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Biomedical subjects

R Wise

Publications and source records attributed to R Wise.

At least 343 records · Page 19Linked to original sources
PubMed1986

The comparative pharmacokinetics and tissue penetration of four quinolones including intravenously administered enoxacin.

The pharmacokinetics and tissue penetration of four quinolones were studied. The compounds were norfloxacin (400 mg p.o.), enoxacin (600 mg p.o. and 400 mg i.v.), ciprofloxacin (100 mg i.v. and 500 mg p.o.) and ofloxacin (600 mg p.o.) given to healthy volunteers. Of the oral agents studied ofloxacin and ciprofloxacin were the most rapidly absorbed (Tmax 1.2 h) and enoxacin the least (Tmax 1.9 h). The serum levels attained were highest in the case of ofloxacin (after allowing for the higher dose administered). The serum half-lives were norfloxacin 3.75 h, ciprofloxacin 3.9 h (p.o.), 4.0 h (i.v.), ofloxacin 7.0 h and enoxacin 6.2 h (p.o.) and 5.1 h (i.v.). All agents penetrated the blister fluid readily. The 24 h urine recovery (as measured by a microbiological assay) was 62% for enoxacin (p.o.), 46.4% following i.v. enoxacin (plus 11.6% oxo-enoxacin, measured by HPLC) 27% for norfloxacin, 30.6% for oral ciprofloxacin, 75.7% for i.v. ciprofloxacin and 73% for ofloxacin.

Adult↗
PubMed1986

In vitro studies of S-25930 and S-25932, two new 4-quinolones.

The in vitro activity of S-25930 and S-25932 was compared with that of ciprofloxacin, norfloxacin and nalidixic acid against 740 clinical isolates. The data indicate that S-25930 was more active against Enterobacteriaceae than S-25932 and the latter was more active against gram-positive species. A study of clinical isolates resistant to chemically non-related classes of antibiotics revealed no cross-resistance. Nalidixic acid resistant Enterobacteriaceae showed an eight-fold decrease in susceptibility to the new agents. The killing kinetics of both compounds were good, S-25932 having an optimal bactericidal effect at a concentration of 0.5 mg/l. The data suggests that both agents are effective broad spectrum antibiotics.

Anti-Bacterial Agents↗
PubMed1986

Cross-resistance of nalidixic acid resistant Enterobacteriaceae to new quinolones and other antimicrobials.

One hundred urine isolates Enterobacteriaceae screened for resistance to 30 micrograms nalidixic acid by disc diffusion test were examined by MIC determination for in vitro susceptibility to nalidixic acid, ciprofloxacin, enoxacin, gentamicin, nitrofurantoin, trimethoprim, cephalexin and ceftazidime. Those resistant to nalidixic acid and also gentamicin or a cephalosporin were further examined to determine the mechanism of resistance. Compared to the total urine isolates of Enterobacteriaceae from the same time period, this population as a whole was less susceptible to all antimicrobials tested except gentamicin. Strains that exhibited multiple resistance had the conventional mechanisms of resistance to those antimicrobials. No multiply resistant strains had a permeability barrier due to outer membrane protein alterations causing cross-resistance to chemically unrelated classes of antimicrobials.

Anti-Bacterial Agents↗
PubMed1986

Teicoplanin, its pharmacokinetics, blister and peritoneal fluid penetration.

The pharmacokinetics of a 440 mg iv dose of teicoplanin were studied in six male volunteers. The levels of the compound were measured microbiologically in serum, blister fluid and urine. The mean serum level 0-5 h after injection was 44.6 mg 1(-1), falling to 3.6 mg 1(-1) at 49 h. The serum elimination half-life of teicoplanin when fitted to a two-compartment model was 34.2 h; a three-compartment model gave a longer half-life. The apparent distribution half-life was 1.5 h. Penetration into cantharides induced blister fluid was moderately fast, the mean maximum concentration (14.8 mg 1(-1)) occurring at 2.7 h, the mean percentage penetration being 77.4%. Urinary recovery of the drug was 48.3% by 96 h. The drug penetrated rapidly into the non-inflammed peritoneal fluid of 34 patients undergoing elective surgery. The percentage penetration being 40% within the first hour, and 94.6% over the period of the study.

