Troxipide, a novel antiulcer compound, has inhibitory effects on human neutrophil migration and activation induced by various stimulants.

BACKGROUND: Neutrophils are considered to be involved in the pathogenesis of Helicobacter pylori-associated gastroduodenal diseases on account of their potent biological functions as effector cells. Troxipide, a new antiulcer compound used for patients with gastric ulcer or gastritis, has been shown to inhibit migration and activation of guinea pig neutrophils, but little is known about the pharmacological effects on human neutrophils. AIMS: To study the effects of troxipide on chemotactic migration and superoxide generation by human neutrophils. METHODS: The chemotactic response of neutrophils was determined in a multi-well chamber with a polycarbonate filter and the generation of O2- by neutrophils was measured using a chemiluminescence method. Concentrations of troxipide in gastric mucosa were measured by high-performance liquid chromatography. RESULTS: Incubation of neutrophils with 10(-6) to 10(4) M troxipide caused inhibition of recombinant interleukin-8-induced migration. These concentrations of troxipide also inhibited superoxide generation by neutrophils stimulated by formyl-methionyl-leucyl-phenylalanine or platelet activating factor. These phenomena were not simply due to the direct cytotoxic effects since the above concentrations of troxipide did not induce neutrophil apoptosis. The concentrations of troxipide detected in the gastric mucosa after oral administration were in the range able to inhibit chemotactic migration and superoxide generation by neutrophils in vitro. CONCLUSION: These results suggest that troxipide may exert its therapeutic effect in patients with gastric ulcer or gastritis by inhibiting inflammatory responses and mucosal injury mediated by neutrophils in gastric mucosa.

A new antimicrobial quinolone (AM-1155) analysed in hair as an index of drug exposure and as a time-marker.

Scalp hair samples were obtained at one-month intervals for up to four months after the administration from each of twelve healthy male volunteers participating in a phase I study of a new antimicrobial quinolone, AM-1155, (+/-)-1-cyclopropyl-6-fluoro-1, 4-dihydro-8-methoxy-7-(cis-3,5-dimethyl-1-piperazinyl)-4-oxo-3-quinoline carboxylic acid. After hair was sectioned into 1 cm lengths from the scalp end, corresponding portions from five pieces of hair were dissolved in 1 M NaOH and assessed for AM-1155 by HPLC. In all subjects who had taken a single dose (600 mg, n = 6) or repeated doses (300 mg twice daily for 6.5 days, n = 6), the drug was detected in hair. The hair portions containing the drug were shown in most subjects to move outwards month by month at the rate of about 1 cm month-1. A single hair, which was obtained from each subject of the repeated-dose study 3 months after the completion of administration, was cut into 2.5-mm lengths from the scalp side and analysed for AM-1155. The drug was shown to be contained in 4 to 6 consecutive 2.5-mm lengths, showing that there was no large axial diffusion of the drug along the hair shaft even after 3 months. These findings indicate the utility of measuring this quinolone derivative in hair as an index of drug exposure and, furthermore, as a time marker for analysing other drugs in hair.

[Human and animal studies on the pharmacokinetics of norfloxacin in renal failure].

The pharmacokinetics of norfloxacin (NFLX) was studied in 5 patients with chronic renal failure and rats with renal obstruction. The drug was orally given to patients on on- and off-dialysis days in a crossover fashion. Serum levels of NFLX showed a similar profile during both on- and off-dialysis days, and the hemodialysis treatment did not affect the elimination of the drug from the serum. The mean serum elimination half-life was 8.8 +/- 1.2 hours (standard error) for on- dialysis day and it was 7.0 +/- 0.8 hours for off-dialysis day. The urinary recovery of NFLX for 24 hours was less than 0.1% of administered doses in these patients. Rats with renal obstruction exhibited higher drug levels in serum for longer periods of time and elevated biliary excretion ratios in comparison to sham-operated rats, and no significant change in the fraction of biliary metabolites was observed. The biliary excretion of NFLX was likely to be enhanced in patients with renal failure.

High-performance liquid chromatographic determination of 6,8-difluoro-1-(2-fluoroethyl)-1,4- dihydro-7-(4-methyl-1-piperazinyl)-4-oxo-3-quinolinecarboxylic acid and its metabolites in laboratory animals.

