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Large quantities of antibiotics are manufactured, used, and eventually discharged into alga-containing water environment as prototypes, by-products, or transformation products. Different activities of Chlamydomonas reinhardtii toward cefradine (CFD) were studied, and the results indicated that CFD is resistant (removal rate of 5.45-14.72%) in simulated natural water environment. Cefradine was mainly removed by hydrolysis, adsorption, desorption, photodecarboxylation, and photoisomerization. The effects of C. reinhardtii density, initial solution pH, and different light sources on CFD removal efficiency were investigated. The optimum conditions occurred at a density of algae 10 × 10 4  cells/mL, a solution pH of 9.0, and the ultraviolet (UV) light. Additionally, the removal kinetics under 16 different conditions was explored. The results showed that the removal of CFD fits well with a pseudo-first-order kinetic, and the half-life times are from 0.8 to 261.6 days. This study summarizes the CFD removal mechanisms in alga-containing water environment, highlights the important role played by light irradiation in eliminating CFD, and obtains the important kinetic data on CFD removal.

Computational enzyme design exhibits excellent performance for identifying potential scaffolds from structural databases and creating new enzymatic catalysts from naught. Using the active site-matching algorithm ProdaMatch, we identified a new scaffold cocaine esterase from Rhodococcus sp. that showed modest activity (k cat /K m = 0.018 M -1 s -1 ) towards the hydrolysis of β-lactam antibiotic cephradine. The identified cocaine esterase scaffold afforded low sequence identity (<30%) with the known β-lactam synthases, such as penicillin G acylase or α-amino acid ester hydrolase, and was able to catalyze the condensation reaction between d-dihydrophenylglycine methyl ester and 7-aminodesacetoxycephalosporanic acid to produce cephradine via a kinetically controlled synthesis. By virtue of the computational enzyme design protocol, hundreds of sequences were predicted in the cocaine esterase scaffold to promote the catalytic activity towards the hydrolytic reaction of cephradine. Moreover, a single mutant (F261T) was experimentally confirmed to have improved the catalytic efficiency by ten times (k cat /K m = 0.193 M -1 s -1 ), indicating that the novel scaffold cocaine esterase may be potentially redesigned to become an industrially useful cephradine synthase.

Two common freshwater algae Microcystis aeruginosa and Scenedesmus obliquus were employed as test organism to evaluate the toxic effects of the widely used antibiotic, cefradine. In general, cefradine had significantly toxic effect on population growth and chlorophyll-a accumulation of two algae and the cyanophyceae was more sensitive than the chlorophyceae. In addition, cefradine UV light degraded products had adverse effect on M. aeruginosa's growth and chlorophyll-a accumulation. In comparison, even if S. obliquus had growth ability when exposed to cefradine UV light-degradation products, the algal photosynthesis function was also disrupted., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Cephalosporins are widely used veterinary and human antibiotics, but their environmental fate and impacts are still unclear. We studied degradation of four cephalosporins (cefradine, cefuroxime, ceftriaxone, and cefepime) from each generation in the surface water and sediment of Lake Xuanwu, China. The four cephalosporins degraded abiotically in the surface water in the dark with half-lives of 2.7-18.7d, which were almost the same as that in sterilized surface water. Under exposure to simulated sunlight, the half-lives of the cephalosporins decreased significantly to 2.2-5.0d, with the maximal decrease for ceftriaxone from 18.7d in the dark to 4.1d under the light exposure. Effects of dissolved organic matter (DOM) and nitrate on photodegradation of the cephalosporins were compound-specific. While DOM (5 mg L(-1)) stimulated the photodegradation of only cefradine (by 9%) and cefepime (by 34%), nitrate (10 microM) had effects only on cefepime (stimulation by 13%). Elimination rates of the cephalosporins in oxic sediment (half-lives of 0.8-3.1d) were higher than in anoxic sediment (half-lives of 1.1-4.1d), mainly attributed to biodegradation. The data indicate that abiotic hydrolysis (for cefradine, cefuroxime, and cefepime) and direct photolysis (for ceftriaxone) were the primary processes for elimination of the cephalosporins in the surface water of the lake, whereas biodegradation was responsible for the elimination of the cephalosporins in the sediment. Further studies are needed on chemical structure, toxicity, and persistence of transformation products of the cephalosporins in the environment., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Intestinal peptide transporters, including hPEPT1, facilitate the absorption of cephalosporins and angiotensin-converting enzyme inhibitors, and have been investigated as a means to improve oral drug absorption. Renal peptide transporters including hPEPT2, may also facilitate renal reabsorption of such compounds. In vitro and animal studies suggest that co-administration of peptidomimetic compounds may alter oral pharmacokinetics, although this has not been well studied in humans. The purpose of this study was to determine whether co-administration of the hPEPT substrates captopril and cephradine alters the oral pharmacokinetics of either agent. Nine healthy male volunteers received a single oral 25-mg dose of captopril, a single oral 500-mg dose of cephradine, or concurrent ingestion of captopril and cephradine in a cross-over manner. Venous blood samples were taken and captopril and cephradine pharmacokinetics were determined using noncompartmental analyses. No significant differences were observed in captopril or cephradine pharmacokinetics when administered together as compared to each agent alone (a marginal decrease in C(max) was observed for both captopril and cephradine during co-administration [5-15%]; however, differences were not statistically significant). The results of our study suggest that hPEPT1 and hPEPT2 are unlikely to contribute to clinically important drug interactions in humans.

