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The aim of the study was to evaluate safety and efficacy of gemcitabine-cisplatin in elderly patients with advanced non small cell lung cancer (NSCLC). This study included 59 patients aged >70 years consecutively admitted to our Department. treatment consisted of gemcitabine 1000 mg/m(2) on days 1 and 8, and low-dose fractionated cisplatin 20 mg/m(2) on days 1, 2, 3 of a 21-day cycle. Toxicity was graded according to the world Health Organization (WHO) criteria.A total of 281 cycles was administered. Hematological toxicities of grade 3 and 4 were seen in 17% and 5% of patients, respectively. Grade 3 gastrointestinal toxicity was 3%, grade 2 neuropathy was 2%. Twenty-nine partial responses with an objective response rate of 49% were obtained. No complete responses were observed. The median progression-free survival (PFS) and overall survival (OS) were 7.8 and 15.5 months respectively. Cisplatin-based combination chemotherapy at low doses appears to be safe and active in older patients with advanced NSCLC.

Malignant pleural effusions (MPEs) represent a common complication of advanced malignancies. However, adequate palliation of this highly symptomatic accompaniment to cancer can be achieved in most patients by adopting the appropriate therapy. Several options are available for the treatment of MPE. Systemic therapy may control the effusion in patients whose underlying malignancy is sensitive to anti-cancer agents. Repeated thoracocentesis can be appropriate for patients with limited life expectancy or slowly recurrent effusions. In the majority of the remaining cases the treatment of choice is pleurodesis with sclerosing agents administered via tube thoracostomy. Controversy still exists as to which drug produces the best results: talc and bleomycin appear to be among the most cost-effective agents. The debate over the best agent to be used for pleurodesis refers to the difficulty in comparing results of studies using different eligibility criteria, response assessment and end-points. This article describes the various treatments which have been reported in the literature to play a role in the management of MPEs. It is also aimed at providing guidelines in allocating patients to appropriate treatments.

A phase I study was designed to assess whether dose intensity of an 'accelerated' cyclophosphamide-doxorubicin-etoposide (CDE) regimen plus granulocyte colony-stimulating factor (G-CSF) could be increased further, in an outpatient setting, by escalating the dose of each single drug of the regimen. Patients with previously untreated small-cell lung cancer (SCLC) received escalating doses of cyclophosphamide (C) 1100-1300 mg m-2 intravenously (i.v.) on day 1, doxorubicin (D) 50-60 mg m-2 i.v. on day 1, etoposide (E) 110-130 mg m-2 i.v. on days 1, 2, 3 and every 14 days for at least three courses. Along with chemotherapy, G-CSF (filgastrim) 5 micrograms kg-1 from day 5 to day 11 was administered subcutaneously (s.c.) to all patients. Twenty-five patients were enrolled into the study. All patients at the first dose level (C 1100, D 50, E 110 x 3) completed three or more cycles at the dose and schedule planned by the protocol and no 'dose-limiting toxicity' (DLT) was seen. At the second dose level (C 1200, D 55, E 120 x 3) three out of five patients had a DLT consisting of 'granulocytopenic fever' (GCPF). Another six patients were treated at this dose level with the addition of ciprofloxacin 500 mg twice a day and only two patients had a DLT [one episode of documented oral candidiasis and one of 'fever of unknown origin' (FUO) with generalised mucositis]. Accrual of patients proceeded to the third dose level (C 1300, D 60, E 130 x 3) with the prophylactic use of ciprofloxacin. Four out of six patients experienced a DLT consisting of GCPF or documented non-bacterial infection. Accrual of patients at the third dose level was then resumed adding to ciprofloxacin anti-fungal prophylaxis (fluconazole 100 mg daily) and anti-viral prophylaxis (acyclovir 800 mg twice a day) from day 5 to 11. Out of five patients treated three experienced a DLT consisting of severe leucopenia and fever or infection. With a simultaneous dose escalation and schedule acceleration it is indeed possible to take maximum advantage of G-CSF activity and to increase CDE dose intensity by a factor 1.65-1.80 for a maximum of 3-4 courses. The role of antimicrobial prophylaxis in this setting deserves to be investigated further.

