Concentrations in plasma, urinary excretion and bactericidal activity of levofloxacin (500 mg) versus ciprofloxacin (500 mg) in healthy volunteers receiving a single oral dose

In a randomised crossover study, 14 volunteers received a single oral dose of 500 mg levofloxacin or 500 mg ciprofloxacin in order to assess plasma concentrations by high-pressure liquid chromatography (up to 24 h), urinary excretion and urinary bactericidal titres (UBTs) at intervals up to 120 h. The median maximum concentration of levofloxacin in plasma was 6.1 mg/L and that of ciprofloxacin was 2.3 mg/L. The median cumulative level of renal excretion of the administered dose of the parent drug was 81.2% for levofloxacin and 36.2% for ciprofloxacin. UBTs were determined for a reference strain and nine clinical uropathogens. The median UBTs of both quinolones measured within the first 12 h were between 0 and 1:≥1024, correlating with the minimum inhibitory concentrations (MICs) of the strains. For Gram-negative strains, the UBTs of both quinolones were comparable despite the lower MICs of ciprofloxacin. During further time courses, however, the UBTs of levofloxacin were significantly higher than those of ciprofloxacin. For Gram-positive strains, for which the MICs of levofloxacin were equal to or lower than those of ciprofloxacin, the UBTs of levofloxacin were already significantly higher from the beginning. It can be concluded that overall the doses of the two tested fluoroquinolones may be considered equivalent with regard to treatment of complicated urinary tract infections, although the recommended dosing is twice daily for ciprofloxacin and once daily for levofloxacin.     

Pharmacokinetics of ciprofloxacin XR (1000 mg) versus levofloxacin (500 mg) in plasma and urine of male and female healthy volunteers receiving a single oral dose

The new extended-release formulation of ciprofloxacin (ciprofloxacin XR) was designed for once-daily administration in the treatment of urinary tract infection (UTI). The aim of this study was to compare concentrations in plasma, urinary excretion (UE) and pharmacokinetic parameters of ciprofloxacin XR (1000 mg) versus those of levofloxacin (500 mg) in healthy volunteers receiving a single oral dose. In this randomised crossover study, 12 volunteers (6 males, 6 females) received a single oral dose of 1000 mg ciprofloxacin XR or 500 mg levofloxacin to assess the concentrations (by high-pressure liquid chromatography) in plasma up to 32 h and the UE at intervals up to 36 h. The following pharmacokinetic parameters were studied: C(max), t(max), t(1/2), AUC(plasma0-->infinity), AUC(plasma0-->last), Cl(ren), maximal urinary concentration (U(max)), AUC(urine0-->last) and UE. Both fluoroquinolones were well tolerated. The plasma concentrations of levofloxacin were significantly higher than those of ciprofloxacin XR throughout the study period. The urinary concentrations of ciprofloxacin XR were significantly higher than those of levofloxacin in the first collection interval (0-4 h), whereas the concentrations of levofloxacin were significantly higher than those of ciprofloxacin XR in the five last collection intervals (12-36 h). The median proportions of cumulative renal excretion of the administered dose of the parent drug up to 36 h were 43.1% for ciprofloxacin XR (range, 13.7-50.8%; mean +/- standard deviation (S.D.), 40.5 +/- 9.9%) and 79.8% for levofloxacin (range, 74.0-88.2%; mean +/- S.D., 80.4 +/- 5.5%). C(max), AUC(plasma0-->infinity), AUC(plasma0-->last) and UE were statistically significantly higher in the levofloxacin than in the ciprofloxacin XR phase; t(max), Cl(ren) and U(max) were statistically significantly higher in the ciprofloxacin XR phase than in the levofloxacin phase; and AUC(urine0-->last) and t(1/2) were not statistically different. After an oral administration of ciprofloxacin XR 1000 mg and levofloxacin 500 mg, C(max) and AUC(plasma0-->infinity) were significantly higher in the levofloxacin phase. UE of ciprofloxacin XR 1000 mg once daily, however, was equivalent to that of levofloxacin 500 mg, and overall comparable urinary concentrations and AUC(urine) were reached by both drugs. Therefore, it can be assumed that the two doses investigated can be considered equivalent for the treatment of UTI.     