Despite the fact that different laboratories have reported large differences in permeability for actively transported substrates, Caco-2 cell monolayers are widely used as in vitro model to study small intestinal drug transport. Therefore, we investigated the effect of cell culture conditions, such as time in culture, membrane support, seeding density and supplements to the medium, on the morphology, the formation of tight junctions, as well as the expression of two peptide transporters (PepT1, HPT1) and the efflux pump, P-glycoprotein (Pgp), in Caco-2 cell monolayers. Tight junction formation was assessed by transepithelial electrical resistance measurements; multi-cell layer formation by confocal laser scanning microscopy, the expression of transporters by RT-PCR and the permeability of the PepT1 substrate, cephradine. Both morphology and the expression of carrier-mediated transporters, varied strongly as a function of culture conditions. An increase of differentiation, as documented by tight, homogeneous cell monolayer formation displaying a strong expression of all carrier-mediated transporters, was found up to 3 weeks post seeding. One week later, multi-layer structures were observed and the expression of Pgp decreased. Polyester and polyethylene terephthalate membrane supports decreased the paracellular transport rates substantially, while collagen-coating of PC inserts showed no influence on the morphology and even increased carrier-mediated transporter expression. An average seeding density of 6x10(4) cells/cm(2) seemed to be most favorable, since lower seeding densities led to thin monolayers with altered tight junctions and higher seeding densities to the formation of multilayers. In summary, the expression of carrier-mediated transporters was strongly affected by the culture conditions. The full differentiation was reached after 21 days on collagen-coated polycarbonate inserts at an initial seeding density of 6x10(4) cells/cm(2).

During the production of Cephradine (a main constituent of anti-osmotic drug) a large quantity of concentrated effluent was produced. The main polluting compounds in this effluent are osmotic drug, acetic acid and ammonia. The feasibility of using a fluidized bed reactor under anaerobic condition with bioaugmentation to treat anti-osmotic drug based pharmaceutical effluent was evaluated. The main objective of the study was to show that bioaugmentation could be used to promote biological treatment to applications where conventional operation might be difficult or unfavourable. The effluent with chemical oxygen demand (COD) of 14000-18000 mg/l was treated in a fluidized bed reactor with a hydraulic retention time of 3-12 h. The reactor was unable to maintain consistent removal in conventional mode of operation due to an inability to retain and grow biomass. The COD reduction (%) after inoculation from a sequencing batch reactor was related to influent concentration, mass of inoculum and hydraulic retention time characterized by calculating the initial food to microorganism ratio. The role of volatile fatty acid (VFA) as cosubstrate was assessed with respect to COD reduction (%). Continuous COD reduction (%) attained a maximum value of 88.5% using bioaugmentation through periodic addition of acclimated cells every 2 days with 30-73.2 g of cells from an off-line enricher reactor.

Purpose: Fractal kinetics was used for the analysis of the carrier-mediated transport for drugs across the intestinal epithelial cells., Methods: The transport was examined under various agitation rates using a monolayer of Caco-2 cells and rabbit ileum sheets., Results: The passive transport of antipyrine across Caco-2 cells was increased with the increasing rate of agitation and was supposed to be caused by a change in the thickness of the unstirred water layer. On the contrary, in the case of L-lactic acid transport, which follows a carrier-mediated transport mechanism, the more the agitation rate controlling the fractal dimension was increased, the more the permeability rate across the Caco-2 cells was decreased. Fractal kinetic analysis of L-lactic acid transport indicated that the permeability was caused by a single saturable process. Similar agitation effects with L-lactic acid transport were observed in the transport of phenylalanine and cephradine in Caco-2 cells. However, the permeability rates of benzoic acid and 3-O-methyl-D-glucose across Caco-2 cells and L-lactic acid transport across the rabbit ileum tissue indicated the maximum levels at a designated agitation rate. This phenomenon was likely to be caused by the agitation effects controlling not only the fractal environment but also the unstirred water layer., Conclusions: Carrier-mediated transports are well defined by fractal kinetics rather than classical kinetic analysis. Fractal kinetics are one of the important areas for understanding and confirming the properties of a carrier-mediated transport process.

Effects of angiotensin-converting enzyme (ACE) inhibitors, captopril, enalapril maleate and quinapril, on the uptake of aminocephalosporin antibiotic, cefroxadine, by rabbit small intestinal brush border membrane vesicles were examined. These ACE inhibitors significantly inhibited the uptake of cefroxadine, which is transported by H+/dipeptide transporter in the membrane, in the order of captopril < enalapril < quinapril in the presence of an inward H+ gradient. Inhibitory effect of quinapril was more marked than that of aminocephalosporin cephradine, while in the absence of an inward H+ gradient inhibition by these ACE inhibitors was much less. Dixon plot analysis showed that the inhibition by enalapril and quinapril in the presence of an inward H+ gradient occurred in a competitive manner and estimated inhibition constants of these two drugs to be 5.3 mM and 0.46 mM, respectively. These results suggested the strong affinity of these ACE inhibitors, especially quinapril, on the H+/dipeptide transporter.

