762, (+/-) 9-fluoro-3-fluoromethyl-2, 3-dihydro-10-[4-(2-pyridyl)-1-piperazinyl]-7-oxo-7H-pyrido[1,2, 3-de][1,4]benzoxazine-6-carboxylic acid, protected MT-4 cells from HIV-1-induced cytopathic effects. Furthermore, the compound inhibited virus replication both in acutely and in chronically HIV-1-infected cells. On the other hand, ofloxacin, levofloxacin, ciprofloxacin, norfloxacin and enoxacin, that were previously reported to be protective against HIV-1-induced cytopathic effects, did not show any protective activity in our assay system. These results indicate that R-71762 is a novel inhibitor of HIV-1 replication and is effective even in HIV-1 chronically infected cells.

Susceptibility testing interpretive criteria for levofloxacin when testing respiratory pathogens, Haemophilus influenzae and Moraxella catarrhalis

The more active L-isomer, levofloxacin, of the racemic ofloxacin mixture has been under development for therapeutic use. In this study, we evaluated the activity of ofloxacin, levofloxacin, and D-ofloxacin against the fastidious respiratory tract pathogens Haemophilus influenzae and Moraxella catarrhalis. Levofloxacin was two-fold more active than ofloxacin against H. influenzae (MIC90, 0.015 microgram/ml), and D-ofloxacin was least active (MIC90, 1 microgram/ml). For M. catarrhalis the MIC90 values were 0.03 microgram/ml, 0.06 microgram/ml, and 2 micrograms/ml for levofloxacin, ofloxacin, and D-ofloxacin, respectively. For disk diffusion susceptibility testing, Chocolate Mueller-Hinton agar (CMH) was considered preferable to Haemophilus test medium (HTM) because it supported the growth of all of 105 H. influenzae strains whereas five strains failed to grow on HTM. In addition, the margins of the zones of inhibition were more distinct on CMH and the Haemophilus species strains with elevated fluoroquinolone MICs were readily distinguished. The superior growth on CMH was reflected in a reduction of inhibition zone diameters of 2-3 mm relative to the inhibition zone diameters on HTM. The previously proposed interpretive criteria for the 5 microgram disk diffusion susceptibility test (susceptible at > or = 17 mm) results in complete categorical agreement with the reference microdilution broth method for M. catarrhalis on Mueller Hinton agar and for H. influenzae on HTM and CMH. However, the minimum diameter of the zone of inhibition recorded for a member of the dominant population of either species was considerably greater (25 mm) than 17 mm on any of the media tested.

Levofloxacin in vitro activity: results from an international comparative study with ofloxacin and ciprofloxacin

Levofloxacin, the S-(-)-isomer of ofloxacin, was compared to ofloxacin and ciprofloxacin against > 6000 recent clinical isolates of Gram-positive and Gram-negative bacteria from six different countries. This international multicenter study demonstrated a high level of antibacterial activity of levofloxacin against all the members of Enterobacteriaceae [minimum inhibitory concentration (MIC)50s, < or = 0.03 to 0.12 mg/L] except Providencia rettgeri (MIC50, 2 mg/L), and Providencia stuartii (MIC50, 1 mg/L). Oxacillin-susceptible staphylococci (MIC50s, 0.12 to 0.25 mg/L), enterococci (MIC50s, 0.5 to 2 mg/L), and streptococci (MIC50s, 0.5 mg/L) were also susceptible to levofloxacin, but most isolates of oxacillin-resistant staphylococci had MICs of > or = 4 mg/L. Levofloxacin was also active against non-enteric Gram-negative bacilli, including Acinetobacter species (MIC50s, < or = 0.03 to 1 mg/L), Pseudomonas species (MIC50s, 0.5 to 1 mg/L) and Xanthomonas maltophilia (MIC50, 0.5 mg/L). Overall, levofloxacin inhibited 50% and 90% of all the tested strains at the concentrations of 0.12 and 4 mg/L, respectively. The activity of levofloxacin was generally two-fold greater than ofloxacin and equal to or slightly less potent than ciprofloxacin.

Effects of aluminium-containing antacid on bioavailability of ofloxacin following oral administration of pivaloyloxymethyl ester of ofloxacin as prodrug

We newly synthesized a pivaloyloxymethyl ester of ofloxacin (OFLX-PVM) as prodrug in order to avoid the chelate formation between new quinolone and metal cations such as Al3+, Mg2+, Ca2+, or Fe2+ in the gastrointestinal tract. This compound was rapidly hydrolyzed in an incubation experiment by 43% in plasma, by 92% in small intestinal mucosal homogenates, and by 97% in liver homogenates during 0.5 h incubation, but was resistant to hydrolysis by pancreatic enzymes. In everted gut sac experiments, this compound was efficiently absorbed even in the presence of aluminium ion, whereas the absorption of ofloxacin (OFLX) was decreased significantly by the presence of aluminium ion. Minimal inhibitory concentration (MIC) values of OFLX-PVM were far higher than OFLX. Effects of aluminium hydroxide on the oral bioavailability of OFLX and OFLX-PVM were investigated in rabbits. The area under the plasma concentration-versus-time curve from zero to 24 h (AUC0-24h) following oral administration of OFLX was decreased significantly by 47.6% by combined administration with aluminium hydroxide, but AUC0-24h values of OFLX-PVM coadministered with and without aluminium hydroxide were similar to that of OFLX alone. These observations indicate that this new compound is likely to offer a prodrug for avoidance of interaction between new quinolone and metal cations.