BACKGROUND: The FAST is a 2 × 2 factorial trial addressing two questions: (1) the role of replacing cisplatin (P) with a non-platinum agent, vinorelbine (N), and (2) the role of adding a third agent, ifosfamide (I), in a doublet based on gemcitabine (G). METHODS: A total of 433 stage IIIB-IV non-small cell lung cancer (NSCLC) patients were randomised to one of four arms: gemcitabine-cisplatin (GP), gemcitabine-vinorelbine, gemcitabine-ifosfamide- cisplatin or gemcitabine-ifosfamide-vinorelbine. Two comparisons were performed: N- vs P-containing regimens and I-triplets vs non-I doublets. RESULTS: For N- vs P-containing regimens, adjusted overall survival was 9.7 vs 11.3 months (P=0.044), progression-free survival was 4.9 vs 6.4 months (P=0.020) and response rate was 24% vs 31% (P=0.124), respectively. No statistically significant difference was observed between doublets and triplets. Grade 3-4 haematological toxicity was significantly more frequent in P-containing therapy; grade 3-4 leucopenia was significantly more common in triplets. Concerning non-haematological toxicity, grade 3-4 nausea-vomiting was significantly increased in P-containing regimens. CONCLUSIONS: This trial provides evidence of a slight survival superiority of GP-containing regimens over platinum-free N-containing chemotherapy. This trial also confirms that the addition of a third chemotherapy agent (I) to a standard G-based doublet does not improve treatment outcome. © 2012 Cancer Research UK. All rights reserved.

An oral chemotherapy schedule based on idarubicin and cyclophosphamide was evaluated in 31 advanced breast cancer patients. Out of 27 patients evaluable for response, 1 (3.7%) achieved a complete response and 5 (18.5%) a partial response, with an objective response rate of 22.2% (95% confidence limits 8.6-42.3%). The median time to progression was 7 months (range 3-12). Fourteen patients (51.9%) showed a disease stabilization, and 7 progressed (25.9%). Toxicity was mild. Considering the low response rate, but also the advantages of oral chemotherapy and the mild toxicity observed, oral idarubicin plus cyclophosphamide can be considered as a second-choice regimen in advanced breast cancer.

Standard treatment for transitional cell carcinoma confined to the bladder is radical cystectomy that allow to obtain an overall 5-year disease-free survival rate only of 50-70%. It has been demonstrated that intra-arterial chemotherapy produces the same survival outcomes as radical cystectomy. This study aimed to evaluate the activity and toxicity of a bladder-sparing loco-regional treatment. Five patients with transitional cell carcinoma of the bladder (4 locally advanced and 1 pelvic relapse) were treated with doxorubycin 25 mg/m2, cisplatin 40 mg/m2 and methotrexate 50 mg/m2, all infused bolus via internal iliac arteries on day 1, every three weeks. We obtained 3 complete responses, 1 stable disease and 1 progression of disease. The treatment was well tolerated with a minimal hematological toxicity and no others major toxicity. Median disease free survival was 8 months (1-17), median overall survival was 22 months (2-55). This loco-regional regimen of chemotherapy is active and safe in locally advanced bladder cancer patients and permits a prolonged good quality of life regarding the maintenance of the physiological functions of the lower urinary tract.

The aim of this study was to evaluate feasibility and toxicity of escalating doses of epirubicin and paclitaxel plus fixed dose of etoposide and to define the activity of the triplet in extensive disease small-cell lung cancer. Thirteen patients entered the phase I study: the maximum tolerated doses were epirubicin (EpiDX) 90 mg m−2 and paclitaxel (P) 175 mg m−2 with febrile neutropenia as dose-limiting toxicity. The recommended schedule for this regimen for the phase II study was EpiDX 75 mg m−2, P 175 mg m−2, etoposide (E) 100 mg m−2 intravenous (fixed dose) days 1–3 with courses repeated every 21 days. The prophylactic use of colony-stimulating factors (CSFs) was not allowed. Twenty patients entered the phase II trial: median age was 61 years (range 50–70), median Eastern Cooperative Oncology Group performance status 0 (0–2); nine patients had visceral disease and 17 had more than two metastatic sites. A total of 100 courses were administered with a median of 5 (range 1–6) per patients. Main toxicity (NCI-CTC) was myelosuppression: neutropenia grades 3 and 4 in 16 and 35% of the courses, respectively. Seven episodes of febrile neutropenia were documented and one patient required hospital admission. Nonhaematological toxicity was moderate. Seven out of 19 evaluable patients achieved a complete response (37%), nine patients (47.3%) a partial response with an overall response rate of 84.2% ((95% confidence interval=60.4–96.6)). In this poor prognostic population of patients the triplet epirubicin/paclitaxel/etoposide showed high antitumour activity with mild nonhaematological side effects. The use of CSFs should be able to improve the haematological profile.

