[Evaluation of the effectiveness of various protocols of antibiotic prophylaxis and therapy in pancreatic necrosis]

The efficiency of various protocols of antibiotic prophylaxis and therapy (APT) used in 63 patients with pancreonecrosis is analyzed. Early treatment with carbapenemes is the most effective in disseminated infectious pancreonecrosis requiring obligatory surgical treatment. Drug efficiency is the key factor in choosing APT for intensive care of patients with destructive pancreatitis.

Comparative pharmacokinetics of the carbapenems: clinical implications

During the last few decades, several carbapenems have been developed. The major characteristic of the newer drugs, such as MK-826, is a prolonged half-life. Alternatively, some carbapenems have been developed that can be given orally, such as CS-834 and L-084. Although imipenem and panipenem have to be administered with a co-drug to prevent degradation by the enzyme dehydropeptidase-1 and reduce nephrotoxicity, the newer drugs such as meropenem, biapenem and lenapenem are relatively stable towards that enzyme. Structural modifications have, besides changes in pharmacology, also led to varying antimicrobial properties. For instance, meropenem is relatively more active against Gram-negative organisms than most other carbapenems, but is slightly less active against Gram-positive organisms. Except for half-life and bioavailability, the pharmacokinetic properties of the carbapenems are relatively similar. Distribution is mainly in extracellular body-water, as observed both from the volumes of distribution and from blister studies. Some carbapenems have a better penetration in cerebrospinal fluid than others. In patients with renal dysfunction, doses have to be adjusted, and special care must be taken with imipenem/cilastatin and panipenem/betamipron to prevent accumulation of the co-drugs, as the pharmacokinetic properties of the co-drugs differ from those of the drugs themselves. However, toxicity of the co-drugs has not been shown. The carbapenems differ in proconvulsive activity. Imipenem shows relatively the highest proconvulsive activity, especially at higher concentrations. Pharmacodynamic studies have shown that the major surrogate parameter for antimicrobial efficacy is the percentage of time of the dosage interval above the minimum inhibitory concentration (MIC). The minimum percentage percentage of time above the MIC (TaM) needed for optimal effect is known in animals (30 to 50%), but not in humans. It is probably less than 100%, but may be higher than 50%. Dosage regimens currently in use result in a TaM of about 50% at 4 mg/L, which is the current 'susceptible' breakpoint determined by the National Committee for Clinical Laboratory Standards (NCCLS) for most micro-organisms. Dosage regimens in patients with reduced renal clearance should be based on the TaM. The increased half-life of the newer carbapenems will probably lead to less frequent administration, although continuous infusion may still be the optimal mode of administration for these drugs. The availability of oral carbapenems will have a profound effect on the use of carbapenems in the community.

Pharmacokinetics and safety of ascending single doses of DZ-2640, a new oral carbapenem antibiotic, administered to healthy Japanese subjects

DZ-2640 is the ester-type oral carbapenem prodrug of an active parent compound, DU-6681. The pharmacokinetics and safety of DU-6681 were investigated in six studies after oral administration of a single dose of DZ-2640 to healthy male Japanese volunteers at doses of 25, 50, 100, 200, and 400 mg (as the equivalents of DU-6681) in the fasted state. The same volunteers received the drug at a dose of 100 mg in the fasted and fed states to examine the effect of food intake on the bioavailability of DZ-2640. The concentrations of DU-6681 in plasma and urine were determined by a validated high-performance liquid chromatography method and a bioassay. A good correlation between both methods was seen, indicating an absence of major active metabolites. The mean maximum concentrations of DU-6681 in plasma (C(max)) ranged from 0.263 microgram/ml (25-mg dose) to 2.489 microgram/ml (400-mg dose) and were reached within 1.5 h following drug administration. After reaching the C(max), plasma DU-6681 concentrations declined in a monophasic manner, with a half-life of 0.47 to 0.89 h. The area under the concentration-time curve (AUC) and C(max) increased almost linearly with the dose up to the 200-mg dose. The AUC and C(max) increased less than proportionally after administration of the 400-mg dose, suggesting a reduction in drug absorption. The plasma protein binding of DU-6681 was in the range of 23.3 to 25.6%. The cumulative urinary recoveries (0 to 24 h) were in the range of 31.9 to 44.9%. The AUC was slightly but statistically significantly reduced by food intake. However, the C(max), half-life, and recovery in urine were not affected by food intake. The renal clearance (402 to 510 ml/min) was much greater than the mean glomerular filtration rate (ca. 120 ml/min), which indicated active tubular secretion of the drug. A mild transient and moderate diarrhea was observed in two of six volunteers in the study with a single dose of 25 mg. Mild soft stools were observed in two of six volunteers who received a 400-mg dose of the drug.

Synthesis and biological evaluation of new oral carbapenems with 1-methyl-5-oxopyrrolidin-3-ylthio moiety

The synthesis and biological properties of 1beta-methylcarbapenems with 1-methyl-5-oxopyrrolidin-3-ylthio group at the C-2 position were studied. The sodium (1R,5S,6S)-6-[(R)-1-hydroxyethyl]-1-methyl-2-[(R)-1-methyl-5-oxopyrro lidin-3-ylthio]-1-carbapen-2-em-3-carboxylate and its (S)-isomer at the 2-position show potent and well-balanced antibacterial activity. The pharmacokinetic parameters of the pivaloyloxymethyl esters of these two carbapenems were compared in mice. The in vivo potency of these carbapenems was compared with that of cefdinir. Good in vivo efficacy of these ester prodrugs reflected the high and prolonged blood levels in parent drugs achieved after oral administration to mice.

Pharmacokinetic changes of a new carbapenem, DA-1131, after intravenous administration to spontaneously hypertensive rats and deoxycorticosterone acetate-salt-induced hypertensive rats

The pharmacokinetics of a new carbapenem, DA-1131, were compared after i.v. administration of the drug, 50 mg/kg, to spontaneously hypertensive rats (SHRs) at 16 weeks of age (an animal model for human primary hypertension) and at 6 weeks of age (corresponding to the early phase of the development of hypertension, at which time blood pressure remains within the normotensive range) and their respective age-matched control normotensive Kyoto-Wistar rats (KW rats), and deoxycorticosterone acetate-salt-induced hypertensive rats at 16 weeks of age (an animal model for human secondary hypertension) and their age-matched control Sprague-Dawley rats. The total area under the plasma concentration-time curve from time zero to time infinity (AUC) (4720 versus 7070 microg x min/ml) was significantly smaller, and the nonrenal clearance (CLNR) (5.37 versus 3.57 ml/min/kg) was significantly faster in 16-week-old SHRs than those in their control KW rats. Similar results were also obtained from 6-week-old SHRs in AUC (3800 versus 4680 microg x min/ml) and CLNR (7.73 versus 3.31 ml/min/kg). However, the values were reversed in 16-week-old deoxycorticosterone acetate-salt rats in AUC (5310 versus 3870 microg.min/ml) and CLNR (2.57 versus 4.90 ml/min/kg). The significantly faster CLNR of DA-1131 in both 6- and 16-week-old SHRs could be supported at least partly by the results of the in vitro metabolism with kidney homogenate and considerably greater total renal dehydropeptidase-I activity. The data above indicated that the significantly faster CLNR of DA-1131 in 16-week-old SHRs than that in their age-matched control KW rats was due to any hereditary characteristics of SHRs and was not due to the hypertensive state itself.

