[Analysis of multiple cephalosporins in blood and urine by HPLC]

OBJECTIVE

To establish a new high performance liquid chromatography (HPLC) method for determining the concentration of cefazolin, cefradine, cefoperazone and cefotaxime in blood and urine, as well as to investigate its applicability.

METHODS

Protein in blood and urine was precipitated directly by acetonitrile with acetanilide was used as the internal standard using Agilent Zorbax SB-Aq column (250 mm x 4.6 mm, 5 microm). The mixed solvents of water (triethylamine 0.12%, acetic acid 0.12%) and acetonitrile were used as the mobile phase to separate cephalosporins using gradient elution method at 1 mL/min (flow rate) and 254 nm (detection wavelength).

RESULTS

The working curve of four cephalosporins showed a good correlation (r = 0.9993), with the detection limit up to 0.01 microg/mL. The recovery rate was more than 81.2%.

CONCLUSION

This method is fast, easy and accurate. It is suitable for biological analysis of the 4 cephalosporins of the blood and urine in practical cases.

A study of the chemiluminescence behavior of cephalosporins with luminol and its analytical application

The chemiluminescence intensity of luminol-dissolved oxygen was decreased when cephalosporins were mixed with luminol. The decrease chemiluminescence intensity was linear with the logarithm of cephalosporins concentration over the range from nanogram to microgramme level, with the limits of detection at nanogram level. The sensitivities of determination for cephalosporins were in the order of cefoperazone > ceftriaxone > cefuroxime > cefaclor > cefalexin > cefradine. The proposed method was applied to monitor the excretion of cefradine in human urine after taken cefradine capsules. The possible chemiluminescence mechanism and relationship between the determination sensitivities and generations of cephalosporins were also discussed.

Pharmacokinetic study of cephradine in Pakistani healthy male volunteers

To observe and discuss the difference in the pharmacokinetics of cephradine in Pakistani population with the reported data of other ethnic origins. A Single group pharmacokinetic study was conducted having six healthy male volunteers of 20-24 years of age. Blood samples were collected at appropriate times up to 7 hours. Plasma concentrations of cephradine was determined by HPLC technique and pharmacokinetic parameters were determined by both compartmental and noncompartmental methods using Kinetica ver 4.4.1 and Winnonlin ver 5.01. Peak plasma concentration was 11.49+/-1.73 microg/ ml achieved at 0.76+/-0.12 hr, after the administration of 250 mg cephradine to fasting volunteers. Area under the serum concentration-time curve was found to be 16.4+/-1.71 g.hr/ ml. Absorption, distribution, disposition and elimination half lives were calculated as 0.183 +/- 0.038 hr, 0.248 +/- 0.143 hr, 2.126 +/- 0.341 hr and 0.441+/-0.193 hr respectively where as the volume of central compartment and total body clearance were found to be 9.65+/-3.78 L and 15.4+/-1.89 L/hr. The plasma concentration time curves showed the absorption rate constant was 3.968 +/- 0.05 hr(-1), disposition rate constant was 0.333+/-0.05 hr(-1), distribution rate constant was 3.64+/-2.18 hr(-1) and elimination rate constant was 1.738+/-0.468 hr(-1). The value of micro-constants i.e. K(12) (central to peripheral compartment) and K(21) (peripheral to central compartment) were found to be 1.529+/- 1.499 hr(-1) and 0.704 +/- 0.44 hr(-1) respectively, where as MRT and AUMC were calculated as 2.04+/-0.09 hr and 35.92+/-1.86 hr(2) microg/ ml. The findings showed that the results of Pakistani subjects are slightly different when compared with the reported data of other ethnic origin.

