Pharmacokinetics of ciprofloxacin and effect of repeated dosage on salivary and fecal microflora

Managing treatment failure in Neisseria gonorrhoeae infection: current guidelines and future directions

Due to the continued emergence of resistance to extended-spectrum cephalosporin antibiotics, clinicians are increasingly more likely to encounter cases of Neisseria gonorrhoeae treatment failure. The current international treatment guidelines offer few regimens for cases of N gonorrhoeae infection that do not respond to first-line therapy, and there are many complexities that should be considered with such regimens; these include regional variations in resistance to alternative agents, access to different antibiotics, and penetration of those antibiotics within different tissues. Further, such regimens do not account for the challenges of treating pharyngeal infections; many patients who have not responded to treatment with extended-spectrum cephalosporin antibiotics to date have had pharyngeal involvement. In addition, pharyngeal infections play a pivotal role in the emergence and spread of antimicrobial resistance in N gonorrhoeae and are more difficult to treat than urogenital infections because of the unfavourable pharmacokinetics of cephalosporins in pharyngeal tissues. Here, we summarise the current guidelines, provide additional approaches and considerations for clinicians, and highlight knowledge gaps that should be addressed to ensure appropriate therapy in cases of treatment failure.

Inhibitory effects of novel ciprofloxacin derivatives on the growth of four Babesia species and Theileria equi

The problems of parasite resistance, as well as the toxic residues to most of the commercially available antipiroplasmic drugs severely weaken their effective, curative, and environmental safe employment. Therefore, it is clear that the development of treatment options for piroplasmosis is vital for improving disease treatment and control. Ciprofloxacin is a broad-spectrum antibiotic that targets mainly the DNA replication machinery by inhibiting DNA gyrase and topoisomerase enzymes. As a result, ciprofloxacin is used for treating several bacterial and parasitic infections. In this study, the efficacy of 15 novel ciprofloxacin derivatives (NCD) that had been developed against drug-resistant Mycobacterium tuberculosis was evaluated against piroplasm parasite multiplication in vitro. The half-maximal inhibitory concentration (IC₅₀) values of the most effective five compounds of NCD (No. 3, 5, 10, 14, 15) on Babesia bovis, Babesia bigemina, Babesia caballi, and Theileria equi were 32.9, 13.7, 14.9, and 30.9; 14.9, 25.8, 13.6, and 27.5; 34.9, 33.9, 21.1, and 22.3; 26.7, 28.3, 34.5, and 29.1; and 4.7, 26.6, 33.9, and 29.1 μM, respectively. Possible detrimental effects of tested NCD on host cells were assessed using mouse embryonic fibroblast (NIH/3T3) and Madin-Darby bovine kidney (MDBK) cell lines. Tested NCD did not suppress NIH/3T3 and MDBK cell viability, even at the highest concentration used (500 μM). Combination treatments of the identified most effective compounds of NCD/diminazene aceturate (DA), /atovaquone (AQ), and /clofazimine (CF) showed mainly synergistic and additive effects. The IC₅₀ values of NCD showed that they are promising future candidates against piroplasmosis. Further in vivo trials are required to evaluate the therapeutic potential of NCD.

A Physiologically-Based Pharmacokinetic Model to Describe Ciprofloxacin Pharmacokinetics Over the Entire Span of Life

Background

Physiologically-based pharmacokinetic (PBPK) modeling has received growing interest as a useful tool for the assessment of drug pharmacokinetics by continuous knowledge integration.

Objective

The objective of this study was to build a ciprofloxacin PBPK model for intravenous and oral dosing based on a comprehensive literature review, and evaluate the predictive performance towards pediatric and geriatric patients.

Methods

The aim of this report was to establish confidence in simulations of the ciprofloxacin PBPK model along the development process to facilitate reliable predictions outside of the tested adult age range towards the extremes of ages. Therefore, mean data of 69 published clinical trials were identified and integrated into the model building, simulation and verification process. The predictive performance on both ends of the age scale was assessed using individual data of 258 subjects observed in own clinical trials.

Results

Ciprofloxacin model verification demonstrated no concentration-related bias and accurate simulations for the adult age range, with only 4.8% of the mean observed data points for intravenous administration and 12.1% for oral administration being outside the simulated twofold range. Predictions towards the extremes of ages for the area under the plasma concentration–time curve (AUC) and the maximum plasma concentration (C_max) over the entire span of life revealed a reliable estimation, with only two pediatric AUC observations outside the 90% prediction interval.

Conclusion

Overall, this ciprofloxacin PBPK modeling approach demonstrated the predictive power of a thoroughly informed middle-out approach towards age groups of interest to potentially support the decision-making process.

Electronic supplementary material

The online version of this article (10.1007/s40262-018-0661-6) contains supplementary material, which is available to authorized users.

The effect of antibiotics on the composition of the intestinal microbiota - a systematic review

OBJECTIVE

Antibiotics change the composition of the intestinal microbiota. The magnitude of the effect of antibiotics on the microbiota and whether the effects are short-term or persist long-term remain uncertain. In this review, we summarise studies that have investigated the effect of antibiotics on the composition of the human intestinal microbiota.

METHODS

A systematic search was done to identify original studies that have investigated the effect of systemic antibiotics on the intestinal microbiota in humans.

RESULTS

We identified 129 studies investigating 2076 participants and 301 controls. Many studies reported a decrease in bacterial diversity with antibiotic treatment. Penicillin only had minor effects on the intestinal microbiota. Amoxicillin, amoxcillin/clavulanate, cephalosporins, lipopolyglycopeptides, macrolides, ketolides, clindamycin, tigecycline, quinolones and fosfomycin all increased abundance of Enterobacteriaea other than E. coli (mainly Citrobacter spp., Enterobacter spp. and Klebsiella spp.). Amoxcillin, cephalosporins, macrolides, clindamycin, quinolones and sulphonamides decreased abundance of E. coli, while amoxcillin/clavulante, in contrast to other penicillins, increased abundance of E. coli. Amoxicllin, piperacillin and ticarcillin, cephalosporins (except fifth generation cephalosporins), carbapenems and lipoglycopeptides were associated with increased abundance of Enterococcus spp., while macrolides and doxycycline decreased its abundance. Piperacillin and ticarcillin, carbapenems, macrolides, clindamycin and quinolones strongly decreased the abundance of anaerobic bacteria. In the studies that investigated persistence, the longest duration of changes was reported after treatment with ciprofloxacin (one year), clindamycin (two years) and clarithromycin plus metronidazole (four years). Many antibiotics were associated with a decrease in butyrate or butryrate-producing bacteria.

CONCLUSION

Antibiotics have profound and sometimes persisting effects on the intestinal microbiota, characterised by diminished abundance of beneficial commensals and increased abundance of potentially detrimental microorganisms. Understanding these effects will help tailor antibiotic treatment and the use of probiotics to minimise this 'collateral damage'.

