Phototoxicity studies of pazufloxacin mesilate,a novel parenteral quinolone antimicrobial agent--in vitro and in vivo studies

Phototoxicity of pazufloxacin mesilate (PZFX mesilate), a novel parenteral quinolone antimicrobial agent, were evaluated in vitro and in vivo studies. In vitro, phototoxicity for cultured cells of PZFX, which is active principle of PZFX mesilate, was studied, and stability for long-wavelength ultraviolet (UVA) was examined. In vivo, phototoxicity tests in guinea pigs and rats, and photoallergenicity tests in guinea pigs were conducted. In the phototoxicity test on cultured cells, CHL/IU cells were irradiated UVA of 300-3000 mJ/cm2 in the presence of PZFX, ofloxacin (OFLX), lomefloxacin (LFLX) or sparfloxacin (SPFX) at 10 micrograms/mL. Phototoxic potencies for cultured cells of the quinolones tested were SPFX > LFLX > OFLX > PZFX. In addition, changes in ultraviolet absorption spectrum and residual rate of PZFX, OFLX, LFLX and SPFX were examined after UVA irradiation of 300-3000 mJ/cm2 to each solution. PZFX was stable for UVA compared with OFLX and LFLX. In the phototoxicity test of guinea pigs, each quinolone was administered intraperitoneally daily for 7 days, and UVA of about 11 J/cm2 was irradiated at 30 minutes after the last administration. Dose levels of each quinolone were 65 and 130 mg/kg of PZFX mesilate (dose levels converted to PZFX: 50 and 100 mg/kg), 50 and 100 mg/kg of nalidixic acid (NA), 100 mg/kg of OFLX, enoxacin (ENX), ciprofloxacin (CPFX), LFLX and SPFX. Grade of skin reaction (erythema) at 24 hours after UVA irradiation decreased in the order: SPFX > CPFX > NA > ENX = OFLX > LFLX > PZFX mesilate. Thus, PZFX mesilate was found to have the weakest phototoxicity. In the maximum plasma concentration of quinolones from 0.5 to 2.5 hours after administration, corresponding to the time of UVA irradiation, the concentration of the group administered PZFX mesilate was about 4.1 times higher than that of CPFX group, and about 1.3 times higher than that of SPFX group. The area under the blood concentration-time curve (AUC0.5-2.5) of the group administered PZFX mesilate was the same as that of SPFX group, and about 3.2 times larger than that of CPFX group. These data showed that phototoxicity of PZFX mesilate was also weaker than that of CPFX or SPFX in consideration of AUC0.5-2.5. In the phototoxicity test of rats injected intravenously, no phototoxicity was observed at 130 mg/kg of PZFX mesilate. In the photoallergenicity test of guinea pigs, no photoallergenicity was observed by PZFX mesilate. As mentioned above, from in vitro studies PZFX was found to be stable for UVA irradiation compared with OFLX and LFLX, and phototoxicity for cultured cells of PZFX was weaker than that of SPFX, LFLX or OFLX. In addition, from in vivo studies phototoxicity of PZFX mesilate was found to be weaker than that of NA, OFLX, ENX, CPFX, LFLX or SPFX, and no photoallergenicity was observed. Therefore, photosensitive potency of PZFX mesilate might be less than that of other quinolones.     

Important role of oxygen metabolites in quinolone antibacterial agent-induced cutaneous phototoxicity in mice

We investigated whether or not the generation of reactive oxygens and toxic photoproducts participated in the cutaneous phototoxicity mechanisms induced by the quinolone derivatives, ofloxacin (OFLX), enoxacin, lomefloxacin, ciprofloxacin and DR-3355 (the s-isomer of OFLX) in a mouse model. Pretreatment of Balb/c mice with allopurinol, soybean trypsin inhibitor, catalase and beta-carotene gave significant protection against ear swelling reactions induced by oral administration of quinolones and following ultraviolet-A (UVA) irradiation. Pretreatment with diethyldithiocarbamate augmented the swelling. No swelling was observed with direct injection into the auricle of UVA-pretreated photoproducts of the quinolones. These results showed that cutaneous phototoxicity did not depend on the generation of toxic photoproducts and suggested that oxygen metabolites generated in the xanthine oxidase pathway participated in the toxicity.     

