Levofloxacin. Its use in infections of the respiratory tract, skin, soft tissues and urinary tract

Pharmacokinetics and pharmacodynamics of intravenous levofloxacin in patients with early-onset ventilator-associated pneumonia

OBJECTIVE

To investigate the pharmacokinetics of levofloxacin and the pharmacokinetic-pharmacodynamic appropriateness of its total body exposure in patients in the intensive care unit (ICU) treated for early-onset ventilator-associated pneumonia (VAP) with intravenous levofloxacin 500mg twice daily.

DESIGN

Prospective non-blinded pharmacokinetic-pharmacodynamic study.

PARTICIPANTS

Ten critically ill adult patients with normal renal function.

METHODS

Blood and urine samples were collected at appropriate times during a 12-hour administration interval at steady state. Levofloxacin concentrations were determined by high-performance liquid chromatography. Clinical and microbiological outcomes were assessed.

RESULTS

Levofloxacin pharmacokinetics were only partially comparable with those obtained from literature data for healthy volunteers. Area under the concentration-time curve (AUC(tau)) over the 12-hour dosage interval was about 30-40% lower than in healthy volunteers (33.90 vs 49.60 mg. h/L). The reduced exposure may be due to a greater clearance of levofloxacin (0.204 vs 0.145 L/h/kg [3.40 vs 2.42 mL/min/kg]), leading to a shorter elimination half-life (5.2 vs 7.6 hours). Cumulative urinary excretion during the 12-hour dosage interval confirmed the greater excretion of unchanged drug in these patients compared with healthy subjects (76% vs 68%). Coadministered drugs used to treat underlying diseases (dopamine, furosemide, mannitol) may at least partially account for this enhanced elimination in critically ill patients. Intravenous levofloxacin 500mg twice daily ensured a median C(max)/MIC (maximum plasma concentration/minimum inhibitory concentration) ratio of 102 and a median 24-hour AUC/MIC ratio of 930 SIT(-1). h (inverse serum inhibitory titre integrated over time) against methicillin-sensitive Staphylococcus aureus and Haemophilus influenzae. The overall success rate of the assessable cases was 75% (6/8). Bacterial eradication was obtained in all of the assessable cases (8/8), but a superinfection (Acinetobacter anitratus,Pseudomonas aeruginosa) occurred in three cases.

CONCLUSIONS

The findings support the suitability of intravenous levofloxacin 500mg twice daily in the treatment of early-onset VAP in ICU patients with normal renal function. Levofloxacin may represent a valid alternative to non-pseudomonal beta-lactams or aminoglycosides in the empirical treatment of early-onset VAP. However, further larger studies are warranted to investigate its efficacy.

Short treatment durations for acute bacterial rhinosinusitis: Five days of gemifloxacin versus 7 days of gemifloxacin

OBJECTIVE

The primary objective of this study was to demonstrate the clinical and radiologic efficacy of 5 days compared with 7 days of gemifloxacin therapy in the treatment of acute bacterial rhinosinusitis (ABRS).

STUDY DESIGN

In this prospective, double-blind, multicenter, parallel-group study, adult patients presenting with ABRS were randomized to receive gemifloxacin 320 mg once daily for either 5 days (n = 218) or 7 days (n = 203).

RESULTS

For the primary efficacy end point, clinical response to therapy at follow-up, 5 days of therapy with gemifloxacin was as effective as 7 days of therapy (per-protocol population; treatment difference 0.44%; 95% confidence interval [CI], -6.54 to 7.41). Five and 7 days of treatment with gemifloxacin were well tolerated.

CONCLUSION AND SIGNIFICANCE

The clinical efficacy of gemifloxacin 320 mg daily for 5 days is at least as good as the efficacy of gemifloxacin 320 mg daily for 7 days in the treatment of ABRS.

