Extravascular penetration of ciprofloxacin. A review

Factors Affecting the Metabolic Conversion of Ciprofloxacin and Exposure to Its Main Active Metabolites in Critically Ill Patients: Population Pharmacokinetic Analysis of Desethylene Ciprofloxacin

The objective of this prospective study was to examine the exposure to the main active metabolites of ciprofloxacin in critically ill patients and to examine the factors (demographic, laboratory and genetic) that could potentially affect the drug metabolic conversion of ciprofloxacin. The secondary aim was to develop a population pharmacokinetic model for the metabolite showing the most associations with the abovementioned factors. A total of 29 patients were treated with intravenous infusion of ciprofloxacin and enrolled on this trial. Blood samples for pharmacokinetic analysis were taken at 1, 4, and 11.5 h following the completion of the infusion. Sex, age, body weight, height, serum creatinine and bilirubin levels, and creatinine clearance (CL_CR) were recorded, and polymorphisms rs2032582 and rs1045642 in the ABCB1 gene, rs4148977 in the SLCO1A2 gene and rs762551 in the CYP1A2 gene were analyzed. A three-stage parent drug–metabolite population pharmacokinetic model was developed. Median (IQR) metabolite/parent ratios of the desethylene ciprofloxacin, formyl ciprofloxacin and oxociprofloxacin were 5.86 (4.09–9.87)%, 4.08 (3.38–6.92)% and 5.91 (3.42–13.65)%, respectively. The desethylene ciprofloxacin metabolic ratio was positively associated with height (r² = 0.2277, p = 0.0089) and CL_CR (r² = 0.2023, p = 0.0144) and negatively associated with age (r² = 0.2227, p = 0.0112). Males had a significantly higher oxociprofloxacin metabolic ratio than females (9.14 vs 3.42%, p = 0.0043). In the desethylene ciprofloxacin population PK model, the volume of distribution decreased with age, the parent drug-metabolite transfer rate constant increased with CL_CR, and the metabolite elimination rate constant decreased with age and is increased in CYP1A2 rs762551 variant allele carriers. We therefore hypothesized that the CYP1A2 inhibition by ciprofloxacin is mediated by its metabolite desethylene ciprofloxacin.

Intranasal delivery of ciprofloxacin to rats: A topical approach using a thermoreversible in situ gel

Intranasal administration of antibiotics is an alternative and attractive delivery approach in the treatment of local infections such as chronic rhinosinusitis. This topical route has the advantage of delivering high drug concentrations directly to the site of infection when trying to eradicate the highly resistant bacterial biofilms. The purpose of this study was to assess and compare the pharmacokinetic parameters of ciprofloxacin following intranasal and intravenous administrations to rats in plasma, olfactory bulb and nasal mucosa of two different nasal regions. For intranasal administration a thermoreversible in situ gel was used to increase drug residence time in nasal cavity. Ciprofloxacin concentration time-profile in nasal mucosa of the studied anterior region (at naso- and maxilloturbinates level) was markedly higher after intranasal administration (0.24mg/kg) than that following intravenous administration (10mg/kg), while in nasal mucosa of the more posterior region (at ethmoidal turbinates level) ciprofloxacin concentrations were found to be higher after intranasal administration when the different dose administered by both routes is taken into account. A plateau in ciprofloxacin concentration was observed in nasal mucosa of both studied regions after intranasal administration, suggesting a slow delivery of the drug over a period of time using the nasal gel formulation. In plasma and olfactory bulb, concentration of ciprofloxacin was residual after intranasal administration, which demonstrates this is a safe administration route by preventing systemic and particularly central nervous system adverse effects. Dose-normalized pharmacokinetic parameters of ciprofloxacin exposure to nasal mucosa revealed higher values after intranasal delivery not only in the anterior region but also in the posterior nasal region. In conclusion, topical intranasal administration appears to be advantageous for delivering ciprofloxacin to the biophase, with negligible systemic and brain exposure using a 41.7-fold lower dose than intravenous administration. Therefore, it may represent a promising approach in the drug management of chronic rhinosinusitis.