Possible direct role of reactive oxygens in the cause of cutaneous phototoxicity induced by five quinolones in mice

The mechanisms of phototoxicity induced in mice by five quinolone antibacterial agents were investigated using mouse 3T3 fibroblast cells and Balb/c mice. In the in vitro study, the cultured cells were exposed to ultraviolet-A (UVA) in the presence of the five quinolones lomefloxacin, enoxacin, ciprofloxacin, ofloxacin and DR-3355 (the s-isomer of ofloxacin). Cytotoxicity after irradiation was assayed by the neutral red and MTT assay methods, both of which revealed dose-dependent phototoxicity for all five quinolones. Phototoxicity was inhibited by the addition of catalase, and was augmented by the addition of Superoxide dismutase. Dimethylthiourea (a hydroxyl radical scavenger) protected against phototoxicity induced by four quinolones, but not against that by enoxacin. These results indicated that Superoxide anions, hydrogen peroxide and hydroxyl radicals were generated in solutions of these quinolones under UVA irradiation. In the in vivo study, mice were injected in the auricle with hydrogen peroxide. Ear swelling reactions appeared dose dependently. When irradiated, these reactions were significantly augmented. These data suggested that cutaneous phototoxicity in Balb/c mice is initiated by the generation of reactive oxygens in the target tissue, especially of hydroxyl radicals.     

Non-competitive inhibition of GABAA responses by a new class of quinolones and non-steroidal anti-inflammatories in dissociated frog sensory neurones.

1. The interaction of a new class of quinolone antimicrobials (new quinolones) and non-steroidal anti-inflammatory agents (NSAIDs) with the GABAA receptor-Cl- channel complex was investigated in frog sensory neurones by use of the internal perfusion and 'concentration clamp' techniques. 2. The new quinolones and the NSAIDs (both 10(-6)-10(-5) M) had little effect on the GABA-induced chloride current (ICI) when applied separately. At a concentration of 10(-4) M the new quinolones, and to a lesser degree the NSAIDs, produced some suppression of the GABA response. 3. The co-administration of new quinolones and some NSAIDs (10(-6)-10(-14) M) resulted in a marked suppression of the GABA response. The size of this inhibition was dependent on the concentration of either the new quinolone or the NSAID tested. The inhibitory potency of new quinolones in combination with 4-biphenylacetic acid (BPAA) was in rank order norfloxacin (NFLX) much greater than enoxacin (ENX) greater than ciprofloxancin (CPFX) much greater than ofloxacin (OFLX), and that of NSAIDs in combination with ENX was BPAA much greater than indomethacin = ketoprofen greater than naproxen greater than ibuprofen greater than pranoprofen. Diclofenac, piroxicam and acetaminophen did not affect GABA responses in the presence of ENX. 4. In the presence of ENX or BPAA, there was a small shift to the right of the concentration-response curve for GABA without any effect on the maximum response. However, the co-administration of these drugs suppressed the maximum of the GABA concentration-response curve, indicating a non-competitive inhibition, for which no voltage-dependency was observed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Apoptotic photoreceptor cell death induced by quinolone phototoxicity in mice

We examined retinal degeneration induced by phototoxicity of quinolone antibacterial agents. Albino Balb/c and pigmented DBA/2 mice fasted overnight were given a single oral administration of ciprofloxacin (CPFX), levofloxacin (LVFX), enoxacin (ENX), lomefloxacin (LFLX) or sparfloxacin (SPFX), followed by ultraviolet-A (UVA) irradiation at 1.5 mW/cm2 for 4 h (21.6 J/cm2). At 24 h after quinolone administration, the mice were sacrificed, and the eyes were then histologically examined. ENX or LFLX at 200 or 400 mg/kg or SPFX at 50 or 100 mg/kg plus UVA induced retinal degeneration in Balb/c mice, whereas no histological change was observed in the eyes of DBA/2 mice. CPFX and LVFX at 800 mg/kg plus UVA had no effect on the eyes in either Balb/c or DBA/2 mice. Agarose gel electrophoresis showed that chromosomal DNA extracted from the eyes of Balb/c mice was fragmented in the SPFX 100 mg/kg group, but not in the LVFX 800 mg/kg group. In the electron microscopic examination, swelling of mitochondria and disruption of the cytoplasm were observed in the photoreceptor inner segment (PIS) at 2 h, and disarrangement of lamellar disks in the outer segment (POS) and condensed chromatin in photoreceptor cell nuclei in the outer nuclear layer (ONL) were observed at 4 h after 100 mg/kg SPFX administration to Balb/c mice. These results suggest that quinolone plus UVA irradiation induces retinal degeneration in albino Balb/c mice, but not in DBA/2 mice, and this degeneration is associated with apoptotic photoreceptor cell death.     