Gatifloxacin: a review of its use in the management of bacterial infections

Gatifloxacin is an 8-methoxy fluoroquinolone antibacterial agent. The drug has a broader spectrum of antibacterial activity than the older fluoroquinolones (e.g. ciprofloxacin) and shows good activity against many Gram-positive and Gram-negative pathogens, atypical organisms and some anaerobes. Notably, gatifloxacin is highly active against both penicillin-susceptible and -resistant strains of Streptococcus pneumoniae, a common causative pathogen in community-acquired pneumonia (CAP), acute sinusitis and acute bacterial exacerbations of bronchitis. Gatifloxacin is absorbed well from the gastrointestinal tract (oral bioavailability is almost 100%). Therefore, patients can be switched from intravenous to oral therapy without an adjustment in dosage. High concentrations of gatifloxacin are achieved in plasma and target tissues/fluids. Gatifloxacin has a long plasma elimination half-life, thus allowing once-daily administration. Few clinically significant interactions between gatifloxacin and other drugs have been reported. In patients with CAP, clinical response rates in recipients of intravenous/oral gatifloxacin 400 mg/day ranged from 86.8 to 98.0% and rates of bacterial eradication ranged from 83.1 to 100% (up to 28 days post-treatment). Gatifloxacin showed efficacy similar to that of amoxicillin/clavulanic acid, ceftriaxone (with or without erythromycin) with or without stepdown to clarithromycin, levofloxacin or clarithromycin. Gatifloxacin was as effective as clarithromycin or amoxicillin/clavulanic acid, and was significantly more effective (in terms of clinical response; p < 0.035) than 7 to 10 days' treatment with cefuroxime axetil in the treatment of acute exacerbations of chronic bronchitis. In acute sinusitis, gatifloxacin showed clinical efficacy similar to that of clarithromycin, trovafloxacin or amoxicillin/clavulanic acid. Genitourinary infections were also successfully treated with gatifloxacin. Gatifloxacin is generally well tolerated. Its tolerability profile was broadly similar to those of comparator agents in comparative trials. The most common adverse events are gastrointestinal symptoms (oral formulation) and injection site reactions.

CONCLUSIONS

Gatifloxacin has an extended spectrum of antibacterial activity and provides better coverage of Gram-positive organisms (e.g. S. pneumoniae) than some older fluoroquinolones. The drug has favourable pharmacokinetic properties, is administered once daily and is at least as well tolerated as other fluoroquinolones. Gatifloxacin is a useful addition to the fluoroquinolones currently available for use in the clinical setting and has an important role in the management of adult patients with various bacterial infections. As with other fluoroquinolones, careful control of gatifloxacin usage in the community is important in order to prevent the emergence of bacterial resistance and thus preserve the clinical value of this agent.

Commonly used antibacterial and antifungal agents for hospitalised paediatric patients: implications for therapy with an emphasis on clinical pharmacokinetics

Due to normal growth and development, hospitalised paediatric patients with infection require unique consideration of immune function and drug disposition. Specifically, antibacterial and antifungal pharmacokinetics are influenced by volume of distribution, drug binding and elimination, which are a reflection of changing extracellular fluid volume, quantity and quality of plasma proteins, and renal and hepatic function. However, there is a paucity of data in paediatric patients addressing these issues and many empiric treatment practices are based on adult data. The penicillins and cephalosporins continue to be a mainstay of therapy because of their broad spectrum of activity, clinical efficacy and favourable tolerability profile. These antibacterials rapidly reach peak serum concentrations and readily diffuse into body tissues. Good penetration into the cerebrospinal fluid (CSF) has made the third-generation cephalosporins the agents of choice for the treatment of bacterial meningitis. These drugs are excreted primarily by the kidney. The carbapenems are broad-spectrum beta-lactam antibacterials which can potentially replace combination regimens. Vancomycin is a glycopeptide antibacterial with gram-positive activity useful for the treatment of resistant infections, or for those patients allergic to penicillins and cephalosporins. Volume of distribution is affected by age, gender, and bodyweight. It diffuses well across serous membranes and inflamed meninges. Vancomycin is excreted by the kidneys and is not removed by dialysis. The aminoglycosides continue to serve a useful role in the treatment of gram-negative, enterococcal and mycobacterial infections. Their volume of distribution approximates extracellular space. These drugs are also excreted renally and are removed by haemodialysis. Passage across the blood-brain barrier is poor, even in the face of meningeal inflammation. Low pH found in abscess conditions impairs function. Toxicity needs to be considered. Macrolide antibacterials are frequently used in the treatment of respiratory infections. Parenteral erythromycin can cause phlebitis, which limits its use. Parenteral azithromycin is better tolerated but paediatric pharmacokinetic data are lacking. Clindamycin is frequently used when anaerobic infections are suspected. Good oral absorption makes it a good choice for step-down therapy in intra-abdominal and skeletal infections. The use of quinolones in paediatrics has been restricted and most information available is in cystic fibrosis patients. High oral bioavailability is also important for step-down therapy. Amphotericin B has been the cornerstone of antifungal treatment in hospitalised patients. Its metabolism is poorly understood. The half-life increases with time and can be as long as 15 days after prolonged therapy. Oral absorption is poor. The azole antifungals are being used increasingly. Fluconazole is well tolerated, with high bioavailability and good penetration into the CSF. Itraconazole has greater activity against aspergillus, blastomycosis, histoplasmosis and sporotrichosis, although it's pharmacological and toxicity profiles are not as favourable.