Continuous infusion of beta-lactam antibiotics

There are considerable laboratory data and information from animal and continuous culture in vitro models to support continuous infusion therapy for penicillins and cephalosporins, but, as yet, the only existing clinical data relate to cephalosporins. Penicillins do not exert concentration-dependent killing in the therapeutic range but have a post-antibiotic effect (PAE) against Gram-positive cocci but not Gram-negative rods. Animal models indicate the time (T) during which the serum concentrations exceed the minimum inhibitory concentration (MIC) of the pathogen [T > MIC] determines outcomes. Pharmacokinetic studies in humans indicate that continuous infusion with penicillins is possible but there are no clinical data on efficacy. Cephalosporins have similar pharmacodynamic properties to penicillins; T > MIC determines outcome. Data related to ceftazidime indicate that the drug concentration at steady-state (Css) should exceed the pathogen MIC by > 1-fold and perhaps by 4- to 5-fold or more. Human pharmacokinetics of ceftazidime administered by continuous infusion to a wide variety of patient groups indicates that Css of > 20 mg/L can easily be achieved using conventional daily doses. Clinical data indicate increased effectiveness of a continuous regimen in neutropenic patients with Gram-negative infection. Furthermore cefuroxime administration by continuous infusion has resulted in lower doses and shorter course durations. Little is known of the pharmacodynamics of monobactams and there are few clinical data on continuous infusion therapy. Carbapenems have different pharmacodynamics to other beta-lactams as they have concentration-dependent killing and a PAE with both Gram-positive and Gram-negative bacteria. While T > MIC has a role in determining outcomes, the proportion of the dosing interval for which serum drug concentrations should exceed the pathogen MIC is less than for other beta-lactams. In vitro models have shown that continuous infusion is effective, as is less frequent dosing. There are few data on continuous infusion of carbapenems but some patients have been treated with once-daily dosing. Clinically, continuous infusion therapy with penicillins and cephalosporins should be considered in patients infected with susceptible Gram-negative rods not responding to conventional therapy. As an approximation, the same total daily dose should be given but a bolus intravenous injection should be give at the start of continuous infusion to ensure Css is reached rapidly. The Css may be difficult to predict and determination of serum drug concentrations may be indicated. Ideally, the Css should be calculated based on the MIC of the potential pathogen and may be higher or lower than the Css achieved by a conventional daily dose.

Pharmacokinetics of a new carbapenem, DA-1131, after intravenous administration to rats with alloxan-induced diabetes mellitus

Because physiological changes occurring in diabetes patients could alter the pharmacokinetics of drugs used to treat the disease, the pharmacokinetics and tissue distribution of DA-1131, a new carbapenem antibiotic, were investigated after 1-min intravenous (i.v.) administration of the drug, 50 mg kg-1, to control and alloxan-induced diabetes mellitus (AIDM) rats. The impaired kidney function was observed by pretreatment with alloxan based on physiological parameters of plasma, creatinine clearance, and the kidney microscopy. After 1-min i.v. infusion of DA-1131, the plasma concentrations of DA-1131 and the total area under the plasma concentration-time curve of DA-1131 from time zero to time infinity (AUC) increased significantly in the AIDM rats (7350 versus 4400 micrograms min mL-1) when compared with those in control rats. This was due to significantly slower total body clearance (Cl) of DA-1131 (6.80 versus 11.4 mL min-1 kg-1) in AIDM rats than that in control rats. The significantly slower Cl of DA-1131 in AIDM rats was due to significantly slower renal (2.62 versus 4.95 mL min-1 kg-1, because of the considerably decreased glomerular filtration rate of DA-1131) and nonrenal (3.99 versus 6.34 mL min-1 kg-1, possibly because of the considerably slower metabolism in rat liver and kidney) clearance in AIDM rats. The amount of DA-1131 recovered from each rat tissue studied was significantly higher in AIDM rats than that in control rats, however, the tissue to plasma ratios were not significantly different between the two groups of rats.

Pharmacokinetics and safety of a new parenteral carbapenem antibiotic, biapenem (L-627), in elderly subjects

The pharmacokinetics and tolerability of a new parenteral carbapenem antibiotic, biapenem (L-627), were studied in healthy elderly volunteers aged 65 to 74 years (71.6 +/- 2.7 years [mean +/- standard deviation], n = 5; group B) and > or = 75 years (77.8 +/- 1.9 years, n = 5; group C), following single intravenous doses (300 and 600 mg), and compared with those of healthy young male volunteers aged 20 to 29 years (23.0 +/- 3.5 years, n = 5; group A). The agent was well tolerated in all three age groups. Serial blood and urine samples were analyzed for biapenem to obtain key pharmacokinetic parameters by both two-compartment model-dependent and -independent methods. The maximum plasma concentration and area under plasma concentration-versus-time curve (AUC) increased in proportion to the dose in all three groups. Statistically significant age-related effects for AUC, total body clearance, and renal clearance (CLR) were found, while elimination half-life (t1/2 beta) and percent cumulative recovery from urine of unchanged drug (% UR) remained unaltered (t1/2 beta, 1.51 +/- 0.42 [300 mg] and 2.19 +/- 0.64 [600 mg] h [group A], 1.82 +/- 1.14 and 1.45 +/- 0.36 h [group B], and 1.75 +/- 0.23 and 1.59 +/- 0.18 h [group C]; % UR, 52.6% +/- 3.0% [300 mg] and 53.1% +/- 5.1% [600 mg] [group A], 46.7% +/- 7.4% and 53.0% +/- 4.8% [group B], and 50.1% +/- 5.2% and 47.1% +/- 7.6% [group C]). A significant linear correlation was observed between the CLR of biapenem and creatinine clearance at the dose of 300 mg but not at 600 mg. The steady-state volume of distribution tended to be decreased with age, although not significantly. Therefore, the age-related changes in parameters of biapenem described above were attributable to the combination of decreased lean body mass and lowered renal function of the elderly subjects. However, the magnitude of those changes does not necessitate dosage adjustment in elderly patients with normal renal function for their age.

Pharmacokinetics of a new carbapenem, DA-1131, after intravenous administration to rats with uranyl nitrate-induced acute renal failure

Because the physiological changes that occur in patients with acute renal failure could alter the pharmacokinetics of the drugs used to treat the disease, the pharmacokinetics of DA-1131, a new carbapenem antibiotic, were investigated after 1-min intravenous administration of the drug (50 mg/kg of body weight) to control rats and rats with uranyl nitrate-induced acute renal failure (U-ARF rats). The impaired kidney function was observed in U-ARF rats on the basis of physiological parameters observed by microscopy of the kidney and obtained by chemical analysis of the plasma. After a 1-min intravenous infusion of DA-1131, the concentrations in plasma and the total area under the plasma concentration-time curve from time zero to time infinity increased significantly in U-ARF rats compared with those in control rats (13,000 versus 4,400 microg x min/ml). This was due to the significantly slower total body clearance (CL) of DA-1131 (3.84 versus 11.4 ml/min/kg) from U-ARF rats than from control rats. The significantly slower CL of DA-1131 from U-ARF rats was due to both significantly slower renal clearance (0.000635 versus 4.95 ml/min/kg because of a significant decrease in the 8-h urinary excretion of unchanged DA-1131 [1.54 versus 43.8% of the intravenous dose] due to impaired kidney function, as proved by the significant decrease in creatinine clearance [0.0159 versus 4.29 ml/min/kg]) and significantly slower nonrenal clearance (3.80 versus 6.34 ml/min/kg because of a significant decrease in the metabolism of DA-1131 in the kidney) in U-ARF rats. The amounts of DA-1131 recovered from all tissues studied (except the kidneys) were significantly higher for U-ARF rats than for control rats; however, the ratios of the amount in tissue to the concentration in plasma (except those for the kidney, small intestine, and spleen) were not significantly different between the two groups of rats, indicating that the affinity of DA-1131 for rat tissues was not changed considerably in U-ARF rats.