New findings on the structure-phototoxicity relationship and photostability of fluoroquinolones

The present study examined the phototoxicities of a series of 7-(3-aminopyrrolidinyl) quinolones containing various substituents at position 1 by use of a mouse model. For the 7-(3-aminopyrrolidinyl) quinolones with a halogen atom at position 8, well-known substituent groups such as a cyclopropyl, an ethyl, or a difluorophenyl at position 1 were found to be responsible for severe phototoxicity. However, when an aminodifluorophenyl or an isoxazolyl group was placed at position 1, even 8-halogeno quinolones were found to be mildly phototoxic. This is the first report of 8-halogeno quinolones that are not severely phototoxic. Two structurally similar 8-chloro quinolones (the 1-aminodifluorophenyl 8-chloro quinolone and the 1-difluorophenyl 8-chloro quinolone) were investigated further. The former was mildly phototoxic; the latter was severely phototoxic. We demonstrate that these two 8-chloro quinolones have practically the same areas under the concentration-time curves from 0 to 4 h in auricular tissue, suggesting that the mild phototoxicity is not due to pharmacokinetic instability. The rates of UV photodegradation of these compounds were also measured. We found that these two quinolones photodegrade at similar rates, suggesting that the mild phototoxicity is not attained through increased photostability. In conclusion, the phototoxic potentials of fluoroquinolones are influenced not only by the substituent at position 8 but also by that at position 1. We also discovered a mildly phototoxic 8-chloro quinolone which did not have increased photostability.     

The history of the development and changes of quinolone antibacterial agents

The quinolones, especially the new quinolones (the 6-fluoroquinolones), are the synthetic antibacterial agents to rival the Beta-lactam and the macrolide antibacterials for impact in clinical usage in the antibacterial therapeutic field. They have a broad antibacterial spectrum of activity against Gram-positive, Gram-negative and mycobacterial pathogens as well as anaerobes. Further, they show good-to-moderate oral absorption and tissue penetration with favorable pharmacokinetics in humans resulting in high clinical efficacy in the treatment of many kinds of infections. They also exhibit excellent safety profiles as well as those of oral Beta-lactam antibiotics. The bacterial effects of quinolones inhibit the function of bacterial DNA gyrase and topoisomerase IV. The history of the development of the quinolones originated from nalidixic acid (NA), developed in 1962. In addition, the breakthrough in the drug design for the scaffold and the basic side chains have allowed improvements to be made to the first new quinolone, norfloxacin (NFLX), patented in 1978. Although currently more than 10,000 compounds have been already synthesized in the world, only two percent of them were developed and tested in clinical studies. Furthermore, out of all these compounds, only twenty have been successfully launched into the market. In this paper, the history of the development and changes of the quinolones are described from the first quinolone, NA, via, the first new quinolone (6-fluorinated quinolone) NFLX, to the latest extended-spectrum quinolone antibacterial agents against multi-drug resistant bacterial infections. NA has only modest activity against Gram-negative bacteria and low oral absorption, therefore a suitable candidate for treatment of systemic infections (UTIs) is required. Since the original discovery of NA, a series of quinolones, which are referred to as the old quinolones, have been developed leading to the first new quinolone, NFLX, with moderate improvements in over all properties starting in 1962 through and continuing throughout the 1970's. Especially, the drug design for pipemidic acid (PPA) indicated one of the important breakthroughs that lead to NFLX. The introduction of a piperazinyl group, which ia a basic moiety at the C7-position of the quinolone nuclei, improved activity against Gram-negative organisms broadening the spectrum to include Pseudomonas aeruginosa. PPA also showed soem activity against Gram-positive bac teria. The basic piperazine ring, which can form the zwitterionic natrure with the carboxylic acid at the C3-position, has subsequently been shown to increase the ability of the drugs to penetrate the bacterial cells resulting in enhanced activity. Further, the zwitterionic forms resulted in significant tissue penetration in the pharmacokinetics. On the other hand, the first compound with a fluorine atom at the C6-position of the related quinolone scaffold was flumequine and the compound indicated that activity against Gram-positive bacteria could be improved in the old quinolones. The addition of a flourine atom at the C6-position is essential for the inhibition of target enzymes. The results show the poten antibacterial activity and the penetration of the quinolone molecule into the bacterial cells and human tissue. The real breakthrough came with the combination of these two features in NFLX, a 6-fluorinated quinolone having a piperazinyl group at the C7-position, NFLX features significant differences from the old quinolones in the activities and pharmacokinetics in humans, resulting in high clinical efficacy in the treatment of many kinds of infections including RTIs.Consequently, those great discoveries are rapidly superseded by even better compounds and NFLX proved to be just the beginning of a highly successful period of research into the modifications of the new quinolone antibacterials. Simce the chemical structure and important features of NFLX had become apparent in 1978, many compounds were patented in the next three years, several of which reached the market. Among the drugs, ofloxacin (OFLX) and ciprofloxacin (CPFX) are recognized as superior in several respects to the oral beta-lactam antibiotics as an antibacterial agent. With a focus on OFLX and CPFX, numerous research groups entered the antibacterial therapeutic field, triggering intense competition in the search to find newer, more effective quinolones. After NFLX was introduced in the market, while resulting by the end of today, eleven kinds of other new quinolones launched in Japan. They are enoxacin (ENX), OFLX, CPFX, lomefloxacin (LFLX), fleroxacin (FRLX), tosufloxacin (TFLX), levofloxacin (LVFX), sparfloxacin (SPFX), gatifloxacin (GFLX), prulifloxacin (PULX) and also pazufloxacin (PZFX). The advantages of these compounds, e.g., LVFX, SPFX and GFLX, are that their spectrum includes Gram-positive bacteria species as well as Gram-negative bacteria and they improve bioavailability results when a daily dose is administered for systemic infections including RTIs. However, unexpected adverse reactions, such as the CNS reaction, the drug-drug interaction, phototoxicity, hepatotoxicity and cardiotoxicity such as the QTc interval prolongation of ECG, have been reported in the clinical evaluations or the post-marketing surveillance of several new quinolones. Moreover, the adverse reactions of arthropathy (the joint toxicity) predicated from studies in juvenile animals have never materialized in clinical use. Therefore, no drugs other than NFLX have yet been approved for pediatric use. Fortunately, the newer quinolones are being developed and tested to reduce these adverse reactions on the basis of recent studies. On the other hand, multi-drug resistant Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant coagulase-negative staphycolocci (MRCNS), penicillin-resistant Streptococcus pneumoniae (PRSP) and vancomycin-resistant enterococci (VRE) have been a serious problem in the medical community. Recently, the new quinolone antibacterials are highly successful class of antibacterial therapeutic field, however, the increased isolation of quinolone-resistant bacteria above them has become a normal outcome. These problems of multi-drug resistance have been the driving force for the development of newer quinolones. The next gereration of quinolone antibacterial agents will be potent against multi-drug resistant bacteria, such as MRSA, and provide a lower rate of emergence in resistance. Further, they should have favorable safety profiles to reduce the adverse reactions. The future of quinolones as the ultimate in pharmaceuticals must be handled cautiously if they are to realize their potential in the medical community.     