Adult↗
PubMed1986

Morphological and biochemical changes in Escherichia coli after exposure to ciprofloxacin.

Examination of morphological and biochemical changes in Escherichia coli KL-16 after exposure to ciprofloxacin revealed distinct concentration-dependent responses. At levels close to the MIC extensive filamentation was seen, whereas at the most bactericidal concentration cells were elongated but not filamented. At higher concentrations ovoid cells were seen. Some cells showed surface vacuoles, but no significant leakage of cell contents was detected. Filamentation and vacuolation were shown to make only a minor contribution to ciprofloxacin-induced cell death, and the data indicate that there are two or more mechanisms involved in the lethal action of ciprofloxacin.

Ciprofloxacin↗
PubMed1986

The comparative pharmacokinetics of five quinolones.

The pharmacokinetics and tissue penetration of five quinolones were studied in volunteers. The compounds were norfloxacin (400 mg po), enoxacin (400 mg iv and 600 mg po), ciprofloxacin (100 mg iv and 500 mg po), ofloxacin (600 mg po) and pefloxacin (400 mg iv). Of the oral agents studied ofloxacin and ciprofloxacin were the most rapidly absorbed (Tmax = 1.2 h) and enoxacin the least (Tmax = 1.9 h). The serum levels attained were highest in the case of ofloxacin (after allowing for the higher dose administered). The serum half-lives were norfloxacin 3.75 h, ciprofloxacin 3.9 h (po), 4.0 h (iv), ofloxacin 7.0 h, enoxacin 6.2 h (po), 5.1 h (iv) and pefloxacin 10.5 h. All agents penetrated blister fluid readily. The 24 h urine recovery was 62% for oral enoxacin, 46.4% for iv enoxacin (plus 12.2% for oxo-enoxacin), 27% for norfloxacin, 30.6% for oral ciprofloxacin, 75.7% for iv ciprofloxacin, 73% for ofloxacin and 4.9% for pefloxacin (plus 9.2% for the norfloxacin metabolite and 17.8% for pefloxacin N-oxide).

Administration, Oral↗
PubMed1986

The pharmacokinetics and tissue penetration of imipenem.

Two studies were performed to investigate the penetration of imipenem into chemically induced inflammatory exudate and into peritoneal fluid. In the first study six volunteers received 500 mg of imipenem, alone and with 500 mg cilastatin. Little difference was noted in the pharmacokinetics or inflammatory fluid penetration of imipenem when given with or without cilastatin. The only significant alteration was the urine recovery (an increase from a mean of 14.7% to 55.6% in the presence of the enzyme inhibitor). The mean inflammatory fluid level of imipenem at 30 min was 6.2 mg/l (or 35% of the plasma level). The inflammatory fluid levels exceeded the plasma levels after 2 h. The overall penetration of imipenem/cilastatin into inflammatory fluid was 67.8% (+/- 13.8) and imipenem alone 73.2% (+/- 13.9). The mean elimination half-life of imipenem from plasma was 1.1 h and from inflammatory fluid 1.4 h (with or without cilastatin). In the second study, 29 patients received 1 g imipenem plus cilastatin before elective surgery and plasma and peritoneal levels were measured over 4 h. There was considerable penetration of the peritoneum, imipenem levels in excess of 30 mg/l being found 15 min after administration declining to 5-7 mg/l by 3-4 h. The mean percentage penetration was 73.4% (+/- 22.1). A brief review of the literature on imipenem tissue penetration is included.

Adult↗
PubMed1986

Properties of the penicillin-binding proteins of four species of the genus Bacteroides.