The LLC-PK1 cells stably transfected with a rat PEPT1 cDNA transported ceftibuten (anion) and cephradine (zwitterion), both oral beta-lactam antibiotics, in a H+-gradient-dependent manner. Diethylpyrocarbonate, a histidine residue modifier, abolished ceftibuten uptake. This inhibition was prevented in the presence of glycylsarcosine or cephradine. When expressed in Xenopus oocytes, replacement of either histidine 57 or histidine 121 of the rat PEPT1 with glutamine by site-directed mutagenesis eliminated ceftibuten and [14C]glycylsarcosine transport activities. Immunostaining of oocyte sections indicated that insertion of the mutant transporters in the plasma membranes was not impaired. These findings suggest that both histidine 57 and histidine 121, which are conserved in the rat, rabbit and human PEPT1, are involved in substrate recognition of this molecule.

The coding sequence of the Haemophilus influenzae ORF I gene was amplified by PCR and cloned into different Escherichia coli expression vectors. The ORF I-encoded protein was approximately 90 kDa and bound 3H-benzyl-penicillin and 125I-cephradine. This high-molecular-weight penicillin-binding protein (PBP) was also shown to possess transglycosylase activity, indicating that the ORF I product is a bifunctional PBP. The ORF I protein was capable of maintaining the viability of E. coli delta ponA ponB::spcr cells in transcomplementation experiments, establishing the functional relevance of the significant amino acid homology seen between E. coli PBP 1A and 1B and the H. influenzae ORF I product. In addition, the physiological functioning of the H. influenzae ORF I (PBP 1A) product in a heterologous species established the ability of the enzyme not only to recognize the E. coli substrate but also to interact with heterologous cell division proteins. The affinity of the ORF I product for 3H-benzylpenicillin and 125I-cephradine, the MIC of beta-lactams for E. coli delta ponA ponB::spcr expressing the ORF I gene, and the amino acid alignment of the PBP 1 family of high-molecular-weight PBPs group the ORF I protein into the PBP 1A family of high-molecular-weight PBPs.

The transport characteristics of p.o. cephalosporin antibiotics by monolayers of the human intestinal epithelial cell line Caco-2 were examined by measuring intracellular accumulation and transcellular transport. In the presence of an inward H+ gradient (at pH 6.0 of the apical medium), cephalosporins were accumulated by the monolayers in the following order: ceftibuten (anion) > cephradine (zwitterion) > cephalexin (zwitterion) > cefixime (anion). The accumulation rate of ceftibuten was more rapid than that of cephradine, whereas both appeared at the same rate in the basolateral compartment. The efflux of ceftibuten from the monolayers to the basolateral compartment was lower than the efflux of cephradine. The accumulation rate of ceftibuten from the basolateral side was markedly lower than that of cephradine. The accumulation of ceftibuten from both the apical and basolateral compartment was significantly inhibited by excess dipeptides. The kinetic parameters indicated that ceftibuten has higher affinity for the apical dipeptide transport system in the presence of a pH gradient, whereas it has much lower affinity for the basolateral dipeptide transport system at physiological pH of 7.4 than cephradine. These results suggest that both cephradine and ceftibuten are transported via the H+/dipeptide cotransport system localized in the apical membranes, and that the flux of these drugs across the basolateral membranes is also mediated by the dipeptide transport system in an H+ gradient-independent manner, exhibiting a rate-limiting step for their transcellular transport in Caco-2 monolayers.

Bestatin [(2S,3R)-3-amino-2-hydroxy-4-phenylbutanoyl-L-leucine] is a dipeptide, comprising L-leucine and an unusual beta-amino acid. We studied its transport mechanism in rat renal brush-border membrane vesicles. Uptake of cephradine, an aminocephalosporin, by isolated brush-border membrane vesicles was trans-stimulated and cis-inhibited by bestatin, indicating that these drugs are transported via the same transport system(s). The uptake of bestatin was trans-stimulated by preloading the vesicles with glycylsarcosine, and was cis-inhibited by substrates for the H+/dipeptide cotransport system. Bestatin inhibited tetraethylammonium (an organic cation) uptake, and bestatin uptake was cis-inhibited by substrates for the H+/organic cation antiport system. In addition, bestatin uptake was stimulated by an outward H+ gradient (the driving force for the H+/organic cation antiport system). These findings suggest that bestatin, in spite of being a dipeptide, is transported via not only the H+/dipeptide cotransport system but also the H+/organic cation antiport system in rat renal brush-border membrane.