体外检测氟喹诺酮类药物光毒性的可靠性

目的：比较四个氟喹诺酮类抗生素的光毒性来确定体外实验的可靠性．方法：用体内Wistar大鼠光毒性实验,Balb／c小鼠光毒性实验和体外中国仓鼠V79细胞微核实验,NIH 3T3 MTT实验在不同的UVA照射条件下测定四个氟喹诺酮类抗生素的光毒性．结果：在所有实验中,司帕沙星、洛美沙星显示出较强的光毒性,与对照组相比,均有非常显著性差异(P＜0．01);环丙沙星光毒性较温和,有显著性差异(P＜0.05);诺氟沙星在体内实验中没有显示出光毒性,但在体外实验中较高剂量(10μmol/L)能产生光毒性．结论：体内外测定药物光毒性有良好的相关性,因此体外检测氟喹诺酮类药物光毒性是可靠的．     

Laboratory and clinical studies on levofloxacin]

A newly developed broad-spectrum fluoroquinolone, levofloxacin (LVFX, DR-3355), was evaluated in vitro and in vivo in comparison with ciprofloxacin (CPFX), ofloxacin (OFLX) and norfloxacin (NFLX). The results were as follows. 1. Antimicrobial activity Minimal inhibitory concentrations (MICs) against 480 clinical isolates including 16 different species were determined using the microbroth dilution method. LVFX showed excellent antimicrobial activities against Gram-positive and -negative bacteria. The MIC values of LVFX for Gram-positive bacteria were superior to those of the other quinolones tested. The MIC values of LVFX for Gram-negative bacteria were comparable to those of CPFX and superior to those of OFLX and NFLX. 2. LVFX concentrations in serum and sputum LVFX was orally administered in a single dose of 200 mg to 2 patients with chronic lower respiratory tract infections, and its concentrations in serum and sputum were measured at intervals using bioassay. The peak concentrations of LVFX in serum were 1.52 and 1.24 micrograms/ml, and 84-95% of serum level were detected in sputum. From these data, it appeared that LVFX penetrate well into the lung. 3. Clinical efficacy and adverse reactions Fifteen patients with respiratory tract infections were treated with LVFX, and the overall efficacy rate was 78.6% (excellent in 3 cases, good in 8, fair in 3, poor in 0). As adverse reactions, anorexia was observed in 2 cases, diarrhea in 1 case and tremor of finger in 1 case. Although an elevation of total bilirubin in serum was observed in a case as an abnormal laboratory finding, it was mild, transient and improved rapidly after the completion of LVFX treatment.     

