Predictive value of nalidixic acid resistance for detecting salmonellae with decreased ciprofloxacin susceptibility

Seventy-three Salmonella isolates classified as ciprofloxacin susceptible when using the criteria of the National Committee for Clinical Laboratory Standards were studied for nalidixic acid (NA) resistance. The aim of the study was to determine the predictive value of nalidixic acid resistance in screening for decreased ciprofloxacin susceptibility. We observed that isolates with decreased ciprofloxacin susceptibility were all resistant to nalidixic acid. Identification of nalidixic acid resistance by the disk diffusion method provided 100% sensitivity and a specificity of 98.4% in strains with minimum inhibitory concentrations (MICs) >0.008 mg/l.     

Pharmacokinetics of nalidixic acid in man: Hydroxylation and glucuronidation

Nalidixic acid is metabolized by hydroxylation to 7-hydroxymethylnalidixic acid and then by oxidation to 7-carboxynalidixic acid. The half-lives of the two elimination phases of nalidixic acid are 0.75 and 2.5 h. The apparent half-lives of the metabolite 7-hydroxymethylnalidixic acid are 2.5 and 5.5 h. Plasma protein binding of nalidixic acid is 95% and that of 7-hydroxymethylnalidixic acid 65%. The renal clearance of nalidixic acid varies between 2 and 25 ml/min and that of 7-hydroxymethylnalidixic acid between 37 and 162 ml/min. Of nalidixic acid 42% is glucuronidated and 40% hydroxylated. Of the hydroxy metabolite 57% is glucuronidated and 32% excreted unchanged. 7-Carboxynalidixic acid is excreted in the urine and is not glucuronidated. The variations in the glucuronidation/ hydroxylation ratio of nalidixic acid and the glucuronidation/renal excretion ratio of the 7-hydroxymethyl metabolite belong to a normal distribution.     

Probenecid inhibits the renal clearance and renal glucuronidation of nalidixic acid

The aim of this pilot study was to demonstrate the possible inhibitory effect of probenecid on the renal glucuronidation and on the renal clearance of nalidixic acid in a human volunteer. Under acidic urine conditions, hardly any nalidixic acid is excreted unchanged (0.2%). It is excreted as acyl glucuronide (53.4%), 7-hydroxymethylnalidixic acid (10.0%), the latter's acyl glucuronide 30.9%, and 7-carboxynalidixic acid (4.2%). Under probenecid co-medication the renal glucuronidation of nalidixic acid is reduced from 53% to 16%; the renal clearance of both nalidixic acid and 7-hydroxymethylnalidixic acid are reduced (p <0.001); the intrinsict _1/2 of the metabolite 7-hydroxymethylnalidixic acid increased from 0.48 h to 4.24 h. The amount of acyl glucuronidation of 7-hydroxymethylnalidixic acid was not altered. Thein vitro protein binding of both acyl glucuronides was increased, while no effect on the unconjugated compounds was seen. Nalidixic acid had no effect on the maximal renal excretion rate of probenecid acyl glucuronide.     

Synthesis,structure, and antibacterial activity of 4-imino-1, 4-dihydrocinnoline-3-carboxylic acid and 4-oxo-1, 4-dihydrocinnoline-3-carboxylic acid derivatives as isosteric analogues of quinolones

Chemical modification of cinnoxacin was studied with the aim of improving its antibacterial activity and spectrum. A series of 4-imino-1, 4-dihydrocinnoline-3-carboxylic acid derivatives was synthesized and their in vitro antibacterial activity was evaluated. These derivatives were designed as isosteric analogues of fluoroquinolones and are characterized by the presence of an imine group instead of an oxo group at the 4-position and a nitrogen atom in position 2. The crystal structure of one analogue determined by X-ray diffraction shows the dipolar form of the compound in the solid state. The in vitro antibacterial activity of the synthesized compounds against Gram-positive and Gram-negative bacteria was examined. The MIC of the most active compounds lies in the range of the first generation of quinolones such as nalidixic acid. The compounds with dichlorobenzyl substituent show enhanced activity against Gram-positive bacteria.     