Effect of Short-Course Oral Ciprofloxacin on Isoflavone Pharmacokinetics following Soy Milk Ingestion in Healthy Postmenopausal Women

Soy isoflavones have several potential benefits related to postmenopausal health. Isoflavone glycosides, found predominantly in nonfermented soy products, e.g., soy milk, require conversion by gut microbiota to their respective bioavailable aglycones prior to absorption into portal circulation. Use of short-course oral ciprofloxacin for the treatment of acute uncomplicated cystitis, the incidence of which is increasing among postmenopausal women, might adversely affect gut microbiota. The objective of this one-group pre-post treatment study was to determine the effect of short-course oral ciprofloxacin on isoflavone pharmacokinetics in healthy postmenopausal women. Eleven postmenopausal subjects were assigned to consume a single oral dose of 375 mL UHT soy milk (SOY phase). Blood samples were collected immediately before soy milk ingestion and at specific times for 32 hours after soy milk ingestion. Following a washout period of at least seven days, subjects were assigned to take 250 mg oral ciprofloxacin after breakfast and dinner for three days, followed by a single oral dose of 375 mL UHT soy milk the next day (CIPRO/SOY phase). Blood samples were collected at the same time points as in the SOY phase. Plasma samples were treated with β-glucuronidase/sulfatase and plasma concentrations of aglycones (genistein and daidzein) were determined using high-performance liquid chromatography. Cmax, AUC0-t, and AUC0-∞ of both aglycones and Tmax of genistein obtained from the CIPRO/SOY phase were significantly lower than those obtained from the SOY phase, while Tmax of daidzein and t1/2 of both aglycones in the two phases were not significantly different.

Ecological impact of ciprofloxacin on commensal enterococci in healthy volunteers

Background

The ecological impact of ciprofloxacin on commensal enterococci is unknown.

Methods

Forty-eight healthy volunteers received ciprofloxacin from day (D) 0 to D14; stools were collected on D7, D14 and D42. Fluoroquinolone-susceptible and -resistant enterococci (FQ-SE and FQ-RE) were detected and quantified by culture, and identified by MALDI-TOF MS. The relative abundance of FQ-RE over FQ-SE was determined. The genetic basis of fluoroquinolone resistance was deciphered by partial sequencing of gyrA and parC genes. Clonal relatedness was determined by random amplification of polymorphic DNA PCR. Clinical trial no.: NCT00190151.

Results

Enterococci were carried by 47/48 (98%) subjects. Total counts were reduced during ciprofloxacin therapy (4.0 and 3.9 log cfu/g on D7 and D14 versus 5.9 log cfu/g before and 6.9 log cfu/g after treatment; P  < 0.05). Twenty-one out of 48 (44%) carried FQ-RE; among them, 21/21 carried Enterococcus faecium , 19 carried Enterococcus faecalis and 11 carried other species. Five out of 48 (10%) harboured FQ-RE (ciprofloxacin MIC >4 mg/L) before treatment (all E. faecium ), 6 on D7 (3 E. faecium and 3 E. faecalis ), 8 on D14 (4 E. faecium and 4 E. faecalis ) and 10 (21%) on D42 (9 E. faecium and 1 E. faecalis ). The relative abundance of FQ-RE increased from 44% on D0 to 73% and 75% on D7 and D14, respectively. No acquisition of fluoroquinolone resistance among endogenous D0 strains was evidenced. All (14/14) distinct Fluoroquinolone-resistant E. faecalis clones were gyrA / parC double mutants with high-level resistance (ciprofloxacin MIC >64 mg/L). In contrast, 34/35 E. faecium exhibited low-level resistance (ciprofloxacin MIC 4-32 mg/L) with no gyrA / parC mutation, but overexpressed the chromosomal Efm qnr gene. As compared with Fluoroquinolone-susceptible strains, Fluoroquinolone-resistant E. faecium were more frequently ampicillin resistant and Fluoroquinolone-resistant E. faecalis were more highly resistant to gentamicin.

Conclusions

Although intrinsically poorly susceptible to fluoroquinolones, gut populations of enterococci are highly impacted both quantitatively and qualitatively by ciprofloxacin.

Amoxicillin-clavulanic acid and ciprofloxacin-treated SPF mice as gnotobiotic model

The experiment was carried out on 24 SPF BALB/c female mice and lasted for 15 days with a 5-day antibiotic (ATB) treatment and then 10 days without ATB treatment. The aim of our study was to acquire an animal model with reduced and controlled microflora and, at the same time, to ensure that the good health of these animals is maintained. Per oral administration of amoxicillin and clavulanate potassium in Amoksiklav (Sandoz, Slovenia) at a dose of 387.11 mg/kg body weight (0.2 ml of dilution per mouse) and subcutaneous administration of ciprofloxacin in Ciloxan (Alcon, Spain) at a dose of 18.87 mg/kg body weight (0.1 ml of dilution per mouse) were performed every 12 h during first 5 days of experiment. Five-day treatment with ATB led to a reduced survivability of microorganisms in faeces (28.33 ± 0.43 % on day 2) and caecum content (28.10 ± 1.56 %), where no cultivable microorganisms in faeces were present. Ten-day convalescence of decontaminated animals under gnotobiotic conditions prevented recovery of species diversity in mice gut microflora. This was reduced to two detectable cultivable species, namely Escherichia coli (GenBank KX086704) and Enterococcus sp. (GenBank KX086705) which were capable to restore its metabolic (CRL 2012) and morphological potential (Baratta et al. Histochem Cell Biol 131:713-726, 2009) within physiological range. Animals obtained under this procedure can be used in further studies. As a result, we created a mouse gnoto model with reduced and controlled microflora without alteration of the overall health status of the respective animals.

Impact of fluoroquinolones on human microbiota. Focus on the emergence of antibiotic resistance

The aggregate of microorganisms residing on the surface of the skin, in the oropharynx and in the GI tract, known as the human microbiota, play a major role as natural reservoirs for bacterial resistance to antibiotics. Fluoroquinolones (FQ) are among the most prescribed antibiotics and a major increase in FQ resistance is occurring worldwide. High concentrations of FQ are found in microbial ecosystems explaining their profound effect on the clinically relevant bacteria that compose them. Yet, because of different local pharmacokinetics, distinct selective pressures occur in the different microbiota. Here we review the qualitative and quantitative impact of FQ on the three main human microbiota and their consequences, particularly in terms of emergence of antibiotic resistance. Finally, we review potential actions that could decrease the impact of FQs on microbiota.

Will targeting oropharyngeal gonorrhoea delay the further emergence of drug-resistant Neisseria gonorrhoeae strains?