Comparison of inhibitory effects of new quinolones on drug metabolizing activity in the liver

The effects of three new quinolones (enoxacin (ENX), norfloxacin (NFLX) and ofloxacin (OFLX] on acetaminophen-induced liver injury in rats were examined and compared with their effects on the elimination half-life (T1/2) of theophylline (in vivo) and on the 7-ethoxycoumarin (7-EC) O-deethylase activity in liver microsomes (in vitro). ENX, NFLX and OFLX (75 or 300 mg/kg) were administered orally to rats 1 hr before, simultaneously with, and 1 hr after the acetaminophen injection (800 mg/kg). Biochemical liver function tests, drug metabolizing activity in liver microsomes, the total glutathione content of the liver and histological changes were examined 5 hr after the acetaminophen injection. ENX markedly reduced acetaminophen-induced liver injury and NFLX slightly but significantly did so, but no protective effect was observed with OFLX treatment. ENX markedly and NFLX slightly prolonged the T1/2 of theophylline, but OFLX did not affect it. In addition, ENX markedly and NFLX slightly inhibited the 7-EC O-deethylase activity in liver microsomes, but OFLX again had no effect. These findings indicated that ENX markedly inhibited the activity of cytochrome P-450 in liver microsomes and NFLX did so slightly, while OFLX had no such effect. Slight variations in the structures of these quinolones might explain the differences in their effects on cytochrome P-450 activity.     

Drug interactions between nonsteroidal anti-inflammatory drug and pazufloxacin mesilate,a new quinolone antibacterial agent for intravenous use: convulsions in mice after intravenous or intracerebroventricular administration

Convulsant activity of pazufloxacin mesilate (PZFX mesilate), a new quinolone antibacterial agent for intravenous use, in combination with nonsteroidal anti-inflammatory drug (NSAID) was investigated in mice after intravenous or intracerebroventricular administration. Following results were obtained. 1. In combination with 4-biphenylacetic acid (BPAA) at an oral dose of 100 mg/kg, PZFX mesilate did not induce any convulsions at intravenous doses up to 200 mg/kg. Reference quinolones induced convulsions at the following intravenous doses: Enoxacin (ENX), 3.13 mg/kg or more; norfloxacin (NFLX) and lomefloxacin (LFLX), 6.25 mg/kg or more; ciprofloxacin (CPFX), 50 mg/kg or more; sparfloxacin (SPFX) and temafloxacin (TMFX), 100 mg/kg or more; fleroxacin (FLRX), 200 mg/kg. 2. PZFX mesilate at an intravenous dose of 50 mg/kg did not induce convulsions in mice after oral administration of any of 14 kinds of NSAIDs. It induced convulsions at 200 mg/kg in combination with aspirin at an oral dose of 600 mg/kg, while it did not with the other 13 kinds of NSAIDs. 3. Convulsion-inducing dose of PZFX mesilate after intracerebroventricular administration was 100 mg/body, which was higher than those of reference quinolones (NFLX, CPFX, ENX, LFLX, TMFX, levofloxacin, ofloxacin, FLRX and SPFX) and beta-lactam antibiotics (penicillin G, cefazoline, imipenem/cilastatin and panipenem/betamipron). In addition, concurrent dosing of BPAA (1 microgram/body) did not reduce the convulsion-inducing dose of PZFX mesilate. These results suggest that PZFX mesilate has remarkably weak convulsant activity.     

Possible relationship between phototoxicity and photodegradation of sitafloxacin, a quinolone antibacterial agent, in the auricular skin of albino mice.

