Levofloxacin and sparfloxacin: new quinolone antibiotics

Prescribed drugs containing nitrogen heterocycles: an overview

Heteroatoms as well as heterocyclic scaffolds are frequently present as the common cores in a plethora of active pharmaceuticals natural products. Statistically, more than 85% of all biologically active compounds are heterocycles or comprise a heterocycle and most frequently, nitrogen heterocycles as a backbone in their complex structures. These facts disclose and emphasize the vital role of heterocycles in modern drug design and drug discovery. In this review, we try to present a comprehensive overview of top prescribed drugs containing nitrogen heterocycles, describing their pharmacological properties, medical applications and their selected synthetic pathways. It is worth mentioning that the reported examples are actually limited to current top selling drugs, being or containing N-heterocycles and their synthetic information has been extracted from both scientific journals and the wider patent literature.

A review of recent advances in anti-tubercular drug development

Tuberculosis is a global threat but in particular affects people from developing countries. It is thought that nearly a third of the population of the world live with its causative bacteria in a dormant form. Although tuberculosis is a curable disease, the chances of cure become slim as the disease becomes multidrug-resistant and the situation gets even worse as the disease becomes extensively drug-resistant. After approximately 5 decades without any new TB drug in the pipeline, there has been some good news in the recent years with the discovery of new drugs such as bedaquiline and delamanid as well as the discovery of new classes of anti-tubercular drugs. Some old drugs such as clofazimine, linezolid and many others which were not previously indicated for tuberculosis have been also repurposed for tuberculosis and they are performing well.

Changing Epidemiology of Group B Streptococcus Susceptibility to Fluoroquinolones and Aminoglycosides in France

Group B Streptococcus (GBS) is the leading cause of neonatal invasive infections and an emerging pathogen in the elderly. Our objectives were to describe the evolution of GBS resistance to antibiotics in France and to investigate the emergence of fluoroquinolone (FQ)-resistant isolates. A total of 8,757 unrelated GBS isolates were collected and tested for antibiotic susceptibility from 2007 to 2014 according to EUCAST recommendations. All isolates were susceptible to penicillin G, amoxicillin, and vancomycin. Resistance to macrolides decreased from 47.0% to 30.0%, whereas high-level resistance to aminoglycosides, especially amikacin, increased from 6.4% to 8.8% and 24 isolates (0.3%) were highly resistant to gentamicin. FQ resistance gradually increased from 0.2% in 2007 (n = 1) to 1.5% in 2014 (n = 18, P < 0.01). Capsular polysaccharide (CPS) genotyping, multilocus sequence typing, and sequencing of the quinolone resistance-determining region (QRDR) showed that GBS isolates of sequence type 19 (ST-19) CPS type V were largely overrepresented in FQ-resistant isolates (n = 30, 45.5%). All 30 strains displayed the same QRDR mutations and were often associated with cross-resistance to macrolides (93.3%) and gentamicin (30%). In conclusion, we report the rise of FQ- and aminoglycoside-resistant GBS in France over an 8-year study period, an evolution likely linked to the clonal expansion of ST-19 CPS V-resistant isolates. This study emphasizes the need for a continuous surveillance of GBS epidemiology and antibiotic susceptibility.

Nonantibiotic Effects of Fluoroquinolones in Mammalian Cells

Fluoroquinolones (FQ) are powerful broad-spectrum antibiotics whose side effects include renal damage and, strangely, tendinopathies. The pathological mechanisms underlying these toxicities are poorly understood. Here, we show that the FQ drugs norfloxacin, ciprofloxacin, and enrofloxacin are powerful iron chelators comparable with deferoxamine, a clinically useful iron-chelating agent. We show that iron chelation by FQ leads to epigenetic effects through inhibition of α-ketoglutarate-dependent dioxygenases that require iron as a co-factor. Three dioxygenases were examined in HEK293 cells treated with FQ. At sub-millimolar concentrations, these antibiotics inhibited jumonji domain histone demethylases, TET DNA demethylases, and collagen prolyl 4-hydroxylases, leading to accumulation of methylated histones and DNA and inhibition of proline hydroxylation in collagen, respectively. These effects may explain FQ-induced nephrotoxicity and tendinopathy. By the same reasoning, dioxygenase inhibition by FQ was predicted to stabilize transcription factor HIF-1α by inhibition of the oxygen-dependent hypoxia-inducible transcription factor prolyl hydroxylation. In dramatic contrast to this prediction, HIF-1α protein was eliminated by FQ treatment. We explored possible mechanisms for this unexpected effect and show that FQ inhibit HIF-1α mRNA translation. Thus, FQ antibiotics induce global epigenetic changes, inhibit collagen maturation, and block HIF-1α accumulation. We suggest that these mechanisms explain the classic renal toxicities and peculiar tendinopathies associated with FQ antibiotics.

Antibiotics for the treatment of rheumatoid arthritis

Antibiotic treatment for rheumatoid arthritis (RA) commenced in the 1930s with the use of sulfasalazine. Later, tetracyclines were successfully used for the treatment of RA. In double-blind and randomized studies, levofloxacin and macrolide antibiotics (including clarithromycin and roxithromycin) were also shown to be effective in the treatment of RA. There have been several reports in the literature indicating that periodontal pathogens are a possible cause of RA. Oral bacteria are one possible cause of RA. In this review, we aimed to investigate the effects of different antibiotics in RA treatment.