Pharmacokinetics and pharmacodynamics of fluoroquinolones

The pharmacokinetic characteristics of levofloxacin, moxifloxacin, and gatifloxacin include excellent oral bioavailability (90-99%), extensive penetration into tissues and body fluids, and an elimination half-life (6-12 hrs) that allows for once-daily dosing in patients with normal renal function. Levofloxacin and gatifloxacin primarily are excreted unchanged in the urine, whereas moxifloxacin undergoes hepatic metabolism. The pharmacodynamic values that correlate with successful clinical and microbiologic outcomes, as well as prevent emergence of bacterial resistance, are ratios of maximum or peak unbound drug concentration (Cmax) to minimum inhibitory concentration (MIC), and 24-hour unbound area under the concentration curve (AUC(0-24hr)) to MIC. For gram-negative infections, a Cmax:MIC greater than or equal to 10 and AUC(0-24hr):MIC greater than or equal to 125 are associated with increased probability of a successful outcome. For infections caused by Streptococcus pneumoniae, an AUC(0-24hr):MIC of 30 or more is suggested for favorable clinical outcomes. Pharmacokinetic and pharmacodynamic values influence rational therapeutic decisions in the selection and dosages of these drugs.

Cerebrospinal fluid penetration and pharmacokinetics of levofloxacin in an experimental rabbit meningitis model

This study was designed to investigate the penetration across the blood-brain barrier of three doses of levofloxacin using a microdialysis probe implanted into the cerebrospinal fluid (CSF) of a rabbit pneumococcal meningitis model. The microdialysis guide cannula was implanted into rabbit subarachnoid space using a stereotaxic frame. After 3 days, 10(4) cfu Streptococcus pneumoniae serotype 3 in 0.3 mL saline was injected via intracisternal puncture and animals were allowed to incubate the organisms for 16-18 h. Groups of animals (n = 5) then received 7, 10.5 or 14 mg/kg iv of the drug over 10 min. Plasma samples were obtained via an ear vein 0, 0.25, 0.5, 0.75, 1, 2, 4, 6 and 8 h after the antibiotic infusion. CSF microdialysis effluent samples were collected every 0.5 h for the entire experiment. Plasma and microdialysis effluent samples were analysed by HPLC. AUC(0-8) in plasma and CSF were computed using the trapezoid rule. The elimination half-life in plasma and CSF was calculated using non-linear regression analysis. The unbound peak plasma concentrations for the three doses studied were 3.9, 6.4 and 10.3 mg/L, respectively. There was a significant increase in the plasma AUC(0-8) [29.7 +/- 6.3, 49.1 +/- 19.1 and 67.6 +/- 8.9 mg x h/L (P < 0.005)]. The unbound peak CSF concentrations were 3.8, 5.7 and 8.6 mg/L and occurred at 0-0.5 h after the administration of the dose. The AUC(CSF(0-8)) was significantly higher as the dose was increased (7 mg/kg, 15.8 +/- 6.6; 10.5 mg/kg, 37.3 +/- 7.8; and 14 mg/kg, 46.4 +/- 20.9 mg x h/L; P < 0.03). The penetration of levofloxacin averaged 53% for the 7 mg/kg dosage group, 76% for the 10.5 mg/kg group and 68% for the 14 mg/kg group. Our results demonstrate that levofloxacin penetration into the CSF averages 66% for the doses that would be used in clinical practice.

[Oral levofloxacin versus intravenous ceftriaxone and amoxicillin/clavulanic acid in the treatment of community-acquired pneumonia that requires hospitalization]

BACKGROUND

Levofloxacin, an antibiotic from the quinolone family, which is used with success in the ambulatory treatment of patients with community-acquired pneumonia, has been recently introduced to the pharmaceutical market. The purpose of this study was to compare the effectiveness and tolerance of oral (v.o.) levofloxacin (LVF) versus intravenous (i.v.) amoxicillin/clavulanate (AMX/CL) and ceftriaxone (CTX) in the treatment of the community-acquired pneumonia that require hospitalization (CAPH).