Efficacy of CS-834 against experimental pneumonia caused by penicillin-susceptible and -resistant Streptococcus pneumoniae in mice

The efficacy of CS-834, a novel oral carbapenem, was assessed by using a murine model of pneumonia caused by penicillin-susceptible and penicillin-resistant Streptococcus pneumoniae and was compared with those of oral cephems, i.e., cefteram pivoxil, cefpodoxime proxetil, cefdinir, and cefditoren pivoxil. Intranasal inoculation of 10(6) CFU of penicillin-susceptible or penicillin-resistant S. pneumoniae in the exponential growth phase induced pneumonia and bacteremia in ddY mice within 48 h. For the treatment of infections caused by the penicillin-susceptible strain the antibiotics were administered orally at 0.4, 2, and 10 mg/kg of body weight twice daily for 2 days beginning at 24 h after bacterial inoculation, and for the treatment of infections caused by a penicillin-resistant strain the antibiotics were administered at 2, 10, and 50 mg/kg twice daily for 2 days beginning at 24 h after bacterial inoculation. Among the antibiotics tested, CS-834 exhibited the most potent efficacy against both types of strains. Against infections caused by penicillin-susceptible S. pneumoniae, CS-834 at all doses significantly reduced the numbers of viable cells in both the lungs and blood. Cefpodoxime proxetil at all doses and cefteram pivoxil and cefditoren pivoxil at doses of 2 and 10 mg/kg showed comparable efficacies. Against infections caused by penicillin-resistant S. pneumoniae, CS-834 at doses of 10 and 50 mg/kg showed the most potent efficacy among the antibiotics tested, resulting in the maximum decrease in the numbers of viable cells in the lungs. Comparable efficacies were observed with cefteram pivoxil and cefpodoxime proxetil at doses of 50 mg/kg each. The concentration of CS-834 in the lungs and blood was higher than that of cefdinir and was lower than those of the other antibiotics tested, suggesting that the potent therapeutic efficacy of CS-834 reflects its strong activity against S. pneumoniae.

[In vitro combination effect of vancomycin and carbapenems against carbapenem-resistant MRSA]

We determined in vitro combined effects of vancomycin (VCM) plus carbapenems (CRBs) on 12 methicillin-resistant Staphylococcus aureus (MRSA) which are resistant to CRBs. Combinations of VCM plus imipenem (IPM) and VCM plus panipenem (PAPM) and VCM plus meropenem (MEPM) indicated synergistic effects, fractional inhibitory concentration (FIC) indices of < or = 0.05, against 67%, 75%, 67% of the strains, respectively. Against forty two percent of strains tested, 1 MIC of VCM was equal to 1 MBC, and similarly, IPM, PAPM and MEPM had 1 MIC = 1 MBC against 42%, 67% and 75% of the strains tested, respectively. Combinations of VCM plus IPM and VCM plus PAPM and VCM plus MEPM showed synergistic effects, hence a fractional bactericidal concentration (FBC) index of < or = 0.50, against 42%, 50%, 75% of the strains, respectively, and the combination of VCM plus MEPM was most synergistic. These results suggest that combination therapy of VCM with CRB is useful for the treatment of MRSA infection in patients with renal dysfunction.

A study of the pharmacokinetics and tolerability of ritipenem acoxil in healthy volunteers following multiple oral dosing

The pharmacokinetics of ritipenem acoxil, the oral prodrug of the antibiotic ritipenem, were studied in volunteers after single and repeated dosing (500 mg, three times daily for 10 days). Concentrations of ritipenem and open beta-lactam ring metabolites were measured using HPLC/UV. Ritipenem did not accumulate significantly in plasma, owing to its half-life of about 0.7 h; the area under the curve for 0-8 h was on average about 10 mg x h/L. Plasma pharmacokinetics of ritipenem and metabolites were time-independent. A decrease of ritipenem renal clearance (87 versus 132 mL/min) and a slight increase in the amount of metabolites excreted in urine were observed following repeated dosing.

Antimicrobial effects of continuous versus intermittent administration of carbapenem antibiotics in an in vitro dynamic model

In an in vitro dynamic model we compared the antimicrobial effects of two carbapenems, imipenem (MIC, 1 microg/ml) and meropenem (MIC, 0.25 microg/ml) on Pseudomonas aeruginosa. The antibiotics were administered either as short-time infusions once or three times a day or as continuous infusions with steady-state levels ranging from 0.5 to 20 microg/ml. From the resulting kill curves the period of time until the onset of bacterial death (dt), the rate constant of bacterial death (ka), the maximal reduction of CFU (mr), and the period of time until bacterial regrowth occurred (tr) were determined. Additionally, the occurrence of bacterial resistance during the simulations (rq) and the postantibiotic effect (PAE) were recorded. For both investigated carbapenems no significant difference in dt, ka, mr, and PAE values between the short-time infusions and continuous infusions with steady-state levels above 2 microg/ml could be detected. The tr was longest with continuous infusions of over approximately 24 h, corresponding to steady-state levels of 3 microg/ml for imipenem and 2.5 microg/ml for meropenem. An increase in MIC was observed only during continuous infusions with steady-state levels below 2 microg/ml. Independent of the chosen method of application and despite the lower MIC of meropenem, imipenem was slightly more effective than meropenem.

Pharmacodynamics of antimicrobial agents and rationale for their dosing

Antimicrobial pharmacodynamics are an area of considerable importance in terms of dose regimen optimisation and clinical outcome. The pharmacodynamic properties of penicillins, cephalosporins, carbapenems, quinolones, glycopeptides and aminoglycosides are reviewed; the impact such knowledge may have in the future on how we dose these agents is discussed.

Determination of a new carbapenem derivative, DA-1131, in plasma and urine by high-performance liquid chromatography

A high-performance liquid chromatographic method was developed for the determination of a new carbapenem, DA-1131 (I), in human plasma and urine and in rat blood and tissue homogenates. The method involved deproteinization of the biological samples with 1 volume each of 0.04 M Ba(OH)2 and ZnSO4 aqueous solution. A 50-microliters aliquot of the supernatant was injected onto a C18 reversed-phase column. The mobile phase employed was 0.015 M KH2PO4-acetonitrile (9:1, v/v) with a pH of 5.0. The flow-rate was 0.8 ml/min. The column effluent was monitored by a ultraviolet detector at 300 nm. The retention time of I was 8.0 min. The detection limits of I in human plasma and urine were 0.1 and 0.5 micrograms/ml, respectively. The coefficients of variation of the assay were generally low (below 8.39%) for human plasma and urine, and rat blood and tissue homogenates. No interferences from endogenous substances were observed.

High-performance liquid chromatographic assay for meropenem in serum

High-performance liquid chromatographic procedures have been developed for the measurement of meropenem in serum. The separation was performed on an Ultrasphere XL-ODS analytical column (75 x 4.6 min I.D.). The mobile phase consisted of 10.53 mmol/l ammonium acetate-acetonitrile (95:5, v/v) (pH 4). The UV detection was at 298 nm. The quantitation limit both in serum and water was 0.25 micrograms/ml. The method was validated in serum and aqueous solution over the concentration range 0.25-50 micrograms/ml. The extraction recovery from serum spiked with meropenem was 99.7 +/- 3.4%. The intra- and inter-assay coefficients of variation were below 6%. Stored at -80 degrees C for three months at various concentrations in serum and in aqueous solution, meropenem did not reveal any appreciable degradation. After 24 h, it was also stable at 4 degrees C in serum, aqueous solution and supernatant of extraction but not at room temperature. The stability of the drug was also confirmed in serum after repeated freezing-thawing cycles at -80 degrees C on four consecutive days.

Species specificity of 2-aryl carbapenem-induced immune-mediated hemolytic anemia in primates

L-695,256 is a novel 2-fluorenonyl carbapenem antibiotic with significant antimicrobial activity against strains of methicillin-resistant Staphylococci. This prototype compound was administered intravenously to rhesus monkeys (Macaca mulatta) at does of 50 or 200 mg/kg/day for 2 weeks to assess toxicity and found to induce a hemolytic anemia characterized by extravascular hemolysis and splenomegaly. A subsequent study in this species in which 100 mg/kg/day was administered i.v. for 4 weeks showed that all animals were direct antiglobulin test (Coombs' test) positive for IgG with 20-25% reductions in the erythron. Following 3 weeks of recovery, the erythron had returned to normal, although it took an additional 2 months for the Coombs' test to become negative. Challenge of these same animals with 0.5 million U/kg (300 mg/kg/day) of penicillin intravenously indicated no apparent cross-reactivity. Since attempts to establish a model for this immune-mediated hemolytic anemia with this drug in rats or mice were unsuccessful, a 2-week i.v. study in squirrel monkeys (Saimiri sciureus) was conducted at a dose of 200 mg/kg/day. All animals in this study remained Coombs' test negative with no changes in the erythron, suggesting an increased sensitivity to beta-lactam-induced anemia in rhesus monkeys compared to other species. Further support for this hypothesis was obtained using the cephalosporin antibiotic, cefotetan. This compound induced a high incidence of Coombs' test positive hemolytic anemia at clinically relevant doses in rhesus monkeys, despite a very low incidence of this adverse effect in patients with many years of clinical use. These data suggest that although rhesus monkeys respond in a qualitatively similar manner to humans with regard to high doses of beta-lactam antibiotics, their sensitivity may overestimate the risk of immune-mediated hemolytic anemia for clinical use.