Quinolones and colonization resistance in human volunteers

The suppression of alimentary canal flora by the three quinolones nalidixic acid, ciprofloxacin and pefloxacin was investigated in fifteen volunteers. They received the three quinolone compounds in tablet form both uncoated and colon-coated.Escherichia coli suppression was poor under nalidixic acid, but complete under ciprofloxacin and pefloxacin for both administration forms. The indigenous anaerobic flora contributing to the control of aerobicStreptococcus faecalis andCandida albicans in the intestines ('colonization resistance') was not affected by nalidixic acid and pefloxacin, and only slightly by ciprofloxacin. Out of the three quinolone compounds, only colon-coated pefloxacin was associated with a considerable absorption rate at colonie level. Using these criteria of successfulEscherichia coli clearing from the intestinal canal - left the indigenous flora more or less intact (in a 'selective' way) - and a good absorption rate, pefloxacin is found to be superior to ciprofloxacin and nalidixic acid. These results suggest that a colon-coated tablet with a low dose of pefloxacin is a promising administration form in the therapy of recurrent urinary tract infections and diarrhoeal diseases and in the prevention of gut colonization in immunocompromised hosts.     

Research on antibacterial and antifungal agents. III. Synthesis of 1-ethyl-1,4-dihydro-4-oxo-7-(1-pyrryl)quinoline-3-carboxylic acid and of some 6-derivatives

A new analog of nalidixic acid, 1-ethyl-1,4-dihydro-4-oxo--7-(1-pyrryl)quinoline-3-carboxylic acid, is described. When tested against gram-positive and gram-negative bacteria this compound showed many significant activities and was more active than nalidixic, piromidic and pipemidic acids. On the contrary its 6-chloro- and 6-methylderivatives lack antimicrobial activities. All new compounds here described were synthesized by standard procedures via Gould-Jacobs reaction.     

Phototoxicity from nalidixic acid: oxygen dependent photohemolysis

Erythrocyte lysis photosensitized by nalidixic acid was investigated. This photohemolysis was found to be oxygen dependent. The effects of various antioxidants and hydroxyl radical scavengers on photohemolysis induced by nalidixic acid suggested a photo-oxidative step. In addition, using the oxygen quencher histidine and the deuterium oxide effect on the singlet oxygen lifetime we obtained evidence indicative of a photodynamic mechanism mediated by oxygen singlet and hydroxyl radicals. On the other hand, pre-irradiated nalidixic acid was not lytic to erythrocytes, yet photoproducts of nalidixic acid demonstrated a greater photohemolytic potential than nalidixic acid itself.     

Effect of some selected salts and non-ionic surfactants on the antimicrobial activity of nalidixic acid

The effect of different concentrations of some selected salts, namely, sodium chloride, potassium chloride, ammonium chloride, monosodium dihydrogen phosphate, calcium chloride, dibasic sodium phosphate, sodium sulphate, aluminium chloride and sodium citrate on the antimicrobial activity of nalidixic acid was investigated. It was found that all the salts tested, except aluminium chloride and sodium citrate, exert no antimicrobial activity. The effect of 10% non-ionic surface active agents, namely, Myrj 51, 52, 59, Brij 35, 58, 98, Tween 20, 40, 60, and 80 on the antimicrobial activity of nalidixic acid was studied. The results indicated that the activity of nalidixic acid was decreased in the presence of these surfactants. Furthermore, the effect of different concentrations of sodium chloride on the antimicrobial activity of nalidixic acid-surfactants systems was reported.     

Pharmacokinetics of nalidixic acid associated with sodium citrate

A pharmacokinetic study of sachets containing nalidixic acid (0.66 g) associated with sodium citrate (3.75 g)--NSC--was carried out in 10 healthy volunteers in order to determine the influence of the urine alcalinization due to sodium citrate on the elimination of nalidixic acid (NA) and its 7-hydroxy (HNA) and 7-carboxy (CNA) derivatives. Urine alcalinization enhanced markedly the urinary excretion of HNA, but not of NA and CNA. The urinary concentrations of bacteriologically active compounds--NA + HNA--remained above five times their minimum inhibitory concentration for 10 h following each dose. After a 3-day treatment using NSC three times daily there was no significant accumulation of NA and derivatives in the plasma and no significant change in their kinetics. Finally, from a pharmacokinetic viewpoint, the daily administration of 3 sachets of NSC each containing 0.66 g of NA seems valuable in the treatment of urinary tract infections.     