Interethnic differences in pharmacokinetics of antibacterials

BACKGROUND

Optimal antibacterial dosing is imperative for maximising clinical outcome. Many factors can contribute to changes in the pharmacokinetics of antibacterials to the extent where dose adjustment may be needed. In acute illness, substantial changes in important pharmacokinetic parameters such as volume of distribution and clearance can occur for certain antibacterials. The possibility of interethnic pharmacokinetic differences can further complicate attempts to design an appropriate dosing regimen. Factors of ethnicity, such as genetics, body size and fat distribution, contribute to differences in absorption, distribution, metabolism and elimination of drugs. Despite extensive previous work on the altered pharmacokinetics of antibacterials in some patient groups such as the critically ill, knowledge of interethnic pharmacokinetic differences for antibacterials is limited.

OBJECTIVES

This systematic review aims to describe any pharmacokinetic differences in antibacterials between different ethnic groups, and discuss their probable mechanisms as well as any clinical implications.

METHODS

We performed a structured literature review to identify and describe available data of the interethnic differences in the pharmacokinetics of antibacterials.

RESULTS

We found 50 articles that met our inclusion criteria and only six of these compared antibacterial pharmacokinetics between different ethnicities within the same study. Overall, there was limited evidence available. We found that interethnic pharmacokinetic differences are negligible for carbapenems, most β-lactams, aminoglycosides, glycopeptides, most fluoroquinolones, linezolid and daptomycin, whereas significant difference is likely for ciprofloxacin, macrolides, clindamycin, tinidazole and some cephalosporins. In general, subjects of Asian ethnicity achieve drug exposures up to two to threefold greater than Caucasian counterparts for these antibacterials. This difference is caused by a comparatively lower volume of distribution and/or drug clearance.

CONCLUSION

Interethnic pharmacokinetic differences of antibacterials are likely; however, the clinical relevance of these differences is unknown and warrants further research.

A case study of in silico modelling of ciprofloxacin hydrochloride/metallic compound interactions

With the development of physiologically based absorption models, there is an increased scientific and regulatory interest in in silico modelling and simulation of drug-drug and drug-food interactions. Clinically significant interactions between ciprofloxacin and metallic compounds are widely documented. In the current study, a previously developed ciprofloxacin-specific in silico absorption model was employed in order to simulate ciprofloxacin/metallic compound interaction observed in vivo. Commercially available software GastroPlus™ (Simulations Plus Inc., USA) based on the ACAT model was used for gastrointestinal (GI) simulations. The required input parameters, relating to ciprofloxacin hydrochloride physicochemical and pharmacokinetic characteristics, were experimentally determined, taken from the literature or estimated by GastroPlus™. Parameter sensitivity analysis (PSA) was used to assess the importance of selected input parameters (solubility, permeability, stomach and small intestine transit time) in predicting percent drug absorbed. PSA identified solubility and permeability as critical parameters affecting the rate and extent of ciprofloxacin absorption. Using the selected input parameters, it was possible to generate a ciprofloxacin absorption model, without/with metal cation containing preparations co-administration, which matched well the in vivo data available. It was found that reduced ciprofloxacin absorption in the presence of aluminium hydroxide, calcium carbonate or multivitamins/zinc was accounted for by reduced drug solubility. The impact of solubility-permeability interplay on ciprofloxacin absorption can be observed in the ciprofloxacin-aluminium interaction, while in ciprofloxacin-calcium and ciprofloxacin-zinc interactions, effect of solubility was more pronounced. The results obtained indicate that in silico model developed can be successfully used to complement relevant in vitro studies in the simulation of physicochemical ciprofloxacin/metallic compound interactions.

Screening rectal culture to identify fluoroquinolone-resistant organisms before transrectal prostate biopsy: do the culture results between office visit and biopsy correlate?

OBJECTIVE

To investigate the performance of screening rectal cultures obtained 2 weeks before transrectal prostate biopsy to detect fluoroquinolone-resistant organisms and again at transrectal prostate biopsy.

MATERIALS AND METHODS

After institutional review board approval for observational study, we obtained a rectal culture on patients identified for a prostate biopsy but before antibiotic prophylaxis from September 12, 2011 to April 23, 2012. The specimen was cultured onto MacConkey agar with and without 1 μg/mL ciprofloxacin. We then obtained a second rectal culture immediately before prostate biopsy after 24 hours of ciprofloxacin prophylaxis. All cultures were blinded to the practitioner until the end of the study.

RESULTS

Of 108 patients enrolled, 58 patients had both rectal cultures for comparison. The median time duration between cultures was 14 (6-119) days. There were 54 of 58 concordant pairs (93%), which included 47 negative cultures and 7 positive cultures; 2 patients (3%) who were culture negative from the first screening culture became positive at biopsy. Sensitivity, specificity, negative, positive predictive values, and area under the operator curve were 95.9%, 77.8%, 95.9%, 77.8%, and 0.868, respectively. When Pseudomonas spp. are removed from the analysis, the area under the curve is increased to 0.927.