[Multicenter comparative study of meropenem vs. imipenem in the intramuscular treatment of hospital infections of the urinary tract]

A clinical, multicentre, randomised, comparative study in 283 adult hospitalized patients was carried out to assess efficacy of meropenem in the treatment of complicated and non-complicated urinary tract infections, in comparison to imipenem/cilastatin. Both antibiotics were administered intramuscularly, at a dose of 500 mg bid. The two groups were homogeneous, as regards the distribution between male and female, the mean age of the patients, the severity of infections and the mean duration of treatment. Clinical results were assessed at the end of therapy and follow-up (4-6 weeks). Bacteriological results were assessed at 5-9 days post-treatment and at follow-up. As regards clinical and bacteriological results patients showing a satisfactory response rate were compared, at the end of the treatments using a Chi square test. With both treatments high satisfactory clinical and bacteriological response rates were seen. As regards clinical satisfactory responses (97% of meropenem assessable patients versus 90% of imipenem/cilastatin assessable patients), there was a statistically significant difference in favor of meropenem. The bacteriological outcome was successful (eradication) for 75% of assessable patients in each group. Most failures were seen in the complicated infections, even when pathogens usually sensitives to carbapenemics were initially isolated. Safety was good with both drugs; no withdrawals in any group of treatment was seen because of side effects. The local tolerance of meropenem was globally rated as good.

Penetration of meropenem into heart valve tissue

Thirty-three patients requiring cardiac valve surgery were administered meropenem 1000 mg by a 5 to 10 min iv injection. Samples of blood, cardiac valve and atrial muscle tissue were removed at valvectomy and analysed for meropenem by high performance liquid chromatography (HPLC) with UV detection. The plasma concentrations observed in the samples from these patients were higher than those reported when meropenem 1000 mg was administered to healthy volunteers by 5 min iv injection. No clinical adverse events attributable to meropenem were reported and the single 1000 mg dose was well tolerated. The penetration of meropenem into cardiac muscle and valve tissue was rapid and in excess of that expected solely on the basis of distribution into extracellular fluid. The concentrations achieved in the tissues were in excess of the MICs of the pathogens commonly causing endocarditis.

Carbapenems

Carbapenems are broad-spectrum beta-lactam antibiotics that cover an absolute majority of all bacterial pathogens that possess a cell wall. The only clinically important exceptions are X. maltophilia, E. faecium, and some strains of methicillin-resistant staphylococci and penicillin-resistant pneumococci. So far, after several years of clinical use of imipenemcilastatin, emergence of resistance has been a problem mainly restricted to P. aeruginosa. The pharmacokinetics of carbapenems, especially imipenem, are complicated by the renal metabolism, necessitating the imipenem-cilastatin combination. This is not required for meropenem. The safety profile of carbapenems is favorable. With imipenem-cilastatin, nausea constitutes a practical problem in that administration times may have to be prolonged. The risk for neurologic reactions with imipenem-cilastatin has become a factor reducing the possibilities to use high doses. For all indications except bacterial meningitis, the now approved maximal dose of 4 g per day should suffice. In this respect, meropenem has an advantage over imipenem-cilastatin in that it can be used in the treatment of bacterial meningitis without apparent increased risk of seizures. Carbapenems are indicated mainly as empiric monotherapy in serious infections, such as intra-abdominal infections and infections in neutropenic patients. Combinations of carbapenems and other antibiotics should not be used routinely.

A comparison of the pharmacokinetics of meropenem after administration by intravenous injection over 5 min and intravenous infusion over 30 min

The pharmacokinetics of meropenem were determined in healthy volunteers after intravenous injection over 5 min or iv infusion over 30 min. Five volunteers received meropenem 500 mg and six volunteers received 1000 mg. For both doses, administration over 5 rather than 30 min doubled the plasma concentrations observed at the end of the dosing period. Comparison of the other data derived from the two modes of administration indicated that rapid administration of meropenem did not appreciably alter its disposition pharmacokinetics. Plasma clearance, renal clearance, non-renal clearance, terminal half-life and volume of distribution were unchanged. Within 1 h of dosing, the plasma concentrations were very similar indicating that dosing over either time period would result in similar antimicrobial cover and thus should not affect efficacy. There were no changes in tolerability of meropenem associated with more rapid administration.

Safety and efficacy of meropenem in hospitalised children: randomised comparison with cefotaxime, alone and combined with metronidazole or amikacin. Meropenem Paediatric Study Group

In this multicentre, randomised study of 170 children hospitalised with bacterial infections, meropenem (10 to 20 mg/kg every 8 h) was found to be as effective and as well tolerated as cefotaxime (100 to 150 mg/kg/day), with or without amikacin or metronidazole. Most drug-related adverse events were mild and self-limiting. Neither regimen was associated with seizures. The overall incidence of clinically significant laboratory changes was similar in the two treatment groups. Satisfactory clinical responses were obtained in 94/96 (98%) patients treated with meropenem monotherapy and 43/46 (93%) children treated with cefotaxime regimens, while satisfactory bacteriological responses were obtained in 25/28 (89%) and 9/10 (90%) patients, respectively. Meropenem monotherapy appears to be a well-tolerated and effective drug for paediatric infections.

Intramuscular meropenem in the treatment of bacterial infections of the urinary and lower respiratory tracts. Italian Intramuscular Meropenem Study Group

In three open, multicentre, prospective randomised studies, the efficacy and safety of meropenem were assessed and compared with ceftazidime (Study 1) and imipenem/cilastatin (Studies 2 and 3) in 864 patients; 417 with urinary tract infections (UTI) and 447 with community acquired lower respiratory tract infections (LRTI). All the antibiotics were administered by intramuscular injection. Clinical and bacteriological responses were assessed at the end of therapy and at follow-up (2-4 weeks for LRTI, 4-6 weeks for UTI). The clinical response rate in UTI at the end of therapy was 93-100% for meropenem 500 mg tds compared with 94-95% for ceftazidime 500 mg tds; for meropenem 500 mg bd it was 97%, significantly higher than that for imipenem/cilastatin 500 mg bd which was 90% (P = 0.03). At follow-up, the response rates were 90% for meropenem tds compared with 81-85% for ceftazidime 500 mg tds and 81% for meropenem bd compared with 78% for imipenem/cilastatin 500 mg bd. The clinical response rate in LRTI at end of therapy was 93% for meropenem 500 mg tds, compared with 92% for ceftazidime 1 g tds; for meropenem 500 mg bd the clinical response rate was 96%, compared with 91% for imipenem/cilastatin 500 mg bd (P = 0.054). At follow-up, the clinical response rates were 96%, 89%, 93% and 96%, respectively. The bacteriological response rates at 5-9 days post-therapy in UTI were 61-84% in patients treated with meropenem 500 mg tds, compared to 73-82% in patients treated with ceftazidime 500 mg tds; the rates for meropenem 500 mg bd and imipenem/cilastatin 500 mg bd were each 75%. At follow-up, the response rates were 40-72%, 57-70%, 51% and 49%, respectively. In LRTI, bacteriological response rates at the end of therapy were 91% for both meropenem 500 mg tds and ceftazidime 1 g tds, and 91% for meropenem 500 mg bd compared with 86% for imipenem/cilastatin 500 mg bd. At follow-up, the response rates were 87%, 77%, 84% and 79%, respectively. All treatments were well tolerated. In these studies, intramuscular meropenem proved to be an effective and well tolerated treatment for LRTI and UTI.