Tear concentration and safety of levofloxacin ophthalmic solution 1.5% compared with ofloxacin ophthalmic solution 0.3% after topical administration in healthy adult volunteers

PURPOSE

This study evaluated the tear concentration and safety of levofloxacin ophthalmic solution 1.5%.

METHODS

Healthy adult volunteers (N = 125) received a single initial two-drop bilateral dose of either levofloxacin 1.5% (n = 100) or ofloxacin 0.3% (n = 25). Tear-fluid drug concentrations were measured at 15 minutes and at 2, 6, 12, and 24 hours after dosing. Subjects were dosed every 2 hours while awake and 4 and 6 hours after retiring (Days 1-3) and four times daily while awake (Days 4-14). Final measurements and evaluations were done on Day 15. Tear concentrations were determined by high-performance liquid chromatography. Safety and tolerability parameters included visual acuity, ophthalmoscopy, biomicroscopy, rose bengal staining, and adverse effects.

RESULTS

Tear concentrations after a single two-drop dose of levofloxacin 1.5% and ofloxacin 0.3% were above 2 microg/mL, a concentration that exceeds the minimum inhibitory concentration90 for levofloxacin in typical ocular bacterial pathogens at all time points through 24 hours. The area under the curve for the first 12 hours for levofloxacin 1.5% was 2703.5 +/- 574.22 microg.h/mL and 414.1 +/- 1179.00 microg.h/mL with ofloxacin 0.3%. Maximal concentrations were 806.9 +/- 8.57 and 73.3 +/- 165.46 microg/mL, respectively. Levofloxacin 1.5% and ofloxacin 0.3% did not differ in adverse event incidence, except for transient mild/moderate dysgeusia (14% of levofloxacin-treated subjects versus 4% of ofloxacin-treated subjects). No corneal epithelial damage or inflammatory changes were associated with levofloxacin.

CONCLUSION

A single dose of levofloxacin 1.5% produced tear fluid concentrations that were well above the minimum inhibitory concentration90 for typical ocular pathogens and was safe and well tolerated.

Staphylococcal skin infections in children: rational drug therapy recommendations

Staphylococcus aureus remains one of the most common and troublesome of bacteria causing disease in humans, despite the development of effective antibacterials and improvement in hygiene. The organism is responsible for over 70% of all skin and soft tissue infections in children and accounts for up to one-fifth of all visits to pediatric clinics. Skin and soft tissue infections that are predominantly caused by S. aureus include bullous and non-bullous impetigo, folliculitis, furunculosis, carbunculosis, cellulitis, surgical and traumatic wound infections, mastitis, and neonatal omphalitis. Other skin and soft tissue infections may also be caused by S. aureus but are often polymicrobial in origin and require special consideration. These include burns, decubitus ulcers (particularly in the perianal region), puncture wounds of the foot, as well as human and mammalian bites. Treatment of staphylococcal skin infections varies from topical antiseptics to prolonged intravenous antibacterials, depending on severity of the lesions and the health of the child. The treatment of choice for oral antibacterials remains the penicillinase-resistant penicillins such as flucloxacillin. Cefalexin and erythromycin are suitable cost-effective alternatives with broader cover, although care must be taken with the use of macrolides because of development of resistance to multiple families of antibacterials, particularly the lincosamides. Other cephalosporins such as cefadroxil and cefprozil are also effective, can be given once daily and have a better tolerability profile -- while azithromycin has a further advantage of a 3-day course. However, all of these agents are more expensive. Although the antibacterials have been given for 10 days in most clinical trials, there is no evidence that this duration is more effective than a 7-day course. In children requiring intravenous therapy, ceftriaxone has a major advantage over other antibacterials such as sulbactam/ampicillin and cefuroxime in that it can be given once daily and may, therefore, be suitable for outpatient treatment of moderate-to-severe skin infections. Newer-generation cephalosporins and loracarbef are also effective and have a broader spectrum of activity, but do not offer any added benefit and are significantly more expensive. Skin and soft tissue infections due to methicillin-resistant S. aureus (MRSA) are still relatively uncommon in children. Well children with community-acquired MRSA infections can be treated with clindamycin or trimethoprim-sulfamethoxazole (cotrimoxazole), but must be observed closely for potentially severe adverse effects. In severe infections, vancomycin remains the treatment of choice, while intravenous teicoplanin and clindamycin are suitable alternatives. Linezolid and quinupristin/dalfopristin are currently showing great promise for the treatment of multi-resistant Gram-positive infections. While the choice of antibacterial is important, supportive management, including removal of any infected foreign bodies, surgical drainage of walled-off lesions, and regular wound cleaning, play a vital role in ensuring cure.

Grepafloxacin Concentration in Ocular Tissues after Intravenous Infusion in Rabbits with Intraocular Inflammation

PURPOSE

To determine the penetration of grepafloxacin into ocular tissues during experimental ocular inflammation.

METHODS

10 albino and 10 pigmented rabbits underwent a continuous intravenous infusion of the drug 24 h after injecting Salmonella typhimurium toxin intravitreously, creating ocular inflammation. The animals were killed and grepafloxacin levels were determined in plasma and ocular tissues using high performance liquid chromatography.