Gonorrhoea is an important sexually transmitted infection associated with serious complications and enhanced HIV transmission. Oropharyngeal infections are often asymptomatic and will only be detected by screening. Gonococcal culture has low sensitivity (<50%) for detecting oropharyngeal gonorrhoea, and, although not yet approved commercially, nucleic acid amplification tests (NAAT) are the assay of choice. Screening for oropharyngeal gonorrhoea should be performed in high-risk populations, such as men-who-have-sex-with-men(MSM). NAATs have a poor positive predictive value when used in low-prevalence populations. Gonococci have repeatedly thwarted gonorrhoea control efforts since the first antimicrobial agents were introduced. The oropharyngeal niche provides an enabling environment for horizontal transfer of genetic material from commensal Neisseria and other bacterial species to Neisseria gonorrhoeae. This has been the mechanism responsible for the generation of mosaic penA genes, which are responsible for most of the observed cases of resistance to extended-spectrum cephalosporins (ESC). As antimicrobial-resistant gonorrhoea is now an urgent public health threat, requiring improved antibiotic stewardship, laboratory-guided recycling of older antibiotics may help reduce ESC use. Future trials of antimicrobial agents for gonorrhoea should be powered to test their efficacy at the oropharynx as this is the anatomical site where treatment failure is most likely to occur. It remains to be determined whether a combination of frequent screening of high-risk individuals and/or laboratory-directed fluoroquinolone therapy of oropharyngeal gonorrhoea will delay the further emergence of drug-resistant N. gonorrhoeae strains.

Human gut microbiota: repertoire and variations

The composition of human gut microbiota and their relationship with the host and, consequently, with human health and disease, presents several challenges to microbiologists. Originally dominated by culture-dependent methods for exploring this ecosystem, the advent of molecular tools has revolutionized our ability to investigate these relationships. However, many biases that have led to contradictory results have been identified. Microbial culturomics, a recent concept based on a use of several culture conditions with identification by MALDI-TOF followed by the genome sequencing of the new species cultured had allowed a complementarity with metagenomics. Culturomics allowed to isolate 31 new bacterial species, the largest human virus, the largest bacteria, and the largest Archaea from human. Moreover, some members of this ecosystem, such as Eukaryotes, giant viruses, Archaea, and Planctomycetes, have been neglected by the majority of studies. In addition, numerous factors, such as age, geographic provenance, dietary habits, antibiotics, or probiotics, can influence the composition of the microbiota. Finally, in addition to the countless biases associated with the study techniques, a considerable limitation to the interpretation of studies of human gut microbiota is associated with funding sources and transparency disclosures. In the future, studies independent of food industry funding and using complementary methods from a broad range of both culture-based and molecular tools will increase our knowledge of the repertoire of this complex ecosystem and host-microbiota mutualism.

Peroral ciprofloxacin therapy impairs the generation of a protective immune response in a mouse model for Salmonella enterica serovar Typhimurium diarrhea, while parenteral ceftriaxone therapy does not

Nontyphoidal Salmonella (NTS) species cause self-limiting diarrhea and sometimes severe disease. Antibiotic treatment is considered only in severe cases and immune-compromised patients. The beneficial effects of antibiotic therapy and the consequences for adaptive immune responses are not well understood. We used a mouse model for Salmonella diarrhea to assess the effects of per os treatment with ciprofloxacin (15 mg/kg of body weight intragastrically 2 times/day, 5 days) or parenteral ceftriaxone (50 mg/kg intraperitoneally, 5 days), two common drugs used in human patients. The therapeutic and adverse effects were assessed with respect to generation of a protective adaptive immune response, fecal pathogen excretion, and the emergence of nonsymptomatic excreters. In the mouse model, both therapies reduced disease severity and reduced the level of fecal shedding. In line with clinical data, in most animals, a rebound of pathogen gut colonization/fecal shedding was observed 2 to 12 days after the end of the treatment. Yet, levels of pathogen shedding and frequency of appearance of nonsymptomatic excreters did not differ from those for untreated controls. Moreover, mice treated intraperitoneally with ceftriaxone developed an adaptive immunity protecting the mice from enteropathy in wild-type Salmonella enterica serovar Typhimurium challenge infections. In contrast, the mice treated intragastrically with ciprofloxacin were not protected. Thus, antibiotic treatment regimens can disrupt the adaptive immune response, but treatment regimens may be optimized in order to preserve the generation of protective immunity. It might be of interest to determine whether this also pertains to human patients. In this case, the mouse model might be a tool for further mechanistic studies.

Quinolone pharmacokinetics

Fluoroquinolones have broad antibacterial spectra and are active against most Gram-negative and many Gram-positive species. They exhibit excellent oral bioavailability, extensive tissue penetration, low protein binding, and a long elimination half-life. This review compares and contrasts the pharmakonetics of some quinolone antibiotics - especially pefloxacin, ciprofloxacin, enoxacin, norfloxacin, ofloxacin, fleroxacin and lomefloxacin - in terms of their adsorption, distribution, metabolism, elimination, and interactions with other drugs and with food. In addition, the pharmacokinetics of these agents in the elderly and in patients with renal or hepatic impairment is discussed. The fluoroquinolones are established as a major class of antibiotics in the treatment of infections but pharmacokinetics factors should be considered when deciding on the most appropriate of these agents to use in individual patients.

Impact of residual and therapeutic doses of ciprofloxacin in the human-flora-associated mice model

A study was conducted to evaluate the effects of therapeutic and residual doses of ciprofloxacin on the human intestinal flora implanted into germ-free mice. Ciprofloxacin was administered daily via drinking water at concentrations to provide doses of 0, 0.125, 1.25, and 12.5mg/kg b.w. Changes in the intestinal flora composition, alteration in bacterial enzyme activities, fecal short chain fatty acid concentration and bacterial cellular fatty acid profiles, overgrowth of resistant bacteria, and disruption of the colonization barrier were the endpoints evaluated in the feces of human-flora-associated (HFA) mice. Ciprofloxacin at all tested doses decreased significantly the aerobic populations and particularly the population of Enterobacteriaceae. Selection of resistant Bacteroides fragilis group was noticed in HFA mice receiving 12.5mg/kg b.w. In mice challenged with a Salmonella strain, exogenous Salmonella persisted in the feces of all treated mice indicating that the flora responsible for the colonization barrier effect was disturbed by the antibiotic treatment. None of the studied metabolic parameters of the flora were affected by ciprofloxacin at any dose level. Under the experimental conditions of the study, the no-observed-effect level of ciprofloxacin was found to be less than 0.125 mg/kg b.w.