A simple, sensitive and specific high-performance liquid chromatographic method for a new quinolone antimicrobial agent, 6,8-difluoro-1-(2-fluoroethyl)-1,4- dihydro-7-(4-methyl-1-piperazinyl)-4-oxo-3-quinolinecarboxylic acid (AM-833, I), and its metabolites in serum and urine has been developed for their simultaneous determination. This method is based on ion-pair extraction and separation by ion-pair reversed-phase chromatography with ultraviolet or fluorescence detection. The major metabolites in the serum and urine of mice, rats, dogs and monkeys were N-desmethyl I (compound II) and I N-oxide (compound III). Rabbit serum and urine contained N-desmethyl-3-oxo I (compound IV), 3-oxo I (compound V) and N-desmethyl-4-formyl I (compound VI) in addition to compounds I, II and III. Unchanged drug accounted for 80-90% of total serum concentrations in mice and more than 90% in rats, dogs and monkeys up to 6 h after dosing, whereas the fraction of compound I in rabbits was 34-67%. Unchanged drug was the most predominant in the urine of mice, rats, dogs and monkeys, whereas compound II was the most abundant in rabbit urine. Although rabbits and monkeys excreted 70-80% of dose in three-day urine, the total urinary excretion of mice, rats and dogs was relatively low, 40-50% of oral dose. The fraction of compound I in total urinary excretion was 63, 73, 27, 55 and 78% in mice, rats, rabbits, dogs and monkeys, respectively. These results suggest that there is a species difference in the metabolism and excretion pathway of compound I.

Uptake and intracellular activity of fleroxacin in phagocytic cells.

The uptake and intracellular activity of fleroxacin in murine J774.1 macrophages and human polymorphonuclear leukocytes were studied. The uptake of fleroxacin by J774.1 macrophages was rapid and reversible. The cellular to extracellular concentration ratios of fleroxacin in both types of phagocytes ranged from 5 to 6. These ratios were almost equal to those of ofloxacin and ciprofloxacin, and higher than those of the beta-lactam antibiotics, flomoxef and piperacillin. The intracellular activity of fleroxacin in J774.1 macrophages, examined with Staphylococcus aurenus as a test bacterium, showed that its bactericidal action was dependent on both the extracellular concentration and the exposure time. Fleroxacin reduced the number of viable cells of ingested S. aureus at an extracellular concentration that simulated the clinical serum levels, that is, killing more than 70% of the bacteria at 4 micrograms/ml. The bactericidal activity of fleroxacin in phagocytes was superior to that of erythromycin, flomoxef and piperacillin. These results indicate that fleroxacin is taken up well by phagocytes, reaching a concentration several fold higher than the extracellular concentration, and that it has potent activity against intracellular pathogens.

Pharmacokinetics of a new quinolone, AM-833, in mice, rats, rabbits, dogs, and monkeys.

The pharmacokinetics of AM-833 [6,8-difluoro-1-(2-fluoroethyl)-1, 4-dihydro-7-(4-methyl-1-piperazinyl)-4-oxo-3-quinolinecarboxylic acid] were studied in mice, rats, rabbits, dogs, and monkeys by reversed-phase high-performance liquid chromatography. AM-833 was rapidly and completely absorbed from the digestive tracts of mice, rats, and dogs. About half of AM-833 bound to rat and dog serum proteins. Drug levels in lung, spleen, liver, and kidney tissues of rats and dogs were greater than the respective levels in serum but lower in brain tissue. Drug levels in tissues declined with the decrease in levels in serum. AM-833 penetrated rapidly and well into inflammatory exudate of rats. Elimination half-lives in serum were species dependent, ranging from 1.57 h in rabbits to 9.42 h in dogs. Profiles of drug levels in serum were dose related over a single dose range from 2 to 40 mg/kg and not modified significantly during multiple dosing in dogs. Unchanged AM-833 was excreted in urine and bile in both rats and dogs. The metabolism of AM-833 was suggested by evidence that 24-h total recovery of unchanged AM-833 in urine and bile accounted for about half of the intravenous dose in rats.

Uptake and intracellular activity of AM-1155 in phagocytic cells.

