Liver initiation activity of norfloxacin but not nalidixic acid, pipemidic acid, and ciprofloxacin on in vivo short-term liver initiation assay in rats.

This study aimed to examine the in vivo initiation activity of the quinolone antimicrobials--nalidixic acid (NA), pipemidic acid (PPA), ciprofloxacin (CPFX), and norfloxacin (NFLX)--by using an in vivo short-term liver initiation assay. Rats were subjected to a two-thirds partial hepatectomy on day 0 and 12 h after completion of this procedure were treated once orally with each quinolone or vehicle. Subsequently, they were fed a basal diet for 14 days and a diet containing 0.015% of 2-acetylaminofluorene for the following 10 days. On day 19, a single oral dose of carbon tetrachloride at 0.8 mL/kg body weight was administered. On day 34, they were sacrificed under ether anesthesia, and liver slices were fixed in 10% neutral buffered formalin for immunohistochemical examination of glutathione S-transferase placental form (GST-P) positive foci. Administration of NFLX resulted in a significant increase in the mean number and area of GST-P positive foci; however, administration of the three other quinolones did not produce any increase. These results suggest that only NFLX has an initiation activity in rats under the conditions used in the present study.

Antimutagenesis of beta-carotene to mutations induced by quinolone on Salmonella typhimurium.

BACKGROUND: Quinolone-induced mutagenesis in the Salmonella typhimurium hisG48 strains suggests that these antibiotics are oxygen free radical generators. The use of beta-carotene as antioxidant was evaluated as an alternative to reduce oxidative cell damage in patients who need therapy with nalidixic acid, norfloxacin, or pipemidic acid. The studied beta-carotene (30%), used by pharmaceutical laboratories as dietary complements, was not toxic or mutagenic for the S. typhimurium TA102 strain at a dose equivalent to 1,500 I.U. At the studied concentrations, the evaluated antimutagen did not modify the minimum inhibitory concentration of nalidixic acid, norfloxacin, or pipemidic acid against uropathogenic Escherichia coli strains. METHODS: The mutagenic effect of nalidixic acid and norfloxacin against hisG48 strains was inhibited with 1500 I.U. of beta-carotene. The antimutagenic effect of beta-carotene against mutations induced by pipemidic acid was observed even with 150 I.U. of beta-carotene. The antimutagenic effect against mutations induced on S. typhimurium TA102 or TA104 strains was observed only when the aroclor 1254 rat-induced liver S9 mixture was used. RESULTS: This mutagenic effect was detected only when the strains were exposed to quinolones and the beta-carotene simultaneously with the S9 mixture, suggesting that quinolones induce oxygen free radicals that may be scavenged by beta-carotene. CONCLUSIONS: The antimutagenic effect of this vitamin A precursor is probably due to the active molecule of vitamin A, a desmutagen with the ability of radical capture. A diet rich in beta-carotene or vitamin A could be a good alternative to reduce genotoxic risk to patients being treated with quinolone.

Quantitative in vitro assessment of drug phototoxicity by a chemiluminescence method.

OBJECTIVE: To establish a test model for phototoxic agents using the method of chemiluminescence. METHODS: The phototoxicity of pipemidic acid, doxycycline, griseofuvin and chlorpromazine was detected. These agents and distilled water were irradiated with ultraviolet A (UVA) in the presence of nicotinamide adenine dinucleotide reduced (NADH), and the duplicated samples were incubated in the dark as dark controls. Then luminol was added to the test samples, and the chemiluminescent value was counted and calculated. RESULTS: Chemiluminescent values of pipemidic acid, doxycycline and griseofuvin were significantly higher than those in controls. The result of linear regression analysis showed that phototoxic intensity was linear correlated with UVA dosage. The regression coefficient for distilled water was 0.56, indicating that the luminescent value (LV) rose slightly after UVA irradiation. For pipemidic acid, griseofuvin and doxycycline, the regression coefficients reached 76.96, 254.33 and 92.61 respectively, significantly increased in comparison with those of negative controls (P < 0.01). CONCLUSION: Phototoxicity of pipemidic acid, doxycycline and griseofuvin can be detected with the method of chemiluminescence.

Genotoxic evaluation of norfloxacin and pipemidic acid with the Escherichia coli Pol A-/Pol A+ and the ames test.

BACKGROUND: Genotoxicity of antibiotics has not been well evaluated, and there is not much information on the genetic risk of quinolone drugs, even though they are widely used as alternative choice drugs in urinary infections. METHODS: Pipemidic acid and norfloxacin were tested for their capacity to induce point mutations using the Ames test and DNA damage on Escherichia coli PolA-/PolA+. RESULTS: At non-toxic doses, all of the drugs studied were negative on the E. coli PolA-/PolA+ test with or without in vitro metabolic activation with induced arochlor 1254 rat liver (S9). They did not produce frameshift mutations in TA98, or base-pair substitutions in S. typhimurium hisG46 strains TA100, or UTH8414. Norfloxacin and its induced metabolites in vitro with S9 rat liver were mutagenic to hisG48 strains TA102 and TA104, both of which detect oxidative chemicals. Pipemidic acid induced mutations in S. typhimurium hisG48 strains only when they had an efficient DNA excision repair system. CONCLUSIONS: These results suggest that the risk of oxygen-free radical generation from quinolones should be considered.