Ciprofloxacin at low levels disrupts colonization resistance of human fecal microflora growing in chemostats

We studied the in vitro effects of a range of ciprofloxacin (CI) concentrations on the human intestinal flora's colonization resistance (CR) to Salmonella kedougou NCTC 12173. Four steady state microbial communities were established in chemostats using inocula from a single pool of human feces. Three chemostats were exposed to CI (0.1, 0.43 and 5 microg/mL, respectively); one served as a no-drug control. The CR of each community was tested by three successive daily challenges of 10(8) S. kedougou, each delivered in a 1 mL bolus. There was no colonization of the no-drug chemostat. Likewise, after exposure to only 0.1 microg/mL CI there was no loss of CR and S. kedougou did not colonize. Conversely, both the 0.43 and the 5 microg/mL-exposed floras suffered a loss of CR and these chemostats were colonized. S. kedougou overgrew faster and reached higher counts in the presence of 0.43 than it did in the presence of 5 microg/mL. One possible explanation is that CI had a dose-dependent effect on both the challenge strain and CR. Thus, at higher levels, even though CR was disrupted by CI, so too was the growth of the challenge strain. Since exposure to CI elicited a dose-dependent reduction in Escherichia coli counts [Reg. Pharmacol. Toxicol. 33 (2001) 276] our new data suggest that E. coli may contribute to the CR against salmonella. We further conclude that, even at fecal levels below those reached during therapy, CI may impact the human gut flora sufficiently to facilitate colonization by S. kedougou.

Effect of parenteral fluoroquinolone administration on persistence of vancomycin-resistant Enterococcus faecium in the mouse gastrointestinal tract

We examined the effect of subcutaneous fluoroquinolone antibiotic administration on persistence and density of vancomycin-resistant Enterococcus faecium stool colonization in mice. Levofloxacin and ciprofloxacin did not promote colonization in comparison to saline controls, whereas moxifloxacin and gatifloxacin promoted persistent overgrowth in a dose-dependent fashion.

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.

Impact of fluoroquinolone administration on the emergence of fluoroquinolone-resistant gram-negative bacilli from gastrointestinal flora

We assessed the risk factors for acquisition of fluoroquinolone-resistant, gram-negative organisms in the gastrointestinal tract of hospitalized patients. We analyzed stool samples from 204 patients and recovered fluoroquinolone-resistant, gram-negative organisms from 63. Receipt of fluoroquinolone during the month preceding admission was the only risk factor identified, whereas female sex, duration of hospitalization, exposure to indwelling devices, admission from another hospital, and history of infection were risk factors for fecal colonization after day 4.

Effect of quinolones on intestinal ecology

Quinolones have a selective effect on the normal human intestinal microflora. Published data on 13 different quinolone agents [ciprofloxacin, enoxacin, norfloxacin, ofloxacin, pefloxacin, lomefloxacin, levofloxacin, sparfloxacin, rufloxacin, sitafloxacin (DU-6859a), gatifloxacin, trovafloxacin and moxifloxacin] show that gram-negative aerobic bacteria, especially Enterobacteriaceae, are strongly suppressed or eliminated during therapy. Gram-positive aerobic cocci are affected strongly by administration of sitafloxacin and moxifloxacin and to minor degrees by the other quinolones. Three new quinolones--gatifloxacin, trovafloxacin and moxifloxacin--are very active against anaerobic bacteria in vitro but have minor effects on the anaerobic intestinal human microflora. Similar findings have been reported for the other 10 quinolones. Thus, the quinolone antibacterials have an ecological impact on the human intestinal microflora, mainly on the enterobacteria, that should be taken into account when these agents are used for prophylaxis or treatment of gastrointestinal bacterial infections.

A controlled trial comparing ciprofloxacin with mesalazine for the treatment of active Crohn's disease. Groupe d'Etudes Thérapeutiques des Affections Inflammatoires Digestives (GETAID)

OBJECTIVE

The aim of this randomized controlled study was to investigate the efficacy of ciprofloxacin compared with mesalazine in treating active Crohn's disease.

METHODS

Patients with a mild to moderate flare-up of Crohn's disease (mean Crohn's Disease Activity Index [CDAI]; 217; range, 160-305) were randomized to receive ciprofloxacin 1 g/day or Pentasa 4 g/day for 6 wk. Complete remission was defined at wk 6 as a CDAI < or = 150 associated with a decrease (delta) in CDAI > 75. Partial remission was defined as a CDAI < or = 150 with 50 < delta CDAI < 75 or a CDAI > 150 with delta CDAI > 50 at wk 6. Group sequential procedure with triangular continuation regions was used to monitor the trial through the difference in complete remission rates, every 20 patients included.

RESULTS

Inclusion of patients was stopped at the second step, i.e., after 40 inclusions, with the conclusion of no difference in complete remission rates between ciprofloxacin- and Pentasa-treated groups. Among the 18 patients taking ciprofloxacin, two decided to stop treatment during the trial and three were considered as treatment failures because of deterioration at wk 3. Among the 22 patients taking mesalazine, one patient was lost to follow-up and eight patients were considered as treatment failures. Complete remission was observed in 10 patients (56%) treated with ciprofloxacin and 12 patients (55%) treated with mesalazine and partial remission was observed in three and one patient, respectively.

CONCLUSIONS

This study suggests that ciprofloxacin 1 g/day is as effective as mesalazine 4 g/day in treating mild to moderate flare-up of Crohn's disease.

Comparison of ceftriaxone, amikacin, and ciprofloxacin in treatment of experimental Yersinia enterocolitica O9 infection in mice

Ceftriaxone and ciprofloxacin were effective in the treatment of Yersinia enterocolitica O9 intestinal infection in mice. Amikacin was less effective. The impact of these drugs on indigenous bacteria from the intestinal microbiota was studied.

Analysis of fluoroquinolones in biological fluids by high-performance liquid chromatography

High-performance liquid chromatographic methods for the analysis of fluoroquinolones in biological fluids are reviewed. In particular, sample preparation and handling procedures, chromatographic conditions, and detection methods are discussed. A summary of published high-performance liquid chromatographic assays for individual fluoroquinolones is included.

Influence of intravenously administered ciprofloxacin on aerobic intestinal microflora and fecal drug levels when administered simultaneously with sucralfate

Ciprofloxacin, when given intravenously (i.v.), is secreted in significant amounts via the mucosa into the intestinal lumen. Sucralfate inhibits the antimicrobial activity of ciprofloxacin. The effect of combined therapy on the intestinal flora was investigated in 16 healthy volunteers. They were randomly assigned to two groups. Group A received 2 g of sucralfate orally three times a day for 7 days and 400 mg of ciprofloxacin i.v. twice a day (b.i.d.) starting 3 days after the sucralfate administration began. Group B was given only 400 mg of ciprofloxacin i.v. b.i.d. for 4 days. A total of 9 stool samples were collected from each subject beginning the week before ciprofloxacin was administered and on days -1, 1, 2, 3, 4, 7, 9, and 10 or 11 after commencement of the infusion period. The aerobic fecal flora was determined by standard microbiological methods. Measurements of fecal ciprofloxacin levels were based on high-performance liquid chromatography. Counts of bacteria of the family Enterobacteriaceae decreased in all subjects and were below 10(2) CFU/g in eight of eight subjects (group A) and six of eight subjects (group B) on day 4, but they returned to normal in all but one subject (group A) 10 days after the last infusion. The decreases in levels of bacteria of the family Enterobacteriaceae were not significantly different in groups A and B (Kaplan-Meier test). Staphylococci and nonfermenters responded variably, enterococci and lactobacilli remained unchanged, and candida levels increased transiently in four subjects (two in each group). Maximum fecal drug levels ranged from 251 to 811 microg/g. No significant difference could be found between the two groups. The i.v. application of ciprofloxacin eliminates intestinal bacteria of the family Enterobacteriaceae in a rapid and selective manner. This effect is not affected by simultaneous oral application of sucralfate.