CONCLUSION

Screening rectal cultures 2 weeks before prostate biopsy has favorable test performance, suggesting screening cultures give an accurate estimate of fluoroquinolone-resistant colonization.

Ciprofloxacin treatment failure in a murine model of pyelonephritis due to an AAC(6')-Ib-cr-producing Escherichia coli strain susceptible to ciprofloxacin in vitro

AAC(6')-Ib-cr is a plasmid-mediated quinolone resistance mechanism described worldwide for Escherichia coli. Since it confers in vitro only a low level of resistance to ciprofloxacin, we evaluated its impact on the in vivo activity of ciprofloxacin. Isogenic strains were obtained by transferring plasmid p449, harboring aac(6')-Ib-cr, into the quinolone-susceptible strain E. coli CFT073-RR and its D87G gyrA mutant. MICs were 0.015, 0.06, 0.25, and 0.5 μg/ml against E. coli strains CFT073-RR, CFT073-RR/p449, CFT073-RR GyrA(r), and CFT073-RR GyrA(r)/p449, respectively. Bactericidal activity was reduced at 1× the MIC for the three resistant derivatives, while at a fixed concentration of 0.5 μg/ml, 99.9% killing was observed for all strains except E. coli CFT073-RR GyrA(r)/p449. In the murine model of pyelonephritis, an optimal regimen of ciprofloxacin (10 mg/kg of body weight twice a day [b.i.d.]) significantly decreased the bacterial count in the kidneys of mice infected with E. coli CFT073 (1.6 versus 4.3 log10 CFU/g of kidney compared to untreated controls; P = 0.0001), while no significant decrease was observed for E. coli CFT073-RR/p449 (2.7 versus 3.1 log10 CFU/g; P = 0.84), E. coli CFT073-RR GyrA(r) (4.2 versus 4.1 log10 CFU/g; P = 0.35), or E. coli CFT073-RR GyrA(r)/p449 (2.9 versus 3.6 log10 CFU/g; P = 0.47). While pharmacokinetic and pharmacodynamic (PK/PD) parameters accounted for ciprofloxacin failure against gyrA-containing mutants, this was not the case for the aac(6')-Ib-cr-containing strains, suggesting an in situ hydrolysis of ciprofloxacin in the latter case.

The treatment of urinary tract infections and use of ciprofloxacin extended release

Urinary tract infections (UTIs) are one of the most common reasons people seek medical attention. There are > 50% of women who will have at least one UTI during their lifetime and most of these will require a physician visit and antibiotic treatment. The high prevalence continues to the in-patient setting where genitourinary infections are the most common nosocomial infection. The efficient diagnosis and effective treatment of UTIs is a major healthcare concern. Factors such as economic efficiency and emerging resistance are increasingly becoming more important considerations in providing patient care. In out-patient uncomplicated UTIs, Escherichia coli has been implicated in < or = 75-90% of cases. Although the prevalence in the in-patient setting decreases, E. coli is still the most common bacteria identified and present in 21-54% of urinary isolates. Trimethoprim-sulfamethoxazole has been the preferred first-line agent for uncomplicated out-patient UTIs where local resistance is < 10 - 20%. In recent years, resistance has superseded this threshold in most regions of the US and Europe. In these areas with increased resistance, fluoroquinolones have become a common first-line agent. Ciprofloxacin has been one of the most widely used fluoroquinolones and has a well-known safety profile, as well as excellent activity against most of the common uropathogens. Ciprofloxacin extended release (ER) is a recently released once-daily formulation that has been increasingly used with good clinical success. The pharmacokinetic and pharmacodynamic parameters of ciprofloxacin ER are shown to be at least equal to twice-daily ciprofloxacin and may even confer superiority as ciprofloxacin ER achieves a higher maximum serum concentration. This is supported by clinical studies, which have shown at least as effective clinical cure and bacteriological eradication rates. These studies have also demonstrated similar tolerability and side-effect profiles. Ciprofloxacin ER combines traditional ciprofloxacin's proven track record of efficacy and safety with favourable pharmacokinetics and convenient once-daily dosing. Increased patient compliance is associated with decreased treatment failures and can help slow the development of antimicrobial resistance. Economic considerations are also increasingly important and providing convenient and effective treatment leading to high clinical success decreases overall costs.