甲磺酸加替沙星片健康人单剂口服药代动力学

目的研究健康人口服单剂甲磺酸加替沙星片后药代动力学特征,为该药II期临床试验提供依据。方法采用3剂量3周期拉丁方实验设计。9名健康受试者单剂口服甲磺酸加替沙星片100、200、300mg,HPLC法测其血清、尿药物浓度。结果受试者口服甲磺酸加替沙星片后,人体耐受良好,体内过程符合二室开放模型。主要药代动力学参数与给药剂量呈线性关系,tmax为0.5～0.7h,Cmax分别为1.42、2.42、3.25μg/ml,AUC0-∞分别为11.33、21.85、32.32μg·h/ml,V/Fc值为50～80L,t1/2β为8～9h,72h尿药累积回收率约为63.5%。结论甲磺酸加替沙星片口服吸收良好,血峰浓度高,组织分布广,消除半衰期长。200mg每日一次口服用于治疗敏感菌感染。     

Urinary concentrations and antimicrobial activity of tobramycin in healthy volunteers receiving a single oral dose of a novel formulation for improved absorption

Oral antibiotics for the treatment of urinary tract infections are scarce. In this ex vivo phase 1 annex study, the clinical safety, urinary concentrations and bactericidal activity of a new formulation for improved oral absorption of tobramycin (Tobrate?) were evaluated. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of five test strains, one reference strain and four clinical uropathogenic strains were determined in cation-adjusted Mueller–Hinton broth (CA-MHB) and in pooled antimicrobial agent-free subjects' urine at different pH values (5.5, 6.5, 7.5 and 8.5). Urinary concentrations and urinary bactericidal titres (UBTs) following single oral administration of 600?mg Tobrate? were measured in nine healthy volunteers up to 24?h. The MIC/MBC values in CA-MHB were 2–4/2–4?mg/L for two Escherichia coli strains, 2/2?mg/L for Klebsiella pneumoniae, 0.5/1?mg/L for Pseudomonas aeruginosa and 8/1?mg/L for Proteus mirabilis. MBCs in pooled alkaline urine were significantly lower than those in acidic urine. The mean maximum urinary concentration following 600?mg tobramycin was 83.9?mg/L (2–4?h collection period). The highest reciprocal median UBT values for each test strain were between 2 and 4 during the collection periods 2–4?h and 4–8?h, respectively. The new enteric oral tobramycin formulation significantly improved the very poor oral absorption of standard tobramycin salt. For all pathogens tested, maximum urinary concentrations of tobramycin were at least two times above the urinary MBC. A twice- or three-times daily dosage regimen and alkalising co-medication may further improve urinary bactericidal activity.     

Urinary concentrations and bactericidal activities of newer fluoroquinolones in healthy volunteers

Eleven healthy male subjects participated in a crossover study to compare the urine concentrations and bactericidal activities of newer fluoroquinolones against common uropathogens. Each volunteer received a single oral dose of gatifloxacin (400 mg), levofloxacin (250 mg), moxifloxacin (400 mg) and trovafloxacin (200 mg), and a urine sample was obtained at 2, 6, 12 and 24 h after the dose. Urine concentrations were highest with gatifloxacin and levofloxacin and lowest with trovafloxacin. Each drug concentration was studied against a levofloxacin susceptible and moderately-susceptible strain of Escherichia coli (minimal inhibitory concentration, MICs: 0.125 and 4 mg/l), K. pneumoniae (MICs: 0.125 and 4 mg/l), Pseudomonas aeruginosa (MICs: 0.5 and 4 mg/l) and Enterococcus faecalis (MICs: 0.25 and 4 mg/l). The duration of urine bactericidal activity (UBA) was based upon the median bactericidal titre at each time period. Both gatifloxacin and levofloxacin exhibited prolonged (> or = 6 h) UBA against all of the study isolates. Moxifloxacin exhibited prolonged UBA against both isolates of E. coli, K. pneumoniae and E. faecalis but not against either strain of P. aeruginosa. Prolonged UBA was not observed for trovafloxacin against the moderately-susceptible strains with the exception of E. faecalis. Furthermore, UBA was not observed for trovafloxacin against the susceptible strain of P. aeruginosa. Although these newer fluoroquinolones exhibited similar in vitro activity against these uropathogens, only those compounds with the highest urinary concentrations (gatifloxacin and levofloxacin) produced prolonged UBA against both strains of P. aeruginosa. The findings from this study suggest that both microbiological activity and urinary concentrations are important parameters to consider when choosing a fluoroquinolone for empirical treatment of urinary tract infections (UTIs).     