Effect of quinolones on the human intestinal microflora

The quinolones exhibit a selective suppressive effect on the intestinal microflora. The aerobic Gram-negative bacteria are strongly suppressed, while the aerobic Gram-positive bacteria are less affected, with ciprofloxacin and ofloxacin having the greatest effect. The anaerobic microflora is not affected by administration of norfloxacin, but is suppressed slightly by ciprofloxacin and ofloxacin, and moderately by sparfloxacin and temafloxacin. Very high concentrations of the quinolones are obtained in faeces, far exceeding the minimum inhibitory concentration for most aerobic and anaerobic bacteria. The discrepancy between in vivo and in vitro outcome is explained by the binding of the quinolones to faeces, and by inoculum effects. These ecological properties of the quinolones on the intestinal microflora make them suitable for treatment of bacterial enteric infections, selective decontamination and prophylaxis against travellers' diarrhoea.

Chemoprophylaxis of bacterial infections in granulocytopenic patients with ciprofloxacin vs ciprofloxacin plus amoxicillin

Ciprofloxacin was compared to ciprofloxacin plus amoxicillin as antibacterial prophylaxis in 53 evaluable patients with neutropenic episodes, because an oral penicillin may help to decrease the incidence of gram-positive infections. The two groups were randomized and evaluated in a number of febrile episodes, in days at fever/at risk, in mean interval of first febrile episode, in duration of antibiotic therapy and in causative organisms in febrile episodes. In conclusion, no significant difference was observed between the two groups in prevention of gram-positive bacteremias.

Impact of the fluoroquinolones on gastrointestinal flora

A number of studies have been performed to evaluate the effect of the fluoroquinolones on gastrointestinal flora. The fluoroquinolones have only slight or no effect on the oropharyngeal flora, except when Neisseria, Haemophilus or Branhamella spp. are present. Studies have consistently shown that Gram-negative facultative bacteria of the lower intestinal flora are strongly suppressed during administration of these agents. Total faecal anaerobes are generally unchanged. The effect of the fluoroquinolones on Gram-positive bacteria is more variable with mild to moderate suppression reported with some agents. In view of the high faecal concentrations of the fluoroquinolones, the general lack of effect on anaerobes is surprising; it may be attributable to the large number of microorganisms found in faeces and faecal binding of the fluoroquinolones. Several recent studies suggest that the effects of some fluoroquinolones on faecal anaerobes and Gram-positive cocci may be more profound in certain patient populations such as bone marrow transplant recipients and patients undergoing gastrointestinal surgery. Colonisation with yeasts and the emergence of resistant bacterial strains have been reported during or after fluoroquinolone administration in some studies. Future studies will need to investigate the effect of the newer agents with greater activity against anaerobes and Gram-positive cocci on the gastrointestinal flora and to continue surveillance for resistant organisms.

Use of quinolones in the treatment of gastrointestinal infections

Bacterial enteropathogens are responsible for between 40% and 80% of diarrheal illness depending upon the age of the persons affected and geographic areas where illness occurs. Antibacterial agents will shorten the illness associated with enteric infection caused by enterotoxigenic Escherichia coli, Shigella spp. and Campylobacter jejuni. These drugs also are effective in the therapy of certain clinical conditions (presumably because they are due to the same agents) which are characterized by moderate to severe diarrhea with one or more of the following: high fever, dysentery (passage of bloody mucoid stools), or high leukocyte counts in stools. Antimicrobial agents are also effective in the therapy of travelers' diarrhea. The quinolone drugs have several advantages in the management of bacterial diarrhea where strains causing illness from nearly all regions of the world will show general susceptibility: high concentrations are achieved in the intestinal lumen following oral administration and resistance development is unusual. A quinolone probably represents the optimal agent for therapy of bacterial diarrhea in adults in areas where trimethoprim-resistant enteric pathogens are common.

Clinical pharmacokinetics of ciprofloxacin

Compared with nalidixic acid, ciprofloxacin is representative of a newer, more potent class of quinolones, termed the fluoroquinolones. It is available in both oral and parenteral dosage forms. The primary target of quinolone activity appears to be the bacterial DNA gyrase enzyme, which is a member of the class of type II topoisomerases. Bacterial do not acquire resistance to fluoroquinolones through mechanisms that are plasmid or R-factor mediated and, additionally, the quinolones do not appear to be vulnerable to degradation by bacterial inactivating mechanisms. Rather, bacterial resistance to ciprofloxacin occurs either through chromosomal mutation in the target enzyme DNA gyrase or through mutations that alter drug permeability into the bacterial cell. Ciprofloxacin and the fluoroquinolones in general are no more likely to select resistant mutant than are aminoglycosides or beta-lactam antibiotics. Ciprofloxacin displays in vitro activity against most Gram-negative and many Gram-positive pathogenic bacteria, many of which are resistant to a wide range of antibiotics. This finding is of considerable potential clinical significance. High pressure liquid chromatography (HPLC) and microbiological agar diffusion assays have been routinely used to quantify ciprofloxacin concentrations in biological fluids. Both methods are reproducible and accurate for serum but HPLC is recommended for other specimens because of the presence of microbiologically active metabolites. Absorption after oral administration is rapid and can be satisfactorily described as a zero-order process; peak serum ciprofloxacin concentrations (Cmax) are reached in approximately 1 to 2 hours. Concomitant administration of food does not cause clinically significant impairment of absorption and may be helpful in minimising gastric distress caused by the drug. A linear relationship between serum ciprofloxacin concentrations and the dose administered either orally or intravenously has been reported. The absolute bioavailability of ciprofloxacin is approximately 70%. The volume of distribution is large with a steady-state range after oral or intravenous dosing of 1.74 to 5.0 L/kg reflecting penetration of the drug into most tissues. Nonrenal clearance accounts for approximately 33% of the elimination of ciprofloxacin; to date, 4 metabolites have been identified. A first-pass effect has been reported but is thought to be clinically unimportant. Faecal recovery of ciprofloxacin accounts for approximately 15% of an intravenous dose. Nonrenal elimination includes metabolic degradation, biliary excretion and transluminal secretion across the enteric mucosa. Glomerular filtration and tubular secretion account for approximately 66% of the total serum clearance. The terminal disposition half-life (t1/2) is about 3 to 4 hours.(ABSTRACT TRUNCATED AT 400 WORDS)

Streptococcus mitis sepsis in bone marrow transplant patients receiving oral antimicrobial prophylaxis

PURPOSE

Streptococcal infection has increasingly become a problem in neutropenic patients. We report on an outbreak of Streptococcus mitis sepsis in six bone marrow transplant patients receiving oral antimicrobial prophylaxis.