Direct gradient reversed-phase HPLC analysis and preliminary pharmacokinetics of nalidixic acid, 7-hydroxymethylnalidixic acid, 7-carboxynalidixic acid,and their corresponding glucuronide conjugates in humans

A gradient reversed-phase high pressure liquid chromatographic analysis was developed for the direct measurement of nalidixic acid with its acyl glucuronide, 7-hydroxymethylnalidixic acid with its acyl and ether glucuronides, and 7-carboxynalidixic acid in human plasma and urine. The glucuronides and 7-carboxynalidixic acid were not present in plasma after an oral dose of 1,000 mg nalidixic acid. The acyl glucuronides of 7-carboxynalidixic acid were not present in plasma and urine. The acyl glucuronides are stable in urine at pH 5.0–5.5. The subject's urine must therefore be acidified by the oral intake of 4×1 g of ammonium chloride per day. With acidic urine, hardly any nalidixic acid was excreted unchanged (0.2%). It was excreted as acyl glucuronide (53.4% of dose), 7-hydroxymethylnalidixic acid (10.0%), the latter's acyl glucuronide (30.9%), and 7-carboxynalidixic acid (4.2%).     

pH-independent sustained release matrix tablet containing doxazosin mesylate: Effect of citric acid

The aim of this study was to develop a pH-independent sustained release matrix tablets of doxazosin mesylate. The matrix tablets were prepared by direct compression technique using polyethylene oxide, sodium alginate and citric acid as a pH modifier. Formulations were evaluated for an in vitro drug release study, erosion study, and the microenvironmental pH was studied using the pH indicator methyl red. For formulations without citric acid, the extent and rate of drug release in simulated gastric fluid were much higher than those in simulated intestinal fluid. By adding the citric acid, the drug release rate in simulated intestinal fluid was increased, and microenvironmental pH values within the tablets were maintained at low pH during drug release. Furthermore, drug release from the matrix tablet containing 20% w/w citric acid was comparable to that from a commercial product, Cardura® XL, and a pHindependent release could be achieved. Therefore, the incorporation of citric acid as a pH modifier to Polyethylen oxide-sodium alginate matrix tablets effectively produced pHindependent doxazocin mesylate release profiles.     

5-Hydroxyindolacetic acid and homovanillic acid in cerebrospinal fluid in manic-depressive psychosis

Summary Cerebrospinal fluid concentrations of 5-hydroxyindoleacetic acid and homovanillic acid were determined in 37 depressed and 47 manic patients, in 30 other psychiatric patients and in 54 healthy controls. There were no differences in the concentrations of 5-hydroxyindoleacetic acid between the four groups. Manic patients had higher concentrations of homovanillic acid than the other three groups. After loading with probenecid (5 g during 50 h), which blocks the outflow of acid metabolites of monoamines from cerebrospinal fluid, the increase in 5-hydroxyindoleacetic acid levels at a second lumbar puncture was significantly smaller in the manic-depressive patients (about 20%) than in the other two groups (about 60%). The rise in the concentration of homovanillic acid was smaller in manic depressive patients (about 80%) than in the two control groups (about 200%). In a further experiment, methylperidol, a neuroleptic compound which increases the turnover rate of brain dopamine, was administered with probenecid in an attempt to accentuate the differences between the groups. Methylperidol increased the differences between the manic-depressives and the controls for homovanillic acid, and removed the differences for 5-hydroxyindoleacetic acid. These findings indicate a lower turnover rate of dopamine and 5-hydroxytryptamine in both phases of manic-depressive psychosis. — In the probenecid experiments, bipolar depressive patients had lower increases of 5-hydroxyindole acetic acid than cases of unipolar endogenous depression. Treatment with lithium, tricyclic antidepressants and various neuroleptics did not affect the concentrations of 5-hydroxyindoleacetic acid and homovanillic acid. The concentrations of these compounds in cerebrospinal fluid in subjects not premedicated at the second lumbar puncture were relatively unchanged when measured on two occasions at different time intervals.     