Influence of diminished susceptibility of Streptococcus pneumoniae to ciprofloxacin on the serum bactericidal activity of gemifloxacin and trovafloxacin after a single dose in healthy volunteers

The serum bactericidal activity against 2 Streptococcus pneumoniae strains (ciprofloxacin MIC 1 and 4 mg/l) was measured in 12 volunteers who received oral single doses of gemifloxacin 320 mg and trovafloxacin 200 mg in a crossover fashion. The 4-fold increase in ciprofloxacin MIC from the susceptible to the resistant strain resulted in a 2-fold increase in MIC (from 0.015 to 0.03 mg/l), a 2-fold decrease in C(max)/MIC (104 vs 52) and in AUC(0-24 h)/MIC (532 vs 266), but a 5.6-fold decrease in area under the bactericidal curve (AUBC: 168 vs 30) for gemifloxacin. Trovafloxacin showed a 4-fold higher MIC (0.25 vs 0.06 mg/l), a 4-fold lower C(max)/MIC (8.6 vs 36), a 4-fold lower AUC(0-24 h)/MIC (85 vs 356) and a 11-fold lower AUBCs (2 vs 22) against the resistant isolate compared with the susceptible one. Trovafloxacin serum bactericidal titres against the ciprofloxacin-resistant strain were measurable generally only at 1 h after dosing (median titre=2). Gemifloxacin showed similar ex vivo bactericidal activity against the ciprofloxacin-resistant strain to that of trovafloxacin against the ciprofloxacin-susceptible strain.     

Concentrations of ceftibuten in plasma and the respiratory tract following a single 400 mg oral dose

Concentrations of ceftibuten in bronchial mucosa, epithelial lining fluid (ELF) and alveolar macrophages were determined from samples taken from 15 subjects at bronchoscopy following a single 400 mg oral dose. Concentrations at all sites were determined using a microbiological assay method which was unaffected by the trans-isomer of ceftibuten. The time from dosage to bronchoscopy ranged from 1.4 to 20.3 h and the subjects were analysed in three groups according to time after dosing. Group A had a mean time since dosing of 1.9 h with mean serum, mucosal and ELF concentrations of 15.2 mg/l, 5.7 mg/kg and 1.6 mg/l. Group B had a mean time of 6.5 h after dosing with mean serum, mucosal and ELF concentration of 14.0 mg/l, 3.2 mg/kg and 1.6 mg/l. Group C had a mean time of 13.3 h with mean serum, mucosal and ELF levels of 4.1 mg/l, 1.8 mg/kg and 1.2 mg/l. Macrophage-related ceftibuten could only be detected in two subjects. These levels are related to the minimum inhibitory concentrations of ceftibuten against common respiratory pathogens with the exception of Strep. pneumoniae.     