Safety profile of meropenem: international clinical experience based on the first 3125 patients treated with meropenem

Data from 3125 patients (3220 patient exposures) treated with meropenem were compared with those from 2886 patients (2960 patient exposures) treated with a variety of comparator agents including cephalosporins (alone or in combination with aminoglycosides or an anti-anaerobe agent) and imipenem/cilastatin. Patients treated included those with bacterial infections of the lower respiratory tract, urinary tract and skin and soft tissues, abdominal, obstetric and gynaecological infections, meningitis, febrile episodes in neutropenic patients and paediatric patients with infections. In three studies, meropenem was administered intramuscularly; in the remainder, meropenem was given by 15-30 min iv infusion or by bolus injection over approximately 5 min. The usual dosages were 500 mg or 1 g 8 hourly in adults and 10 or 20 mg/kg 8 hourly in children. In bacterial meningitis, the meropenem dosage in adults was 2 g 8 hourly and 40 mg/kg 8 hourly in children. The overall pattern and frequency of adverse events with meropenem were similar to those of the other beta-lactam antibiotics with which it was compared. The most frequently reported adverse events were diarrhoea, rash, nausea and vomiting, thrombocytosis, eosinophilia and changes in hepatic biochemistry. Abnormal laboratory tests occurred with similar frequencies between meropenem and the comparator agents. The safety profile of meropenem was similar in adults and children, and the presence of renal impairment did not alter the safety profile of meropenem. Experience in clinical studies in 3220 patient exposures has revealed no unusual or unexpected toxicity. The possibility of administration by either iv infusion or bolus injection with a low incidence of nausea and vomiting also provides flexibility in the clinical management of patients. Moreover, the low incidence of reported seizures and good tolerability at high doses, make meropenem particularly useful for the treatment of meningitis and other indications which carry a risk of seizures, or in the treatment of serious infections where high doses of antibiotics are frequently indicated.

[New approaches in the use of antibiotics in the treatment of postoperative intra-abdominal infections]

The authors present the results of a clinical investigation on the therapeutic use of carbapenem, imipenem/cilastatin in 20 patients operated on account of intraabdominal inflammatory affections, hospitalized at the intensive care unit of the Surgical Clinic of the Third Medical Faculty, Charles University, Prague in 1993. Imipenem/cilastatin was administered to patients during surgery--500 mg i.v.--and subsequently after 8--hour intervals for 5-8 days. During comprehensive treatment no superinfection developed and the patients recovered.

[Clinical study of SY5555 dry syrup in the pediatric field]

SY5555 dry syrup (powder to be dissolved before use) was clinically used in pediatric patients. The following results were obtained: 1. The subjects were 6 pediatric patients including 1 case each with pharyngitis, tonsillitis, lacunar tonsillitis and impetigo contagiosa and 2 cases with scarlet fever. The drug was administered at a daily dose of 14.5-29.0 mg/kg divided into 3 dosages. The clinical results were excellent in 5 cases and good in 1 case with an efficacy rate of 100%. 2. Identified bacteria included 3 strains of Haemophilus influenzae, 2 strains of Streptococcus pyogenes and 1 strain of Staphylococcus aureus. Five strains were eradicated but 1 strain still remained with an bacteriological eradication rate of 83.3%. 3. No side effects were observed throughout the study period. In laboratory test results, elevated eosinophil count was observed in only 1 case. 4. Patients' compliance was good in general. 5. Based on the results mentioned above, the drug was considered to be a useful new oral antibiotic in the pediatric field.

[Clinical and laboratory studies on SY5555 in pediatric infectious diseases]

Clinical effects of SY5555 dry syrup, a new oral penem antibiotic, were analysed in 20 children with various bacterial infections. Ages of the patients varied from 8 months to 14 years. Doses of SY5555 were varied from 12.8 mg/kg/day to 30.5 mg/kg/day, and it was administered in 3 divided dosages. Clinical efficacy rates were as follows; 6/7 in acute bronchitis, 5/5 in pharyngotonsillitis, 3/3 in acute otitis media and 2/2 in cystitis and 3/3 in impetigo contagiosa. The overall rate was 95.0% (19/20). Bacteriologically, eradications were obtained with 1/2 strains of Streptococcus pyogenes, 3/3 of Staphylococcus aureus, 1/1 of Haemophilus influenzae, and each of Staphylococcus epidermidis, Haemophilus parainfluenzae, coagulase-negative staphylococci and Serratia marcescens. Diarrhea was observed in 1 patient. And elevated eosinophiles or GPT was observed in one patient each. In vivo pharmacokinetics of SY5555 was examined in 2 cases. Peak plasma levels were observed at 1 hour after dosage in one patient and at 2 hours in another upon oral administration of 8.3 mg/kg of SY5555, and peak levels were 2.44 and 1.38 micrograms/ml respectively. Half-lives of SY5555 were 1.39 and 0.59 hr. Concentrations of SY5555 in urine after administration were 70.2 (2-4 hrs.) to 91.0 (0-5 hrs.) micrograms/ml, respectively. SY5555 dry syrup is considered as an useful and safe antibiotic in treating the infectious diseases in children.

[Bacteriological and clinical studies of SY5555 in pediatric field]

Clinical studies were carried out on SY5555, a new oral penem, in the field of pediatrics. The results obtained are summarized below. The clinical efficacies were examined in a total 31 patients consisting of 4 patients with pharyngitis, 10 with purulent tonsillitis, 4 with scarlet fever, 7 with impetigo, one with balanitis, one with cellulitis and 4 with UTI. The clinical efficacy rate was 96.8% (30/31). Bacteriological efficacies of SY5555 were examined on identified pathogens including 7 strains of Staphylococcus aureus, 6 of Streptococcus pyogenes, 3 of Enterococcus faecalis, 3 of Haemophilus influenzae, one of Escherichia coli and one of Citrobacter freundii. The bacteriological eradication rate was 81.0%. As for side effects, loose stool in one patient was noted. Abnormal laboratory findings test results included eosinophilia in 2 patients, eosinophilia and elevation of serum transaminase in one patient, and thrombocytosis in another.

[Pharmacokinetic and clinical studies on SY5555 dry syrup in children]

SY5555 is a new oral penem antibiotic. Pharmacokinetic and clinical studies using SY5555 dry syrup (powder which is dissolved before use) were performed in pediatric patients. 1. Pharmacokinetic investigation Peak plasma concentrations of SY5555 after dose of 5 mg/kg, 10 mg/kg and 15 mg/kg were, respectively, 1.58 +/- 0.37 micrograms/ml, 2.78 +/- 0.54 micrograms/ml and 5.28 micrograms/ml at 1 hour. The average half-life with 5 mg/kg administration was 0.94 +/- 0.05 hours, that with 10 mg/kg was 1.46 +/- 0.31 hours and that with 15 mg/kg was 0.88 hours. 2. Clinical investigation Enrolled in the study were 15 patients including 5 with acute otitis media, 5 with urinary tract infections and 1 each with pharyngitis, tonsillitis, bronchitis, pneumonia and subcutaneous abscess. Responses were excellent in 4 patients, good in 8 patients, fair in 2 patients and poor in 1 patient. In the assessment of the bacteriological efficacy, 8 out of 10 strains of organism identified previous to treatment were eradicated and 2 strains were unchanged, hence the eradication rate was 80.0%. 3. No adverse reactions attributable to the drug were observed and good drug compliance were obtained. From the above results, it has been concluded that SY5555 is a highly effective and safe agent for mild to moderate respiratory and urinary tract infections in children.