We compared the phototoxic potential of the quinolone antibacterial agent sitafloxacin with those of lomefloxacin and sparfloxacin. Female BALB/c mice were given a single intravenous administration of sitafloxacin, lomefloxacin, or sparfloxacin at 10 or 40 mg/kg, followed by ultraviolet-A (UVA) irradiation for 4 h (21.6 J/cm(2)). At 10 mg/kg, all quinolones induced either none or minimum inflammation in the auricle. At 40 mg/kg, sitafloxacin induced mild phototoxic inflammation in the dermal skin, while lomefloxacin and sparfloxacin induced very severe inflammation. In particular, 2/5 animals of the lomefloxacin group showed partial necrosis in the dermis and epidermis. We then determined the time course change of sitafloxacin concentrations in serum and auricular tissue by high performance liquid chromatography. Sitafloxacin concentrations in the auricle were markedly decreased under UVA irradiation, whereas those in sera were not affected. Furthermore, we examined the severity of sitafloxacin-induced phototoxicity under varied duration of UVA irradiation. The severity of phototoxicity increased with increasing duration of UVA irradiation, and statistical analysis showed a close correlation between the severity and the decreased area under the drug concentration curve under UVA irradiation (DeltaAUC(auricle)). The severity was decreased with delay in commencement of UVA irradiation, indicating the importance of commencement time of irradiation in the experimental condition of the phototoxicity study. It might be attributed to the decrease in DeltaAUC(auricle) after administration. These results suggest that sitafloxacin possesses milder phototoxic potential than lomefloxacin or sparfloxacin and is degraded in the auricular skin under UVA irradiation, and that the severity of phototoxicity is directly proportional to the DeltaAUC(auricle).     

In vitro phototoxic properties of new 6-desfluoro and 6-fluoro-8-methylquinolones

A representative set of potent antibacterial 6-desfluoro-8-methylquinolones, in which the C-6 fluorine atom is replaced by –NH₂ or –H, and their 6-fluoro counterparts, were investigated to evaluate their phototoxic potential and to explore the mechanism behind their phototoxicity. The capacity to photosensitize biological substrates (lipids, proteins, DNA) has been analyzed, as well as their photocytotoxicity on red blood cells and 3T3 murine fibroblasts. The results obtained show that the quinolones studied are able to photosensitize red blood cell lysis in an oxygen-dependent way and induce a high decrease in cell viability after UVA irradiation. A major correlation with phototoxicity lies in the structure of the individual antibacterials and their hydrophobicity; in particular, 6-amino derivatives are less phototoxic than corresponding unsubstituted and fluorinated compounds. Cellular phototoxicity was inhibited by the addition of free radical and hydroxyl radical scavengers (BHA, GSH and DMTU), suggesting the involvement of a radical mechanism in their cytotoxicity. A good correlation was observed between lipid peroxidation and phototoxicity, indicating that the test compounds exert their toxic effects mainly in the cellular membrane. Preliminary experiments on pBR322 DNA show that these derivatives do not photocleave DNA, differently from the two photogenotoxic fluoroquinolones, ciprofloxacin and lomefloxacin, used as reference compounds.     

Comparative studies on activities of antimicrobial agents against causative organisms isolated from urinary tract infections (1987). III. Secular changes in susceptibility

Sensitivity spectra of major species of bacteria (namely Escherichia coli, Klebsiella spp., Proteus spp., Citrobacter spp., Enterobacter spp., Serratia marcescens and Pseudomonas aeruginosa) which were among the clinical isolates mentioned in the first and second reports to various antibacterial and antibiotic agents and time courses of the spectra are reported below. 1. E. coli was sensitive to cefmenoxime (CMX), latamoxef (LMOX), ceftazidime (CAZ), cefzonam (CZON) and flomoxef (FMOX) which are third generation cephems, carumonam (CRMN) which is a monobactam, imipenem (IPM) which is a carbapenem, ofloxacin (OFLX) and ciprofloxacin (CPFX) which are new quinolones. Compared to the preceding 5-year period, sensitivities to most drugs have increased. 2. Klebsiella spp. were sensitive to CMX, CZON and FMOX which are third generation cephem antibiotics, CRMN which is a monobactam and gentamicin (GM) and arbekacin (HBK) which are aminoglycosides. Compared to the preceding 5-year period, the sensitivity on the whole has increased slightly. 3. Proteus spp. were sensitive to CMX, LMOX, CAZ and CZON which are third generation cephems, CRMN, a monobactam and OFLX and CPFX which are new quinolones. Compared to the preceding 5-year period, increased sensitivities, particularly to parenteral cephems, were found. 4. Citrobacter spp. were sensitive to CPFX which is a new quinolone antibiotic and CRMN, a monobactam. Compared to the preceding 5-year period, the sensitivity as a whole increased but there were still strains against which cefotiam, cefmetazole and, cefoperazone (CPZ) showed high MIC values. 5. Enterobacter spp. were sensitive to OFLX and CPFX, which are new quinolones, IPM, a carbapenem, and GM and HBK which are aminoglycosides. Compared to other bacteria, bacteria of this group were less sensitive to CPZ, CAZ, CZON, and FMOX which are third generation cephems. Compared to the preceding 5-year period, slight increases in sensitivity were found in cases of simple urinary tract infections. 6. S. marcescens as a whole was not very sensitive to antibiotics tested. Compared to the preceding 5-year period, sensitivities to CRMN and minocycline improved slightly. 7. P. aeruginosa was not very sensitive to any drug, as other bacteria were. Compared to the preceding 5-year period, sensitivities to new quinolones OFLX and CPFX and carbapenem IPM decreased slightly.     

