Bioactivity of Isostructural Hydrogen Bonding Frameworks Built from Pipemidic Acid Metal Complexes.

We report herein three novel complexes whose design was based on the approach that consists of combining commercially available antibiotics with metals to attain different physicochemical properties and promote antimicrobial activity. Thus, new isostructural three-dimensional (3D) hydrogen bonding frameworks of pipemidic acid with manganese (II), zinc (II) and calcium (II) have been synthesised by mechanochemistry and are stable under shelf conditions. Notably, the antimicrobial activity of the compounds is maintained or even increased; in particular, the activity of the complexes is augmented against Escherichia coli, a representative of Gram-negative bacteria that have emerged as a major concern in drug resistance. Moreover, the synthesised compounds display similar general toxicity (Artemia salina model) levels to the original antibiotic, pipemidic acid. The increased antibacterial activity of the synthesised compounds, together with their appropriate toxicity levels, are promising outcomes.

Earlier generation quinolones can be useful in identifying Haemophilus influenzae strains with low susceptibility to quinolone isolated from paediatric patients.

PURPOSE: Haemophilus influenzae strains with low susceptibility to quinolones have recently emerged in the paediatric field in Japan. These strains are judged as 'susceptible' in routine susceptibility tests, although they may survive after quinolone treatment. Therefore, we aimed to construct a simple and cost-effective identification method for low-susceptibility strains using disc diffusion assays. METHODOLOGY: A total of 33 H. influenzae clinical isolates and a control strain were used. For the disc diffusion assay, levofloxacin, norfloxacin, nalidixic acid and pipemidic acid were employed. Correlations between the inhibition zone diameter and amino acid substitutions were evaluated. RESULTS: All of the tested strains formed clear inhibition zones on both levofloxacin and norfloxacin discs. By contrast, none of the low-susceptibility strains showed inhibition zones against nalidixic acid, while the low-susceptibility strains with amino acid substitutions in both GyrA and ParC did not show inhibition zones against pipemidic acid discs, indicating that low-susceptibility strains can be detected with high sensitivity and specificity by the presence or absence of inhibition zones for earlier quinolones. CONCLUSION: A disc diffusion test combining results from nalidixic acid and pipemidic acid can detect low-susceptibility strains harbouring amino acid substitutions without the need for genetic analysis. This test can help reduce inappropriate and unnecessary fluoroquinolone use.

A New Approach for Improving the Antibacterial and Tumor Cytotoxic Activities of Pipemidic Acid by Including It in Trimethyl-ß-cyclodextrin.

Pipemidic acid (HPPA) is a quinolone antibacterial agent used mostly to treat gram-negative infections of the urinary tract, but its therapeutic use is limited because of its low solubility. Thus, to improve drug solubility, natural cyclodextrins (CDs) are used for their ability of including guest molecules within their cavities. The aim of this work was to evaluate the antibacterial activity and the preliminary anticancer activity of HPPA included into Heptakis (2,3,6-tri-O-methyl)-ß-cyclodextrin (TRIMEB) as a possible approach for a new innovative formulation. The inclusion complex of HPPA with TRIMEB was prepared in solid state by the kneading method and confirmed by FT-IR and powered X-ray diffraction. The association in aqueous solutions of pipemidic acid with TRIMEB was investigated by UV-Vis spectroscopy. Job's plots have been drawn by UV-visible spectroscopy to confirm the 1:1 stoichiometry of the host⁻guest assembly. The antibacterial activity of HPPA, TRIMEB and of their complex was tested on Escherichia coli, Pseudomonas aeruginosa, and Staphilococcus aureus. The complex was able to increase 47.36% of the median antibacterial activity of the free HPPA against E. coli (IC50 = 249 µM vs. 473 µM). Furthermore, these samples were tested on HepG-2 and MCF-7. After 72 h, the median tumoral cytotoxicity exerted by the complex was increased by 78.08% and 94.27% for HepG-2 and MCF-7 respectively, showing a stronger bioactivity of the complex than the single HAPPA.

Synthesis and in vitro antimicrobial activity screening of new pipemidic acid derivatives.