RESULTS

Grepafloxacin levels achieved a steady-state plasma concentration of 1.5 microg/ml. The drug diffused more towards vascularized tissues (chorioretina and iris) in both albino and pigmented rabbits with a tissue/serum ratio higher than 1. Grepafloxacin showed more affinity to pigmented tissue, rising levels of 40,000-50,000 ng/g in the chorioretina and iris in pigmented animals. After inflammation, grepafloxacin intraocular penetration increased in albino animals with levels exceeding the minimum inhibitory concentration for the most common ocular pathogens.

CONCLUSION

Grepafloxacin intraocular penetration is higher in pigmented tissues. Ocular inflammation increases the drug penetration into the vitreous.

Prolonged electroconvulsive therapy seizure in a patient taking ciprofloxacin

Electroconvulsive therapy (ECT) can be used for the treatment of mental disorders, either alone or along with psychotropic agents and/or drugs for other medical conditions. We present in this case report a patient with postpartum depression on ciprofloxacin therapy for a urinary tract infection. The seizure in the first ECT treatment lasted for 30 seconds. While under the care of ECT, the patient was diagnosed as having a urinary tract infection; therefore, ciprofloxacin therapy of 1000 mg/day was initiated. Her second ECT seizure, which was on the third day of ciprofloxacin therapy, was terminated with 3 mg of intravenous midazolam at the 150th second. The ciprofloxacin therapy was discontinued. The patient had not previous history of epilepsy, and the investigation results for the extended seizure were found to be normal. The ECT therapy was restarted 3 days later, and total of 8 treatments were completed, lasting 35-70 seconds. Because the first ECT lasted for 30 seconds and subsequent therapy, which was reinitiated 3 days after the discontinuation of ciprofloxacin, lasted no longer than 70 seconds, the extended seizure in this patient is thought to be related to ciprofloxacin.

Search compounds with antimicrobial activity by applying molecular topology to selected quinolones

Molecular topology was used to obtain substances with antimicrobial activity. Selected quinolones were employed to develop the corresponding connectivity functions and discriminant equation. Limiting functions were selected that allowed the discriminant function to more efficiently distinguish substances with and without antibacterial activity. Antibacterial tests were run to confirm the theoretically established activity.

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.

Intrinsic resistance of Mycobacterium smegmatis to fluoroquinolones may be influenced by new pentapeptide protein MfpA

The fluoroquinolones (FQ) are used in the treatment of Mycobacterium tuberculosis, but the development of resistance could limit their effectiveness. FQ resistance (FQ(R)) is a multistep process involving alterations in the type II topoisomerases and perhaps in the regulation of efflux pumps, but several of the steps remain unidentified. Recombinant plasmid pGADIV was selected from a genomic library of wild-type (WT), FQ-sensitive M. smegmatis by its ability to confer low-level resistance to sparfloxacin (SPX). In WT M. smegmatis, pGADIV increased the MICs of ciprofloxacin (CIP) by fourfold and of SPX by eightfold, and in M. bovis BCG it increased the MICs of both CIP and SPX by fourfold. It had no effect on the accumulation of (14)C-labeled CIP or SPX. The open reading frame responsible for the increase in FQ(R), mfpA, encodes a putative protein belonging to the family of pentapeptides, in which almost every fifth amino acid is either leucine or phenylalanine. Very similar proteins are also present in M. tuberculosis and M. avium. The MICs of CIP and SPX were lower for an M. smegmatis mutant strain lacking an intact mfpA gene than for the WT strain, suggesting that, by some unknown mechanism, the gene product plays a role in determining the innate level of FQ(R) in M. smegmatis.

Human aqueous humor levels of oral ciprofloxacin, levofloxacin, and moxifloxacin

PURPOSE

To evaluate the penetration of ciprofloxacin, levofloxacin, and moxifloxacin into the aqueous humor after oral administration.

SETTING

Alcorcon Hospital, Madrid, Spain.

METHODS

Forty-two patients having cataract surgery were randomly divided into 3 groups the day before surgery. The first group received 2 oral 500 mg doses of ciprofloxacin at 12-hour intervals. The second group received a single oral 500 mg dose of levofloxacin. The third group received a single oral 400 mg dose of moxifloxacin. At the time of surgery, 0.1 mL aqueous fluid was aspirated from the anterior chamber just before the operation and immediately stored at -80 degrees C. Drug concentrations were measured using a biological assay.

RESULTS

The mean aqueous level of ciprofloxacin was 0.50 microg/mL +/- 0.25 (SD); of levofloxacin, 1.50 +/- 0.50 microg/mL; and of moxifloxacin, 2.33 +/- 0.85 microg/mL. The mean aqueous levels of levofloxacin and moxifloxacin were above the 90% minimum inhibitory concentration for most of the common microorganisms that cause endophthalmitis.

CONCLUSIONS

Therapeutic concentrations of fluoroquinolones, mainly levofloxacin and moxifloxacin, were reached with oral administration. These antibiotics may be effective for prophylaxis and adjuvant therapy of bacterial endophthalmitis.

Seizures associated with fluoroquinolones

OBJECTIVE

To report two cases of seizures following administration of levofoxacin and ciprofloxacin.

CASE SUMMARY

A 75-year-old white woman admitted to the hospital was prescribed levofloxacin for ischemic toes. After receiving three doses of oral levofloxacin, the patient experienced a seizure. One month later, the patient was rechallenged with ciprofloxacin and again experienced a seizure. The patient was hypomagnesemic and had elevated serum creatinine at the time of both seizures, and was hyponatremic during the second seizure. A 74-year-old white woman admitted to the hospital was prescribed levofloxacin for bacterial pneumonia. After five doses, the patient experienced a seizure. The woman had no electrolyte imbalances at the time of the seizure and no history of a seizure disorder.