The uptake and intracellular activity of AM-1155 in murine J774.1 macrophages and human polymorphonuclear leukocytes were investigated. AM-1155 penetrated phagocytic cells rapidly and reversibly, although the penetration process was not affected by metabolic inhibitors such as sodium fluoride, cyanide m-chlorophenylhydrazone, or ouabain or by nucleoside transport system inhibitors such as adenosine. The intracellular concentration-to-extracellular concentration ratio of AM-1155 in both cell types of phagocytes ranged from 5 to 7. These ratios were almost equal to those for sparfloxacin. The intracellular activity of AM-1155 in J774.1 macrophages, examined with Staphylococcus aureus 209P as a test bacterium, was dependent on the extracellular concentration. AM-1155 at a concentration of 1 microgram/ml reduced the number of viable cells of S. aureus ingested by more than 90%. The intracellular activity of AM-1155 was more potent than those of sparfloxacin, ofloxacin, ciprofloxacin, flomoxef, and erythromycin. These results suggest that the potent intracellular activity of AM-1155 might mainly be due to the high intracellular concentration and its potent in vitro activity.

Toxicokinetic study of norfloxacin-induced arthropathy in juvenile animals.

A toxicokinetic study of norfloxacin-induced arthropathy in juvenile animals was undertaken using nalidixic acid as a standard drug. Norfloxacin and nalidixic acid were subcutaneously administered to rats and rabbits, orally administered to dogs, and norfloxacin was orally dosed to monkeys once a day for 7 consecutive days. Of the dose levels tested, the minimum arthropathic doses of norfloxacin were 100, 25, and 50 mg/kg/day in rats, rabbits, and dogs, respectively. At these doses, the peak serum concentrations (Cmax) on Day 6 were 16.1, 9.73, and 5.11 micrograms/ml, and the areas under the serum concentration/time curve (AUC0----infinity) were 31.9, 22.9, and 26.2 micrograms.hr/ml, in respective animals. Monkeys showed no arthropathy with norfloxacin at doses of less than 500 mg/kg/day, at which the Cmax and AUC0----infinity were 15.6 micrograms/ml and 103 micrograms.hr/ml, respectively. The minimum arthropathic doses of nalidixic acid were 50, 100, and 25 mg/kg/day in rats, rabbits, and dogs, respectively. The Cmax and AUC0----infinity of nalidixic acid were higher than those of norfloxacin in all animals. Joint tissues took up more norfloxacin than nalidixic acid, but when arthropathy was present the articular cartilage concentrations of the two drugs were in the same range. The penetration of norfloxacin into the articular cartilage was the same regardless of the joint's anatomical locations, but differed among species, being highest in rats and lowest in monkeys. The Cmax and AUC0----infinity of norfloxacin in animals at their arthropathic doses were far higher than those measured clinically in children, whereas those of nalidixic acid in animals did not differ much from its clinical parameters.

Mechanism of renal excretion of AM-715, a new quinolonecarboxylic acid derivative, in rabbits, dogs, and humans.

The mechanisms of the renal excretion of AM-715, a synthetic antimicrobial agent, were studied in rabbits, dogs, and humans. In both rabbits and humans, AM-715 clearance was greater than creatinine clearance and was profoundly decreased by the administration of probenecid. Thus, in these subjects, AM 715 was cleared by both tubular secretion and glomerular filtration. In dogs, however, the excretion ratio (close to unity), biological half-life, and stop-flow pattern of AM-715 were not affected by probenecid, indicating that the renal excretion of AM-715 took place mostly through glomerular filtration. These results suggest that renal excretion of AM-715 differs with animal species.

[Effects of calcitriol and alfacalcidol on an osteoporosis model in rats with hepatic failure].