Poly(PEG-Lys), a new, water-soluble poly(ether urethane), derived from L-lysine and poly(ethylene glycol) was investigated as a precursor for the preparation of polymeric drug conjugates. To facilitate a wide variety of coupling chemistries, the pendent carboxyl groups of poly(PEG-Lys) were converted to other reactive functional groups (amino, hydroxyl, active ester, and aldehyde) in high yield. These reactive pendent chains were then used as anchors for the covalent attachment of penicillin V and cephradine, two clinically used antimicrobial agents. Coupling to the carrier was achieved in good yields and the chemical versatility of this system was demonstrated by the preparation of conjugates having antibiotic ligands linked via biostable or biodegradable linkages to the carrier, either directly or via a spacer. Conjugate 4, poly(PEG-Lys-penicillin V ester), was obtained by linking penicillin V to the polymer backbone via hydrolytically labile ester bonds. This conjugate exhibited activity similar to that of the parent drug against three clinically important strains of bacteria. Drug activity coincided with the release of the drug from the carrier. Hydrolytically stable cephradine-containing conjugates were prepared by three different coupling methods but showed no antibiotic activity. 14C-labeled poly(PEG-Lys) was injected into mice and its biodistribution was monitored for 48 h. The carrier showed no preferential uptake by liver, spleen, or kidney. No signs of acute toxicity were evident in mice or rats when poly(PEG-Lys) was administered iv and ip at doses up to 10 g/kg. These results indicate that poly(PEG-Lys) is a promising precursor for the preparation of soluble drug conjugates.

The cephalosporins have been available for clinical use for nearly 20 years and a large number is presently marketed, including drugs with a wide range of different pharmacokinetic and microbiologic properties. While some of these agents have certain specific uses in which they excel, the cephalosporins have not replaced older antibiotics but do provide the physician with a broader range of choices for the treatment of many infections, allowing greater individualization of therapy.

The pharmacokinetic interaction of the monobactam antibiotic aztreonam with cephradine, clindamycin, gentamicin, metronidazole, and nafcillin was investigated in five separate studies in 48 healthy male volunteers. All drugs were administered by 30-minute intravenous infusions in single-dose, three-way balanced cross-over studies. Drug levels were measured in serum, protein-free filtrate of serum, and urine. Small changes of no clinical significance were seen when aztreonam was given simultaneously with another antibiotic as compared with each drug alone. Maximum serum concentrations of aztreonam were reduced by 12.6 and 9.8 per cent when it was given with gentamicin and metronidazole, respectively. The percentage of serum aztreonam bound to protein fell by a maximum of 5.0 per cent when the monobactam was given in conjunction with nafcillin and rose by 5.1 per cent when accompanied by cephradine. Twenty-four-hour cumulative urinary excretion of aztreonam and clindamycin rose by 5.2 and 10.9 per cent, respectively, when they were administered simultaneously.

Basic and clinical evaluations of a new oral cephalosporin cefroxadine (CXD) in pediatric fields were investigated, and the following results were obtained. 1. MICs of CXD against various bacteria were compared with those of cephalexin (CEX). MIC peaks of CXD against clinically isolated S. aureus (22 strains), S. pyogenes (25), S. pneumoniae (8), H. influenzae (23), and E. coli (23) in pediatric fields, were 1.56, 0.2, 1.56, 25 approximately 50 and 6 .25 microgram/ml, respectively in the inoculum size of 10(8) cells/ml, and they were 1.56, less than 0.1, 0.78, 25 and 6.25 microgram/ml respectively in the inoculum size of 10(6) cells/ml. In comparison with CEX, MIC peaks of CXD against S. aureus, S. pyogenes, H. influenzae and E. coli were almost the same with those of the former, it was, however, better by 1 approximately 2 tubes than that of CEX against S. pneumoniae. 2. CXD in the form of dry syrup was administered orally at a dose of either 10 mg/kg or 20 mg/kg to 5 children, and the serum levels and the urinary excretion were evaluated. In the case of 3 children who were administered a dose of 10 mg/kg the mean serum levels were 11.9 microgram/ml after 30 minutes, 13.7 microgram/ml after 1 hour, 4.7 microgram/ml after 2 hours, 0.7 microgram/ml after 4 hours, and 0.3 microgram/ml after 6 hours, while those 2 children who were administered a dose of 20 mg/kg, they were 15.1, 28.5, 12.5, 2.0 and 0.9 microgram/ml respectively. The mean periods of half-life in serum were 0.87 hour in the case of 10 mg/kg and 0.94 hour in the case of 20 mg/kg. The mean excretion rates were 83.8% in the case of 10 mg/kg and 59.8% in the case 20 mg/kg. 3. CXD dry syrup was administered to 31 children with various bacterial infections i.e. acute pharyngitis (15 cases), acute purulent tonsillitis (10 cases), acute bronchitis (4 cases) and 1 case each of acute pyelonephritis and acute purulent cervical lymphadenitis, and the clinical and bacteriological responses and side effect were investigated. The clinical response was either excellent or good in all of the cases. Out of the S. pyogenes (20 strains), S. aureus (1), S. pneumoniae (2), E. coli (1) and H. influenzae (1), bacteriological eradication was observed in all strains with the exception of 1 strain each in S. pyogenes and H. influenzae in which reduction was observed. No side effects and abnormal laboratory findings were observed.

Cefroxadine (CXD) was studied in the field of obstetrics and gynecology and the following results were obtained. MIC values of CXD against 55 clinical isolates were investigated, from 6.25 to 12.5 micrograms/ml for 8 strains of E. coli, 6.25 micrograms/ml for 3 strains of K. pneumoniae and from 0.39 to 3.13 micrograms/ml for 9 strains of anaerobes such as Peptostreptococcus and Peptococcus in 10(6) cells/ml. Transfer of CXD into intrapelvic organ such as uterus, uterine tube and ovary after the oral administration of 500 mg was investigated. The concentrations in the tissues of genitalia ranged from 5.84 to 7.44 micrograms/g about 2 hours later after the administration. CXD was orally given to 18 patients with infections of genital organs at daily dose of 1,500 mg (500 mg 3 times a day). The clinical response was good, and efficacy rate was 88.9%. No remarkable side effects were observed.