The penicillin-binding proteins (PBPs) of four species of the genus Bacteroides were examined in cell envelope preparations from exponentially growing cultures and intact cells. Upon examination by sodium dodecyl sulfate-polyacrylamide electrophoresis, three major high-molecular-weight PBPs (molecular weight, 58,000 to 82,000) were resolved, and low-molecular-weight PBPs were seen in all strains except Bacteroides fragilis. The sporadic appearance of PBP 4 in B. fragilis (molecular weight, approximately 45,000) was shown not to be influenced by the concentration of free iron available in the medium or by the stage of growth at which the batch culture was harvested. No PBP that was inhibited by an aerobic environment was demonstrated. The affinity of 35 beta-lactam antibiotics for the PBPs from envelope preparations was examined and correlated with the morphological response. Most compounds bound initially to PBP 2 and then PBP 1, correlating with a primary response of filamentation and then spheroplasting and lysis. Compounds such as clavulanic acid bound to PBP 3 at concentrations causing round cells. Based on the data from this study, it is proposed that the three high-molecular-weight PBPs of Bacteroides fragilis, Bacteroides vulgatus, Bacteroides thetaiotaomicron, and Bacteroides ovatus correlate to the three high-molecular-weight PBPs of Escherichia coli and that the PBPs of Bacteroides species perform the same enzymic role in cell wall biosynthesis as their counterparts in E. coli. Therefore, the components of PBP 1 are involved in cell elongation, PBP 2 is involved in septum formation, and PBP 3 is involved in maintenance of cell shape (i.e., PBP 2 in Bacteroides spp. = PBP 3 in E. coli, and PBP 3 in Bacteroides spp. = BPB 2 in E. coli).

Anti-Bacterial Agents↗
PubMed1986

In vitro activity of Ro 15-8074 and Ro 19-5247, two orally administered cephalosporin metabolites.

The activity of two iminomethoxy aminothiazoly cephalosporins, Ro 15-8074 and Ro 19-5247, was compared with that of other beta-lactams against a total of 491 bacterial strains. Both were highly active (MIC for 90% of the strains tested [MIC 90], less than or equal to 2 micrograms/ml) against the majority of the members of the family Enterobacteriaceae, Haemophilus influenzae, Neisseria spp., and Streptococcus pneumoniae, being at least 16-fold more active than cephalexin and 8-fold more active than cefuroxime. There was no activity against Pseudomonas aeruginosa and poor activity against Morganella morganii (in the case of Ro 15-8074), Enterobacter sp., and Citrobacter sp. Staphylococcus aureus was moderately susceptible to Ro 19-5247 (MIC90, 8 micrograms/ml), but Ro 15-8074 was eightfold less active. The protein binding of the two compounds at 5 micrograms/ml was 9.1% for Ro 15-8074 and 69.9% for Ro 19-5247. The major target site for the two cephalosporins was PBP 3.

Bacteria↗
PubMed1986

In vitro activity of Ro 23-6240, a new difluoroquinolone derivative, compared with that of other antimicrobial agents.

Ro 23-6240 is a new difluorinated quinolone antimicrobial agent. Its in vitro activity against a wide range of bacteria was compared with those of other quinolones and beta-lactams. Generally, members of the family Enterobacteriaceae were inhibited by low concentrations of Ro 23-6240 (MIC90 [MIC for 90% of isolates tested], less than or equal to 1 microgram/ml). Ninety percent of Staphylococcus aureus (including methicillin-resistant strains) and Neisseria gonorrhoeae isolates were inhibited by 0.5 microgram/ml. Pseudomonas aeruginosa (MIC90, 2 micrograms/ml) and Bacteroides fragilis (MIC90, 4 micrograms/ml) showed intermediate susceptibility, and Streptococcus pneumoniae (MIC90, 8 micrograms/ml) was less susceptible. Strains resistant to nalidixic acid were less susceptible to all the quinolones tested. The protein binding of Ro 23-6240 (5 micrograms/ml) was 27%.

Anti-Bacterial Agents↗
PubMed1986

Penetration of amoxycillin and clavulanic acid into bone.

The levels of amoxycillin and clavulanic acid have been measured in bone, serum and synovial fluid following the administration of 1.2 g Augmentin prior to hip replacement. Both antibiotics readily enter synovial fluid in levels similar to that found in serum. The levels found in bone are a minimum of ten times lower than those found in serum. Sequential administration of Augmentin with a six-hourly dose schedule does not increase the levels found in any of the tissues studied.

Aged↗