PATIENTS AND METHOD

In this prospective and randomized study 84 patients were included, 28 per group, from both sex with CAPH. The patients were assigned randomly to receive one of the next treatments: AMX/CL, 1.02 g i.v. every 8 h, CTX, 1 g i.v. every 12 h or LVF, 500 mg v.o. every 24 h. At the beginning clinical, biochemical and radiological characteristics were recorded from each case and at the 72 h the effect of treatment was evaluated using the evolution of the thermal curve and radiological images. The quantitative variables were analyzed with ANOVA, the qualitatives parameters with *2 test and Yates correction. The level of signification was * = 0.05.

RESULTS

Age, sex, clinical presentation, biochemical measurements and radiological images in the 3 groups were similar and no adverse effects were recorded in any of them. Number of patients with favorable outcome in the groups AMX/CL, CTX and LVF was 25 (89%), 25 (89%) and 26 (93%); p = 0,870.

CONCLUSIONS

Levofloxacin can be a simple, effective and safe therapeutic option for patients with CAPH.

Pharmacokinetics of ofloxacin enantiomers after intravenous administration for antibiotic prophylaxis in biliary surgery

The pharmacokinetics of S-(-)- and R-(+)-ofloxacin, enantiomers of the fluoroquinolone ofloxacin, were characterized after prophylactic administration in 15 patients undergoing elective biliary surgery. A single dose of ofloxacin 400 mg given intravenously as an infusion was administered 1 hour before surgery. Plasma levels of S-(-)- and R-(+)-ofloxacin showed very small differences between both enantiomers, although the ratio of S-(-)- to R-(+)-enantiomer concentration in plasma showed significant differences (p < 0.05) at 4 and 12 hours. Adequate S-(-)-ofloxacin (levofloxacin, the active enantiomer) plasma levels (> or = minimum inhibitory concentration [MIC90] for Escherichia coli) were found throughout the procedure. For pharmacokinetic parameters, the authors found small but statistically significant differences (p < 0.05) in the area under the concentration-time curve, AUC0-infinity (22.30 +/- 2.72 mg h/L for S-(-)-ofloxacin vs. 20.50 +/- 2.06 mg h/L for R-(+)-ofloxacin), and in the clearance (0.15 +/- 0.04 L/h/Kg for S-(-)-ofloxacin vs. 0.16 +/- 0.04 L/h/Kg for R-(+)-ofloxacin). To test the penetration of ofloxacin enantiomers into tissues, the authors measured levels in subcutaneous cell tissue and gall-bladder cell tissue. They did not observe statistical differences between the two isomers, which means that distribution is not an estereoselective process. Enantiomer levels in these two tissues decreased rapidly, but the highest concentrations were reached during the 4 first hours (i.e., when the surgical procedure was being performed). In conclusion, with the prophylactic treatment used, levofloxacin plasma and tissue levels are high enough to prevent surgical infections.

Moxifloxacin: a review of its clinical potential in the management of community-acquired respiratory tract infections

Moxifloxacin is an extended-spectrum fluoroquinolone which has improved coverage against gram-positive cocci and atypical pathogens compared with older fluoroquinolone agents, while retaining good activity against gram-negative bacteria. The antibacterial spectrum of moxifloxacin includes all major upper and lower respiratory tract pathogens; it is one of the most active fluoroquinolones against pneumococci, including penicillin- and macrolide-resistant strains. In in vitro studies, emergence of bacterial resistance was less common with moxifloxacin than with some other fluoroquinolones, but this requires confirmation in large-scale clinical studies. As with other fluoroquinolones, moxifloxacin achieves good penetration into respiratory tissues and fluids. It shows a low potential for drug interactions and dosage adjustment is not required for patients of advanced age or those with renal or mild hepatic impairment. The efficacy of oral moxifloxacin has been demonstrated in large, well-designed clinical trials in patients with community-acquired pneumonia, acute exacerbations of chronic bronchitis or acute sinusitis. Moxifloxacin 400 mg once daily achieved bacteriological and clinical success rates of approximately 90% or higher. It was as effective as, or more effective than, comparators including clarithromycin, cefuroxime axetil and high dose amoxicillin in these trials. The most commonly reported adverse events in patients receiving moxifloxacin are gastrointestinal disturbances. Moxifloxacin is also associated with QTc prolongation in some patients; there are, as yet, no data concerning the possible clinical sequelae of this effect in high-risk patients. Moxifloxacin has a low propensity for causing phototoxic reactions relative to other fluoroquinolones, and animal data suggest that it has a low potential for causing excitatory CNS and hepatotoxic effects.