Novel 1-8-bridged chiral quinolones with activity against topoisomerase II: stereospecificity of the eukaryotic enzyme

A series of novel C-7 quinolyl-substituted enantiomers of ofloxacin were used to determine the stereospecificity of topoisomerase II for the C-11 methyl group in tricyclic quinolones. In all cases, the S isomer was the most active compound against the eukaryotic enzyme. It was approximately 2.2-fold more potent than the R isomer at inhibiting the overall catalytic activity of topoisomerase II (as monitored by DNA relaxation assays). A markedly greater difference in quinolone activity was observed in enzyme-mediated DNA cleavage reactions. While the S enantiomer stimulated nucleic acid breakage approximately 3.5-fold, the R compound did not enhance and, in fact, decreased initial DNA cleavage levels by approximately 50%. The activity of the racemic mixture more closely resembled that of the R enantiomer. In competition experiments, the DNA cleavage-enhancing effects of the S isomer were attenuated by the R compound. Taken together, these latter results indicate that the R enantiomer is an antagonist of S isomer-promoted topoisomerase II-mediated DNA cleavage. Finally, the cytotoxic potential of quinolyl-substituted ofloxacin analogs correlated with the ability to stimulate enzyme-mediated DNA cleavage. Thus, stereochemistry appears to be a governing factor for the potential development of tricyclic quinolones as topoisomerase II-targeted drugs with antineoplastic activity.

Species-related stereoselective disposition of ofloxacin in the rat, dog and monkey

1. The stereoselective disposition of ofloxacin (OFLX) was studied in rats, dogs and monkeys after oral administration of racemic OFLX. 2. In rats serum concentrations of (R)-(+)-OFLX were much greater than those of (S)-(-)-OFLX, which is the active form of OFLX. In monkeys, by contrast, serum concentrations of (S)-(-)-OFLX predominated over (R)-(+)-OFLX levels. In dogs there were no differences in AUC or Cmax between the enantiomers. Thus, there exists a species-related difference in the stereoselective disposition of OFLX. 3. In rats the stereoselective differences were mainly due to stereoselective glucuronidation; OFLX is hardly metabolized in dogs, monkeys and humans. 4. In monkeys the AUC of (S)-(-)-OFLX was increased by co-administration of the (R)-(+)-form, indicating that the stereoselectivity of OFLX disposition in monkeys may be caused by competition between the enantiomers for renal excretion, especially for renal tubular secretion.

[Clinical efficacy of levofloxacin (LVFX) single-dose therapy in female acute uncomplicated cystitis]

Treatment of infections by the use of antimicrobial agents should be made essentially in a dose close to the minimally required dose. Acute uncomplicated cystitis in female fits as the subject for a single-dose therapy since it is an infection reactive relatively easily to antimicrobial agents. Accordingly, an assessment has been made regarding the therapeutic results of the single-dose therapy in 76 female cases of acute uncomplicated cystitis by the use of LVFX 200 mg which is a new quinolone. The urinary concentration more than MIC90 to Escherichia coli is sustained for about 3 days by this single-dose therapy. As a result of judging the therapeutic results from the reactions of the three clinical findings of pain on micturition, pyuria and bacteriuria, excellent therapeutic results were obtained with effective rates being 100% (76/76) on the day 3, 93.9% (46/49) on the day 7 and 94.4% (34/36) on the day 14. The rate of cystitic symptoms which recurred posed no problem, being 12.5% (5/40) up to three months, as investigated by a questionnaire. As a result of performing close urological examinations such as cystoscopy on six cases with insufficient results or recurrence, we could detect mild underlying conditions which are considered to be intractable factors in the bladder in three cases. From the above results, the single-dose therapy of acute uncomplicated cystitis in the female by LVFX which is a new quinolone was considered to be an excellent therapeutic drug from its characteristics such as its therapeutic results being the same as the conventional therapy by daily administration, excellent drug compliance, low cost, hard selectiveness of resistant strains, less side effects and furthermore it gives the opportunity of detecting a latent and mild underlying condition.

Synthesis and antipseudomonal activities of some ofloxacin esters as prodrugs

Three new ofloxacin esters have been synthesized as prodrug by the reaction of ofloxacin (CAS 82419-36-1) with chloromethylacetate, 1-chloroethylacetate and 1-chloroethylethylcarbonate in acetonitrile. The structures of the compounds have been elucidated by UV, IR, 1H-NMR, Mass spectra and elementary analysis. In vitro activities of these compounds against clinical isolates of various Pseudomonas aeruginosa species have been determined by microtiter tube dilution method, and octanol/water partition coefficients and pH dependent hydrolysis rates have been investigated in comparison with ofloxacin.