Despite a high probability of response to first-line chemotherapy, most patients with small-cell lung cancer (SCLC) will eventually have progression of their disease because of the development of resistant disease. Second-line testing of new drugs is an accepted research strategy in SCLC. In this context, the Italian Lung Cancer Task Force (FONICAP) has tested a new synthetic bifunctional alkylating agent, Ambamustine, with preliminary evidence of activity in other solid tumors. Patients with measurable SCLC, progressive after one first-line chemotherapy regimen (either "sensitive" or "refractory"), were eligible for the study. Ambamustine was administered at the dose of 2 mg/kg as a 1-hour intravenous infusion on day 1 every 21 days. The dose was to be increased to 3 mg/kg if no grade IV toxicity and complete hematologic recovery had occurred by day 22. Sample size was calculated according to a two-stage optimal Simon's design. Seventeen patients were entered into the study. Twelve patients were refractory to prior chemotherapy; 12 had extensive disease; the median age was 64 years (range: 46-75 years) and the median performance status was 1. Among 13 patients who received more than one cycle, 9 patients could increase Ambamustine dose from 2 to 3 mg/kg. No objective response was observed: one patient obtained a 50% regression of the primary tumor with contemporary disease progression in the liver and was qualified as having progressive disease. The treatment was well tolerated: grade IV leukopenia occurred in only 1 patient; grade III anemia occurred in 17.6%, grade III leukopenia in 11.8%, and grade III thrombocytopenia in 23.5%. Nonhematologic toxicity was minimal. Ambamustine, at the dose and schedule used in this study, is well tolerated in pretreated patients with SCLC but has no significant antitumor activity in this unfavorable group of patients.

In the present multicentre randomized phase II trial, the activity and toxicity of three platinum-based combination regimens for the treatment of advanced non-small-cell lung cancer (NSCLC) were evaluated. The three regimens were: MVP (mitomycin-C 6 mg m(-2) on day 1, vindesine 3 mg m(-2) on days 1 and 15, and cisplatin 80 mg m(-2) on day 1 every 28 days), PIN (cisplatin 80 mg m(-2) day 1, ifosfamide 3 g m(-2) day 1 and vinorelbine 25 mg m(-2) day 1 and 8 every 21 days) and CaN (carboplatin 350 mg m(-2) day 1 and vinorelbine 25 mg m(-2) days 1 and 8 every 28 days). A total of 140 chemotherapy-naive patients entered the study; 49 patients were treated with MVP, 48 with PIN and 43 with CaN. Sixty-seven per cent of the patients had stage IV disease. Response rates, calculated on an 'intention to treat' basis, were as follows: MVP, 14.3% (95% CI 5.94-27.2%); PIN, 16.7% (95% CI 7.4-30.2%); and CaN, 14% (95% CI 5.3-27.9%). The overall median survivals were 256, 269 and 243 days for patients treated with MVP, PIN and CaN respectively. Myelosuppression was the most frequent toxicity: grade 3-4 leucopenia was observed in 14.3%, 25% and 18.6% of patients treated with MVP, PIN and CaN respectively. This multicentre phase II randomized trial shows that MVP, PIN and CaN can be administered on an outpatient basis with acceptable toxicities. Unfortunately, the three regimens showed an activity significantly lower than that reported in previous single-institution phase II trials.

Malignant pleural mesothelioma (MPM) is an uncommon malignancy characterized by a rapid clinical course. Few patients are possible candidates for radical surgery. According to most reviews, radiotherapy has a limited role in the treatment of MPM. The role of chemotherapy in the management of pleural mesothelioma still remains uncertain. The available data indicate that although 10-20% of patients are known to achieve on objective response to a number of chemotherapeutic agents, the impact on survival appears limited and improvement in the quality of life remains uncertain. The results of combination chemotherapy are comparable to those of single-agent chemotherapy and no major difference is detectable among the various combinations. Prospective phase II trials are recommended for the identification of new active treatments while large-scale randomized phase III trials are needed to identify the best available treatment. In addition, new standard criteria for eligibility and response assessment are required. This paper reviews the available literature on the systemic drug therapy of MPM.