DISCUSSION

Quinolone antibiotics vary in their ability to induce seizures, with trovafloxacin having the greatest potential and levofloxacin possibly having the least potential. Neither patient had a history of a previous seizure disorder. Electrolyte imbalances are common with previous reports of fluoroquinolone-induced seizures.

CONCLUSIONS

Although levofloxacin monotherapy has not been implicated in inducing seizures, it appears to be the causative agent in the second case. In the first case, the quinolones may have been a necessary, but not sufficient, cause in a patient with electrolyte abnormalities. Risk factors for fluoroquinolone-induced seizures may Include seizure history, electrolyte imbalances,dose unadjusted for renal insufficiency, and concomitant treatment with agents that lower the seizure threshold.

Comparative pharmacokinetics and pharmacodynamics of the newer fluoroquinolone antibacterials

A number of new fluoroquinolone antibacterials have been released for clinical use in recent years. These new agents exhibit enhanced activity against Gram-positive organisms while retaining much of the Gram-negative activity of the earlier agents within the same class. The pharmacokinetics of most of these agents are well described including serum pharmacokinetics, tissue and fluid distribution, and pharmacokinetics in renal and hepatic disease. When compared with earlier agents within this class (i.e. ciprofloxacin), the newer agents retain the wide distribution characteristics; however, they exhibit a more prolonged elimination, which, in part, supports single daily administration for these agents. Based on their predominant renal elimination, dosage adjustment is necessary in the presence of renal disease for ciprofloxacin, levofloxacin, gatifloxacin and sitafloxacin. Drug interactions, particularly with multivalent cations (calcium/aluminium-containing antacids and iron products), remain a problem for the newer agents, resulting in reduced absorption requiring separate administration times to maximise bioavailability. However, the newer agents do not appear to interfere significantly with the cytochrome P450 system, thus minimising the potential for interactions with other drugs metabolised by this system. The pharmacodynamic properties of the fluoroquinolones have been well described. The bactericidal activity is maximised when the ratios of peak plasma drug concentration (Cmax): minimum inhibitory concentrations (MIC) or area under the concentration-time curve (AUC): MIC exceed specific threshold values. Knowledge of the pharmacodynamic relationships allows for appropriate drug selection and enables design of dosage regimens to maximise the bactericidal activity. Therapeutic drug monitoring of the fluoroquinolones may provide a means of optimising the dosage regimen in certain clinical situations (that is, meningitis and hospitalised pneumonias) with the goals of achieving a more predictable therapeutic response and minimising the potential for the development of resistance.

Acute exacerbations of chronic bronchitis: what role for the new fluoroquinolones?

Acute exacerbations of chronic bronchitis (AECB) are a major cause of morbidity and mortality. Bacterial pathogens are implicated in about half the episodes of AECB. Empirical antibacterials have a significant benefit in AECB; however, several recent developments have considerably complicated antibacterial choice for this condition. New fluoroquinolone antibacterials introduced in the last decade are theoretically well suited for the treatment of AECB, as the in vitro antimicrobial spectrum of these drugs includes all the major pathogens involved. The pharmacokinetic and pharmacodynamic properties of the new fluoroquinolones are superior to many other antibacterials used to treat AECB. In trials, clinical success with the new fluoroquinolones was equivalent and bacteriological success was occasionally superior to nonfluoroquinolone comparators. However, these clinical trials did not assess several potentially important end-points for which the theoretical superiority of the fluoroquinolones may translate into differences in outcome. Rare but serious adverse effects with some of the new fluoroquinolones have shaken the confidence of prescribing physicians in this class of drugs. Emergence of the resistance of Streptococcus pneumoniae to fluoroquinolones has raised concerns about indiscriminate and widespread use of the new agents for trivial infections. Patients with AECB are a heterogeneous population who should be stratified in order to appropriately choose empirical antibacterial therapy. Highly efficacious antibacterial therapy, such as the new fluoroquinolones, is appropriate as a first-line choice for patients who have risk factors for a poor outcome or are in intensive care units. Such selected use of the new fluoroquinolones balances individual benefit with societal concerns of the use of these agents for AECB.

Clinical utility of the new fluoroquinolones for treating respiratory and urinary tract infections

Increasing antimicrobial resistance among most common urinary and respiratory tract pathogens has been the catalyst for the development of fluoroquinolones that are effective against these prevalent resistant organisms. Important attributes of the newly developed fluoroquinolones include once-daily dosing, maintained extensive tissue penetration and high oral bioavailability added to targeted antibacterial activities, all pharmacodynamic characteristics that may reduce the need for parenteral therapy or prevent patients being hospitalised. Some fluoroquinolones also offer same-dose bioequivalency between iv. and oral formulations, a feature that allows iv.-to-oral dosing (step-down or 'switch' therapy) without the need for dosage adjustments. These features suggest that the newer fluoroquinolones may be near-ideal agents for the empirical treatment of many common infections. This review discusses the efficacy and clinically relevant antimicrobial and pharmacokinetic qualities of the fluoroquinolones in comparison with other agents traditionally used to treat patients with urinary and respiratory tract infections.