Pharmacokinetic-pharmacodynamic analysis of fluoroquinolones against Bacillus anthracis

Based on the pharmacokinetic-pharmacodynamic (PK-PD) parameters of ciprofloxacin in rhesus monkeys, the efficacies of levofloxacin, sparfloxacin, norfloxacin, and tosufloxacin against anthrax in humans were examined. The optimal PK-PD parameter for the prophylaxis or treatment of infection with Bacillus anthracis is not clearly defined. To evaluate the efficacy of fluoroquinolones against anthrax, PK-PD parameters and the protein-binding effect of fluoroquinolones are used. B. anthracis is very susceptible to fluoroquinolones in vitro, and levofloxacin, sparfloxacin, and tosufloxacin may be as effective against anthrax as ciprofloxacin by PK-PD analysis. However, additional studies of the in vivo model are necessary to define more clearly efficacy against anthrax and the pharmacodynamic relationship of fluoroquinolones.

Drug transport and metabolism characteristics of the human airway epithelial cell line Calu-3

Pulmonary drug delivery serves two purposes, namely the application of locally active compounds for treatment of diseases afflicting the lung, and the utilization of the pulmonary epithelia as absorption sites for macromolecular drugs. To elucidate the mechanisms involved in the pulmonary absorption and metabolism of compounds on a cellular level, cell culture models have shown to be, though limited, rather useful in predicting in vivo conditions. The Calu-3 cell line has been employed recently as a model for the airway epithelium in a number of drug transport and metabolism studies. The results of these studies, as well as an evaluation of the predictive potency of the model, are presented here.

Bacillus anthracis and antibacterial agents

Anthrax is one of the oldest threats to humankind, and remains endemic in animals in many parts of the world. Human cases are infrequent, and some result from biological warfare. This review summarizes the current knowledge on the antibacterial activity of available antibiotics. For potential use in the most severe cases of anthrax, antibacterials need to exhibit potent in vitro activity, intracellular bioactivity, and suitable locations in lymph nodes. In animal models, it has been shown that doxycycline and fluoroquinolones are the most active compounds. There is a lack of data for animal models for macrolides and ketolides, some of them exhibiting good in vitro activity. However, systemic anthrax (inhalation or gastrointestinal) is mainly due to anthrax toxin, and therapy directed against intoxication is needed as basic treatment.

Bioequivalence of two brands of ciprofloxacin 750 mg tablets (Sarf and Ciprobay) in healthy human volunteers

An open, randomized, two-way crossover study was carried out in 28 healthy volunteers at Gulf Pharmaceutical Industries (Julphar), as a joint venture with Saqr Hospital, Ras Al-Khaimah, UAE. The two commercial brands used were Sarf (Julphar, UAE) as test and Ciprobay (Bayer AG, Germany) as reference product. The drug was administered to each subject with 240 mL of water after an overnight fasting in two treatment days separated by a one-week washout period. After dosing, serial blood samples were collected for a period of 24 hr and serum was separated and analyzed for ciprofloxacin using a sensitive, reproducible, and accurate high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection. Various pharmacokinetic parameters, including AUC0-t, AUC0-infinity, Cmax, Tmax, t1/2, and lambdaz, were determined from ciprofloxacin serum concentration-time profiles for both formulations and found to be in good agreement with reported values. The parameters AUC0-t, AUC0-infinity, and Cmax were tested for bioequivalence after log-transformation of data. No significant difference was found based on analysis of variance (ANOVA); the 90% confidence intervals (95.73-107.62%, 94.98-108.26%, 92.80-103.90% for AUC0-t, AUC0-infinity, Cmax, respectively) for the test/reference ratios of these parameters were within the bioequivalence acceptance range of 80-125%. Based on this data, it is concluded that both formulations are bioequivalent and are interchangeable in medical practice.

Effects of parenterally administered ciprofloxacin in a murine model of pulmonary Pseudomonas aeruginosa infection mimicking ventilator-associated pneumonia

BACKGROUND AND METHODS

We compared the bacteriological, pharmacological and histopathological effects of parenterally administered ciprofloxacin (CPFX) to those of imipenem/cilastatin (IMP/CS) and cefozopran (CZOP) in a murine model of mucoid Pseudomonas aeruginosa pneumonia mimicking ventilator-associated pneumonia.