Bioenhancing and antimycobacterial agents from Ammannia multiflora

The methanolic extract of Ammannia multiflora (Lythraceae) showed significant bioenhancing activity with the antibiotic nalidixic acid. Bioassay-guided fractionation of MeOH extract resulted in the isolation of a novel compound, 2,5-bis-(3,3'-hydroxyaryl)tetrahydrofuran, named as ammaniol (5), along with 9 other known compounds (1-4, 6-10). Furthermore, compound 4-hydroxy- α-tetralone (1) was converted into five semisynthetic acyl derivatives, 1A-1E, which were evaluated along with compounds 1, 5, 6, 9, and 10 for their bioenhancing activity in combination with nalidixic acid against the two strains, CA8000 and DH5 α, of Escherichia coli. The results showed that the methanolic extract of A. multiflora and compounds 1 and 9 possessed significant bioenhancing activity and reduced the dose of nalidixic acid fourfold while compounds 5, 6, 10 and semisynthetic derivatives 1A- 1E reduced the dose of nalidixic acid twofold. Compound 5 was also tested for antimycobacterial activity against Mycobacterium H37Rv and was found to show moderate activity (MIC 25?μg/mL) against this pathogen.     

The human biotransformation of nalidixic acid.

Authors have developed new chemical methods for studying the human metabolism of nalidixic acid. The methods are suited for the quantitative determination of nalidixic acid, hydroxynalidixic acid, nalidixic acid glucuronide, hydroxynalidixic acid-glucuronide, and of free and total glucuronic acid excretion. The total urinary excretion of NA and its metabolites was found to be 50 to 100% of the ingested dose. The percentual distribution of the individual metabolites was as follows: NA 0,5-5, HNA2,5-6, NAG24-80, and HNAG11-26%. It was unanimously proved by enzymatic decomposition and specific chemical reactions that the excreted conjugates were monoglucuronides. The significance of individual differences, bilirubin metabolism, urinary pH and the pharmacokinetical behaviour of the individual metabolites is discussed from the therapeutic view.     

In vitro antibacterial activity of irloxacin (E-3432) on clinical isolates

Irloxacin (E-3432) is a new quinolone derivative. In this study, the activity of irloxacin was compared with that of nalidixic acid, norfloxacin and ciprofloxacin against strains of clinical isolates. Irloxacin showed greater in vitro activity than nalidixic acid, similar activity to norfloxacin and lower activity than ciprofloxacin. Against Staphylococcus, the MIC range of E-3432 was 0.06-1 mg/l, better than the other compounds studied.     

In vitro activity of norfloxacin in synthetic media and human urine compared to that of cinnoxacin, nalidixic acid and pipemidic acid

Activity of norfloxacin was compared to that of cinnoxacin, nalidixic acid and pipemidi acid in DST-agar and human urine solidified by adding 1.2% agar. Norfloxacin was the most active compound when tested on DST-agar but the MIC values increased from 64 to 128 fold when tested in urine. Other compounds also showed an increase in MIC in urine-agar, but the increase was less marked. MICs for norfloxacin in DST-agar and Müller-Hinton-Agar were similar. Higher concentrations were required in Müller-Hinton-Broth than in Müller-Hinton-Agar.     

咖啡酸和阿魏酸及其类似物对内皮素-1生物效应的拮抗作用

目的：对咖啡酸和阿魏酸以及两者化学衍生物肉桂酰胺类似物Ｎ３（５甲基异吓恶唑）基３，４二羟基肉桂酰胺（化合物１）和Ｎ４安替比林基４羟基３甲氧基肉桂酰胺（化合物２）拮抗内皮素１（ＥＴ１）的缩血管及致血管平滑肌细胞增殖效应进行了初步研究。方法：用这四种化合物对ＥＴ１缩血管及致血管平滑肌细胞增殖作用的拮抗效应拮抗进行了研究。结果：咖啡酸和阿魏酸及其衍生物对ＥＴ１缩血管及致血管平滑肌细胞增殖效应有明显的拮抗作用，该作用具剂量依赖性，经药效动力学分析，阿魏酸及其衍生物的拮抗活性显著大于咖啡酸及其衍生物；这四种化合物能剂量依赖性地抑制ＥＴ１致血管平滑肌细胞增殖作用。结论：咖啡酸和阿魏酸及其衍生物为一类新的ＥＴ拮抗剂。     

In vitro nitrosation of methapyrilene.