Quinolone Resistance: Older Concepts and Newer Developments

New quinolone compounds have been recommended for use in the treatment of respiratory tract infections, particularly pneumonia caused by multi drug-resistant Streptococcus pneumoniae. Of concern, however, is the recent emergence of pneumococcal isolates with reduced susceptibilities to both old and new quinolone compounds. This necessitates the employment of quinolone-use strategies aimed at restricting the emergence of resistance, to extend the effectiveness of this very important class of antibacterial agents. This article provides a comprehensive review of the recent discoveries in type II topoisomerase/quinolone structure-function relationships. It also addresses new insights into the mechanisms of quinolone resistance, the predicted trends in quinolone resistance, and possible strategies for quinolone use against S. pneumoniae.

[Use of levofloxacine in primary care for outbreaks in COPD]

OBJECTIVE

To find scientific evidence to support the indication for treating outbreaks in COPD patients on an out-patient basis with levofloxacine, as against conventional treatments.

DESIGN

Standardised review, following the criteria of medicine based on the evidence. A bibliographic search of the MEDLINE data base from 1966 to June 2000 was the basis for an analysis of the evidence found.

SETTING

Non-hospital treatment.

PATIENTS AND OTHER PARTICIPANTS

COPD patients suffering a light outbreak of probable bacterial origin, according to the Anthonisen criteria.

INTERVENTIONS

The intervention analysed was treatment with 500 mg/day of levofloxacine taken orally. An attempt was made to compare this with conventional treatments such as amoxycillin-clavulanic acid and acetyl cefuroxime. The indicators of results analysed were reduction in mortality or in the number of hospital admissions.

MEASUREMENTS AND MAIN RESULTS

No clinical trial was found that compared levofloxacine and amoxycillin-clavulanic acid. Two clinical trials were found that compared levofloxacine and acetyl cefuroxime. These found no significant differences between the group treated with levofloxacine and the group treated with cefuroxime.

CONCLUSIONS

No scientific evidence demonstrating advantages of levofloxacine treatment over amoxycillin-clavulanic acid was found, or over acetyl cefuroxime as empirical PC first-choice treatment for patients with outbreaks of COPD.

Levofloxacin pharmacokinetics and serum bactericidal activities against five enterobacterial species

After oral administration of 500 mg of levofloxacin to 12 volunteers, we investigated the pharmacokinetics and serum bactericidal activities (SBAs) against five strains of members of the family Enterobacteriaceae. Pharmacokinetic data were as follows: maximum concentration in serum, 6.36 +/- 0.57 mg/liter; area under the concentration-time curve, 43.6 +/- 6.23 mg. h/liter; elimination half-life 4.23 +/- 0.87 h. SBAs were present for 24 h against Escherichia coli and Citrobacter freundii. The SBAs at 1, 12, and 24 h after administration against E. coli were 1:108, 1:29, and 1:7, respectively, and those against Citrobacter freundii were 1:74, 1:25, and 1:7, respectively. The SBAs were present for 12 h against the other three organisms tested. The SBAs against Serratia marcescens were 1:28 and 1:9 at 1 and 12 h, respectively; the SBAs against Klebsiella pneumoniae were 1:25 and 1:7 at 1 and 12 h, respectively; and the SBAs against Enterobacter cloacae were 1:24 and 1:10 at 1 and 12 h, respectively.

Proarrhythmic effects of fluoroquinolone antibacterial agents: in vivo effects as physiologic substrate for torsades

Drug-induced prolongation of the QT interval is often associated with the onset of Torsades de Pointes (TdP) resulting in a life-threatening ventricular arrhythmia. The potential of the proarrhythmic effects of the new fluoroquinolone antibacterial agents, levofloxacin and sparfloxacin, was examined in the chronic complete atrioventricular block dogs with stable idioventricular automaticity using Holter ECG monitoring in conscious state (Experiment 1). Next, to better analyze the mechanisms of the proarrhythmic property, the cardiovascular effects of these two drugs were compared in the halothane-anesthetized dogs under the monitoring of ECG, His bundle electrogram, systemic and left ventricular pressure, monophasic action potential, cardiac output, and effective refractory period (Experiment 2). In Experiment 1, oral administration of 6 mg/kg (n = 4) as well as 60 mg/kg (n = 4) of levofloxacin did not induce any ventricular premature depolarization. On the other hand, oral administration of 60 mg/kg of sparfloxacin (n = 4) induced TdP leading to ventricular fibrillation in all animals within 24 h, while 6 mg/kg of sparfloxacin (n = 4) did not induce any ventricular premature depolarization. In Experiment 2, intravenous administration of 0.3 mg/kg as well as 3.0 mg/kg of levofloxacin slightly increased cardiac output, but no significant changes were detected in the other parameters (n = 6). On the other hand, intravenous administration of 0.3 mg/kg of sparfloxacin prolonged the effective refractory period. Additional administration of 3.0 mg/kg of sparfloxacin decreased the heart rate and prolonged the effective refractory period and ventricular repolarization phase in a similar extent, but no significant changes were detected in the other parameters (n = 6). These results suggest that backward shift of the relative repolarization period in a cardiac cycle may be the mechanism responsible for the torsadegenic effect of sparfloxacin.