PATIENTS AND METHODS

We performed an epidemiologic study of all patients in our bone marrow transplant program from 1986 to 1988. The hospital and microbiology records for all patients were reviewed. All bone marrow patients were treated according to specified protocols, including an oral prophylactic antimicrobial regimen that was changed in late 1987 from vancomycin/polymyxin/tobramycin to norfloxacin. Identification, susceptibility testing, and whole cell protein analysis of streptococcal isolates were performed at the Reference and Antimicrobial Investigations Laboratories at the Centers for Disease Control.

RESULTS

We detected six cases of S. mitis sepsis among 21 patients undergoing bone marrow transplantation. No other concurrent pathogen was isolated from any patient at the time of the S. mitis bacteremia. Bacteremia developed within 72 hours of transplant in five of six patients and was associated with severe mucositis in four patients. An environmental study failed to reveal any common source for the outbreak, and whole cell protein analysis of all six S. mitis isolates revealed each to be distinct. Of 12 patients receiving oral vancomycin/polymyxin/tobramycin, one developed S. mitis bacteremia, versus five of nine patients receiving norfloxacin (p less than 0.03).

CONCLUSION

We believe S. mitis bacteremia is a potential complication of bone marrow transplantation and is associated with antimicrobial prophylaxis with norfloxacin, especially in the setting of mucositis.

Impact of antimicrobial agents on human intestinal microflora

The most common and significant cause of disturbances in the normal intestinal microflora is the administration of antimicrobial agents. The microflora can be influenced by antimicrobial agents because of incomplete absorption of any orally administered antimicrobial agent, secretion of an antimicrobial agent in the bile, or secretion from the intestinal mucosa. In most cases, the influence is not beneficial to the patient because suppression of the indigenous microorganisms often permits potential pathogens to overgrow and cause septic conditions, stomatitis, diarrhea, or colitis. Antimicrobial agents that influence the normal microflora also promote the emergence of antimicrobial-resistant strains. During the last fifteen years, the impact of different antimicrobial agents on the human microflora has been studied by several investigators. In this article published data on the impact of beta-lactam antibiotics, macrolides, tetracyclines, nitroimidazoles, clindamycin and quinolones on the human intestinal microflora are reviewed.

The life and times of the Enterococcus

Enterococci are important human pathogens that are increasingly resistant to antimicrobial agents. These organisms were previously considered part of the genus Streptococcus but have recently been reclassified into their own genus, called Enterococcus. To date, 12 species pathogenic for humans have been described, including the most common human isolates, Enterococcus faecalis and E. faecium. Enterococci cause between 5 and 15% of cases of endocarditis, which is best treated by the combination of a cell wall-active agent (such as penicillin or vancomycin, neither of which alone is usually bactericidal) and an aminoglycoside to which the organism is not highly resistant; this characteristically results in a synergistic bactericidal effect. High-level resistance (MIC, greater than or equal to 2,000 micrograms/ml) to the aminoglycoside eliminates the expected bactericidal effect, and such resistance has now been described for all aminoglycosides. Enterococci can also cause urinary tract infections; intraabdominal, pelvic, and wound infections; superinfections (particularly in patients receiving expanded-spectrum cephalosporins); and bacteremias (often together with other organisms). They are now the third most common organism seen in nosocomial infections. For most of these infections, single-drug therapy, most often with penicillin, ampicillin, or vancomycin, is adequate. Enterococci have a large number of both inherent and acquired resistance traits, including resistance to cephalosporins, clindamycin, tetracycline, and penicillinase-resistant penicillins such as oxacillin, among others. The most recent resistance traits reported are penicillinase resistance (apparently acquired from staphylococci) and vancomycin resistance, both of which can be transferred to other enterococci. It appears likely that we will soon be faced with increasing numbers of enterococci for which there is no adequate therapy.

Quinolones and the gastrointestinal tract

A number of studies have evaluated the efficacy of the new fluoroquinolones for therapy of bacterial enteric diseases and for prevention of gram-negative sepsis in granulocytopenic patients. The success of the quinolones in these settings is related to several special features of these agents, including their spectrum of activity and high fecal levels, which are in turn reflected in their effect on the gastrointestinal flora. Other factors that are important, particularly for invasive disease such as typhoid fever and shigellosis, include good intracellular and bowel wall penetration, and lymph node and systemic drug concentrations many times higher than the MICs of the causative organisms. This article reviews the factors that contribute to the changes in fecal flora, and the results of clinical studies in patients with diarrhea, granulocytopenic patients, and patients with selected other infections of, or related to, the gastrointestinal tract.

Penetration of ciprofloxacin into saliva and nasal secretions and effect of the drug on the oropharyngeal flora of ill subjects

The pharmacokinetics of ciprofloxacin and its effect on the oropharyngeal bacterial flora were examined in 21 ill patients being treated for methicillin-resistant Staphylococcus aureus infections or colonization or both. Oral ciprofloxacin (750 mg twice a day) produced peak and trough concentrations in serum of 2.56 +/- 1.80 and 0.97 +/- 0.81 micrograms/ml and steady-state salivary and nasal secretory concentrations of 1.29 +/- 1.0 and 1.84 +/- 0.91 micrograms/ml, respectively. Because of technical problems, nasal secretory concentrations were felt to represent rough approximations of true values. Oral ciprofloxacin therapy did not promote colonization of the oropharynx by gram-negative bacilli.

Pharmacokinetics of ciprofloxacin in the elderly: increased oral bioavailability and reduced renal clearance

The pharmacokinetics of ciprofloxacin was studied after single intravenous and oral doses of 250 mg and during and after a five-day oral regimen of 500 mg twice daily in eight young (22-34 years) and eight elderly (63-76 years), healthy male volunteers. The absolute bioavailability of an oral dose was greater in the elderly than in the young subjects at both 250 mg (72 versus 58%; p less than 0.05) and 500 mg (79 versus 63%; p less than 0.05). Distribution was unaffected by age. The physiological aging of the kidneys resulted in a reduced renal clearance, while no significant changes in non-renal clearance, total clearance and terminal half-life were found in the elderly. The age-related increase in the bioavailability of ciprofloxacin, whether due to facilitated absorption and/or reduced first-pass elimination, is a hitherto unique finding for antibiotics. As a consequence, reduction of orally administered doses of ciprofloxacin should be considered for elderly patients.

Clinical impact of newer quinolones: influence on normal microflora

This review article summarizes the published data concerning the impact of ciprofloxacin and norfloxacin on the oropharyngeal and intestinal human microflora. The use of ciprofloxacin and norfloxacin for selective decontamination in compromised patients and for prophylaxis of recurrent urinary tract infections is also reviewed.