In vitro evaluation of betamethasone esters for phototoxic potential

The phototoxicity of Betamethasone valerate and betamethasone dipropionate has been investigated on irradiation in the wavelength range of 300-400 nm, using some basic in vitro phototoxicity tests. Both esters cause photohemolysis of mouse red blood cells and photoperoxidation of linoleic acid. The photoproducts of both esters have also been found to be phototoxic. The toxicity of these photoproducts increases with further irradiation; however, they exhibit toxicity, even in the dark. The efficient inhibition of photohemolysis by the well-known free radical scavengers, such as butylhydroxyanisole and reduced glutathione, and minor inhibition by singlet-oxygen quenchers, such as sodium azide, suggests that cellular damage is mainly mediated by free radicals whereas singlet oxygen plays a minor role.     

Treatment of gonococcal urethritis]

Results of the treatment of 5 cases of males with uncomplicated gonoccocal urethritis using levofloxacin (LVFX, DR-3355), the L-type optical isomer of ofloxacin (OFLX), were compared with those treated with OFLX itself. Three hundred mg/day of LVFX or 600 mg/day of OFLX was given to each patient for 5 days. Both drugs showed excellent clinical results in all the patients. When MICs of the 2 drugs were compared against 57 isolated strains of Neisseria gonorrhoeae including 3 penicillinase-producing N. gonorrhoeae, it was found that MICs of LVFX were approximately one half of those of OFLX.     

In vitro evaluation of betamethasone esters for phototoxic potential

The phototoxicity of Betamethasone valerate and betamethasone dipropionate has been investigated on irradiation in the wavelength range of 300–400?nm, using some basic in vitro phototoxicity tests. Both esters cause photohemolysis of mouse red blood cells and photoperoxidation of linoleic acid. The photoproducts of both esters have also been found to be phototoxic. The toxicity of these photoproducts increases with further irradiation; however, they exhibit toxicity, even in the dark. The efficient inhibition of photohemolysis by the well-known free radical scavengers, such as butylhydroxyanisole and reduced glutathione, and minor inhibition by singlet-oxygen quenchers, such as sodium azide, suggests that cellular damage is mainly mediated by free radicals whereas singlet oxygen plays a minor role.     

Comparative studies on activities of antimicrobial agents against causative organisms isolated from urinary tract infections (1987). I. Susceptibility distribution