The new antibiotics

It is easy to become overwhelmed by the amount of information available on the new antibiotics and difficult to keep abreast of the appropriate indications for each of them. For most patients with community-acquired infections, the first-line agent is usually not one of the newer agents, but a standard regimen, or at times, no antibiotic at all. The development of resistance is likely to parallel the extent to which these agents are prescribed. They should be used only when standard treatment fails, when compliance with treatment is a real and serious issue, or when the patient has a real allergic reaction to the standard regimen.

The safety profile of the fluoroquinolones

BACKGROUND

Premarketing trials showed the fluoroquinolone agents to have a favorable side-effect profile, with treatment-related adverse events comprising gastrointestinal, central nervous system, and dermatologic effects that were generally mild and reversible on cessation of treatment. However, postmarketing surveillance studies have identified severe adverse events, including severe anaphylaxis, QTc-interval prolongation, and potential cardiotoxicity, associated with 3 quinolone agents that either resulted in the removal of the agent from the market (temafloxacin and grepafloxacin) or significantly restricted its use due to substantial mortality and morbidity associated with liver toxicity (trovafloxacin). To date, there have been no such significant adverse events associated with the older fluoroquinolone agents, including ciprofloxacin, ofloxacin, norfloxacin, and levofloxacin. However, there are fewer data from postmarketing surveillance studies on the most recently approved agents, such as moxifloxacin and gatifloxacin, or agents awaiting approval, such as gemifloxacin.

OBJECTIVE

This paper examines safety data from the premarketing trials and postmarketing surveillance studies of fluoroquinolones available in the United States.

METHODS

A MEDLINE search was performed to identify all English-language studies published since 1980 concerning the safety profiles of the fluoroquinolones.

CONCLUSIONS

The fluoroquinolone antibacterial agents offer broad-spectrum therapy in patients with a variety of infections. Given similar spectra of activity, the choice between quinolones may be based on differences in efficacy and safety or tolerability profiles. Most drug reactions involving these agents are minor and reversible on discontinuing treatment, but adverse effects can be associated with significant mortality and morbidity, as was seen in the case of trovafloxacin and temafloxacin.

Sparfloxacin: a review

BACKGROUND

The continuing increase in the rate of penicillin and cephalosporin resistance among respiratory pathogens and of cross-resistance to macrolide antibiotics has led to the recommendation that fluoroquinolone antibiotics be used to treat high-risk patients with community-acquired pneumonia (CAP) and acute bacterial exacerbations of chronic bronchitis (ABECB).

OBJECTIVE

This review focuses on sparfloxacin, an oral fluoroquinolone, discussing its mechanism of action, activity, pharmacokinetic characteristics, safety, and efficacy in CAP and ABECB.

METHODS

Studies were identified by a MEDLINE search of the literature from 1990 to 1999, supplemented by educational materials from conferences and symposia.

RESULTS

Sparfloxacin is active against the major respiratory pathogens and against the atypical pathogens in pneumonia that are being reported with increasing frequency. Its long half-life permits once-daily dosing. In large trials in CAP and ABECB in which all isolates were susceptible to both comparators, sparfloxacin was found to have similar efficacy to erythromycin, cefaclor, amoxicillin, ofloxacin, and clarithromycin. Its safety profile is similar to that of the macrolides and other quinolone antimicrobial agents. Photosensitivity, nausea, and diarrhea are the most common adverse events reported in clinical trials of sparfloxacin. Its use is contraindicated in patients with QTc-interval prolongation.

CONCLUSION

The increasing prevalence of beta-lactam- and macrolide-resistant bacteria in respiratory infections emphasizes the need for newer agents such as the fluoroquinolones. The choice between agents should be based on activity against the relevant respiratory pathogens in high-risk patients.

Clinical use of fluoroquinolones in children

OBJECTIVE

To review the pharmacokinetics, efficacy, and safety of fluoroquinolones in children.

DATA SOURCES

A MEDLINE search (January 1966-March 1998) was conducted for relevant literature.

STUDY SELECTION AND DATA EXTRACTION

Data from compassionate use and published studies were reviewed for the assessment of pharmacokinetics, efficacy, and safety of fluoroquinolones in children.

DATA SYNTHESIS

Fluoroquinolones have a broad spectrum coverage of gram-positive and gram-negative bacteria, including Pseudomonas aeruginosa and intracellular organisms. Fluoroquinolones are well absorbed from the gastrointestinal tract, have excellent tissue penetration, low protein binding, and long elimination half-lives. These antibiotics are effective in treating various infections and are well tolerated in adults. However, the use of fluoroquinolones in children has been restricted due to potential cartilage damage that occurred in research with immature animals. Fluoroquinolones have been used in children on a compassionate basis. Ciprofloxacin is the most frequently used fluoroquinolone in children, most often in the treatment of pulmonary infection in cystic fibrosis as well as salmonellosis and shigellosis. Other uses include chronic suppurative otitis media, meningitis, septicemia, and urinary tract infection. Safety data of fluoroquinolones in children appear to be similar to those in adults. Fluoroquinolones are associated with tendinitis and reversible arthralgia in adults and children. However, direct association between fluoroquinolones and arthropathy remains uncertain.

CONCLUSIONS

Fluoroquinolones have been found to be effective in treating certain infections in children. Additional research is needed to define the optimal dosage regimens in pediatric patients. Although fluoroquinolones appear to be well tolerated, further investigations are needed to determine the risk of arthropathy in children. However, their use in children should not be withheld when the benefits outweigh the risks.