Half life and distribution volume of Cefradin were investigated in 22 patients with various degrees of renal function in which Cefradin was indicated and set in relation to glomerular filtration (determined by the 51Cr EDTA method). An average distribution volume of 21.8 +/- 3.5% of the body weight was found and a correlation between the half life of Cefradin and the glomerular filtration in the form of a power function. Estimations of levels were made from the pharmacokinetic data (half life, distribution volume) which serve as a basis for the recommendation of isoconcentration dosages. These are graduated according to the different degrees of renal insufficiency and given in tabular form for single injections and for continuous infusion drip therapy.

The administration of cephradine prophylactically to patients who were undergoing vaginal hysterectomies resulted in a marked and significant reduction in the incidence of postoperative infections when compared to a placebo group. Cephradine was the cephalosporin studied because of its unique pharmacodynamic properties, which result in high uterine tissue levels. The protective effect was similar whether 1 g was given preoperatively followed by 500 mg IV q. 6 hours for 4 doses, or a single dose of 2 g IV given approximately 1 hour before surgery. Uterine tissue and serum levels of antibiotic were high and correlated with the degree of protection noted.

Serum and bone levels of antibiotics were measured after the intramuscular injection of either 1 g cephradine or 500 mg flucloxacillin plus 500 mg ampicillin in 48 patients undergoing total hip replacement. The results showed that both regimens produced adequate blood levels, but that the levels after cephradine were higher and more prolonged. Bone levels of cephradine were significantly higher than for flucloxacillin or ampicillin. In half of the patients studied, flucloxacillin bone levels were below the limit of detection in both cancellous and cortical bone samples. In all 24 patients, cortical levels of cephradine were satisfactory for anti-staphylococcal activity although cancellous levels were unsatisfactory in 4 patients. The penetration of the antibiotics was greater into cortical bone than into cancellous bone.

The cefradine-tobramycine association was used in 11 cases of septicaemia and in 10 cases of non-septicaemic severe poly-infections. In 15 cases, the treatment was undertaken because of the serious state of the patients before the bacteriologic results were known. This association is characterized by its great effectiveness and its very good tolerance, mainly from the renal point of view. The results shown here corroborate those two elements.

The diffusion of cephradine into the pericardial exudate was measured in 19 patients undergoing heart surgery. Every patient received 2 grams of cephradine (=30 mg/kg) during a 20 minute infusion period, before, during, and after the operation, and than at intervals of 6 hours, together 8 grams per day. The highest mean serum level, 10 minutes after the end of the first injection was 150 microgram/ml and after repeated dosages 102.5 microgram/ml, and at the end of the infusion interval 3.2 microgram/ml in the mean. At the time of opening the pericardium the concentration of the substance in the pericardial exudate, 15, 30, 45 and 60 minutes after finishing the first injection, varied from 4.1 to 38.6 microgram/ml in the average. The postoperative maximum levels were higher than 50 microgram/ml and 6 hours after the respective administrations the levels varied between 12.83 and 15.77 microgram/ml in each case. These high concentrations of cephradine in the pericardial exudate could not be attributed to seepage of blood into the pericardium.-At specific "check points" bacteriological materials were taken. Out of 1168 specimens only 6.7% were bacteriological positive. Drains in wounds, the pleura or the pericardium were sterile in most cases. Intravenous catheters were contaminated only in 1%. However the contamination rate rises with period of storage. The results show that cephradine exhibits good diffusion into the exudate of pericardium. With the chosen dosage the concentrations of the antibiotic in the pericardial exudate are higher than the MIC values of most pathogen bacteria.

Pharmacokinetics of 2 oral cephalosporin antibiotics, i.e. cephalexin and cephradin in surgical patients with normal function of the liver and kidneys was studied. Both the drugs were satisfactorily absorbed into the blood reaching the maximum level in 1 hour. The antibiotics were determined in close concentrations in the blood serum of the patients during 5 hours of the observation. No differences in the time of a two-fold decrease in the antibiotic serum level and the value of the area limited by the antibiotic blood level were found. Cephalexin and cephradin were excreted with the urine in equal amounts.

One of 4 antibiotics with antistaphylococcal activity was given in a conventional oral dose for one day to each of 20 hospitalised patients with synovial effusion of a knee joint requiring aspiration. Serial synchronous samples of serum and synovial fluid (SF) were taken over 36 hours through indwelling cannulae. No morbidity was experienced either during or after this procedure. Satisfactory antistaphylococcal concentrations in SF were achieved with sodium fusidate (500 mg 8 hourly) and amoxycillin (250 mg 8 hourly). Cephradine (500 mg 6 hourly) frequently failed to reach the minimum inhibitory concentration for Staphylococcus aureus in the SF, and flucloxacillin (250 mg 6 hourly) was unpredictable in its penetration of the synovial space. Wide interpatient variation of both serum and SF concentrations was found. Our results indicate that sodium fusidate is an appropriate early treatment for a nonresistant staphylococcal joint infection. Amoxycillin is a suitable alternative or second antistaphylococcal drug and would also be appropriate initial therapy when the infecting organism is unknown. We strongly recommend that SF antibiotic concentrations be measured, to ensure adequate penetration of the synovial cavity, in the treatment of septic arthritis.