The reactions of sodium nitrite and methapyrilene were studied in aqueous solution at neutral pH and under simulated gastric fluid conditions. Reaction product formation was much more complex than nitrosation of the parent molecule dimethylamino moiety to form nitrosodimethylamine. Several new nitroso compounds were formed under the reaction conditions studied. The simultaneous incorporation of 2 moles of ascorbic acid/mole of nitrite ion prevented any destruction of methapyrilene under all conditions studied. The implications of these observations with respect to nitrosation theory, the general carcinogenicity of nitroso compounds, and methapyrilene dosage formulation are discussed.     

Toxicity and carcinogenicity studies of nalidixic acid in rodents

Toxicity and carcinogenicity studies of nalidixic acid, an antimicrobial agent used to treat bacterial infections of the urinary tract, were conducted in F344/N rats and B6C3F1 mice of each sex for 13 weeks or 2 years. In the 13-week studies, nalidixic acid was administered at dietary concentrations ranging from 1,000 to 16,000 ppm. Body weights of both rats and mice were reduced in the groups receiving diet containing 8,000 and 16,000 ppm, and feed consumption of rats in the highest treatment groups was approximately two-thirds that of controls. Degeneration of the germinal epithelium in the seminiferous tubules of the testis was observed in male rats that received 16,000 ppm; no other compound-related histopathologic effects were observed in either species. Two-year studies were conducted by feeding diets containing 0, 2,000, or 4,000 ppm nalidixic acid to groups of 50 rats and mice/sex/group. The average daily feed consumption was slightly reduced compared to control groups and resulted in approximate daily doses of 82 or 175 mg nalidixic acid/kg for low dose and high dose rats, and 220 or 475 mg/kg for low dose and high dose mice. Mean body weights of dosed rats and mice were lower than those of controls, except for groups of low dose female rats and male mice. The incidences of preputial gland neoplasms in dosed male rats and of clitoral gland neoplasms in dosed female rats were significantly increased compared to those in controls; responses in low dose groups were similar to those in high dose groups. There were decreased incidences of leukemia and mammary gland neoplasms in dosed female rats and of pituitary gland neoplasms in dosed male rats. Subcutaneous tissue fibrosarcomas were marginally increased in dosed male mice. There were no increased incidences of neoplasms in dosed female mice. Under the conditions of these studies, the dietary administration of nalidixic acid was carcinogenic for rats, causing preputial gland or clitoral gland neoplasms in males and females, respectively. The association of subcutaneous neoplasms with administration of nalidixic acid to male mice was equivocal.     

全反式维甲酸-正丁酸（丙戊酸）前体药物的设计、合成及抗肿瘤活性研究

目的合成全反式维甲酸（ATRA）的前体药物，增强ATRA对急性早幼粒白血病（APL）细胞的分化诱导作用。方法以乙二醇、对苯二酚、乙醇胺及乙二胺等为连接物，通过酯键和酰胺键将分化诱导剂ATRA与组蛋白去乙酰酶（mAC）抑制剂正丁酸、丙戊酸连接起来，形成前体药物。结果合成了13个ATRA与正丁酸或丙戊酸相连接的前体药物，化合物的结构经^1H-NMR、MS和IR确证。结论考察部分化合物对急性早幼粒细胞白血病细胞株NB4的生长抑制作用和对急性早幼粒白血病（APL）细胞分化诱导作用，初步的药理实验结果表明，ATRA与丙戊酸通过酰胺键连接时，对NB4细胞分化诱导能力显著增加。