A specific and rapid HPLC assay for the determination of cefroxadine in human plasma and its application to pharmacokinetic study in Korean

A specific and rapid high performance liquid chromatographic (HPLC) method with UV detection (254 nm) was developed for the determination of cefroxadine in human plasma. The sample extraction was performed by a simple procedure, vortexing and centrifugation of sample following addition of 60% trichloroacetic acid. Cephalexin was used as an internal standard (I.S.). The HPLC analysis was carried out on a Capcell Pak C18 analytical column with a mobile phase of 50 mM ammonium formate buffer/pH 3.5 and acetonitrile (90:10, v/v). No interference was observed near the peaks of cefroxadine and I.S. The calibration curve was linear over the range of 0.5-40 microg/mL and the lower limit of quantification (LLOQ) was 0.5 microg/mL. The method was validated with excellent sensitivity, accuracy, precision and stability. This assay was successfully applied to determine the pharmacokinetic parameters of cefroxadine in Korean healthy volunteers after an oral administration of two 250 mg cefroxadine capsules. As a result, the plasma half-life was 1.00+/-0.26 h and the mean AUC(0-6 h) was 46.25+/-6.41microgh/mL. The maximum plasma concentration (C(max)) of 17.62+/-4.87 microg/mL reached 1.44+/-0.39 h after administration.

A recirculatory model with enterohepatic circulation by measuring portal and systemic blood concentration difference

The present study describes a recirculatory model for the evaluation of pharmacokinetic characteristics of drugs possessing enterohepatic circulation (EHC). The advantage of the model is to separately define the extent and rate of absorption for the dosage and EHC after oral administration. Cephradine was used as a model drug and was intravenously or orally administered to rats. Portal and systemic bloods were simultaneously collected in order to estimate various local moments after defining the global moments obtained by non-compartment analysis. For the zero-order moments, bioavailability (BA), the hepatic recovery ratio (Fh), the sum of the local absorption ratio for the dosage and recirculatory local absorption ratio for EHC (F(a)po), and the recirculatory local absorption ratio for EHC (F(a)ehc) after oral administration were estimated to be 95.6, 77.9, 172, and 71.5%, respectively. These data indicate that a complete absorption and substantial EHC contribute high oral exposure of cephradine. For the first-order moments, the sum of the mean local absorption times for the dosage and EHC (t(a)po) and the mean transit time for a single pass of EHC (tc) were 2.50 and 0.117 hr, suggesting a rapid EHC of cephradine compared with the absorption from the dosage. With this model, the absorption rate-time profiles for the dosage and EHC were separately simulated by using a program of nonlinear least squares (MULTI) with fast inverse Laplace transform (FILT). The cumulative biliary excretion ratio (Fbile) calculated by the model was in good agreement with the experimental value obtained in the bile ductcannulated rats. These results suggest that the model proposed in this study would be useful for evaluating the extent and rate of ECH along with absorption from the dosage after oral administration of drugs.

Prolonged intestinal absorption of cephradine with chitosan-coated ethylcellulose microparticles in rats

Cephradine-containing ethylcellulose microparticles (MPC) were prepared by the solvent evaporation method. Chitosan-coated MPC (Chi-MPC) were prepared by doping MPC with viscous chitosan solution and subsequently drying. When fluorescein isothiocyanate (FITC)-labeled chitosan-coated ethylcellulose microparticles without drug were administered intraduodenally, they moved slowly in the intestine, that is, most of them were retained at the upper and middle parts of the small intestine for more than 8 h, which is considered due to mucoadhesive properties of coated chitosan. When MPC and Chi-MPC was incubated at 37 degrees C in the JP 14 second fluid, pH 6.8, both released the drug slowly with similar release rates. Cephradine solution and suspension, MPC and Chi-MPC were administered intraduodenally to investigate intestinal drug absorption. Only Chi-MPC suppressed the initial plasma level and maintained the plasma concentration for a long time up to 24 h, suggesting Chi-MPC would be useful for prolonged intestinal absorption of cephradine.

Initial study of using a laminar fluid diffusion interface for sample preparation in high-performance liquid chromatography

This report describes a new microfluidic device called the H Filter for sample preparation prior to HPLC. The H Filters make possible a diffusional transfer of an analyte from a sample stream into a stream of a "receiver" fluid. Existing mathematical models can be used for optimizing experimental conditions. The authors have selected the extraction of the antibiotic cephradine from blood to demonstrate the utility of the new device. The extracts of blood samples spiked with cephradine levels between 0.2 and 100 microg/ml were analyzed using a C8 reversed-phase column and UV detection at 260 nm. The HPLC results were in good agreement with theory. The recovery of 32.2+/-2.8% was uniform over the entire range of cephradine concentrations. The new method completely avoids the use of centrifuges, that is otherwise typical for most current methodologies for the preparation of blood samples prior to HPLC analysis.