This article describes the synthesis and antimicrobial activity evaluation of new pipemidic acid derivatives. New compounds were obtained on the basis of Mannich reaction of 4,5-disubstituted 1,2,4-triazole-3-thiones with pipemidic acid. Antimicrobial tests revealed high antibacterial activity of obtained derivatives. Gram-negative rods belonging to Enterobacteriaceae family were particularly most sensitive to new pipemidic acid derivatives. Synthesized compounds exhibited very strong activity towards Proteus mirabilis ATCC 12453, Salmonella typhimurium ATCC 14028 and Escherichia coli ATCC 25922. The minimum inhibitory concentrations of new pipemidic acid derivatives which inhibited the growth of these bacteria were 0.98-7.81 µg/ml, 0.98-7.81 µg/ml and 0.98-3.91 µg/ml, respectively. The antibacterial activity of newly synthesized pipemidic acid derivatives in many cases was far better than the activity of substances used as positive controls (nitrofurantoin, cefuroxime, ampicillin and pipemidic acid).

T cell-mediated hypersensitivity to quinolones: mechanisms and cross-reactivity.

BACKGROUND: Quinolones are widely used, broad spectrum antibiotics that can induce immediate- and delayed-type hypersensitivity reactions, presumably either IgE or T cell mediated, in about 2-3% of treated patients. OBJECTIVE: To better understand how T cells interact with quinolones, we analysed six patients with delayed hypersensitivity reactions to ciprofloxacin (CPFX), norfloxacin (NRFX) or moxifloxacin (MXFX). METHODS: We confirmed the involvement of T cells in vivo by patch test and in vitro by means of the lymphocyte proliferation test (LTT). The nature of the drug-T cell interaction as well as the cross-reactivity with other quinolones were investigated through the generation and analysis (flow cytometry and proliferation assays) of quinolone-specific T cell clones (TCC). RESULTS: The LTT confirmed the involvement of T cells because peripheral blood mononuclear cells (PBMC) mounted an enhanced in vitro proliferative response to CPFX and/or NRFX or MXFX in all patients. Patch tests were positive after 24 and 48 h in three out of the six patients. From two patients, CPFX- and MXFX-specific CD4(+)/CD8(+) T cell receptor (TCR) alphabeta(+) TCC were generated to investigate the nature of the drug-T cell interaction as well as the cross-reactivity with other quinolones. The use of eight different quinolones as antigens (Ag) revealed three patterns of cross-reactivity: clones exclusively reacting with the eliciting drug, clones with a limited cross-reactivity and clones showing a broad cross-reactivity. The TCC recognized quinolones directly without need of processing and without covalent association with the major histocompatability complex (MHC)-peptide complex, as glutaraldehyde-fixed Ag-presenting cells (APC) could present the drug and washing quinolone-pulsed APC removed the drug, abrogating the reactivity of quinolone-specific TCC. CONCLUSION: Our data show that T cells are involved in delayed immune reactions to quinolones and that cross-reactivity among the different quinolones is frequent.

[Study on the molecular mechanism of quinolone resistance in Shigellae spp].

OBJECTIVE: To study the resistance and its mechanism of Shigellae spp. to quinolones. METHODS: Seventy-three clinical isolates were collected. Susceptibility tests of pipemidic adcid (PI), ofloxacin (OFL), norfloxacin (NOR), and ciprofloxacin (CIP) were performed in all clinical isolates and Shigella 51573. The N-terminal coding region of gyrA and parC were amplified by polymerase chain reaction (PCR) respectively. Restriction fragment length polymorphism (RFLP) was applied to all PCR procucts of gyrA and parC, and single strand conformational polymorphism analysis (SSCP) was also applied to PCR procucts of parC. RESULTS: The resistance rates for all the Shigella spp. to PI, CIP, NOR and OFL were 79.5%, 60.3%, 41.1% and 36.9%. Sixty-seven strains (91.8%) were quinolone-reduced-sensitive isolates, in which 61 strains (91%) were found carrying mutations in gyrA with 5 strains (7.5%) found carrying mutations in parC. No mutation was found in 6 quinolone-sensitive isolates or Shigella 51573. CONCLUSION: The Shigella spp. had high resistance rates to quinolones. The target gene mutations which were mainly found in gyrA and secondarily in parC, played an important role in the quinolone-resistance in Shigella spp.

Structural features of piperazinyl-linked ciprofloxacin dimers required for activity against drug-resistant strains of Staphylococcus aureus.