In a previous FONICAP trial, the combination of doxorubicin (D) and cisplatin (P) yielded an objective response rate of 25% and a subjective response rate of 50% in patients with mesothelioma. In human mesothelioma cell lines, mitomycin (M) showed a synergic activity with P and in a recent randomized study, the combination of M and P showed slightly superior activity when compared with the PD regimen.The authors tested the activity and toxicity of a combination chemotherapy regimen including P, 60 mg/m2, D, 60 mg/m2, and M, 10 mg/m2, all by intravenous infusion on Day 1 every 28 days in a Phase II study.Twenty-four chemotherapy-naive mesothelioma patients were enrolled in the study. Patient characteristics were the following: the median age was 58 years; the median performance status was 1; there were 6 Stage I patients, 15 Stage II patients, 2 Stage III patients, and 1 Stage IV patient; and 10 patients had previous asbestos exposure. All patients had pretreatment symptoms: 13 had chest pain, 9 had pleural effusion, and 7 had dyspnea. A total of 78 cycles of chemotherapy were administered. The only significant side effect was myelosuppression, with only 9.5% of patients having Grade 4 toxicity. Among 23 patients evaluable for response, 5 achieved a partial response (20.8%; 95% confidence interval, 7.1-42.1%), 9 had stable disease, and 9 had progressive disease (including 1 early death). One patient was not evaluable because of treatment refusal. A clinical improvement was observed in 7 of 24 patients (29%).The combination of PDM in patients with pleural mesothelioma is feasible and moderately active. However, the observed level of activity is similar to that obtained with other two-drug regimens.

Fourteen patients with diffuse malignant pleural mesothelioma (DMPM) were enrolled in a Phase II study to assess activity and toxicity of the systemic administration of recombinant (r)-alpha-interferon (IFN)-2b. The IFN schedule was: 3 x 10(6) IU i.m. days 1-4, 6 x 10(6) IU days 5-8, 10 x 10(6) IU days 9-12; then IFN was administered at 10 x 10(6) IU 3 days/week. If grades II-III toxicity occurred, IFN dose was reduced and drug continued at the previous dose level. All patients were evaluated by CT scan. Only one patient was not evaluable for response and toxicity because of inadequate follow-up. Of 13 evaluable patients, we observed 1 objective response, 6 stable disease, and 6 failures (3 progressive disease and 3 early interruptions due to subjective toxicity). The median time to progression was 19 weeks, and the median overall survival was 62 weeks. Toxicity was mild: of 13 patients evaluable for toxicity we observed fever (9 patients), flu-like syndrome (3 patients), fatigue (4 patients), anorexia (2 patients), myelosuppression (3 patients), and muscle pain (1 patient). The results of this study indicate only marginal activity of r-alpha-IFN in the treatment of DMPM.

Preclinical data suggested that alpha-interferon (IFN) may potentiate chemotherapy cytotoxicity.A prospective multicentric randomized trial was initiated to assess the clinical benefit of adding recombinant alpha-2-IFN to combination chemotherapy in patients with metastatic non-small cell lung cancer. A total of 182 patients were randomized to receive either cisplatin-epidoxorubicin-cyclophosphamide (CEP) combination chemotherapy (cisplatin, 60 mg/m2; epidoxorubicin, 50 mg/m2; and cyclophosphamide, 400 mg/m2 intravenously) alone on day 1 or the same chemotherapy plus recombinant alpha-2-IFN at the dose of 5 MU intramuscularly from day -2 to +4, then 3 times weekly.The median survival was 6 months in the CEP plus IFN arm versus 5.5 months in the control arm. The log-rank test showed a marginal statistically significant difference (P = 0.045) in favor of CEP chemotherapy, which disappeared when survival curves were adjusted for prognostic factors. Progression-free survival was similar in the two treatment arms. Considering all eligible patients, the response rate was 7.6% in the CEP arm versus 18.9% in the CEP plus IFN arm (P = 0.042). Nearly 40% of the patients receiving IFN had grade 3-4 nadir leukopenia versus 15% in the control arm (P = 0.01) and 12.5% versus 4.2% had grade 3-4 thrombocytopenia. Apart from the usual constitutional symptoms, IFN was also responsible for increased emesis and mucositis.This study indicates that the addition of recombinant alpha-IFN to CEP chemotherapy can increase response rate and toxicity to treatment without a positive effect on progression-free survival and survival.