[Pharmacokinetic, bacteriological and clinical studies of SY5555 in the pediatric field]

Pharmacokinetic, bacteriological and clinical studies on SY5555, a new oral penem, were carried out, and the following results were obtained. 1. MICs were determined for 6 drugs, SY5555, clavulanic acid/amoxicillin (CVA/AMPC), cefaclor (CCL), cefotiam (CTM), cefpodoxime (CPDX), cefdinir (CFDN) against 20 strains of bacteria isolated from patients who were subsequently treated with SY5555. MICs of SY5555 for Gram-positive cocci ranged from 0.05 to 0.10 microgram/ml against 10 strains of Staphylococcus aureus. The MIC was < or = 0.025 microgram/ml against one strain of Streptococcus pyogenes, and MICs were from < or = 0.025 to 0.39 microgram/ml against Streptococcus pneumoniae. These MIC values were equivalent or superior to those of the other 5 drugs. MICs of SY5555 for Gram-negative bacilli were 0.39 and 6.25 micrograms/ml against Haemophilus influenzae, and these values were equivalent to those of the other drugs, except CPDX. The MIC of SY5555 was 0.39 microgram/ml against 2 strains of Escherichia coli, and this value was equivalent or superior to those of CVA/AMPC and CCL, similar or inferior to those of CPDX and CFDN, and inferior to that of CTM. The MICs of several drugs were determined for 10 strains of Bordetella pertussis and 30 strains of Campylobacter jejuni isolated from patients before this clinical study. The MICs of SY5555 against the 10 strains of B. pertussis were compared with those of 7 drugs, CCL, CTM, CPDX, ampicillin (ABPC), piperacillin (PIPC), imipenem (IPM) and erythromycin (EM). The MIC of SY5555 was 0.78 microgram/ml against all of the strains. This value was superior to those of CCL, CTM and CPDX, similar or inferior to that of IPM and inferior to those of PIPC and EM. The MICs of SY5555 against the 30 strains of C. jejuni were compared with those of 7 drugs. CCL, CTM, CPDX, CFDN, ABPC, IPM and EM, and the MIC of SY5555 was < or = 0.025 microgram/ml or 0.05 microgram/ml and these values were equivalent or superior to those of the 7 reference drugs. 2. SY5555 dry syrup was administered orally at 30 min. after meals, to a total of 5 patients, at doses of 5.0 and 10.0 mg/kg to 2 patients each and at a dose of 15.0 mg/kg to one patient and the plasma concentrations were determined. Peak concentrations were detected 1 to 3 hours after administration in all patients and the peak concentrations were 0.93 and 1.21 micrograms/ml at the 5.0 mg/kg dose, 2.85 and 5.49 micrograms/ml at the 10.0 mg/kg dose and 5.79 micrograms/ml at the 15.0 mg/kg dose.(ABSTRACT TRUNCATED AT 400 WORDS)

[A clinical evaluation of SY5555 in the treatment of pediatric infections]

1. SY5555 dry syrup (powder which is dissolved before use) was administered to 25 patients with bacterial infections (6 cases of bronchitis, 2 cases of bronchopneumonia, 1 case of pertussis, 3 cases of scarlet fever, 5 cases of tonsillitis, 3 cases of urinary tract infections, 2 cases of staphylococcal scalded skin syndrome, 1 case of impetigo, 2 cases of purulent lymphadenitis). 2. Clinical efficacies were excellent in 11 patients and good in 13, poor in 1 with an efficacy rate of 96.0%. As pathogenic organisms, 15 strains were identified and 14 of them were eradicated with eradication rate of 93.3%. 3. No side effects were observed. As for abnormal laboratory test results increase in eosinophiles in 2 cases, decrease in filamented neutrophiles in 1 case, elevation of GOT and GTP in 1 case and elevation of GPT and gamma-GTP were observed. 4. There was no rejection incidence of the drug during the therapy. From the above results, we consider SY5555 in dry syrup form to be a useful and safe drug in the treatment of various bacterial infections in pediatric patients.

[Clinical studies on SY5555 in pediatrics]

SY5555 in dry syrup (powder which is dissolved before use) or tablet form was given orally to 21 children with acute bacterial infections including 4 with acute pharyngitis, 5 with acute tonsillitis, 7 with acute bronchitis, 2 with acute gastroenteritis, 1 each with scarlet fever, acute lymphadenitis and urinary tract infection. Good to excellent clinical responses were obtained in all of the 21 patients and 8 of 11 strains found as causative organisms in these cases were eradicated and 3 strains were decreased. Loose stools were observed in 3 cases and eosinophilia was observed in 1 case. From the above clinical results, it appears that SY5555 is a useful antibiotic for the treatment of pediatric patients with various bacterial infections.

[Clinical evaluation of a new oral penem, SY5555, in infants and children]

A clinical study was performed on SY5555, a newly developed penem antibiotic, in children. SY5555 was given orally to 14 patients at 19-29 mg/kg/day in 3 doses for 4 to 12 days. Clinical evaluations were made on the 14 patients including 4 with pharyngitis, 7 with tonsillitis, one with urinary tract infection, and 2 with impetigo. Overall clinical effects were excellent in 2, good in 12, with an efficacy rate of 100%. Causative organisms (Staphylococcus aureus and Streptococcus pyogenes) were all eradicated. As to adverse reactions, mild diarrhea was observed in 4 patients. These data suggest that SY5555 is a useful oral antibiotic for the treatment of bacterial infections in children.

[Fundamental and clinical studies of SY5555 in pediatrics]

We assessed the in vitro antimicrobial activity and the clinical efficacy and safety of SY5555 in the field of pediatrics. The results obtained are summarized below. 1. In vitro antibacterial activities of SY5555 against 52 clinical isolates were compared with those of clavulanic acid/amoxicillin (CVA/AMPC), cefotiam (CTM), cefpodoxime (CPDX), cefaclor (CCL) and cefdinir (CFDN). Against Gram-positive bacteria, including Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes, SY5555 displayed antimicrobial activities superior or nearly equivalent to those of the reference agents used in the study. In cases of Gram-negative bacteria, the antimicrobial activity of SY5555 against Haemophilus influenzae was inferior to those of CPDX and CFDN. Against Klebsiella pneumoniae, the antimicrobial activity of SY5555 was less potent than that of CPDX. 2. Forty-seven children with infectious diseases were treated with SY5555 dry syrup (powder dissolved just before use). The clinical results were excellent in 24 and good in 16, with an efficacy rate of 85.1%. 3. Bacteriological screening identified 30 pathogenic organisms, and the eradication rate was 76.7%. 4. Side effects consisted of diarrhea in 12.5% (6 cases), loose stools in 4.2% (2 cases) and urticaria in 2.1% (1 case) of the patients. The only abnormal laboratory test value observed was an increase in eosinophil count in one child. 5. The palatability of SY5555 dry syrup was very good; it was very easily ingestable or easily ingestable by 32 of the 48 children. From the above results, SY5555 dry syrup appears to be a useful drug with a preferable safety profile in the treatment of pediatric patients with infectious diseases.

[Studies on SY5555 in the field of pediatrics]

SY5555, a new oral penem, in the form of dry syrup (powder which is dissolved before use) was evaluated for its pharmacokinetics and clinical efficacy in pediatric patients. Oral administration of 5 mg/kg and 10 mg/kg of SY5555 in dry syrup resulted in respective maximum plasma concentrations of 1.08 +/- 0.38 micrograms/ml (n = 4) and 2.50 +/- 1.81 micrograms/ml (n = 4), half-lives (T 1/2) of 2.72 +/- 1.86 hours (n = 3) and 1.14 +/- 0.88 hours (n = 4), and urinary excretion until 6 hours of 4.7% (n = 1) and 3.86 +/- 2.01% (n = 4). Clinical efficacy was evaluable in 22 patients, and the overall efficacy rate was 100%. As for bacteriological efficacy, all 5 strains of pathogenic organisms identified were eradicated (eradication rate, 100%). No remarkable adverse reactions or abnormal laboratory values were observed.