To predict the potential utility of calcitriol in human osteoporosis with hepatic dysfunction, we examined the effects of calcitriol and alfacalcidol in ovariectomized (OVX) aged-rats with CCl4-induced hepatic failure. In OVX+CCl4 rats, GOT, GTP, alkaline phosphatase and total bilirubin increased and hepatic enzyme activity (cytochrome b5 and P450) decreased. Repeated oral doses of calcitriol (0.1 and 0.2 microgram/kg) for 51 days inhibited a decrease in serum calcium concentration. This effect was more potent than that of alfacalcidol at the same dose. Both drugs tended to inhibit a decrease in femoral calcium contents. Calcitriol (0.2 microgram/kg) prevented a decrease in femoral bone density (dry and ash weight per volume), unlike alfacalcidol. Soft X-ray imaging analysis revealed that both drugs tended to inhibit the decrease in femoral bone density. There were no differences in the femoral bone strength between OVX+CCl4 and sham-operated rats. The serum calcitriol concentrations increased after the last doses of calcitriol, while they did not increase after the last dose of alfacalcidol. All these effects of calcitriol were related to the serum calcitriol levels. These results suggest that calcitriol, unlike alfacalcidol, may have a clinical therapeutic effect in osteoporosis with hepatic dysfunction.

Single- and multiple-dose pharmacokinetics of AM-1155, a new 6-fluoro-8-methoxy quinolone, in humans.

The pharmacokinetics of AM-1155, a new 6-fluoro-8-methoxy quinolone, was examined in healthy male volunteers after the oral administration of a single dose of 100, 200, 400, or 600 mg and multiple doses of 300 mg twice daily for 6.5 days (13 total doses). Throughout the whole study period, AM-1155 was well tolerated in every subject. In the single-dose study, the concentrations in serum reached a peak between 1 and 2 h, and the peak concentrations were 0.873, 1.71, 3.35, and 5.41 micrograms/ml at the doses of 100, 200, 400, and 600 mg, respectively. The elimination half-life was 7 to 8 h, independently of the doses. The unchanged drug was excreted mainly in the urine, with 82 to 88% of the doses appearing for 72 h. The fecal recovery of the unchanged drug amounted to 5.7% for 72 h after a single oral administration of a 400-mg dose. Urinary excretion of metabolites was minimal. The serum protein binding was 20%, independently of the concentrations in serum. The concentrations in saliva were approximately 80% of those in serum. The intake of food had no effect on the pharmacokinetic parameters and urinary excretion of AM-1155 except the slight decrease in area under the concentration-time curve. The concurrent administration of probenecid prolonged the elimination half-life, increased the area under the concentration-time curve, and decreased the apparent total body clearance, renal clearance, urinary recovery of unchanged drug, and the excretion ratio (intrinsic renal clearance of AM-1155/creatinine clearance). This indicated that the tubular secretion contributed to the renal excretion of AM-1155. In the multiple-dose study, the concentrations of AM-1155 in serum and urine reached a steady state within 2 to 3 days. The measured concentrations in serum fitted well the simulation curve, which reflected the persistence of linear pharmacokinetics of AM-1155. In conclusion, AM-1155 is expected to be clinically useful because of its potent antibacterial activity and favorable pharmacokinetics.

Renal handling of fleroxacin in rabbits, dogs, and humans.

The renal handling of fleroxacin was studied by renal clearance and stop-flow techniques in rabbits and dogs and by analyzing the pharmacokinetics with and without probenecid in humans. In rabbits the excretion ratios (fleroxacin intrinsic renal clearance/glomerular filtration rate) were greater than unity (2.01) without probenecid and were decreased to a value below unity (0.680) with probenecid. In dogs, on the other hand, the excretion ratios were less than unity (0.608 and 0.456) both without and with probenecid, and so were not affected by probenecid. This fact suggested that fleroxacin was excreted into urine by both glomerular filtration and renal tubular secretion in rabbits, but only by glomerular filtration in dogs, accompanied by partial renal tubular reabsorption in both species; these mechanisms were also supported by stop-flow experiments. In humans probenecid treatment induced increases in the elimination half-life and area under the serum concentration-time curve and decreases in apparent serum clearance, renal clearance, and urinary recovery of fleroxacin. The excretion ratio without probenecid was 1.13, which was significantly decreased to 0.750 with probenecid. These results indicated that both renal tubular secretion and reabsorption contributed to renal excretion of fleroxacin in humans. The contribution of tubular secretion was species dependent and was extensive in rabbits, minimal in dogs, and moderate in humans. Renal tubular reabsorption was commonly found in every species. The long elimination half-life of fleroxacin in humans might be explained by its small total serum clearance and small renal clearance, which are attributed to less tubular secretion and more tubular reabsorption.