RESULTS

The minimum inhibitory concentrations (MICs) of CPFX, IMP and CZOP were 1.0, 1.0 and 4.0 mg/l, respectively. Treatment with CPFX resulted in a significant decrease in the number of viable bacteria [control, IMP/CS, CZOP and CPFX (mean +/- SEM): 5.02 +/- 0.20, 4.96 +/- 0.38, 5.44 +/- 0.13 and 3.27 +/- 0.02 log(10) colony-forming units lung, respectively]. Histopathological examination revealed that inflammatory changes in the CPFX-treated group were less marked than in other groups. Of the drugs analyzed, the pharmacokinetic parameters of area under the time-concentration curve (AUC)/MIC, AUC exceeding MIC and the time that lung concentrations of drug remained above the MIC were highest for CPFX.

CONCLUSION

Our results suggest that parenterally administered ciprofloxacin is effective in ventilator-associated P. aeruginosa pneumonia.

Mixed pharmacokinetic population study and diffusion model to describe ciprofloxacin lung concentrations

The pharmacokinetics of ciprofloxacin in plasma and lung tissue at steady-state (500 mg b.i.d.) were studied in 38 patients subjected to lung surgery for bronchial epithelioma. The mean characteristics of the patient population were: age = 60 years (range: 48-70), weight=70kg (47-95), height=165cm (range 160-170) and serum creatinine=85microM (range 62-168). Plasma samples, two for each patient and lung samples, one for each patient, were obtained and analyzed. Seven groups were made according to the time of sampling after ingestion of the 5th dose. A three-compartment model was used to describe ciprofloxacin kinetics in plasma and lung. The non-linear mixed effect model approach was used to estimate the mean and variance of the pharmacokinetic parameters. The mean +/- SD of the estimates (coefficient of variation of interindividual variability as a percentage) were central volume of distribution, 39.45+/-52.47l(133%); steady-state volume of distribution, 145.86+/-97.51l(60%), clearance of influx into lung tissue, 35.83+/-22.57l/h(63%), extrapolated elimination rate constant, 0.173+/-0.25/h and extrapolated elimination half-life, 4.02+/-0.89h. The mean +/- SD ciprofloxacin concentration versus time curve in plasma and lung at steady state was simulated using pharmacokinetic parameters and lung physiological parameters, another approach was studied to model the transport of ciprofloxacin into the lung tissue by diffusion. Ciprofloxacin concentration-time history was obtained both by experiments or simulations. The ciprofloxacin level in the lung tissue followed the ciprofloxacin plasma level with a lag time resulting from the time necessary for ciprofloxacin to diffuse through the lung.

Comparison of intravenous/oral ciprofloxacin plus metronidazole versus piperacillin/tazobactam in the treatment of complicated intraabdominal infections

OBJECTIVE

To compare the safety and efficacy of intravenous (IV) ciprofloxacin plus IV metronidazole (CIP+MET) with that of IV piperacillin/tazobactam (PIP/TAZO) in adults with complicated intraabdominal infections, and to compare the efficacy of sequential IV-to-oral CIP+MET therapy with that of the IV CIP-only regimen.

SUMMARY BACKGROUND DATA

Treatment of intraabdominal infections remains a challenge, mainly because of their polymicrobial etiology and attendant death and complications. Antimicrobial regimens using sequential IV-to-oral therapy may reduce the length of hospital stay.

METHODS

In this multicenter, randomized, double-blind trial involving 459 patients, clinically improved IV-treated patients were switched to oral therapy after 48 hours. Overall clinical response was the primary efficacy measurement.

RESULTS

A total of 282 patients (151 CIP+MET, 131 PIP/TAZO) were valid for efficacy. Of these patients, 64% CIP+MET and 57% PIP/TAZO patients were considered candidates for oral therapy. Patients had a mean APACHE II score of 9.6. The most common diagnoses were appendicitis (33%), other intraabdominal infection (29%), and abscess (25%). Overall clinical resolution rates were statistically superior for CIP+MET (74%) compared with PIP/TAZO (63%). Corresponding rates in the subgroup suitable for oral therapy were 85% for CIP+MET and 70% for PIP/TAZO. Postsurgical wound infection rates were significantly lower in CIP+MET (11%) versus PIP/TAZO patients (19%). Mean length of stay was 14 days for CIP+MET and 17 days for PIP/TAZO patients.

CONCLUSION

CIP+MET, initially administered IV and followed by CIP+MET oral therapy, was clinically more effective than IV PIP/TAZO for the treatment of patients with complicated intraabdominal infections.