We previously demonstrated that piperazinyl-linked fluoroquinolone dimers possess potent antibacterial activity against drug-resistant strains of Staphylococcus aureus. In this study, we report the preparation and evaluation of a series of incomplete dimers toward ascertaining structural features of piperazinyl-linked ciprofloxacin dimers that render these agents refractory to fluoroquinolone-resistance mechanisms in Staphylococcus aureus.

Synthesis, characterization, and antibacterial activities of some rare Earth metal complexes of pipemidic acid.

Eight new solid complexes of pipemidic acid (PPA) with trichlorizated rare earth metals LaCl(3), CeCl(3), PrCl(3), NdCl(3), SmCl(3), TbCl(3), DyCl(3), and YCl(3) have been synthesized. The complexes were characterized by elemental analyses, IR, NMR, and molar conductance measurements. The general formulas of the complexes are [M(PPA)(4)]Cl(3) (M=Ce(III), Pr(III), Nd(III), Sm(III), Tb(III), Dy(III), Y(III)), and [La(PPA)(4)Cl]Cl(2). At the same time, the antibacterial activities of PPA and four of its complexes were tested. The results show that PPA and its complexes all have inhibitory action against bacteria of Escherichia coli, Bacillus subtilis, Streptococcus pneumoniae, and Pseudomonas aeruginosa but not Staphylococcus aureus. We compared their antibacterial activities and found that the antibacterial activity of [La(PPA)(4)Cl]Cl(2) against S. pneumoniae is much stronger than that of PPA and the other complexes.

[Quinolone-resistant Escherichia coli in the health area of a 650-bed hospital]. / Escherichia coli resistente a quinolonas en el area sanitaria de un hospital de 650 camas.

Report of a retrospective study to evaluate susceptibility of Escherichia coli to quinolones covering the March-December 1992 interval. During this time, intra and extra-hospital strains were indistinctly studied in patients with urinary infections seen in a health district serving a total of 200.000 inhabitants. Resistance to Pipemidic acid, Norfloxacin and Ciprofloxacin was evaluated. The values found were 14.8% resistance to Pipemidic acid, 11.1% to Norfloxacin and 8.5% to Ciprofloxacin. It seems necessary to develop and apply methods addressed to minimize the appearance of quinolone resistance, which should be implemented in order to preserve the usefulness of these drugs.

Determination of pyridonecarboxylic acids in plasma by reverse-phase high-performance liquid chromatography.

A simple qualitative and quantitative determination for pyridonecarboxylic acids including nalidixic acid (NA), oxolinic acid (OA) and pipemidic acid (PPA) in chicken plasma was carried out by microbiological, spectrophotometric, thin-layer chromatographic (TLC) and reverse-phase high-performance liquid chromatographic (HPLC) methods. As a test organism for bacteriological bioassay, Bacillus subtilis ATCC-6633 was the most sensitive of seven organisms investigated. Using the cup and the disc methods, a standard curve was obtained by determining the relationship between various drug concentrations and the diameter of the inhibition zone. The three drugs had two strong UV absorbance wavelengths (257 and 330 nm) on spectrophotometry. TLC analysis using a silica gel 60 F254 plate was investigated, and a solution of methanol:chloroform:acetic acid (3:1:1, v/v/v) was found to be the most suitable solvent for separation. The minimum concentration of drug detectable by this method was 0.5 microgram/ml for NA, 0.075 microgram/ml for OA and 0.39 microgram/ml for PPA. For HPLC analysis, a solution of acetonitrile:0.2 M phosphoric acid (1:1, v/v) was superior, and simultaneous determination of all three drugs was possible under the HPLC conditions used. The lowest measurable amount of drug in chicken plasma was 0.01 microgram/g. Recovery from extracts spiked with each drug at a known concentration was close to 100% for NA and OA, but only about 50% for PPA.

Biotransformation of methylxanthines in mammalian cell lines genetically engineered for expression of single cytochrome P450 isoforms. Allocation of metabolic pathways to isoforms and inhibitory effects of quinolones.