Rectal tissue,plasma and urine concentrations of mesalazine after single and multiple administrations of 500 mg suppositories to healthy volunteers and ulcerative proctitis patients

OBJECTIVE: Patients with ulcerative proctitis may have rectal mucosal properties different from healthy volunteers. This project compared the pharmacokinetics of rectally administered mesalazine in these two populations. METHODS: In two separate studies, nine patients with ulcerative proctitis and 16 healthy volunteers received a single 500 mg mesalazine suppository and then 500 mg every 8 h for 5 days. Blood samples were collected for 12 h in healthy volunteers and 30 h in patients, and urine for 24 h in healthy volunteers and 30 h in patients. Rectal biopsies were performed 8 h after the last dose. RESULTS: After a single dose to patients, mean mesalazine half-life (s.d.) was 5.0 (3.6) h. At steady-state, means (s.d.) were 89.1 (78.9) ng/mL for C(min), 361.1 (240.8) ng/mL for C(max), and 7.1 (7.3) h for half-life. Mean (range) rectal mesalazine concentrations were 167 (1.4-541.6) ng/mg tissue. After a single dose in healthy volunteers, mean (s.d.) half-life was 4.0 (4.7) h. At steady-state, means (s.d.) were 22.4 (61.6) ng/mL for C(min), 359.4 (166.3) ng/mL for C(max), and 0.9 (0.5) h for half-life. CONCLUSION: Mesalazine is released in the rectum of patients, with a bioavailability of about 40%. Tissue distribution is also appreciable. Both parameters appear higher than in healthy volunteers.     

Serum levels and urinary excretion of mequitazine after a single oral dose

Pharmacokinetics of mequitazine, a recently introduced peripheral H1-histamine receptor antagonist of phenothiazine type, was followed up to 72 h after the single oral dose of 5 mg of the drug to eight fasted healthy volunteers. Each subject was treated thrice with a dosing interval of 15 days or more. Thus all the results were triplicated. Serum mequitazine was measured by mass fragmentography using a gas-liquid chromatograph/mass spectrometer set in the electron impact mode. Urine phenothiazines were determined fluorometrically before and after cleaving phenothiazines from their glucuronide conjugates. Peak concentration of mequitazine in serum was 3.19 +/- 1.70 (s.d.) ng.ml-1, time to peak concentration 5.67 +/- 1.68 h, elimination half-life 45 +/- 26 h, and elimination rate constant 0.018 +/- 0.007 h-1. Only 10.9 +/- 3.3% of the dose appeared in urine in unconjugated plus the glucuronidated form during the first 72 h. About 46% of the urinary phenothiazines were glucuronide conjugates. The results suggested that after the oral administration only low mequitazine concentrations appeared in serum, most of the drug seemed to be deactivated by the extrarenal route, and the kinetic properties of the drug resembled those of several phenothiazines used for psychiatric therapy.     

Artemisinin pharmacokinetics in healthy adults after 250, 500 and 1000 mg single oral doses

Eight healthy male, Vietnamese subjects were administered 1×250, 2×250 and 4×250 mg artemisinin capsules in a cross-over design with randomized sequence with a 7-day washout period between administrations. The inter-individual variability in artemisinin pharmacokinetics was large with parameter coefficients of variation (CV) typically between 50–70%. The parameter with the smallest variability was the elimination half-life (CV≈30–40%). Analysis of variance indicated also a large intra-subject variability (CV≤24%) for the dose-normalized area under the plasma concentration–time curve (AUC/dose). The pharmacokinetic results suggested artemisinin to be subject to high pre-systemic extraction. Artemisinin half-life could not predict the extent ofin vivo exposure to the drug, there being no correlation between half-life and oral clearance. Artemisinin oral plasma clearance was about 400 L h⁻¹ exhibiting a slight decrease with dose, although the effect was weak. Thus results from studies using different artemisinin doses may, within the studied dose range, be compared without the complication of disproportionate changes in drug exposure with varying dose levels. Half-lives appeared to increase with dose. An observed period effect in the analysis of variance was tentatively associated with time-dependency in artemisinin pharmacokinetics. There was a high correlation between artemisinin plasma concentrations determined at various time-points after drug administration and the AUCs after the 500 and 1000 mg doses, but less so after the 250 mg dose. This may show a tentative approach to assess the systemic exposure of the patients to artemisinin from the determination of artemisinin plasma concentrations in one or two plasma samples only. Artemisinin was well tolerated with no apparent dose or time dependent effects on blood pressure, heart rate or body temperature. © 1998 John Wiley & Sons, Ltd.     