Potential interactions of the extended-spectrum fluoroquinolones with the CNS

The new generation fluoroquinolones -- sparfloxacin, levofloxacin, grepafloxacin and trovafloxacin -- have been designed to respond to the clinical need for extended antimicrobial cover in the face of increasing global microbial resistance. Their main focus is in the treatment of respiratory infections, particularly those acquired in the community. CNS adverse effects, such as dizziness and headache, are known to occur relatively commonly with some fluoroquinolones and are not, in general, well tolerated by patients. The structural component of the fluoroquinolone molecule believed to be responsible for improved gram-positive activity is also believed to be implicated in the production of CNS adverse effects, including those arising from drug interactions with theophylline and NSAIDs. Inhibition of brain gamma-aminobutyric acid (GABA) receptor binding appears to be a strong indicator of CNS activity, though N-methyl-D-aspartate receptor binding has also been implicated. In accordance with the results of these predictive studies, clinical trials have found sparfloxacin, levofloxacin and grepafloxacin to be associated with a low incidence of CNS events. Trovafloxacin has been found to be associated with a higher incidence of CNS events (particularly lightheadedness and dizziness) than the other 3 agents. Ongoing and future clinical studies will help to define the usefulness of the predictive models, as well as reveal the full CNS adverse event profile of these and other investigational fluoroquinolones.

A randomized, crossover design study of the pharmacology of extended-spectrum fluoroquinolones for pneumococcal infections

STUDY OBJECTIVES

The objectives of this study were to characterize the single-dose and steady-state plasma pharmacokinetics of IV levofloxacin and IV alatrofloxacin, and to compare the results to pneumococcal isolate sensitivities in order to estimate the clinical efficacy of current community-acquired pneumonia treatment regimens against pneumococcal infections.

DESIGN

Two-way, open-label, randomized, crossover study.

PARTICIPANTS

Each of 12 healthy volunteer subjects received IV levofloxacin, 500 mg qd for 7 days, and IV alatrofloxacin, 200 mg qd for 7 days. The two regimens were separated by a 2-week washout period.

MEASUREMENTS AND RESULTS

Plasma concentration profiles were collected around the first and final doses of both regimens and were assayed for their respective quinolone concentrations. When the peak concentrations for both agents were compared to standard twofold dilution minimum inhibitory concentration (MIC) values for pneumococcal isolates, it was discovered that the breakpoint MIC value at which each compound would no longer achieve a peak plasma concentration/MIC ratio of at least 12:1 was 0.5 mg/L for levofloxacin and 0.25 mg/L for alatrofloxacin.

CONCLUSIONS

Based on the MIC that inhibits 90% of isolates of Streptococcus pneumoniae for both of these agents (1.0 to 2.0 mg/L for levofloxacin and 0.125 to 0.25 mg/L for trovafloxacin), our results indicate that although the once-daily regimen of alatrofloxacin appears to be appropriate for this pathogen, a more aggressive regimen may need to be investigated to optimize the clinical and microbiological effects of levofloxacin.

Safety profile of sparfloxacin, a new fluoroquinolone antibiotic

The safety profile of sparfloxacin, a newer fluoroquinolone antibiotic, was examined through an integrated analysis of safety data from 6 multicenter phase III trials. These consisted of 5 double-masked, randomized, comparative trials of sparfloxacin (a 400-mg oral loading dose followed by 200 mg/d for 10 days) versus standard therapies (erythromycin, cefaclor, ofloxacin, clarithromycin, and ciprofloxacin) and I open-label trial (noncomparative) in patients with: community-acquired pneumonia (2 trials); acute bacterial exacerbations of chronic bronchitis (1 trial); acute maxillary sinusitis (2 trials, one of which was the noncomparative trial); and complicated skin and skin-structure infections (1 trial). Overall, 401 (25.3%) of 1585 patients treated with sparfloxacin and 374 (28.1%) of 1331 receiving a comparator regimen experienced at least 1 adverse event considered to be related to the study medication. Photosensitivity reactions, usually of mild-to-moderate severity, were seen more frequently with sparfloxacin (7.4%) than with comparator agents (0.5%), whereas gastrointestinal reactions (diarrhea, nausea, dyspepsia, abdominal pain, vomiting, and flatulence), insomnia, and taste perversion were more common in patients taking comparator drugs (22.3% vs 12.1%, 4.3% vs 1.5%, and 2.9% vs 1.2%, respectively). Analysis of electrocardiographic findings showed that the mean change from baseline in QT interval corrected for heart rate (QTc) was significantly greater in sparfloxacin-treated patients (10 msec) than in patients given comparator drugs (3 msec), but no associated ventricular arrhythmias were detected. Adverse events led to discontinuation of study medication in 104 (6.6%) patients receiving sparfloxacin and 118 (8.9%) given com parator drugs. Sparfloxacin may be considered an appropriate choice for the treatment of certain community-acquired infections for patients who are not at risk for photosensitivity reactions or adverse events associated with prolongation of the QTc interval.