V79 Chinese hamster cells genetically engineered for stable expression of single forms of rat cytochromes P450IA1, P450IA2, P450IIB1, human P450IA2, and rat liver epithelial cells expressing murine P450IA2 were used to allocate metabolic pathways of methylxanthines to specific isoforms and to test the suitability of such cell lines for investigations on drug interactions occurring at the cytochrome expressed. The cell lines were exposed to caffeine and/or theophylline and concentrations of metabolites formed in the medium were determined by HPLC. Caffeine was metabolized by human, rat and murine P450IA2, resulting in the formation of four primary demethylated and hydroxylated metabolites. However, there were differences in the relative amounts of the metabolites. The human and the mouse P450IA2 isoforms predominantly mediated 3-demethylation of caffeine. The rat cytochrome P450IA2 mediated both 3-demethylation and 1-demethylation of caffeine to a similar extent. The results support the hypothesis that caffeine plasma clearance is a specific in vivo probe for determining human P450IA2 activity. Addition of the quinolone antibiotic agents pipemidic acid or pefloxacin, both known to inhibit caffeine metabolism in vivo and in human liver microsomes, reduced formation rates of all metabolites of caffeine in cells expressing rat and human P450IA2. Theophylline was mainly metabolized via 8-hydroxylation. All cell lines tested were able to carry out this reaction, with highest activities in cell lines expressing rat or human P450IA2, or rat P450IA1.

Ten-year survey of quinolone resistance in Escherichia coli causing urinary tract infections.

In a ten-year survey (1983-1992) of quinolone resistance in Escherichia coli causing urinary tract infections in a general practice patient population, 9,934 strains were tested. Resistance increased remarkably from 1989 onwards. The rate of resistance to pipemidic acid was < or = 6% before 1989 and 18% in 1992; the rate of resistance to ciprofloxacin (MIC > or = 4 mg/l) was 0.8% in 1989 and 7.1% in 1992. Although the consumption of older quinolones decreased the total consumption of quinolones increased yearly.

Sensibilidad a antimicrobianos comunes de bacterias obtenidas en urocultivos positivos de niños / Common antimicrobial susceptibility of bacteria from positive urine cultures of children

Se describe la frecuencia relativa de las bacterias patógenas y su sensibilidad a los antimicrobianos en 400 urocultivos sucesivos con recuentos de colonias * 10 elevado a 5 de personas de 15 o menos años de edad, ambulatorias (n: 216) y hospitalizadas, de ambos sexos (300 niñas). Escherichia coli fue el agente aislado con mayor frecuencia (75,7% del total, 89,1% en niñas y 58,5% en varones ambulatorios, 76,8% en niñas y 45,7% en niños hospitalizados), seguido de klebsiella pneumoniae en niñas (3,5%) y proteus mirabilis en varones (22,0%) ambulatorios. En pacientes del hospital, klebsiella pneumoniae y klebsiella species fueron segundas en frecuencia en niñas (13,4%) y varones (18,5%). Pseudomonas aeruginosa sólo se detectó en pacientes del hospital (10,1% varones, 1,6% niñas). Un tercio de las cepas de E. coli eran resistentes a cefalosporinas de primera generación, más de la mitad a ampicilina y cotrimoxazol, siendo la mayoría (*96%) sensibles a gentamicina y nitrofurantoína. En las muestras de niños hospitalizados, 28% E. coli eran resistentes a ampicilina-sulbactam (p 0,0000053), más de 40% a cefalosporinas de primera generación y más de 50% a cotrimoxazol y ampicilina, mientras 95% o más eran sensibles a amikacina y gentamicina (p 0,000). K. pneumoniae fueron casi siempre sensibles a amikacina (93,7%), pero sólo 20% a gentamicina (p 0,000148), siendo alrededor de la mitad sensibles a nitrofurantoína. Seis de siete cepas de pseudomonas aeruginosa eran sensibles a ceftazidima. A menos que estudios locales muestren una situación diferente, parece razonable sugerir que pacientes ambulatorios con infecciones urinarias aparentemente bajas sean tratados inicialmente de preferencia con nitrofurantoína y se prefiera amikacina si se sospecha infección alta, modificando posteriormente la conducta, si es conveniente, según el análisis de sensibilidad

Pyrimidines as the chemotherapeutic drugs.

Investigations on new chemotherapeutic drugs have attracted a worldwide interest during the past few years. The pyrimidine derivatives possessing such the activity have a considerable pharmaceutical significance. The works on these compounds are led in various directions, but a particular importance have modifications of the drug Trimetoprime as well as syntheses of new pipemidic acid derivatives and pyrimidines with the amide group.

Effects of quinolone carboxylic acid derivatives on GABAA receptor-mediated stimulation of gastric acid secretion and intestinal motility.