1) The half-life of serum concentration of cephradine (CED) in patients with normal renal function, was 30 minutes and it prolonged to 83 minutes when combined with probenecid. 2) In the patients with severely impaired renal function, mean serum concentration of CED was 33 mcg/ml 24 hours after 1 g intravenous injection. 3) In clinical observations of 17 cases with infections of lung, urinary tract, and bile duct, the treatment with CED showed excellent results in 5 cases, good in 6, undetermined in 1. No remarkable side effect was observed.

Cephradine was given to two control and twenty subjects with varying degrees of renal failure. Serum levels at various times were recorded and side-effects noted. Recommendations for dosage schedules for subjects with renal failure have been made.

The therapeutic activity of antibiotics depends on several factors including absorption, elimination kinetics, distribution in the body, minimal inhibitory concentrations (MIC), stability against enzymes, and plasma-protein binding. Some of these factors are interrelated, for example, the extent of protein binding of an antibiotic influences its elimination kinetics, distribution into tissues, MIC, and antibacterial activity. To evaluate the potential efficacy of an antibiotic, it is important to know the extent of its binding to plasma proteins especially since the protein-bound fraction of the antibiotic is devoid of antibacterial activity. Cephalosporins are a new class of broad-spectrum antibiotics that bind to plasma proteins in different degrees. Reported values for protein binding range from 6% for cephradine to 92% for cefazolin. The effects of protein binding of some of the commonly used cephalosporins on antibacterial activity and several pharmacokinetic parameters are discussed in this communication.

Clinical effect and excretion into wound exudate of a new semisynthetic cephalosporin cefroxadine (CXD), were studied. CXD was given in 25 cases of surgical infections; 6 cases of wound infection, 9 cases of abscess, 9 cases of infected atheroma and 1 case of furuncle. CXD was orally administered in daily dose of 750 to 1,500 mg. Clinical results were excellent in 1 case, good in 18 cases, fair in 3 cases and poor in 3 cases. The overall clinical efficacy rate was 76.0%. Clinical efficacy classified by diagnosis was 66.7% in wound infection, 66.7% in abscess, 88.9% in infected atheroma, and 100% in furuncle. Side effects were not observed in all cases among 25 patients in CXD trials. Studies of excretion into wound exudate of CXD were performed in 1 postoperative case of mamma carcinoma after oral administration of 500 mg of CXD. The concentration of CXD in exudate was 1.12 micrograms/ml in 2 hours, 3.48 micrograms/ml in 3 hours, 4.13 micrograms/ml in 4 hours, 5.56 micrograms/ml in 5 hours and 4.41 micrograms/ml in 6 hours after administration, which was observed that CXD was excreted in wound exudate in high concentration.

11 patients with peripheral arterial circulatory insufficiency with ulcers on the big toe or on the heel were given 1 g of cephradine intravenously (i.v.) and later 1 g of cefazolin i.v., two cephalosporins with different degrees of protein binding. Antibiotic concentrations were followed in serum and wound secretions after the injections. The peripheral circulatory state of the patients and the degree of protein binding of the cephalosporins used seemed to be of minor importance for the concentrations of the antibiotics in the ulcers, i.e. the infectious focus, compared to local factors such as the bacterial flora of the ulcers. In-vitro studies with bacterial strains isolated from the ulcers of 2 of the patients indicated that beta-lactamases from gram-negative bacteria might be at least part of the explanation for the low concentrations in wound secretion of one or other of the agents used in 4 out of the 11 patients.

The pharmacokinetics of the oral cephalosporins cefaclor, cephradine, and cephalexin were examined following single 500 mg oral doses to fasted, healthy volunteers. Absorption of the three compounds was rapid following a brief lag period and peak serum levels were obtained in 1-1.5 hours. Serum levels of cefaclor tended to be lower than those of cephradine and cephalexin during the 2-5 hour postdosing period and cefaclor was eliminated more rapidly than other cephalosporins from serum. No difference was observed in the overall bioavailability of the three antibiotics based on comparable FD/V values. Urine levels of the three cephalosporins greatly exceeded the minimum inhibitory concentrations of susceptible organisms during 0-6 hours postdosing, but were considerably reduced during the 6-12 hour collection period. Total urinary recovery of antibiotic activity accounted for almost 90 percent of dosed cephradine and cephalexin compared to 55 percent of dosed cefaclor. Lower serum levels and reduced urinary recovery of intact cefaclor are probably due primarily to its chemical instability. The reduced levels of cefaclor may be compensated for therapeutically by its greater in vitro antibacterial activity.