[Clinical studies on SY5555 in the field of pediatrics]

Clinical studies on SY5555 dry syrup, a new oral penem antibiotic, were carried out in the field of pediatrics. The following results were obtained. 1. SY5555 was administered to 10 children with various bacterial infections (2 patients with acute tonsillitis, 2 with acute bronchitis, 1 with pharyngitis, 2 with scarlet fever, 1 with pertussis and 2 with urinary tract infections). The overall clinical efficacy rate was 90%. 2. Side effects or abnormal laboratory test values were not observed except for loose stool in 1 and eosinophilia in 1.

[Clinical evaluation of a new oral penem, SY5555, in the pediatric field]

A new oral penem antibiotic, SY5555, was evaluated for its safety and efficacy in 35 children with various bacterial infections. SY5555 was effective in 100% of scarlet fever, pharyngotonsillitis, pneumonia, otitis media, bacterial diarrhea, urinary tract infections and skin and soft tissue infections. The etiologic bacteria were eradicated except Salmonella sp. Side effects were observed in 3.5% cases; one was diarrhea and Candida dermatitis, one was loose stool, and one was Candida dermatitis. From these data, SY5555 is thought to be a safe and effective antibiotic in the pediatric field. Regular dose of suspension preparation is 15 mg/kg/day in 3 divided dosages, and when needed the dose may be doubled.

[Clinical studies on SY5555 in pediatric infections]

Pharmacokinetic and clinical studies on SY5555, a new oral penem antibiotics, were performed in pediatric infections and the following results were obtained. 1. Pharmacokinetics studies Pharmacokinetics of SY5555 was studied in 5 children (5y1m-10y11m) using doses of 5 mg/kg (n = 3) and 10 mg/kg (n = 2). The average peak plasma levels were 0.65 microgram/ml at 1 or 2 hours after administration of 5 mg/kg and 2.12 micrograms/ml at 1 or 2 hours after administration of 10 mg/kg, and the plasma half-lives were 0.81 and 1.08 hours, respectively. Average cumulative urinary recovery rates at 0-6 hours were 2.97 and 3.96%, respectively. 2. Clinical studies SY5555 was administered to 45 patients with various infectious diseases (2 with acute pharyngitis, 8 with acute tonsillitis, 4 with lacunar tonsillitis, 3 each with acute bronchitis, pneumonia and pertussis, 7 with scarlet fever, 3 with impetigo contagiosa, 6 with acute urinary tract infections, 2 with balanoposthitis and 1 each with cervical lymphadenitis, S.S.S.S., vulvitis and acute colitis) at daily doses between 3.4-10 mg/kg, t.i.d., for 3-14 days. Clinical responses were excellent in 27 patients, good in 15 patients, fair in 1 patient, and poor in 2 patients, and the efficacy rate was 93.3%. Causative organisms were examined and 39 strains of 11 species were identified. The eradication rate was 78.9%. Side effects were observed in 1 patient with diarrhea. An abnormal laboratory test value was observed in 1 patient with elevation of eosinophils. The above results suggest that SY5555 may be a very useful and safe drug for the treatment of pediatric infection.

[Fundamental and clinical studies on MIC breakpoint of SY5555 for Enterococcus faecalis in complicated urinary tract infections of moderate severity]

A multicenter clinical study was carried out to investigate the clinical efficacy of SY5555 from viewpoint of its MIC breakpoint for Enterococcus faecalis. SY5555 was administered in dosages of 150 mg x 3/day and 300 mg x 3/day, for 7 days, to patients with complicated urinary tract infections of moderate severity (no indwelling catheter). Based primarily on the bacteriological efficacy (eradication) as the criterion for evaluation, the MIC breakpoint of SY5555 was investigated. SY5555 showed potent antimicrobial activity towards E. faecalis, and its MIC80 value for the clinical isolates of this bacterial species was 1.56 micrograms/ml. Analysis was carried out to determine the extent to which this in vitro activity is corroborated by the drug's clinical efficacy in eradicating E. faecalis. 1. Experimental study In a study employing an experimental model of complicated bladder infections of moderate severity, it was judged that the MIC breakpoints of SY5555 administered at 150 mg x 3/day and 300 mg x 3/day were 2 micrograms/ml and 8 micrograms/ml. 2. Clinical study SY5555 was administered at 150 mg x 3/day (7 days) to six patients and at 300 mg x 3/day (7 days) to 32 patients, and the clinical efficacy of these treatments was investigated. 2.1. Investigation of the clinical MIC breakpoint showed it to be 12.5 micrograms/ml for both the 150 mg x 3/day and 300 mg x 3/day regimens. However, since the number of cases in this study was small, analysis was performed of the data from a large number of cases by including the cases registered in a nation-wide Phase II study of SY5555. That analysis showed the clinical MIC breakpoint for the two dosages to be 3.13 micrograms/ml and 6.25 micrograms/ml. Thus, this analysis of large number of cases yielded clinical MIC breakpoint that are in agreement with the abovementioned experimental MIC breakpoints. 2.2. In the evaluation of the efficacy rate using the UTI drug efficacy evaluation criteria, cases rated as "good" or "excellent" numbered five of the six patients in the 150 mg x 3/day treatment group and 25 of the 32 (78.1%) patients in the 300 mg x 3/day treatment group, or 30/33 (78.9%) cases overall. These efficacy rates are about the same as the 82.0% reported for the nation-wide Phase II study. 2.3. Each of the strains of E. faecalis isolated from the patients was found to be eradicated by the SY5555 treatment: four strains in the 150 mg dosage group (the MIC of each was 3.13 micrograms/ml or less) and 18 strains in the 300 mg dosage group (the MIC of each was 6.25 micrograms/ml or less). Moreover, in both dosage groups, E. faecalis was not found to recur after the SY5555 treatment. 3. Conclusions In consideration of the above findings in the investigations of treatment of patients with complicated urinary tract infections of moderate severity, the following conclusions can be drawn. 3.1. In antimicrobial treatment employing SY5555 in a regimen consisting of 300 mg x 3/day for 7 days, the clinical breakpoint is in the range of 6.25-12.5 micrograms/ml. 3.2. In particular, as would be surmised from the fact that the MIC80 value of SY5555 for E. faecalis isolated is 1.56 micrograms/ml, this drug shows quite strong efficacy in the eradication of E. faecalis from cases of complicated urinary tract infection.

[Pharmacokinetic and clinical studies of SY5555 in the pediatric field. Pediatric Study Group of SY5555]

SY5555, a new oral penem, was pharmacokinetically and clinically evaluated in the pediatric field and the following results were obtained: 1. Pharmacokinetics Pharmacokinetics of SY5555 dry syrup (powder which is dissolved before use) was investigated in 64 children. At a dose level of 3 mg (potency)/kg, Cmax and T1/2 were 0.33 micrograms/ml and 0.95 hours (n = 1), respectively, in the non-fasting state. At a dose level of 5 mg/kg Cmax and T1/2 were 2.09 +/- 1.25 micrograms/ml and 1.20 +/- 1.07 hours, respectively, in the fasting state, and were 1.21 +/- 0.70 micrograms/ml and 1.33 +/- 0.90 hours, respectively, in the non-fasting state. At a dose level of 10 mg/kg, Cmax and T1/2 were 2.96 +/- 1.89 micrograms/ml and 0.89 +/- 0.43 hours, respectively, in the fasting state, and were 2.45 +/- 1.37 micrograms/ml and 1.17 +/- 0.53 hours, respectively, in the non-fasting state. At a dose level of 15 mg/kg, Cmax and T1/2 were 4.30 +/- 2.15 micrograms/ml and 0.82 +/- 0.09 hours, respectively, in the non-fasting state. Data of Cmax and AUC showed that plasma concentration of the drug depended on dose levels. Urinary recovery rates in the first 6 hours were 1.71% (n = 1) in the non-fasting state at a dose level of 3 mg/kg, 4.13 +/- 1.40% in the fasting state and 4.17 +/- 3.29% in the fasting and the non-fasting state, respectively at a dose level of 5 mg/kg, and 6.02% (n = 1) and 4.64 +/- 2.81%, respectively, at a dose level of 10 mg/kg. At a dose level of 15 mg/kg, urinary recovery rate in the first 6 hours was 7.97% (n = 2) in the non-fasting state. 2. Clinical results 1) Dry syrup The clinical efficacy of the SY5555 dry syrup was evaluated in 506 cases. SY5555 was administered at daily doses of 15-30 mg/kg divided into 3 equal doses to most patients. Daily doses of 12- < 18 mg/kg were given to 46.6% of the patients. The overall clinical efficacy rate was 92.9%, and this drug was effective in 93.0% of the 301 patients for whom the causative pathogens were identified, and in 92.7% of the 205 patients with infections for whom the causative pathogens were unknown. The efficacy rate at daily doses of 12 - < 18 mg/kg was 94.5% similar to those obtained at daily doses of 18- < 27 mg/kg (91.7%) or 27- < 33 mg/kg (91.3%). The bacteriological eradication rate was 82.3%.(ABSTRACT TRUNCATED AT 400 WORDS)