The present study investigates the effects of some quinolone carboxylic acid derivatives on GABAA receptor-mediated excitatory responses in gastrointestinal preparations in vivo and in vitro. In stomach-perfused rats, norfloxacin, nalidixic and pipemidic acid dose dependently antagonized acid hypersecretion induced by muscimol. Under the same conditions, the quinolone derivatives failed to modify acid hypersecretion evoked by 2-deoxy-D-glucose. In the isolated guinea-pig ileum, norfloxacin, nalidixic and pipemidic acid antagonized muscimol-elicited contractions in a non-competitive manner. In contrast, these drugs did not influence ileal cholinergic contractions evoked by transmural electrical stimulation or by exogenous acetylcholine. Taken together, these results suggest that the quinolone derivatives tested act as antagonists at both central and peripheral GABAA receptors. In addition, GABAA-mediated gastrointestinal responses might represent a simple and reliable method to assay the GABAA receptor antagonist properties of new quinolone derivatives.

Effect of nalidixic acid, pipemidic acid and cinoxacin on chondrocyte metabolism in explants of articular cartilage.

Explants of immature bovine articular cartilage were exposed to nalidixic acid, pipemidic acid and cinoxacin at one and ten times the human therapeutic plasma level for 7 days. Only nalidixic acid had significant effects on the chondrocyte metabolism. 20 micrograms/ml nalidixic acid caused an increase of 35S-sulfate incorporation into glycosaminoglycans at day 7. Two hundred micrograms/ml nalidixic acid inhibited the incorporation of 3H-thymidine into DNA. The incorporation of 35S-sulfate into glycosaminoglycans was decreased at day 0, while at day 7 the incorporation had returned to the control value. Pipemidic acid and cinoxacin had no significant effects on either the 3H-thymidine or the 35S-sulfate incorporation.

Pharmacokinetic determination of relative potency of quinolone inhibition of caffeine disposition.

Quinolone is reported to interact with caffeine, often resulting in an increase both in the plasma half-life and AUC, a decrease in total plasma clearance, and little change in the absorption rate constant and maximum plasma level. These complex changes in the pharmacokinetics of caffeine were analyzed experimentally and from published reports in order to determine the nature of the interaction, which is thought to be due to inhibition of caffeine metabolism by quinolones. A simple pharmacokinetic model for the caffeine-quinolone interaction was developed, which provides a unified method for evaluation and comparison of the effect of quinolones on the disposition of caffeine. The model is applicable to other methylxanthines, such as theophylline. The relative potency of the interactions of quinolones with caffeine in humans has been established as enoxacin (100), pipemidic acid (29), ciprofloxacin (11), norfloxacin (9) and ofloxacin (0).

[A clinical trial of the preparation palin in women with refractory colpitis]. / Klinichno izpitvane na preparata palin pri zheni s uporiti kolpiti.

The authors carried out clinical trial of the preparation Palin (pipemidinic acid) on 43 women with persistent colpitis after preliminary testing. There was negative microbiological finding in 67% of women. The results of the authors differed from those of other authors, since Palin was used mainly in women with chronic colpitis resistant to routine treatment. Minimal side effects were found. Usage of Palin is recommended in women with colpitis, caused by: E. coli, Enterococcus, Klebsiella and mixed aerobic flora.

Reversible suppression by nalidixic acid of anchorage-independent growth of mouse cells transformed by 3-methylcholanthrene or an activated c-Ha-ras gene.

Effects of nalidixic acid and its derivatives were investigated on mouse cells transformed by methylcholanthrene or an activated c-Ha-ras oncogene. Our findings were as follows. Nalidixic acid preferentially suppressed growth in soft agar of transformed Balb/3T3 mouse cells induced by methylcholanthrene. The suppressive effect of nalidixic acid on growth in soft agar was reversible. Nalidixic acid reversibly reduced saturation density of these transformed cells. Oxolinic acid and pipemidic acid, which are derivatives of nalidixic acid, were less effective than nalidixic acid in suppressing growth in soft agar. Nalidixic acid suppressed growth in soft agar of NIH/3T3 mouse cells transformed by an activated c-Ha-ras, without affecting the amount of ras p21 proteins as detected by an immunoblotting analysis using a monoclonal antibody. These results show that nalidixic acid reversibly suppressed the expression of transformed phenotypes that were already being expressed.