Determination of the cephalosporin antibiotic cephradine in human plasma by high-performance liquid chromatography with ultraviolet detection

A simple and sensitive high-performance liquid chromatographic method, for the determination of cephradine in human plasma samples has been developed and validated. Cephradine and cephaloridine (internal standard) were extracted from human plasma by perchloric acid protein precipitation followed by centrifugation. Aliquots of the extracts were analysed by reversed-phase high-performance liquid chromatography (HPLC) utilising a polymeric reversed-phase PLRP-S column, followed by ultraviolet detection at 260 nm. The method has a working dynamic range from 0.2 to 30.0 microg/ml from 200 microl human plasma. The precision of the method at 0.2 microg/ml was 4.9% (intra-assay) and negligible (inter-assay) as calculated by one-way analysis of variance and the accuracy of the method at 0.2 microg/ml was -4.1% in terms of percentage bias. This method has been successfully applied to clinical studies including an oral bioequivalence study comparing the pharmacokinetics of 500 mg tablets of Kefdrin with 500 mg tablets of Velosef in healthy human volunteers.

An alternative approach for assessment of rate of absorption in bioequivalence studies

The partial area method was investigated for evaluation of equivalency in the rate of absorption of immediate release formulations. The applicability of the method was demonstrated with four drugs with different pharmacokinetic/pharmacodynamic characteristics. The confidence interval approach currently employed for bioequivalence determinations was applied to the relevant absorption parameters, including Cmax and partial AUCs. The method was found to be more discriminating than Cmax and/or Tmax in the evaluation of the absorption rate of drugs. The cutoff time or point for partial AUC calculation may vary with the type of drug under study, depending on its clinical use and onset of action. The method was shown to be useful in the assessment of rate of absorption in bioequivalence studies.

Peroral absorption of cefroxadine in patients within the first day after severe trauma: comparison to cefroxadine pharmacokinetics in fasted, healthy volunteers

Peroral absorption of cefroxadine given to 7 24-h fasted trauma patients by nasogastric tube within the first day of admission was compared to that obtained in fasted healthy volunteers. The trauma patients exhibited significantly lower Cmax and reduced AUC. Even though rate and extent of bioavailability cannot be determined from these two different population groups since the total clearance must be assumed to be different in patients and healthy subjects, a reduced bioavailability is assumed based on pathophysiologic reflections.

Pharmacokinetics of cefroxadine after infusion to healthy volunteers

The pharmacokinetics of cefroxadine in healthy human volunteers was studied in plasma and urine, after an infusion administration of 1 g of this drug for 0.5 h. Blood and urine samples were microbiologically quantified by diffusion on solid gelose using Bacillus Subtilis ATCC 6633 as the test organism. Plasma and urine profiles were fitted to a reduced two-compartment model not having inactivating biotransformation as a route of elimination. The parameters of distribution for this model show a rapid disposition (t1/2 alpha = 0.28 h) and an average volume of the central compartment of 0.15 +/- 0.04 l/kg (range 0.20-0.09). The dominant terminal half-life (beta-phase) was 1.17 +/- 0.26 h (range 0.90-1.67). The total body volume 0.41 +/- 0.09 l/kg (range 0.30-0.52) indicates that there is no diffusion of the antibiotic into intracellular fluids of poorly perfused tissues due to its high elimination rate.

Pharmacokinetics of cephradine administered intravenously and orally to young and elderly subjects

The pharmacokinetics of IV and oral cephradine in healthy young male and female volunteers (ages 19 to 25, n = 10) were compared to those of older individuals (ages 65 to 81, n = 9). Subjects received 1 gram of cephradine by a 5-minute intravenous (IV) infusion followed the next day by a 1-gram oral dose. Serial serum and urine samples collected over a period of 12 hours after the dose were analyzed for cephradine concentration by a microbiologic assay. After IV administration, mean serum cephradine concentrations in the elderly group were significantly higher at both 6 hours (1.52 +/- 0.41 mcg/mL) and 8 hours (0.73 +/- 0.22 mcg/mL) than in the young group at 6 hours (0.43 +/- 0.11 mcg/mL). Total systemic clearance was significantly lower (2.64 +/- 0.34 vs. 4.81 +/- 0.59 ml/min/kg) and the elimination half-life was significantly longer (1.71 +/- 0.20 vs 1.12 +/- 0.13 hours) in the elderly group (P = .0001). Systemic cephradine clearance correlated positively with creatinine clearance (r2 = 0.34, P = .0110) and negatively with age (r2 = 0.79, P = .0052). The mean volume of distribution was not significantly different between the two groups. Mean renal clearance was significantly lower in the elderly group (P = .0001), but more than 80% of the dose was excreted in the urine within 6 hours in both groups. After oral administration, the mean peak concentration and time to peak concentration did not differ between groups. The relative oral bioavailability was approximately 94% in both groups. The mean serum concentrations in the elderly were higher at both 6 and 8 hours than in the young group at 6 hours. There were no differences in pharmacokinetic parameters between male and female subjects. Because of reduced cephradine clearance secondary to an age-related decline in renal function, administration of cephradine every 8 hours, rather than every 6 hours, may be sufficient in elderly patients.