Significance of the methyl group on the oxazine ring of ofloxacin derivatives in the inhibition of bacterial and mammalian type II topoisomerases

A study was made of the correlation between the in vitro inhibitory effects of several quinolones, including four ofloxacin derivatives, on bacterial DNA gyrase from Escherichia coli KL-16 and on topoisomerase II from fetal calf thymus. No correlation was observed between the inhibitions of DNA gyrase activity and topoisomerase II activity. On the other hand, the inhibitory effects of these quinolones against topoisomerase II were closely correlated with their inhibition of cell growth. Furthermore, among the oxazine derivatives tested, the derivative with a methyl group at position 3 in an S configuration showed the highest activity against DNA gyrase and derivatives without a methyl group on the oxazine ring were more potent against topoisomerase II than those with a methyl group. Among these derivatives, DR-3355, the S isomer of ofloxacin, showed the highest activity against DNA gyrase and low activity against topoisomerase II. These results indicate that the methyl group on the oxazine ring plays an important role in the inhibitory activities of ofloxacin derivatives for these enzymes.

Pharmacokinetics of ofloxacin. An overview

Ofloxacin pharmacokinetics after oral and parenteral doses were investigated in healthy young and geriatric volunteers and renally impaired patients. After oral administration of single 100- to 600-mg doses to healthy younger volunteers, renal recovery indicates that the amount absorbed increases linearly from 100 to 600 mg. More than 70 percent of an oral dose is recovered in the urine as unchanged ofloxacin, and only minimal amounts, less than 5 percent of the dose, are recovered as the metabolites, desmethyl ofloxacin and ofloxacin N-oxide. After multiple (twice daily) oral administration of 400-mg doses to younger and older (65 to 81 years) healthy volunteers, a modest accumulation (i.e., maximal concentration increased about 50 percent), as predicted by single-dose data, is observed, and steady-state is achieved within 48 hours of the initiation of twice-daily dosing. In the young and elderly, ofloxacin is eliminated with a half-life of five to seven hours, independent of dose. In the renally impaired, however, there is a linear correlation between the half-life of ofloxacin and creatinine clearance, and this requires dose adjustment when the creatinine clearance rate is less than 50 ml/minute. The pharmacokinetics of ofloxacin also were investigated after intravenous administration of single 200- and 400-mg doses and multiple twice-daily 400-mg doses. After intravenous dosing, ofloxacin exhibits a pharmacokinetic profile similar to that seen after oral dosing, which supports the almost total oral absorption and the interchangeability of both forms of therapy. The pharmacokinetics of the compound indicate that, except for cases of renal impairment, little or no dosage adjustment is necessary.

In-vitro activity of DR-3355, an optically active isomer of ofloxacin, against bacterial pathogens associated with travellers' diarrhoea

The in-vitro activity of DR-3355, the S-(-)-isomer of ofloxacin, was determined against bacterial pathogens associated with travellers' diarrhoea. DR-3355 was highly active against isolates of enteropathogenic Escherichia coli (MIC90 0.05 mg/l), Salmonella spp. (MIC90 0.10 mg/l), Shigella spp. (MIC90 0.10 mg/l), Campylobacter jejuni (MIC90 0.39 mg/l) and Vibrio parahaemolyticus (MIC90 0.39 mg/l). The activity of DR-3355 against these bacteria was generally two- to eight-fold greater than that of ofloxacin and equal to, or only two-fold less than, that of ciprofloxacin with the exception of isolates of C. jejuni, which were two-fold less susceptible to ciprofloxacin than to DR-3355.

The pharmacokinetics of ofloxacin, desmethyl ofloxacin and ofloxacin N-oxide in haemodialysis patients with end-stage renal failure

Six patients with end-stage chronic renal failure undergoing haemodialysis were given ofloxacin (600 mg) orally and blood samples were taken at intervals up to 32 h. In four patients samples were also taken before and after haemodialysis. Serum concentrations of ofloxacin, desmethyl ofloxacin and ofloxacin N-oxide were measured by HPLC. The drug was well tolerated. Mean pharmacokinetic parameters for ofloxacin were Cmax 5.5 h (S.D. 1.97 h), Tmax 3.9 h (S.D. 3.25 h), T1/2 28 h (S.D. 17.37 h), AUC0-24 83.1 mg/1 h (S.D. 32.69 mg/l h). The desmethyl metabolite was produced in all patients but only half produced N-oxide. Cmax values were 0.21 mg/l (desmethyl) and 0.37 mg/l (N-oxide). Ofloxacin and desmethyl ofloxacin were variably and only slightly removed by haemodialysis whilst ofloxacin N-oxide was not removed at all. These results confirm that dosage reduction of ofloxacin is required in haemodialysis patients. Therapeutic drug monitoring by HPLC is recommended because of the observed variability in absorption and plasma half life.