At equivalent oral doses, cefadroxil has a longer serum half-life, slower urinary excretion rate, greater area under the serum level versus time curve than cephalexin or cephradine, and peak serum concentrations that are 75 to 80% those of cephalexin. The calculated, apparent in vivo volume of distribution of cefadroxil is greater than that of cephalexin. These properties infer greater persistence of cefadroxil in serum and urine and more prolonged in vivo bacterial exposure to cefadroxil than to cephalexin or cephradine. Neither cefadroxil nor cephalexin demonstrates drug accumulation on repeated administration. The serum levels achieved by cefadroxil are unaffected by food. The pharmacokinetic properties of cefadroxil are supportive of the development of clinical efficacy data which could indicate that cefadroxil could be administered at 12-h intervals.

The degree of binding of ampicillin, cephradine, co-trimoxazole, gentamicin, nalidixic acid, neomycin, polymyxin B and tobramycin by faecal substance as well as the influence of these antibiotics on human intestinal obligate anaerobes was investigated. In contrast to ampicillin, cephradine, co-trimoxazole and nalidixic acid, the nonabsorbable antibiotics polymyxin B and neomycin were bound to a considerable degree by human faeces. The binding of tobramycin and gentamicin to the solid part of faeces was less effective. The inhibitory effect of co-trimoxazole, gentamicin, nalidixic acid, neomycin, polymyxin B and tobramycin on the human obligate anaerobes was weak as compared with ampicillin and cephradine. Drugs which effectively eliminate Enterobacteriaceae from the gastrointestinal tract and which have a moderate effect on obligate anaerobes, like polymyxin B, are particularly suitable for selective decontamination of the gastrointestinal tract. The strong inactivating binding of aminoglycosides and polymyxin B to faeces accounts for the relatively high oral dose needed for a suitable faecal concentration.

The pharmacokinetic parameters of cefroxadin and cephalexin were compared after simultaneous oral administration of the two cephalosporins to 21 subjects. The influence of the dose, the formulation, and food intake on these parameters was investigated. Both drugs were equally well absorbed from all of the tested formulations; identical percentages of the dose were recovered in the urine in all cases. The elimination half-life of cefroxadin and, consequently, the area under the plasma concentration-time curve were about 10% less than those of cephalexin. Plasma concentrations and cumulative excretion curves of the two drugs were almost superimposable. Food intake had the same effect on both drugs; absorption was slowed, but the amounts absorbed were almost the same as those in fasted subjects.

The passage of two antibiotics, cephradine and epicillin, into the milk of 12 lactating women and the amniotic fluid of 48 pregnant women was investigated. All women were given a 500-mg capsule every six hours for at least two days prior to our taking multiple biologic samples from them. Constant levels of both antibiotics were reached in the milk of lactating women as well as in the amniotic fluid of mid-term and full-term pregnant women during the sample period. The ratio of drug concentrations in serum to that in milk was about 5.0 for each antibiotic. In the midtrimester women, the ratio of concentrations in serum to amniotic fluid of both antibiotics was approximately 1.0, suggesting the development of an equilibrium between these two compartments. This ratio was 0.2 for both drugs in the full-term women, demonstrating that the antibiotics concentrated in the amniotic fluid compartment.

The pharmacokinetics of cephradine suspension were studied in 16 infants and children who were 13 months to 8 years and 3 months of age (means age, 3.5 years). Mean peak concentrations of 21.3 and 9.9 mug/ml were achieved at 30 min after administration of 60-mg/kg doses to fasting and nonfasting patients. The area under the serum concentration-time curve was 26% larger in fasting than in fed subjects. The half-life of cephradine in serum was 0.8 and 1.0 h in fasting and fed groups, respectively. Antimicrobial activity was detected in 49% of all salivary samples; in 75% of specimens, the concentrations were less than the 50% minimum inhibitory concentration for most pneumococci and group A streptococci. Urinary concentrations of cephradine ranged from 28 to 8,760 mug/ml and were independent of feeding status.

The absorption mechanism of amino beta-lactam antibiotics was investigated by using the whole small intestine of a rat. Mutual inhibition among amino beta-lactam analogues and the effects of dipeptides were studied. The influences of glycylglycine on the absorption of cephradine at the four different parts of intestine were also studied. Similarly to the case of cephalexin and cephradine, the absorption of amoxicillin was significantly inhibited by cyclacillin, cephradine, and cephalexin, but the absorption of ampicillin was not reduced by all tested antibiotics. In the experiments using dipeptides (6.0 mM), the absorption of cyclacillin was reduced significantly by glycylglycine, not by L-carnosine. And cephalexin absorption was influenced by L-carnosine (6.0, 10 mM), not by glycylglycine (6 mM). On the contrary, the absorption of cephradine was not reduced at all by these dipeptides. And from the experiment using the four different parts of intestine, it was shown that the transport interaction of glycylglycine with cephradine was observed in only one segment (the upper part of jejunum). These result suggest that the carrier-mediated transport system correlated to dipeptides participates only to a small degree in the common absorption mechanisms of these amino beta-lactam antibiotics.

A crossover experiment was utilized to compare the pharmacokinetics of a 1-g dose of cephalexin tablets, cephalexin capsules, or cephradine capsules in nine normal human volunteers. These antibiotics were administered as three formulations: two 500-mg capsulin every 6 hr for five doses, and one 1000-mg tablet of cephalexin every 6 hr for five doses. Pharmacokinetic parameters in the experimental groups showed no statistical differences (p greater than 0.1), indicating that these drugs are equivalent pharmacokinetically.