Pharmacokinetics and burn eschar penetration of intravenous ciprofloxacin in patients with major thermal injuries

Adequate penetration of antibiotics into burn tissue and maintenance of effective serum levels are essential for the treatment of patients sustaining major thermal injuries. The pharmacokinetics and burn eschar penetration of intravenous ciprofloxacin were determined in 12 critically ill patients with burn injuries. Mean age for the 12 patients was 45 +/- 17 (range 25-82 years), total body surface area burned (TBSAB) = 38 +/- 15% and Acute Physiology and Chronic Health Evaluation (APACHE) II score = 8 +/- 6. Patients received recommended doses of ciprofloxacin, 400 mg q12h iv, for three doses beginning 72 h post-burn. Serum concentrations were measured at t = 0, 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 2.0, 4.0 and 12.0 h after the first and third doses. Burn eschar biopsies were obtained after the third ciprofloxacin dose. Three of these 12 patients (25%) manifested later signs of clinical sepsis (TBSAB = 61 +/- 6% and APACHE II score = 11 +/- 3) and underwent a second infusion of three doses of intravenous ciprofloxacin, blood sampling and eschar biopsy. Serum and eschar concentrations were determined by high performance liquid chromatography. Serum ciprofloxacin concentrations were comparable to those of normal volunteers (C(max) = 4.0 +/- 1 mg/L and AUC = 11.4 +/- 2 mg.h/L) during the immediate post-burn period after dose 1 (C(max1) = 4.8 +/- 3 mg/L and AUC(0-12) = 12.5 +/- 7 mg. h/L) and dose 3 (C(max3) = 4.9 +/- 2 mg/L and AUC(24-36) = 17.5 +/- 11 mg.h/L). Mean burn eschar concentration during the 72 h post-burn was significantly lower than that found during clinical sepsis (18 +/- 17 compared with 41.3 +/- 54 microg/g; P < 0.05 by t test). Similar serum concentrations were achieved in patients with clinical sepsis (C(max1) = 4.2 +/- 0.2 mg/L and AUC(0-12) = 15.0 +/- 3 mg. h/L; C(max3) = 5.0 +/- 1 mg/L and AUC(24-36) = 22.8 +/- 9 mg.h/L). A positive correlation between burn eschar concentrations and C(max) (r = 0.71, r(2) = 0.51, P = 0.01) was found by linear regression analysis. A C(max)/MIC ratio > 10 (MIC = 0.5 mg/L) and an AUC/MIC ratio > 100 SIT(-1).h (serum inhibitory titre) (MIC = 0.125 mg/L) were achieved. High burn eschar concentrations and serum levels, similar to those found in normal volunteers, can be achieved after intravenous ciprofloxacin infusion in critically ill burns patients.

Effect of ciprofloxacin on the proliferation of osteoblast-like MG-63 human osteosarcoma cells in vitro

Locally applied antibiotic therapy is gaining popularity for the treatment of infections associated with open fractures and posttraumatic osteomyelitis. With use of local techniques, ciprofloxacin levels as high as 1,300 microg/ml, or over 200 times the bone levels achieved with intravenous administration, have been reported. To study the possible effects of ciprofloxacin on bone, osteoblast-like cells from the MG-63 human osteosarcoma cell line were studied. The cells were grown in antibiotic-free media and exposed to concentrations of ciprofloxacin at 0, 10, 100, 200, and 1,000 microg/ml to establish an initial dose-response curve. Media containing the appropriate dose of ciprofloxacin were changed every 24 hours. Cell number and [3H]thymidine incorporation per cell were determined at 0, 24, and 72 hours. A second dose-response curve was performed at concentrations of 0, 10, 20, 40, and 80 microg/ml. Three experiments, each with four observations, were performed. The results of this study demonstrated that ciprofloxacin caused significant decreases (p < 0.05) in cell number at 40 microg/ml at 24 hours and 20 microg/ml at 72 hours. [3H]thymidine incorporation per cell decreased significantly at levels of 80 microg/ml at 24 hours and 20 microg/ml at 72 hours. The authors conclude that reported local levels of ciprofloxacin seen in vivo inhibit the proliferation of human osteoblast-like cells in vitro.