Twenty-one patients with advanced stage, non-small-cell lung carcinoma were treated with a chemotherapy regimen including: mitomycin (6 mg/m2), ifosfamide (3 g/m2), cisplatin (80 mg/m2). The regimen was administered on an outpatient basis. Two patients were lost to follow-up. Among the 29 patients evaluable for response we registered a response rate of 36.8 %; 36.8% of patients had stable disease, and 15.7 % progressed during treatment. Median duration was 8.7 months and median survival was 11 months. Toxicity was low and easily manageable on an outpatient basis.

Twenty-six symptomatic patients with diffuse malignant pleural mesothelioma (DMPM) were enrolled in a Phase II Italian Lung Cancer Task Force (FONICAP) study to assess the activity and toxicity of doxorubicin and cisplatin combination chemotherapy. The drug schedule was as follows; 60 mg/m2 of doxorubicin and 60 mg/m2 of cisplatin both given intravenously (IV) on day 1 every 3 to 4 weeks. Of the 24 evaluable patients, 6 objective partial responses (25%; 95% confidence limits, 9.77% to 46.71%) were observed. Twelve of 24 patients (50%), including 6 with no radiologic evidence of response, had a clinical improvement as demonstrated by an objective reduction of symptom or performance status scores along treatment. The overall median survival time was 10 months. Toxicity was mild and dose reductions or suspensions were not required. The combination of doxorubicin and cisplatin is effective and well tolerated. It might be considered for palliation of symptomatic patients with DMPM.

Both CAV (Cyclophosphamide, Doxorubicin, Vincristine) and PE (Cisplatin, Etoposide) are effective and non cross-resistant regimens in the treatment of SCLC. We designed a chemotherapeutic scheme including CAV and PE given in an alternating fashion with the following schedule: Cyclophosphamide 1000 mg/sm, Doxorubicin 50 mg/sm, Vincristine 2 mg/sm I.V. on day 1, alternated every 21 days with Cisplatin 20 mg/sm and Etoposide 80 mg/sm I.V. days 1-5 for 6 cycles. Following chemotherapy (CT) chest radiotherapy in patients (pts) with limited disease (LD) in complete response (CR) or partial response (PR) and prophylactic cranial irradiation (PCI) in CRs were given, 32 pts entered the study and 27 were evaluable: 9/27 (33.3%) had CR (8/15 with LD had CR) and 15/27 (55.5%) PR. The overall median survival was 53.71 weeks: 79.85 weeks for LD pts and 32.86 for ED.4 pts with LD were alive after 2 years and 2 of them are still alive without disease at 44 and 46 months. Toxicity was acceptable in all patients. Alternating chemotherapy with CAV and PE followed by chest and brain RT in responding LD pts is an effective induction treatment for SCLC although long-term survival still remains disappointing.

beta-lactamase production was evaluated by chromogenic cephalosporin 87/312 in 116 E. coli isolated from clinical sources. Such test revealed beta-lactamase production in 54 strains out of 116 (46%): MICs of eight beta-lactam antibiotics (Ampicillin, Piperacillin, Cefazoline, Cephaloridine, Cephalexine, Cefuroxime, Cefotaxime, Cefotaxime) were determined using a miniaturized dilution broth method. Cefotaxime and Ceftriaxome and Ceftriaxone showed the highest antibacterial activity. All beta-lactamases produced by E. coli strains under examination were isolated and purified by ultrasonic disruption and high speed centrifugation. Sensitivity of the eight antibiotics to purified beta-lactamases was assessed by a spectrophotometric method that utilizes the velocity of cytochrome c reduction. The sensitivity to beta-lactamases was reflected in the in vitro activity of the antibiotics as assessed by the determination of the MICs.

Sixteen patients with previously untreated small-cell lung cancer, unsuitable for standard aggressive intravenous chemotherapy due to advanced age or poor performance status or very advanced disease including brain metastases or either extensive liver or marrow involvement with impaired organ function, were treated with combined oral chemotherapy including 4-demethoxydaunorubicin (IMI30, idarubicin) 30 mg/sm on day 1 and etoposide (VP16) 150 mg/sm on days 2,3,4 every 4 weeks. Out of 13 evaluable patients 1 had a complete response and 2 had a partial response with an overall objective response rate of 23% (95% confidence-limits 5-53.8%). Toxicity was generally very mild. Although the compliance of this regimen is excellent, its antitumor activity seems unsatisfactory even in this category of poor-risk small-cell lung cancer patients.