Parenteral cephalosporins are widely used to treat peritonitis associated with continuous ambulatory peritoneal dialysis (CAPD). Few data exist on oral antibiotics in treating this disease. This study examined the pharmacokinetics of oral cephradine in noninfected patients on CAPD. Assays for cephradine in dialysate and urine were performed by high-performance liquid chromatography. Following a 500-mg dose, the peak dialysate cephradine concentration was 8.7 +/- 1.4 micrograms/ml. The peak urinary concentration was 201 +/- 119 micrograms/ml. The maximum peritoneal clearance was 4.3 +/- 0.3 ml/min/1.73 m2. Dialysate cephradine concentrations were inadequate against Staphylococcus epidermidis and most gram-negative bacteria found in CAPD-associated peritonitis, but may be adequate for most strains of other gram-positive organisms causing this disease.

Distribution regularities of cephalexin and cephradine, 2 semisynthetic cephalospor in antibiotics for oral use were studied on rats. It was found that the cephalosporins had a capacity for satisfactory penetration through the histochematological barriers. The drugs were rather rapidly absorbed from the gastrointestinal tract of the rats into the blood. Their maximum blood levels were determined 1 hour after the administration. The highest cephalosporin concentrations were detected in the kidneys and liver. Still, the level of cephradine in the kidneys was lower and that in the liver was higher than the levels of cephalexin. The lowest concentrations were found in the skeletal muscles. The character of cephradine distribution in the lungs, heart and spleen differed from that of cephalexin; the maximum concentrations of cephradine in these organs were achieved 1 hour after its administration, while those of cephalexin were achieved in 30 minutes. The antibiotics were not detected in the brain tissue. No increase in the concentration gradient with time was observed.

A study was made with the newly developed cefroxadine (CXD) dry syrup by measuring the serum level, urine excretion and recovery rate in 10 children who were orally administered 5, 10 and 20 mg/kg at 1 hour after meals and the following results were gained. Also, its clinical efficacies and side effects were investigated in the following cases who were treated with a mean dose of 33 mg/day divided into 3 to 4 portions for a period of 9 days on the average; viz. a total of 151 cases consisting of 9 cases of pharyngitis, 39 of tonsillitis, 11 of streptococcal infection, i.e. scarlet fever, 7 of bronchitis, 6 of pneumonia, 1 of otitis media, 6 of purulent lymphadenitis, 1 of purulent parotitis, 1 of subcutaneous abscess and 3 of impetigo. 1. The serum level tends to reach its maximum level within 1 hour after administration. The mean concentrations of 5, 10 and 20 mg/kg dose in the foregoing time were 6.35, 9.12 and 21.62 mcg/ml respectively and dose response was observed. CXD showed higher concentration than CEX, CED and CFT. The mean half-life periods of the 3 dose were 72, 84 and 66 minutes respectively and variations were observed, but the drugs maintains a satisfactory serum level. 2. The time which showed highest urine excretion was mainly in the 0 to 2 hours bracket and the average concentrations of 5 , 10 and 20 mg/kg dose in the foregoing time were 381.2, 771.7 and 1,577.7 mcg/ml respectively. The dose response was more evident than in the serum concentrations. The average recovery rates within 6 hours were 93.6, 88.3 and 94.3% respectively and they were similar to those of CEX, CED and CFT. 3. The clinical effects were evaluated were in 148 cases out of the total of 151 and 136 cases, or 91.9% showed good or excellent efficacy response. 4. The daily dose groups of less than 30 mg/kg and 31 to 40 mg/kg formed the majority and there was no difference in the comparison of the clinical effectiveness in these 2 groups. Administration of a daily dose of 20 to 40 mg/kg is sufficient for the treatment of the aforementioned mild diseases except for pneumonia. 5. The clinical effects were compared between the 3 and 4 times a day treatment groups, but there was no difference between these two groups with regard to the foregoing daily dose. The 3 times a day treatment is acceptable, but the 4 times a day treatment is preferable when pharmacokinetics if taken into account. 6. The bacteriological effects in 41 cases, or 97.6% out of the 42 cases were above the efficacy base line and a high efficacy rate was achieved. 7. With regard to side effects, diarrhea developed in 4 cases and eosinophilia in 6 cases, abnormal simultaneous increases in GOT and GPT in 1 case and 1 case each for abnormal values in LDH and BUN were seen in the clinical test values. The foregoing results show that CXD has high efficacy and safety and it can be said that it is a drug required in the pediatric field.

The pharmacokinetics of cefroxadin have been studied after the administration of single oral and intravenous doses to healthy volunteers. Cefroxadin was assayed by HPLC. The kinetics in plasma following i.v. administration were described by using a three-compartment model. An additional disposition phase was observed following oral administration that could not be detected after the low i.v. dose. The terminal half-life was 1.03 h. The apparent volume of distribution at the steady state was consistent with a diffusion of the antibiotic in all extracellular fluids. The AUC after oral administration was linearly related to the dose. The urinary excretion amounted to 95% of the dose with virtually complete absorption of orally administered drug.