Transepithelial transport of the fluoroquinolone ciprofloxacin by human airway epithelial Calu-3 cells

Although fluoroquinolone antibiotics such as ciprofloxacin are able to gain access to lung tissue and both pleural and bronchial secretions, the characteristics of transport and cellular uptake of ciprofloxacin in human epithelial lung tissue remain obscure. We have chosen human airway epithelial (Calu-3) cells, reconstituted as functional epithelial layers grown on permeable filter supports, as a model with which to assess both transepithelial transport and cellular uptake of ciprofloxacin. Transepithelial ciprofloxacin fluxes in absorptive (apical-to-basal) and secretory (basal-to-apical) directions were similar throughout the concentration range studied (1.0 microM to 3.0 mM). Transepithelial mannitol fluxes measured concurrently were substantially smaller than ciprofloxacin fluxes in Calu-3 epithelia, suggesting the existence of a mediated transcellular route in addition to a paracellular route for transepithelial permeation. Apical-to-basal ciprofloxacin flux (at 10 microM) was inhibited by a 100-fold excess of unlabelled norfloxacin, enoxacin, and ofloxacin, while secretory flux was unaffected. Cellular uptake of ciprofloxacin, determined as a cell/medium ratio, was greater from the basal compartment (2.7-fold) than apical uptake (1.39-fold) measured at 100 microM ciprofloxacin and showed no saturation up to 3 mM ciprofloxacin. Comparison of the permeation of ciprofloxacin was made with that of lipophilic substrates such as vinblastine and digoxin. There was a linear correlation between transepithelial permeability (Pa-b) and their oil/water partition coefficients with mannitol < ciprofloxacin < digoxin < vinblastine. Comparison of transport of ciprofloxacin across human airway Calu-3 epithelia with that across intestinal Caco-2 epithelia emphasizes the absence of a specific secretory pathway; ciprofloxacin permeation in Calu-3 epithelia appears to be mediated primarily by a transcellular route, with mediated transfer at apical and basal membranes occurring via transporters with low affinity to ciprofloxacin.

Ciprofloxacin. An updated review of its pharmacology, therapeutic efficacy and tolerability

Ciprofloxacin is a broad spectrum fluoroquinolone antibacterial agent. Since its introduction in the 1980s, most Gram-negative bacteria have remained highly susceptible to this agent in vitro; Gram-positive bacteria are generally susceptible or moderately susceptible. Ciprofloxacin attains therapeutic concentrations in most tissues and body fluids. The results of clinical trials with ciprofloxacin have confirmed its clinical efficacy and low potential for adverse effects. Ciprofloxacin is effective in the treatment of a wide variety of infections, particularly those caused by Gram-negative pathogens. These include complicated urinary tract infections, sexually transmitted diseases (gonorrhoea and chancroid), skin and bone infections, gastrointestinal infections caused by multiresistant organisms, lower respiratory tract infections (including those in patients with cystic fibrosis), febrile neutropenia (combined with an agent which possesses good activity against Gram-positive bacteria), intra-abdominal infections (combined with an antianaerobic agent) and malignant external otitis. Ciprofloxacin should not be considered a first-line empirical therapy for respiratory tract infections if penicillin-susceptible Streptococcus pneumoniae is the primary pathogen; however, it is an appropriate treatment option in patients with mixed infections (where S. pneumoniae may or may not be present) or in patients with predisposing factors for Gram-negative infections. Clinically important drug interactions involving ciprofloxacin are well documented and avoidable with conscientious prescribing. Recommended dosage adjustments in patients with impaired renal function vary between countries; major adjustments are not required until the estimated creatinine clearance is < 30 ml/min/1.73m2 (or when the serum creatinine level is > or = 2 mg/dl). Ciprofloxacin is one of the few broad spectrum antibacterials available in both intravenous and oral formulations. In this respect, it offers the potential for cost savings with sequential intravenous and oral therapy in appropriately selected patients and may allow early discharge from hospital in some instances. In conclusion, ciprofloxacin has retained its excellent activity against most Gram-negative bacteria, and fulfilled its potential as an important antibacterial drug in the treatment of a wide range of infections. Rational prescribing will help to ensure the continued clinical usefulness of this valuable antimicrobial drug.

Effect of probenecid on the distribution and elimination of ciprofloxacin in humans

OBJECTIVE

Probenecid-sensitive anion transport systems may be involved in distribution and elimination processes of anionic drugs. The aim of this study was to determine the effect of multiple probenecid treatment on the pharmacokinetic disposition of the zwitterionic fluoroquinolone ciprofloxacin in 12 healthy volunteers.