Pharmacokinetics of ciprofloxacin with reference to other fluorinated quinolones

The third generation quinolones, ciprofloxacin, enoxacin, fleroxacin, norfloxacin, ofloxacin and pefloxacin are all quickly and quantitatively well (75-95% of an oral dose) absorbed upon oral administration. The maximum serum concentrations appear after 1-2 hours. The serum and urine concentrations after oral or intravenous ciprofloxacin are directly proportional with the doses and follow normal, dose-independent pharmacokinetics. Ciprofloxacin and norfloxacin reach the same serum levels after the same doses. Steady-state levels are indifferent from those after the first dose. In contrast, enoxacin, oflaxacin and pefloxacin do reach somewhat higher levels after chronic administration. Ciprofloxacin is eliminated by the kidneys (active tubular secretion which is blocked by probenecid) (60% after an intravenous administration), by metabolism and by the transintestinal route. Metabolism is minimal (ca. 15-20% for ciprofloxacin and norfloxacin). Transintestinal elimination implies that the drug is eliminated by transport across the intestinal wall without significant biliary elimination (which is less than 1%). Penetration into tissues occurs readily. Concentrations in prostate secretion are high for ciprofloxacin and norfloxacin. Ciprofloxacin reaches high intracellular concentrations; within human neutrophils the levels reach 6 times the concentrations in the surrounding fluid. Concentrations in bile and tissues are in general comparable to those in serum. Cerebrospinal fluid (CSF) concentrations are low when meningi are normal, but 40-90% of the serum levels when the meninges are inflamed. Because the transintestinal route of elimination compensates for loss of renal elimination, the serum half-life of ciprofloxacvin is raised only to 5-10 hours even in total renal failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Ciprofloxacin. A review of its antibacterial activity, pharmacokinetic properties and therapeutic use

Ciprofloxacin is one of a new generation of fluorinated quinolones structurally related to nalidixic acid. The primary mechanism of action of ciprofloxacin is inhibition of bacterial DNA gyrase. It is a broad spectrum antibacterial drug to which most Gram-negative bacteria are highly susceptible in vitro and many Gram-positive bacteria are susceptible or moderately susceptible. Unlike most broad spectrum antibacterial drugs, ciprofloxacin is effective after oral or intravenous administration. Ciprofloxacin has been most extensively studied following oral administration. It attains concentrations in most tissues and body fluids which are at least equivalent to the minimum inhibitory concentration designated as the breakpoint for bacterial susceptibility in vitro. The results of clinical trials with orally and intravenously administered ciprofloxacin have confirmed the potential for its use in a wide range of infections, which was suggested by its in vitro antibacterial and pharmacokinetic profiles. It has proven an effective treatment for many types of systemic infections as well as for both acute and chronic infections of the urinary tract. Ciprofloxacin generally appeared to be at least as effective as alternative orally administered antibacterial drugs in the indications in which they were compared, and in some indications, to parenterally administered antibacterial therapy. However, further studies are needed to fully clarify the comparative efficacy of ciprofloxacin and standard antibacterial therapies. Bacterial resistance to ciprofloxacin develops infrequently, both in vitro and clinically, except in the setting of pseudomonal respiratory tract infections in cystic fibrosis patients. The drug is also well tolerated. Thus, as an orally active, broad spectrum and potent antibacterial drug, ciprofloxacin offers a valuable alternative to broad spectrum parenterally administered antibacterial drugs for use in a wide range of clinical infections, including difficult infections due to multiresistant pathogens.

Ciprofloxacin: chemistry, mechanism of action, resistance, antimicrobial spectrum, pharmacokinetics, clinical trials, and adverse reactions

Ciprofloxacin, considered a benchmark when comparing new fluoroquinolones, shares with these agents a common mechanism of action: inhibition of DNA gyrase. While ciprofloxacin demonstrated a fairly good activity against gram-positive bacteria, it is against gram-negative organisms that it proved to be more potent than other fluoroquinolones. It is the most active quinolone against Pseudomonas aeruginosa, with MIC90s on the order of 0.5 micrograms/ml. When given orally, ciprofloxacin exhibited 70% bioavailability and attained peak serum levels ranging between 1.5 and 2.9 micrograms/ml after a single 500-mg dose. Nineteen percent of an oral dose was excreted as metabolites in both urine and feces. In most cases, body fluids and tissue concentrations equaled or exceeded those in concurrent serum samples. In clinical trials, oral and intravenous ciprofloxacin yielded similar clinical and bacteriologic results compared to standard therapy in a wide array of systemic infections, including lower and upper urinary tract infections; gonococcal urethritis; skin, skin structure, and bone infections; and respiratory tract and gastrointestinal tract infections. Major benefits with the oral form of this quinolone are expected in chronic pyelonephritis and bone infections, and in pulmonary exacerbations in patients with cystic fibrosis. Emergence of ciprofloxacin-resistant microorganisms has been noted in clinical practice, primarily Pseudomonas aeruginosa and Staphylococcus aureus. The most frequent side effects are related to the gastrointestinal tract; but attention should be given to adverse central nervous system effects.

Worldwide clinical data on efficacy and safety of ciprofloxacin

During the clinical trials 8,861 patients have been treated with ciprofloxacin worldwide. 3,822 of the therapeutic courses were valid for analysis of efficacy according to FDA standards. The following dosages were usually administered: UTI: 100 to 500 mg twice daily orally or 100 mg twice daily intravenously; RTI: 250 to 1000 mg twice daily orally or 200 mg twice daily intravenously; septicemia: 200 mg intravenously twice daily; gonorrhea: 250 to 500 mg single tablet orally; all other infections: 500 to 1000 mg twice daily orally or 200 mg twice daily intravenously. Ciprofloxacin was administered to 762 courses of lower RTI, 88 courses of upper RTI, 108 courses of bacteremia, 766 courses of skin structure infection, 142 courses of bone and joint infections, 149 courses of intra-abdominal infections, 33 courses of gastrointestinal infections, 1,633 courses of UTI, 49 courses of pelvic infections, 279 courses of STD, mainly gonorrhea, and three courses of meningitis. The clinical response was resolution in 76%, improvement in 18% and failure in only 6%. Bacteriologic response by all sites evaluable: pathogens were eradicated from 74%, markedly reduced in 2%, persisted in 10%. Relapse occurred in 4% and reinfection was observed in another 6%. The overall response was favourable for 90% of the patients. Drug safety was established on a data base of 8,861 courses worldwide. The following side-effects according to COSTART terminology were observed: digestive 5%, metabolic nutritional 4.6%, central nervous 1.6%, skin 1.4%, hemic and lymphatic 1%, cardiovascular 0.4%, body as a whole 0.4%, urogenital 0.3%, special senses 0.3%, musculo-skeletal 0.1%, respiratory 0.08%. Several courses had more than one reaction. Thus the total incidence of side-effects for the treated patient population was 10.2%. Ciprofloxacin is a highly effective drug and a breakthrough in several areas of medical interest. It is relatively safe and side-effects are usually mild or moderate in intensity and transient.