326 gram negative bacteria have been isolated and quantitative bacteria counts performed from midstream urine of as many patients affected with symptomatic and non symptomatic urinary tract infections. Susceptibility of bacteria to four quinoline derivatives (Norfloxacin, Oxolinic acid, Pipemidic acid and Nalidixic acid) was studied determining the minimal inhibitory concentrations (MICs) of each drug by a miniaturized dilution broth method. The frequency of bacterial species isolated, the frequency of symptoms and the frequency of bacterial counts were studied to establish a possible relationship between these data. It has been observed that patients affected with pyuria without any other subjective symptoms demonstrate a colony count ranging between less than 10(4) and greater than 10(5) bacterial/ml of urine and these bacteriuria were determined by several different bacterial species. E. coli was much more frequently responsible for low or high count bacterial infections of the urinary tract than other species. In fact E. coli was detected in 64.4% of patients, P. mirabilis in 15.9%, E. agglomerans in 5.2%, P. aeruginosa in 4.9. Other species were detected in much lower percentages. Norfloxacin proved to be the most effective drug in vitro, out of those under examination. Its MIC50 never exceeded 8 mcg/ml even against Pseudomonas and Serratia strains, which were resistant to all the other antimicrobial agents.

Three hundred seventy-five Gram-negative bacterial strains were isolated from urine specimens of as many patients affected by symptomatic or asymptomatic urinary tract infections. Susceptibility of bacteria to five chemotherapeutics (norfloxacin, oxolinic acid, pipemidic acid, nalidixic acid and nitrofurantoin) was studied determining minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of each compound by a miniaturized dilution broth method. Norfloxacin, a quinoline carboxylic acid compound structurally related to nalidixic acid, showed a much higher antibacterial activity against all bacterial strains under examination including Pseudomonas sp. The best activity of norfloxacin was expressed either by lower MICs and lower MBCs with respect to those of the other compounds, or by a low MBC/MIC ratio, which represents an important advantage in clinical practice.

A total of 127 Gram-negative bacteria resistant to nalidixic acid were isolated from as many patients affected by urinary tract infections and hospitalized in the first Clinic of Infectious Diseases, University of Naples. Enterobacteria were identified by Enterotube system (Roche) and API 20 system (Ayerst). Non-fermentative bacteria were identified by OXI/FERM system (Roche). The following bacteria were collected: Escherichia coli 50, Proteus spp. 35, Enterobacter agglomerans 12, Serratia sp. 5, Pseudomonas aeruginosa 25. The in vitro antibacterial activity of nalidixic acid and three other quinoline derivatives (pipemidic acid, oxolinic acid and ciprofloxacin) were studied by determining the MICs by a miniaturized dilution broth method. The MICs were compared to evaluate the eventual cross resistance to the drugs under examination within each bacterial species. The results showed that 23% of bacteria were resistant to nalidixic acid, pipemidic acid and oxolinic acid; 49.6% to nalidixic and pipemidic acid and 0.7% to nalidixic acid and oxolinic acid. On the other hand none of the bacteria were resistant to ciprofloxacin. The last showed very low MICs against all the bacteria under examination, including Pseudomonas and Serratia. The high antibacterial activity of ciprofloxacin even against bacteria highly resistant to the other quinolines could be due to a greater affinity of the target sites or to the better permeability of resistant strains to the newer drug or because it is unaffected until now by mutations of genes responsible for cross resistance.

A total of 375 Gram-negative bacterial strains were isolated from midstream urine specimens of the same number of patients affected by urinary tract infections. All bacteria were identified by standard bacteriological methods and their susceptibility to six quinoline derivatives (ciprofloxacin, cinoxacin, norfloxacin, oxolinic acid, pipemidic acid, nalidixic acid) was studied by determining the MICs and MBCs for each compound using a miniaturized dilution broth method in microtitre plates and twofold dilutions of each drug from 256 to 0.12 mcg/ml. Ciprofloxacin, a new quinoline carboxylic acid compound structurally related to nalidixic acid, showed a much higher antibacterial activity against all bacterial strains under examination, including Pseudomonas, than the other compounds, except for norfloxacin. The MIC90 and MBC90 of ciprofloxacin never exceeded 1 mcg/ml with any of the bacterial species; and MBC/MIC ratios were very low, which represents an important clinical advantage. Only norfloxacin showed comparable effectiveness. No bacterial strain showed resistance to the drug and the MIC90 and MBC90 never exceeded 8 mcg/ml.