METHODS

A single intravenous dose of 200 mg ciprofloxacin was given with and without multiple oral administration of probenecid in a randomized crossover fashion. Serial plasma, urine, saliva, tear, and sweat samples were drawn and analyzed for ciprofloxacin and its 2-aminoethylamino-metabolite (M1) by reversed-phase HPLC.

RESULTS

Plasma area under the concentration-time curve and elimination half-life of ciprofloxacin were increased (p < 0.05), and urinary recovery and total and renal clearance decreased (p < 0.05) in the presence of probenecid. Nonrenal clearance and volume of distribution did not differ significantly with and without coadministration of probenecid. Peak plasma concentration, plasma area under the concentration-time curve, and elimination half-life of M1 were increased (p < 0.05) because of the higher amount of M1 formed and the reduced renal clearance (p < 0.05) of the metabolite. Saliva, tear, and sweat exposure were elevated (p < 0.05), but the alterations can be attributed primarily to the different kinetics of ciprofloxacin in plasma.

CONCLUSIONS

Coadministration of probenecid altered the renal excretion and hence the plasma concentrations of ciprofloxacin. Metabolite kinetics and distribution into saliva, tears, and sweat were affected accordingly, but there was no direct effect of probenecid on these processes. This type of drug-drug interaction might be of clinical relevance when ciprofloxacin is combined with drugs eliminated by the organic anion transport system in the kidney tubules.

Penetration of ciprofloxacin into the human pancreas

The aim of this study was to determine the concentrations of ciprofloxacin in human pancreatic tissue and juice. Concentrations were measured by high-pressure liquid chromatography (HPLC). Two hundred mg of ciprofloxacin were administered as a short i.v. infusion (30 min). The median ciprofloxacin concentrations 140 min (median) after the start of infusion in pancreatic tissue as well as in pancreatic juice were 0.9 mg/kg (mg/l). The penetration ratio was 1.0 for pancreatic tissue and 0.83 for pancreatic juice. With regard to the minimal inhibitory concentrations (MIC) for the respective bacteria, ciprofloxacin seems to be an appropriate drug for the treatment of septic complications in necrotizing pancreatitis. Future clinical trials are necessary to prove this assumption.

Penetration of intravenous and oral ciprofloxacin into sterile and empyemic human pleural fluid

OBJECTIVE

To compare the penetration of oral and intravenously administered ciprofloxacin into infected (empyemic) and noninfected (sterile) human pleural fluid.

DESIGN

Eleven men and 5 women (aged 29-76) were consecutively selected from adult patients referred to the respiratory unit for pleural effusion. In this open-label, prospective trial, 13 patients with sterile pleural effusions were nonrandomly assigned to receive either ciprofloxacin 200 mg (single intravenous dose), 750 mg (single oral dose), or 750 mg (two oral doses per day for 3 days); 3 patients with infected pleural effusions received 750 mg oral doses for 10 days. Simultaneous pleural fluid and venous blood specimens were drawn over 5 hours after single dose or when steady-state was attained, and ciprofloxacin concentrations were measured by HPLC.

RESULTS

Pleural fluid concentrations of ciprofloxacin equaled plasma concentrations 1.5 hours after 200 mg was given intravenously and the pleural/plasma ratio remained > or = 0.9 for 4 hours. After a single 750-mg oral dose, pleural ciprofloxacin concentrations rose from 0 to 1.4 micrograms/mL over 5 hours with the highest pleural fluid/plasma ratio (0.7) at 5 hours. Average steady-state ciprofloxacin concentrations in sterile pleural fluid after 750 mg administered twice daily for 3 days, ranged between 1.1 and 1.8 micrograms/mL with ratios between 0.3 and 0.9 over 4 hours. In empyemic pleural fluid at the same dosage, average steady-state ciprofloxacin concentrations ranged between 1.9 and 3.4 micrograms/mL with ratios between 1.0 and 2.0 over 5 hours.

CONCLUSIONS

Oral ciprofloxacin penetrates into sterile and empyemic pleural fluid with concentrations 30-90 percent and 100-200 percent of plasma concentrations, respectively.

Renal malacoplakia with papillary necrosis and renal failure

Renal parenchymal malacoplakia is a rare cause of renal failure. Patients presenting with renal failure carry a poor prognosis, the majority either dying or requiring chronic dialysis. In this report, we describe an alcoholic man who presented with renal failure due to bilateral renal parenchymal malacoplakia and papillary necrosis. The patient, who initially required dialysis, partially recovered renal function following prolonged antibiotic treatment with a fluoroquinolone antibiotic.