Pharmacokinetics of ciprofloxacin

The fluorination of piperazinyl substituted quinolones has led to an interesting development of a series of new broad spectrum antibacterial agents that may be administered orally as well as parenterally and are well tolerated. Norfloxacin was an early compound, later followed by ciprofloxacin, enoxacin, ofloxacin and pefloxacin. In this overview the emphasis will be on the most extensively studied compound including comparisons, where data are available, with norfloxacin and ofloxacin. Enoxacin and pefloxacin will be omitted due to their pattern of side effects, which at present curtail their therapeutic use. More recent substances such as fleroxacin and defloxacin have not been sufficiently investigated to be considered in this context.

Ciprofloxacin concentrations in tonsils following single or multiple administrations

Penetration of ciprofloxacin into human tonsils was studied in 20 adult humans undergoing tonsilectomy. Ten patients received a single intravenous infusion of 200 mg ciprofloxacin within 15 min (group A) and 14 patients were treated orally for three days with 500 mg ciprofloxacin b.i.d. prior to a preoperative infusion of 200 mg (group B). Ciprofloxacin concentrations in serum and tonsils were determined microbiologically. Mean ciprofloxacin serum concentrations did not differ significantly between both groups. Similarly, mean distribution ratios between tonsils and serum were not dissimilar, being on average 150% irrespective of whether the drug was administered once or repeatedly. Thus, a significant accumulation of ciprofloxacin was not observed either in the intravascular or in the extravascular space.

A review on the impact of 4-quinolones on the normal oropharyngeal and intestinal human microflora

During the last few years the impact of the newer 4-quinolones, ciprofloxacin, enoxacin, norfloxacin, ofloxacin and pefloxacin, on the human microflora has been studied by several investigators. This review article summarizes the published data concerning these studies. The results show that the oropharyngeal flora is affected only slightly or not at all by the 4-quinolones. All the newer 4-quinolones have a similar effect on the normal intestinal flora. The gram-negative aerobic flora is strongly suppressed during administration of 4-quinolones, while the gram-positive flora is only slightly affected. The anaerobic microflora is hardly affected at all. The emergence of resistant bacterial strains is uncommon, although one study shows increased MIC-values for anaerobes during ciprofloxacin administration. Replacement by yeasts or other inherently resistant microorganisms does not often seem to be a problem. High concentrations of the 4-quinolones are reached in faeces, values between 100-2,200 mg/kg being reported. Since the 4-quinolones do not cause marked ecological disturbances in the intestinal microflora, they may be suitable for selective decontamination in immunocompromised patients, for prophylaxis of urinary tract infections and for treatment of bacterial intestinal infections.

Comparative effects of enoxacin and norfloxacin on human colonic microflora

Ten healthy volunteers received 400 mg of enoxacin and another ten healthy volunteers received 200 mg of norfloxacin orally twice a day for 7 days. Fecal specimens were collected before, during, and after drug administration to study the impact of enoxacin and norfloxacin on the normal colonic microflora. On day 7, the mean concentrations of enoxacin and norfloxacin were 350 and 950 mg/kg of feces, respectively. Enoxacin and norfloxacin affected the colonic microflora in similar ways. The number of strains of the family Enterobacteriaceae was markedly suppressed during drug administration, whereas the gram-positive and anaerobic microfloras were not significantly altered. Two weeks after withdrawal of the drugs, the colonic microflora had returned to normal.

Altered pharmacokinetic disposition of ciprofloxacin and vancomycin after single and multiple doses in rabbits

The pharmacokinetic disposition of vancomycin and ciprofloxacin was assessed in rabbits before the efficacy of these compounds in experimental staphylococcal endocarditis was compared. Ciprofloxacin was given in single intravenous bolus doses of 25 and 35 mg/kg and also in a multiple-dose regimen of 35 mg/kg every 6 h. Vancomycin was given in a similar manner in single doses of 17.5 and 25 mg/kg and in a multiple-dose regimen of 17.5 mg/kg every 6 h. Serum was sampled frequently after injections and analyzed by microbiologic assay for drug concentration. The pharmacokinetic parameters of clearance and steady-state volume of distribution were calculated by compartment-independent methods. These studies revealed that clearance of ciprofloxacin was reduced significantly after multiple doses (7.42 +/- 0.85 [standard deviation] versus 6.09 +/- 0.71 liters/h, P less than 0.01). Although the half-life and volume of distribution increased after multiple dosing, the differences were not statistically significant. The disposition of vancomycin following single doses was significantly altered after the 25-mg/kg dose compared with the 17.5-mg/kg dose. Half-life, clearance, and volume of distribution changed from 1.27 +/- 0.2 to 1.60 +/- 0.21 h (P less than 0.05), 0.54 +/- 0.05 to 0.39 +/- 0.04 liters/h (P less than 0.01), and 0.37 +/- 0.04 to 0.31 +/- 0.03 liters/kg (P less than 0.05), respectively. The disposition of ciprofloxacin was not altered with increases in dose size, and the disposition of vancomycin was not altered after multiple doses. If such alterations in the pharmacokinetic disposition of antimicrobial agents are unanticipated, the higher and more prolonged than expected serum concentrations may have an effect on the outcome of experimental infections.

Pharmacokinetics of ciprofloxacin in cystic fibrosis

We studied the pharmacokinetics of ciprofloxacin in 12 adult males with and 12 adult males without cystic fibrosis (CF). In a randomized crossover sequence, the subjects received 200 mg intravenously or 750 mg orally. With intravenous dosing, subjects also received 651 mg of iothalamate, a marker of glomerular filtration, and 700 mg of antipyrine, an indicator of hepatic oxidative drug metabolism. Pharmacokinetic parameters were determined by model independent methods. In the CF subjects, the ciprofloxacin concentration in serum during the first hour after intravenous administration was higher, and the oral absorption rate was slower. Other parameters did not differ between the groups. Mean concentrations in serum 5 min postinfusion were 3.08 and 2.14 micrograms/ml, and mean peak concentrations after oral dosing were 3.24 and 3.34 micrograms/ml in subjects with and without CF, respectively. Mean values for elimination half-life in all subjects were 4.8 and 5.0 h after intravenous and oral administration, respectively. The mean renal clearances in all subjects after intravenous and oral administration were 19.4 and 14.5 liters/h and accounted for 64 and 47% of the total clearance, respectively. These values were significantly greater than renal iothalamate clearance, indicating that tubular secretion contributed to the renal clearance of ciprofloxacin. A total of 69 and 35.4% of the administered ciprofloxacin was recovered from the urine within 48 h after intravenous and oral administration, respectively. The mean bioavailability was 71.2% and did not differ between the groups. We conclude that similar dosing regimens can be used to treat patients with CF and their normal counterparts.