Expanded activity and utility of the new fluoroquinolones: a review

In general, the fluoroquinolones developed over the past few years have greater potency, a broader spectrum of antimicrobial activity, greater in vitro efficacy against resistant organisms, and a better safety profile than other antimicrobial agents, including the older quinolones. The present review focuses on 4 new quinolones that are commercially available (levofloxacin, trovafloxacin, grepafloxacin, and sparfloxacin) and 3 that are currently undergoing clinical trials (gatifloxacin, moxifloxacin, and clinafloxacin). Examination of the minimum inhibitory concentrations of these drugs against gram-positive, gram-negative, anaerobic, and atypical organisms demonstrates their increased potency in vitro. The available clinical evidence, although sparse, suggests the potential enhanced efficacy of these drugs in the treatment of various community-acquired and nosocomial infections (eg, respiratory, urinary tract, and skin infections and sexually transmitted diseases). Compared with ciprofloxacin, their pharmacokinetic profiles demonstrate equivalent or greater bioavailability, higher plasma concentrations, and increased tissue penetration, as reflected in greater volume of distribution. Adverse events seen with most quinolones are mild. Serious adverse effects that may occur are phototoxicity (particularly with sparfloxacin) and prolongation of the QTc interval (seen with sparfloxacin and grepafloxacin). Drug interactions are possible between multivalent cation-containing compounds and all quinolones and between theophylline and both ciprofloxacin and grepafloxacin. Drugs that prolong the QTc interval should not be coadministered with sparfloxacin and grepafloxacin. Step-down therapy, a therapeutic and cost-saving advantage possible with gatifloxacin, levofloxacin, and moxifloxacin, allows the switching of patients from intravenous to oral therapy without having to change the dosage regimen or class of antibiotics. In addition to shortening the hospital stay and reducing the risk of venous complications, step-down therapy has been shown to cut hospital drug costs by 40% and hospitalization costs by 20%.

Levofloxacin: a therapeutic review

This therapeutic review discusses the pharmacology, pharmacokinetics, in vitro activity, drug interactions, and adverse effects of levofloxacin, a fluoroquinolone antibiotic. Particular emphasis is placed on the clinical efficacy of levofloxacin and its place in therapy. Compared with ciprofloxacin and the earlier quinolone agents, levofloxacin has an improved pharmacokinetic profile that allows convenient once-daily dosing in either an oral or parenteral formulation. Levofloxacin has enhanced activity against gram-positive aerobic organisms, including penicillin-resistant pneumococci. In published comparative trials involving commonly used treatment regimens, levofloxacin had equivalent if not greater activity in the treatment of community-acquired pneumonia, acute bacterial exacerbations of chronic bronchitis, acute bacterial sinusitis, acute pyelonephritis, and complicated urinary tract infection. Levofloxacin is well tolerated and induces minimal adverse drug reactions. Based on the above attributes, it may be reasonable to include levofloxacin on the hospital formulary in place of older quinolones. More recently released quinolones such as trovafloxacin exhibit similar advantages; however, until direct comparative trials between levofloxacin and these newer agents are conducted, it is difficult to advocate one agent over another. Regardless of which quinolone is the primary agent on the formulary, it is imperative that this class of antimicrobial drugs be used with discretion to minimize the development of resistance.

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

Levofloxacin, the optically pure levorotatory isomer of ofloxacin, is a fluoroquinolone antibacterial agent. Like other fluoroquinolones, it acts on bacterial topoisomerase and has activity against a broad range of Gram-positive and Gram-negative organisms. Levofloxacin also appears to have improved activity against Streptococcus pneumoniae compared with ciprofloxacin or ofloxacin. Levofloxacin distributes well and achieves high levels in excess of plasma concentrations in many tissues (e.g., lung, skin, prostate). High oral bioavailability allows switching from intravenous to oral therapy without dosage adjustment. In patients with mild to severe community-acquired pneumonia receiving treatment for 7 to 14 days, oral levofloxacin was similar in efficacy to amoxicillin/clavulanic acid, and intravenous and/or oral levofloxacin was superior to intravenous ceftriaxone and/or oral cefuroxime axetil. With levofloxacin use, clinical success (clinical cure or improvement) rates were 87 to 96% and bacteriological eradication rates were 87 to 100%. In the 5- to 10-day treatment of acute exacerbations of chronic bronchitis, oral levofloxacin was similar in efficacy to oral cefuroxime axetil or cefaclor. Levofloxacin resulted in clinical success in 78 to 94.6% of patients and bacteriological eradication in 77 to 97%. Oral levofloxacin was also similar in efficacy to amoxicillin/clavulanic acid or oral clarithromycin in patients with acute maxillary sinusitis treated for 7 to 14 days. Equivalence between 7- to 10-day therapy with oral levofloxacin and ciprofloxacin was seen in patients with uncomplicated skin and soft tissue infections. Clinical success was seen in 97.8 and 96.1% of levofloxacin recipients and bacteriological eradication in 97.5 and 93.2%. Complicated urinary tract infections, including pyelonephritis, responded similarly well to oral levofloxacin or ciprofloxacin for 10 days or lomefloxacin for 14 days. Clinical success and bacteriological eradication rates with levofloxacin occurred in 92 to 93.3% and 93.6 to 94.7% of patients.

CONCLUSIONS

Levofloxacin can be administered in a once-daily regimen as an alternative to other fluoroquinolones in the treatment of infections of the urinary tract, skin and soft tissues. Its more interesting use is as an alternative to established treatments of respiratory tract infections. S. pneumoniae appears to be more susceptible to levofloxacin than to ciprofloxacin or ofloxacin. Other newer fluoroquinolone agents that also have enhanced in vitro antipneumococcal activity may not share the well established tolerability profile of levofloxacin, which also appears to improve on that of some older fluoroquinolones.