Cephradine (Velosef) penetration of mandibular bone

The concentration of cephradine in serum and mandibular bone was assayed in 28 patients undergoing 3rd molar surgery following a single 1 g intravenous injection. Serum and cortical bone samples taken simultaneously, contained mean cephradine concentrations of 42.11 micrograms/ml and 2.61 micrograms/g respectively. These results, when compared with those reported for other bony sites including the femoral head and knee, show a reduced bone penetration with a bone-to-serum ratio of approximately 0.06:1.

Cephradine penetration of mandibular bone

The concentration of cephradine in serum and mandibular bone was assayed in 22 patients undergoing third molar surgery following a single 1-g intramuscular injection. Serum and cortical bone samples taken simultaneously contained mean cephradine concentrations of 12.41 micrograms/mL and 1.25 micrograms/g, respectively. These results, when compared with those reported for other bony sites, including femoral head and knee, show a reduced bone penetration with a bone-to-serum ratio of approximately 0.10:1.

Determination of serum and bone concentrations of cephradine and cefuroxime by HPLC in patients undergoing hip and knee joint replacement surgery

Bone and serum concentrations of cephradine and cefuroxime were measured by HPLC in 21 patients undergoing hip and knee joint replacement surgery. An intravenous dose of 750 mg of each cephalosporin was given to patients at induction of anaesthesia. The serum and bone concentrations of both compounds were similar in individual patients although there was considerable interpatient variation. The mean concentrations in the femoral head bone supernatant in hip replacements were 7.2 mg/kg of cephradine and 8.0 mg/kg of cefuroxime. In knee replacement the femoral condyle bone concentrations were 5.1 mg/kg of cephradine and 4.2 mg/kg of cefuroxime, and for tibial bone 5.6 and 4.6 mg/kg respectively. Both cephradine and cefuroxime diffuse well into bone giving bone concentrations effective against common pathogens such as Staphylococcus aureus and S. epidermidis.

Microbore liquid chromatographic determination of cadralazine and cephalexin in plasma with large-volume injection

The application of microbore systems (15 cm X 1 mm I.D. columns filled with Nucleosil C18, 5 microns particle size) to the determination of cephalexin and cadralazine in plasma was investigated. Factors such as mobile phase flow-rate, detector flow-cell volume and injection volume were examined with regard to the needs of routine drug analysis. Mobile phase flow-rates of 50-60 microliters/min were used. A flow cell with an optical path length of 6 mm and an intermediary volume (2.4 microliters) was selected for UV detection in order to obtain sufficient sensitivity. Large volumes of non-eluting solvent containing the drug were injected on the column. The addition of an ion-pairing reagent to samples containing cephalexin and cefroxadin prior to the injection was found to improve the chromatographic performance. The blood sample size required for analysis with microbore columns was smaller than that with conventional columns. The analysis time was similar and the limit of quantitation was also similar, provided that large sample volumes were injected on the microbore column.