Adjunctive antimicrobials in surgery of soft tissue infections: evaluation of cephalosporins and carbapenems

The authors report three trials of B-lactams and carbapenems for soft tissue infections treated on a surgical service: 1) cefmetazole versus cefoperazone, n = 44; 2) cefotetan versus cefoxitin, n = 24; and 3) meropenem versus imipenem, n = 44. A total of 138 hospitalized patients were enrolled with 112 meeting evaluability criteria. Four hundred twenty-three isolates were cultured (mean, three/patient) of which 67 per cent were aerobes and 33 per cent anaerobes. Cure rates for each trial were: 1) 93 per cent; 2) 92 per cent; 3) 100 per cent. Failures were caused by resistant organisms (Streptococcus group D, Bacteroides fragilis and Pseudomonas) appearing in incompletely drained infection sites. Three patients receiving meropenem had adverse effects (headache, nausea) and one receiving cefoxitin (truncal rash). Operative drainage and debridement remain the critical elements in therapy. Agents with longer half lives allowing twice daily dosing (cefmetazole and cefotetan) were as effective and less expensive than multiple doses of short-acting agents. The extended spectrum carbapenems are most useful for severe infections or resistant organisms.

Comparative study of certain antibiotics on epileptogenic property, including (1Rpi, 5S, 6S)-2-[(6,7-dihydro-5H-pyrazolo[1,2-a][1,2,4]triazolium-6-yl)] thio-6-[(R)-1-hydroxyethyl]-1-methyl-carbapenem-3-carboxylate (LJC10627), a carbapenem antibiotic with broad antimicrobial spectrum

The epileptogenic effects of (1R, 5S, 6S)-2-[(6,7-dihydro-5H-pyrazolo[1,2-a][1,2,4]triazolium-6- yl)]thio-6-[(R)-1-hydroxyethyl]-1-methyl-carbapenem-3-carboxylate (LJC10627), a new derivative of carbapenem were studied in comparison with those of imipenem (imipenem/cilastatin), cefazolin and penicillin G. In intraventricular injection in rats, LJC10627 caused no epileptogenic activity at a dose of 32 micrograms. In contrast, imipenem, cefazolin and penicillin G showed dose-related seizure signs, continuous rhythmic spikes or high voltage spike-wave complexes and convulsive behaviors at doses higher than 10 micrograms. After intravenous injection of LJC10627, no epileptogenic signs on the electroencephalogram (EEGs) or in behavioral symptoms were observed, even at a dose of 500 mg/kg in rats and 300 mg/kg in rabbits, respectively. By contrast, imipenem/cilastatin provoked severe seizure patterns characterized by high voltage spikes-wave complex and convulsive behavior, both in rats and rabbits, using the same doses of LJC10627. Cefazolin and penicillin G also induced obvious epileptogenic signs in both rats and rabbits after intravenous injection. From these results, it was concluded that LJC10627, unlike imipenem (imipenem/cilastatin) and cefazolin, dose not elicit epileptogenic activity, and may therefore be safely used for clinical purpose.

Animal pharmacokinetics and interspecies scaling of FCE 22101, a penem antibiotic

The pharmacokinetics of FCE 22101 were studied in rats, rabbits, Cynomolgus monkeys and dogs after intravenous administration. Pertinent pharmacokinetic parameters were determined according to a two-compartment model and correlated among species as an exponential function of body weight, thereby allowing an estimation of pharmacokinetic parameters corresponding to a 70 kg man. Allometric equations, including data on humans reported in the literature, were also established and used to study similarities and differences in the disposition of FCE 22101 among species. The pharmacokinetic profile of FCE 22101 was consistent with the principles of allometry in all animal species studied (and in man) with the exception of the Cynomolgus monkey, in which clearance of FCE 22101 was slower than expected.

High-performance liquid chromatographic method for the simultaneous assay of a new synthetic penem molecule and its salt-forming agent in injectable formulations

Rapid, stability-indicating, reversed-phase high-performance liquid chromatographic method for the direct and simultaneous determination of a new beta-lactam molecule and its salt-forming agent in finished dosage forms was studied for the development of injectable formulations.

Pharmacokinetics in healthy subjects of FCE 22101 and its acetoxymethyl ester, FCE 22891: effect of co-administration of imipenem/cilastatin on the renal metabolism of FCE 22101

The pharmacokinetics of FCE 22101 were studied in eight healthy male subjects who received FCE 22101 intravenously alone or together with imipenem/cilastatin which was given to inhibit dehydropeptidase-I, a renal enzyme metabolizing penem and carbapenem antibiotics. The kinetics of FCE 22101 were also studied following oral administration of its acetoxymethyl ester, FCE 22891. For comparative purposes, the kinetics of imipenem and cilastatin, given alone or together with FCE 22101, were calculated. Intravenously administered FCE 22101 at a dose of 250 mg gave peak plasma concentrations of about 12 mg/l and the plasma half-life was about 60 min. Co-administration of FCE 22101 with imipenem/cilastatin did not affect the plasma kinetics of FCE 22101, nor did FCE 22101 influence the kinetics of imipenem or cilastatin. Cilastatin increased the urinary recovery of FCE 22101 from 17.5% to 53.0% with FCE 22101 alone to 73.2% to 91.8% when it was given with cilastatin. There was a high correlation between the urinary recovery of FCE 22101 in this study and that of imipenem given alone to the same subjects in previous studies; subjects who were high metabolizers of imipenem were also high metabolizers of FCE 22101. When FCE 22891 was given orally at a dose of 500 mg (corresponding to 400 mg of FCE 22101 free acid), peak concentrations of 2.2 to 6.1 mg/l were found. The absorption was rapid with peak concentrations achieved 20 to 80 min after administration. In comparison with imipenem, FCE 22101 seems to undergo less non-renal metabolism.

Comparative in vitro activity of the new oral penem ALP-201 against aerobic and anaerobic bacteria

The in vitro activity of the new penem derivative ALP-201 against 226 aerobic and 350 anaerobic clinical bacterial isolates was determined using agar dilution techniques. For comparison amoxicillin, cefaclor, ceftazidime, doxycycline, erythromycin, imipenem and trimethoprim/sulfamethoxazole were also tested with aerobic bacteria, and cefoxitin, chloramphenicol, clindamycin, imipenem, metronidazole and piperacillin with anaerobic bacteria. ALP-201 was found to be highly active against Escherichia coli, Klebsiella spp., Enterobacter spp., Haemophilus influenzae, Branhamella catarrhalis, Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, anaerobic cocci, Propioni-bacterium acnes, Clostridium perfringens, Bacteroides fragilis, Bacteroides spp. and fusobacteria. Pseudomonas aeruginosa and Clostridium difficile were resistant to ALP-201. When tested against aerobic bacteria using a high inoculum or using the broth dilution technique, the activity of ALP-201 showed little dependence on inoculum size and the bactericidal activity was similar to the inhibitory activity. Further investigations are warranted with ALP-201, which is absorbed from the gastrointestinal tract after oral administration.