单次口服莫达芬尼片在中国健康志愿者的药代动力学

目的研究单次口服莫达芬尼片的药代动力学。方法选择9名健康成年男性受试者分别单次口服100,200,300mg 3个剂量的莫达芬尼片后,用HPLC法测定血中原形药莫达芬尼及代谢产物莫达芬尼酸浓度,用3P97软件进行数据处理,计算药代动力学参数。结果原形药莫达芬尼的药-时曲线符合二房室模型,其主要药代动力学参数的Cmax、AUC0-∞、AUC0-t随剂量加大而增加;t1/2b、tmax、b、CL与给药剂量无关。莫达芬尼片原形药经肾排泄较少,48h经肾累积排泄率分别为(4.44±4.28)%,(3.35±2.20)%和(2.86±1.39)%。主要代谢产物莫达芬尼酸药-时曲线符合二房室模型,48h莫达芬尼酸经肾累积排泄率分别为(33.51±18.90)%,(32.36±19.92)%和(22.88±6.89)%。结论莫达芬尼在100～300mg内,呈线性动力学特征而无饱和性,其消除过程是经肝脏代谢,代谢产物为莫达芬尼酸,代谢产物主要经肾排泄。     

单次口服阿奇霉素片在中国健康志愿者的药代动力学

目的研究阿奇霉素(大环内酯类抗生素)在中国健康人体的药代动力学。方法 10名健康志愿者单剂量口服阿奇霉素500 mg后,高效液相色谱-紫外检测法测定血清药物浓度;用AIC法结合F检验判别房室模型, DAS程序计算药代动力学参数。结果主要的药代动力学参数:Ka为(0．87 ±0．27)h-1,t1／2β为(39．66±10．85)h,tmax为(2．60±0．52)h,Cmax为(451．19 ±67．72)μg·L-1,CL／F为(0．56±0．13)L·(h·kg)-1,AUC0-144和 AUC0-∞分别为(13．68±2．92)mg·h·L-1和(13．71±2．91)mg·h·L-1。结论最佳房室模型为二室模型。     

Urinary bactericidal activity of single doses (250, 500, 750 and 1000 mg) of levofloxacin against fluoroquinolone-resistant strains of Escherichia coli

Increasing resistance to fluoroquinolones in uropathogens has become a clinical concern. The purpose of this study was to analyse the urinary bactericidal activity (UBA) of levofloxacin against fluoroquinolone-resistant strains of Escherichia coli. Ten healthy adult subjects (aged 23-60 years) received single doses of levofloxacin (250, 500, 750 and 1000mg) and then blood and urine samples were collected in intervals (0-1.5, 1.5-4, 4-8, 8-12 and 12-24h) over 24h. Both serum and urine concentrations were measured by a validated high-performance liquid chromatography assay. Bactericidal titres in urine were determined against E. coli isolates with minimum inhibitory concentrations of 0.125, 4, 8, 16, 32 and 64mug/mL for levofloxacin. The mean serum pharmacokinetic parameters for these doses of levofloxacin were similar to previously published values. The mean peak urinary concentrations (0-1.5h) were 210, 347, 620 and 536mug/mL for the 250, 500, 750 and 1000mg dose, respectively. Each dose of levofloxacin exhibited early (0-1.5h time period) bactericidal activity in urine in virtually all subjects against E. coli strains with MICs相似文献   

Pimecrolimus: absorption, distribution, metabolism, and excretion in healthy volunteers after a single oral dose and supplementary investigations in vitro.