CONCLUSIONS

As an extended-spectrum fluoroquinolone, moxifloxacin offers the benefits of excellent activity against pneumococci, once daily administration and a low propensity for drug interactions. Although studies are needed regarding its tolerability in at-risk patients with QT interval prolongation, available data suggest that moxifloxacin is likely to become a first-line therapy option for the treatment of community-acquired lower respiratory tract infections, particularly in areas where drug-resistant S. pneumoniae or H. influenzae are common.

Levofloxacin in the empirical treatment of patients with suspected bacteraemia/sepsis: comparison with imipenem/cilastatin in an open, randomized trial

An open, randomized, multinational, multicentre study was conducted to compare the efficacy, safety and tolerability of levofloxacin 500 mg twice daily with imipenem/cilastatin 1 g iv three-times daily in the treatment of hospitalized adult patients with clinically suspected bacteraemia/ sepsis. Levofloxacin patients could change from iv to oral administration after a minimum of 48 h iv treatment if clinical signs and symptoms of sepsis had improved. The primary efficacy analysis was based on the clinical and bacteriological response at clinical endpoint. A total of 503 patients were randomized and 499 included in the intent-to-treat population. The per-protocol population comprised 287 patients with bacteriologically proven infection. Clinical cure rates at clinical endpoint in the intent-to-treat population and per-protocol population were 77% (184/239) and 89% (125/140), respectively, for levofloxacin and 68% (178/260) and 85% (125/147), respectively, for imipenem/cilastatin. At follow-up, the cure rates in the per-protocol population were 84% for levofloxacin and 69% for imipenem/cilastatin. The 95% confidence interval for both populations showed that levofloxacin was as effective as imipenem/cilastatin. A satisfactory bacteriological response was obtained in 87% (96/110) of levofloxacin patients and 84% (97/116) of imipenem/cilastatin patients at clinical endpoint. Adverse events possibly related to the study drug were reported in 74 (31%) levofloxacin patients and 79 (30%) imipenem/cilastatin patients. There were no clinically appreciable differences between the treatment groups. Levofloxacin 500 mg twice daily, either iv or as sequential iv/oral therapy, was as effective and well tolerated as imipenem/cilastatin 1 g iv three-times daily in the treatment of hospitalized patients with suspected bacteraemia/sepsis.

Levofloxacin versus cefuroxime axetil in the treatment of acute exacerbation of chronic bronchitis: results of a randomized, double-blind study

A randomized, double-blind, double-dummy, three-arm parallel design, multicentre study was conducted among adult patients with acute exacerbation of chronic bronchitis (AECB) in order to compare the efficacy and safety of two different doses of levofloxacin with cefuroxime axetil. A total of 832 patients were randomized to receive oral levofloxacin (250 mg od or 500 mg od) or oral cefuroxime axetil (250 mg bd) for 7-10 days. The primary efficacy analysis was based on the clinical response in patients with bacteriologically confirmed AECB, determined 5-14 days after the end of therapy (per-protocol population). Of 839 patients enrolled (at 71 centres in 14 countries), seven were not treated, giving an intention-to-treat (ITT) population of 832. In total, 281 patients received levofloxacin 250 mg, 280 received levofloxacin 500 mg and 271 received cefuroxime axetil. The cure rates in the ITT population were: levofloxacin 250 mg, 70% (196/281); levofloxacin 500 mg, 70% (195/280); cefuroxime axetil, 61% (166/271); those in the per-protocol population were: 78% (121/156), 79% (108/137) and 66% (88/134), respectively. Both doses of levofloxacin were at least as effective as cefuroxime axetil and were active against the main pathogens of clinical relevance (Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis). All three treatment regimens were equally well tolerated. In conclusion, the results show that levofloxacin (250 mg and 500 mg) od is effective and well tolerated in the treatment of AECB in adult patients.