Since 1979, Ikemoto et al. have been retrospectively surveying the sensitivity of major species of bacteria isolated from patients with urinary tract infections to various antibacterial agents and antibiotics. Their findings for the past year are reported below. A total of 825 clinical strains of bacteria was investigated. Of this total, Gram-positive bacteria accounted for 28.0% (231 strains) and Gram-negative bacteria for 72.0% (594 strains). Taxonomically, Escherichia coli accounted for 34.7% (286 strains), Enterococcus faecalis for 14.3% (118), Pseudomonas aeruginosa for 11.0% (91), Klebsiella pneumoniae for 7.8% (64), and coagulase-negative staphylococci for 7.3% (60). Sensitivity spectra of these major bacteria to various drugs were as follows. 1. E. faecalis was sensitive to parenteral imipenem (IPM) and ampicillin and oral vancomycin. It was also sensitive to ofloxacin (OFLX) and ciprofloxacin (CPFX), which are new quinolones. Some strains were only slightly sensitive to second and third generation cephems cefmenoxime (CMX) and cefuzonam (CZON) aminoglycosides amikacin (AMK) and arbekacin (HBK), and erythromycin which is a macrolide. 2. Staphylococcus aureus was sensitive to dicloxacillin (MDIPC) which is a penicillin drug, cefotiam (CTM) which is a cephem, IPM, minocycline (MINO), and HBK. A fairly large number of strains were only slightly sensitive to cefazolin (CEZ), OFLX and CPFX. 3. Coagulase-negative staphylococci were sensitive to MDIPC which is a penicillin derivative, cephems CTM and CZON, IPM, HBK, clindamycin (CLDM) and MINO. Some strains, however, were only slightly sensitive to a majority of these drugs. 4. E. coli was sensitive to CTM, CMX, latamoxef (LMOX), ceftazidime (CAZ), CZON, and flomoxef (FMOX), all of which are second or third generation cephems. It was also sensitive to IPM, a carbapenem, carumonam (CRMN), a monobactam, and new quinolones, OFLX and CPFX. 5. K. pneumoniae was sensitive to cephems, viz. CTM, CAZ, CZON, FMOX and cefixime, CRMN which is a monobactam, IPM, a carbapenem and new quinolones, OFLX and CPFX. Some strains were only slightly sensitive to CTM, cefmetazole cefoperazone (CPZ), and FMOX. 6. Citrobacter freundii was sensitive to CRMN which is a monobactam, and new quinolones, OFLX and CPFX. Many strains were only slightly sensitive to cephems, viz. CEZ, CTM, CPZ and CAZ. 7. Enterobacter cloacae was sensitive to gentamicin and AMK which are aminoglycosides, but showed a bimodal pattern of sensitivity to CPZ, CAZ and CZON, all of which are cephems, and to quinolones, OFLX and CPFX.(ABSTRACT TRUNCATED AT 400 WORDS)     

Chemotherapy of biliary tract infections (XXXVII). Excretion into bile and gallbladder tissue levels of levofloxacin and its clinical effect in biliary tract infections]

Evaluations were made on biliary excretion and penetration into the gallbladder tissue of levofloxacin (LVFX, DR-3355), a new quinolone antibacterial agent, and its clinical efficacy in biliary tract infections. 1. Gallbladder tissue concentrations and biliary concentrations of LVFX at 2-6 hours at oral administration of 100 mg were 0.58-1.99 micrograms/g and 0.49-5.63 micrograms/ml, respectively. These tissue and biliary levels are almost equal or somewhat higher than the serum levels (0.55-1.63 micrograms/ml) of the compound. 2. The concentrations of LVFX and optical isomer DR-3354 in the serum, gallbladder tissue, and bile were determined after a single or a concomitant administration of LVFX 100 mg and/or ofloxacin (OFLX) 100 to 200 mg. The concentration ratio of LVFX to DR-3354 paralleled with the ratio of the 2 compounds administrated. 3. At a dose of 100 mg, the glucuronide of LVFX in the common duct bile was detected at proportions between 0.9 and 36.0%. 4. A total of 11 patients with biliary tract infections, including 6 cholecystitis 3 cholangitis, and 1 each of cholecystocholangitis and liver abscess was treated with LVFX at 100-200 mg t.i.d. for 3-14 days. Clinical results were excellent or good in 8 cases and fair in 3 cases, resulting in an efficacy rate of 72.7%. 5. A side effect and an abnormal change in laboratory findings were observed in both 1 case each and they were both mild. It was concluded that LVFX showed good penetration to the biliary tract as does OFLX, and that it would be a useful oral agent for the treatment of biliary tract infections.     

Cross-resistance of clinical isolates of methicillin-resistant Staphylococcus aureus to aminoglycosides and fluoroquinolones.

Susceptibilities of 117 clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) to aminoglycosides and fluoroquinolones were investigated during 1987 and 1990. Gentamicin, tobramycin, sisomicin, micronomicin, and astromicin showed the bimodal antimicrobial activity pattern against MRSA, revealing cross-resistance to these antibiotics. However, amikacin, netilmicin, isepamicin and arbekacin (ABK) exhibited the monomodal antimicrobial activity pattern, suggesting the presence of less resistant strains. All 117 MRSA strains were susceptible to ABK with MICs less than 3 micrograms/ml. MRSA also showed the bimodal antimicrobial susceptibility pattern to fluoroquinolones such as ofloxacin (OFLX), ciprofloxacin (CPFX) and tosufloxacin (TFLX). Frequencies of TFLX susceptible MRSA isolates decreased progressively from 1987 to 1989 when this drug was not even in general clinical use. The cross-resistance of MRSA between TFLX and OFLX or CPFX persisted. Cross-resistance between aminoglycosides and fluoroquinolones, however, was less frequently observed.