Genotoxic evaluation of Norfloxacin and Pipemidic acid with the Eschirichia coli PolA-/polA+ and the ames test

Background. Genotoxicity of antibiotic has not been well evaluted, and there is not much information on the genetic risk of quinolone drugs, even though they are widely used as alternative choice drugs in urinary infections. Methods. Pipemidic acid and norfloxacin were tested for their capacity to induce point mutations using the Ames test and DNA damage on Escherichia coli PolA-/PolA+. Results. At non-toxic doses, all of the drugs studied were negative on the E. coli PolA-/PolA+ test with or without in vitro metabolic activation with induced arochlor 1254 rat liver (S9). They did not procedure frameshift mutations in TA98, or base-air substitutions in S. typhimurium hisG46 strains TA100, or UTH8414. Norfloxacin and its induced metabolites in vitro with S9 rat liver were mutagenic to hisG48 strains TA102 and TA104, both of which detect oxidative chemicals. Pipemidic acid induced mutations in S. typhimurium hisG48 strains only when they had an efficient DNA excision repair system. Conclusions. These results suggest that the risk of oxygen-free radical generation from quinolones should be considered

Quinolone-induced arthropathy in the neonatal mouse. Morphological analysis of articular lesions produced by pipemidic acid and ciprofloxacin.

Quinolone antibiotics are extensively utilized in antimicrobial chemotherapy. However, quinolone treatment in developing adolescents of several animal species is associated with acute arthropathy of the weight-bearing joints. Although arthropathy has rarely been observed following quinolone therapy in man, the toxicity observed in immature animals has resulted in restricted use of these drugs in children and pregnant women. Therefore, identification of novel quinolone antibiotics which do not cause arthropathy is highly desirable. This task would be facilitated by a bioassay of cartilage toxicity which utilizes small quantities of test material and has greater sensitivity than current toxicity assays. This study evaluated the utility of neonatal mice as a potential bioassay of quinolone-induced joint toxicity. Seven-day-old CF-1 mice (8-10/dose group) were treated subcutaneously with either pipemidic acid (50, 400, or 3150 mg/kg/day) for 7 or 14 days or ciprofloxacin (50 or 200 mg/kg/day) for 5, 7, or 14 days. Lameness was observed only after high-dose pipemidic acid treatment for 2-7 days. Histopathological assessment of the principal weight-bearing joints (knee, elbow, and multiple articulations in the fore- and hind-feet) revealed a lesion characterized by chondrocyte loss, matrix degeneration, and erosion of the articular cartilage in mice treated with pipemidic acid at 400 or 3150 mg/kg/day for 7 days or ciprofloxacin at 200 mg/kg/day for 5 days. Mice treated for 14 days with 400 mg/kg/day pipemidic acid demonstrated a lower incidence of lesions than mice treated for 7 days, suggesting the potential for reversibility during ongoing treatment. The results suggest that neonatal mice are sensitive to quinolone-induced arthropathy, but less so than previously reported for adolescent dogs. It is concluded that the neonatal mouse may be an appropriate screening system for identifying novel quinolones devoid of cartilage toxicity; however, follow-up studies with select compounds in a more sensitive species, such as the dog, are encouraged.

Evaluation of the DNA-damaging and mutagenic activity of oxolinic and pipemidic acids by the granuloma pouch assay.

The mutagenic and DNA-damaging activities of oxolinic acid and pipemidic acid were evaluated in the rat granuloma pouch assay. After oral administration at high doses both the chemicals produce DNA alkali-labile sites in granuloma tissue cells, and with oxolinic acid an increase of liver and kidney DNA elution rate was also observed. In contrast, after direct injection into the granuloma tissue, DNA damage was absent. This indicates that DNA lesions are induced by a stable intermediate presumably formed in liver and converted to the ultimate DNA-damaging species in extrahepatic tissues. The simultaneous analysis of 6-thioguanine-resistant cells in the granuloma tissue revealed no statistically significant mutation induction either after local treatment or oral administration. No clear dose-response curve was obtained. However, after oral application in some of the animals an enhanced mutation frequency was detected, and the cloning efficiency of cells exposed to the drugs was reduced even after culturing them for 6 days. The most likely explanation is that functional multilocus mutations are induced which cannot be recovered efficiently at the HGPRT locus.

Metabolites of pipemidic acid in human urine.

1. The urine of men dosed orally with pipemidic acid, contained the metabolites acetylpipemidic, formylpipemidic and oxopipemidic acids together with unchanged pipemidic acid. 2. Each metabolite was equivalent to less than 2% of the unchanged pipemidic acid present in human urine. 3. All metabolites showed a similar antibacterial spectrum to pipemidic acid, but their potency was about 10 times lower than that of pipemidic acid. The acute toxicity of the metabolites in mice was as low as the parent compound. 4. These results indicate that the role of the metabolites in the clinical efficacy and toxicity of the drug is likely to be small.

Toxicological studies on pipemidic acid. V. Effect on diarthrodial joints of experimental animals.

Pipemidic acid (PPA) orally given in a dose of 100 mg/kg/day or more was found to cause lame gait in immature beagle dogs of about 3 months old. Their diarthrodial joints were abnormal with increased synovial fluid and blister formation under the outer layer of the articular cartilage. However, such an abnormality was not found in dogs younger than 2 weeks or older than 12 months. The blisters were formed at the joint areas bearing the body weight at a time when PPA was considered to be present there. Nalidixic and piromidic acids, structural analogues of PPA, also caused abnormality similar to PPA. The severity of the arthropathy was slight with piromidic acid as compared with PPA and nalidixic acid. The gait abnormality was almost disappeared spontaneously even if medication was continued. The incidence of the arthropathy was not or rarely observed in any young rats, rabbits and monkeys.