The absorption and disposition of pimecrolimus, a calcineurin inhibitor developed for the treatment of inflammatory skin diseases, was investigated in four healthy volunteers after a single oral dose of 15 mg of [(3)H]pimecrolimus. Supplementary information was obtained from in vitro experiments. Pimecrolimus was rapidly absorbed. After t(max) (1-3 h), its blood concentrations fell quickly to 3% of C(max) at 24 h, followed by a slow terminal elimination phase (average t(1/2) 62 h). Radioactivity in blood decreased more slowly (8% of C(max) at 24 h). The tissue and blood cell distribution of pimecrolimus was high. The metabolism of pimecrolimus in vivo, which could be well reproduced in vitro (human liver microsomes), was highly complex and involved multiple oxidative O-demethylations and hydroxylations. In blood, pimecrolimus was the major radiolabeled component up to 24 h (49% of radioactivity area under the concentration-time curve(0-24) h), accompanied by a large number of minor metabolites. The average fecal excretion of radioactivity between 0 and 240 h amounted to 78% of dose and represented predominantly a complex mixture of metabolites. In urine, 0 to 240 h, only about 2.5% of the dose and no parent drug was excreted. Hence, pimecrolimus was eliminated almost exclusively by oxidative metabolism. The biotransformation of pimecrolimus was largely catalyzed by CYP3A4/5. Metabolite pools generated in vitro showed low activity in a calcineurin-dependent T-cell activation assay. Hence, metabolites do not seem to contribute significantly to the pharmacological activity of pimecrolimus.     

Plasma pharmacokinetics and urinary excretion of thalidomide after oral dosing in healthy male volunteers

The plasma pharmacokinetics and urinary excretion of thalidomide have been evaluated in eight healthy male volunteers receiving a single oral dose of 200 mg. Concentrations of thalidomide were determined by a new HPLC assay. Plasma concentration vs. time data were well fit by a one-compartment model. The mean (+/- SD) peak concentration, 1.15 +/- 0.2 microgram/ml, was achieved at 4.39 +/- 1.27 hr. Absorption and elimination half-lives were 1.70 +/- 1.05 hr and 8.70 +/- 4.11 hr, respectively, with a lag time of 0.41 +/- 0.17 hr observed in six subjects. The apparent volume of distribution and total body clearance rate, based on assumed complete bioavailability, were 120.69 +/- 45.36 liters and 10.41 +/- 2.04 liters/hr. The urinary excretion of thalidomide accounted for only 0.6 +/- 0.22% of the total dose administered over 24 hr, and the renal clearance rate was 0.08 +/- 0.03 liter/hr. This suggests that the major route of elimination of thalidomide is nonrenal.     

Concentrations of moxifloxacin in plasma and urine, and penetration into prostatic fluid and ejaculate, following single oral administration of 400 mg to healthy volunteers

The spectrum of chronic bacterial prostatitis (CBP) comprises Gram-negative, Gram-positive and atypical pathogens. Because of its broad spectrum of activity, moxifloxacin might be a suitable antibiotic for the treatment of CBP. In this pharmacokinetic study, plasma concentrations and the penetration of moxifloxacin into prostatic fluid and ejaculate were investigated. Twelve healthy male volunteers received a single oral dose of 400mg moxifloxacin and at the same time received 3.24 g of iohexol intravenously to assess urinary contamination of prostatic fluid and ejaculate. Plasma concentrations were determined at 0, 0.5, 1, 2, 3 and 4h and prostatic fluid and ejaculate (mean+/-standard deviation (S.D.)) were determined at 3.5+/-0.4h and 3.6+/-0.4h, respectively, following administration of drugs. Urinary concentrations were determined in the urine collected from 0-4.5h. Concentrations of moxifloxacin and iohexol in plasma, secretions and urine were determined by high-performance liquid chromatography. The mean+/-S.D. peak plasma concentration of moxifloxacin was 2.8+/-0.5 mg/L observed after 1.6+/-0.9h. In prostatic fluid, the concentration of moxifloxacin was 3.8+/-1.2 mg/L and the prostatic fluid/plasma ratio was 1.6+/-0.5. In ejaculate, the concentration was 2.5+/-0.7 mg/L and the ejaculate/plasma ratio was 1.0+/-0.2. Moxifloxacin concentrations in prostatic fluid were ca. 60% (P<0.05) higher than in plasma and concentrations in ejaculate were approximately the same as in plasma. Therefore, moxifloxacin might be a good alternative for the treatment of CBP, but further studies are warranted to establish this indication.