Correlation between plasma and tonsillar levels of cefroxadine

Serum and tonsillary tissue levels of cefroxadine, a new broad-spectrum cephalosporin, proving to be effective in several infections, particularly in the ENT ones, were measured in patients scheduled for tonsillectomy. Twenty patients (12 males, 8 females) aged between 11 and 25 years (mean 18.0 years) were given cefroxadine for 2 days (500 mg every 12 h), and on the 3rd day 500 mg of the drug was given before surgical operation. Tonsillar tissues were taken 2 h after dosing and blood samples before, 1, 2, 4 and 6 h after the drug administration in 8 out of 20 enrolled patients. Cefroxadine concentrations were measured according to microbiological methods. Cefroxadine tonsillary levels were 1.13 +/- 1.73 micrograms/g, approaching the MIC for sensitive bacteria. The time course of plasma levels is superimposable to previous studies. These findings suggest a rapid penetration of cefroxadine in tonsillar tissue and seem to confirm the clinical efficacy of the drug in ENT infections.

Liquid-chromatographic determination of five orally active cephalosporins--cefixime, cefaclor, cefadroxil, cephalexin, and cephradine--in human serum

We report an isocratic "high-performance" liquid-chromatographic (HPLC) procedure for measurement of five orally administered cephalosporins (cefixime, cefaclor, cefadroxil, cephalexin, and cephradine) in 0.1 mL of human serum. Serum protein is precipitated with acetonitrile, the sample is centrifuged, and the supernate is evaporated under nitrogen. The residue is reconstituted in 0.1 mL of mobile phase, and 50 to 80 microL of this is injected onto a reversed-phase Altex Ultrasphere Octyl (C8) column. The five cephalosporins are resolved by elution with a pH 2.6 mobile phase of methanol/monobasic phosphate buffer (20/80) by vol), flow rate 2 mL/min. The column effluent is monitored at 240 nm. Cefixime serves as the internal standard for the analysis of the four other compounds, cephalexin as the internal standard for cefixime. We used two standard curves for all compounds: a low-range curve for concentrations commonly observed clinically and a higher-range curve for higher concentrations. The former were linear from 1.0 to 10 mg/L for cefaclor, cefadroxil, cephalexin, and cephradine and from 0.1 to 1 mg/L for cefixime. The high-concentration curves were linear from 1 to 10 mg/L for cefixime and from 10 to 100 mg/L for the other compounds. The detection limits were 0.1 mg/L for cefixime, 1 mg/L for the other cephalosporins. Mean within-run and day-to-day CVs were always less than 15% for all compounds studied.

One and two doses of cephradine in the prophylaxis of experimental streptococcal endocarditis

The efficacy of cephradine in the prophylaxis of rabbit Streptococcus sanguis endocarditis was investigated. Three days after cardiac catheterization and prior to challenge with S. sanguis, rabbits received either 1000 mg/kg (ten animals) or 500 mg/kg cephradine intramuscularly. Infective endocarditis was prevented in only 30% of the animals. The addition of a second dose of cephradine (100 mg/kg) 8 h after an initial dose of 400 mg/kg did not prevent streptococcal endocarditis in 80% of animals tested. In one or two dose regimens cephradine was found to be inferior to a single 400 mg/kg prophylactic dose of amoxycillin. Cephradine is not recommended for prophylaxis against streptococcal endocarditis.

Qualitative and quantitative analysis of cephradine in biological materials by high performance liquid chromatography

A reversed phase high performance liquid chromatographic method was developed for the determination of cephradine, one of the commonly used antibiotics, in biological materials. Mimic samples for stomach contents, miso soup, were applied to high performance liquid chromatography (HPLC) after centrifugation and purification by Sep-Pak C18 cartridge treatment. Serum samples deproteinized or urine samples diluted were directly injected into the HPLC. The recoveries of cephradine from these materials were 95-97% and the detection limit was 0.01 microgram/injection. This method was applied to the analysis of cephradine in stomach contents obtained by autopsy. After purification by the cartridge treatment, cephradine in the sample was identified and determined by HPLC and further confirmed by thin-layer chromatography (TLC) and mass spectrometry (MS).

Comparison of the pharmacokinetics of cephradine and cefazolin in pregnant and non-pregnant women

The pharmacokinetics of cephradine, a cephalosporin with a low degree of protein binding, was studied in 12 women after oral and intravenous administration of the drug during and after pregnancy. Six of the 12 women also received a cephalosporin with a high degree of protein binding, cefazolin, intravenously during and after pregnancy. For both drugs most pharmacokinetic parameters were altered in pregnancy. The area under the plasma concentration-time curve (AUC) following intravenous administration was smaller for both drugs during as compared to after pregnancy (mean change 39% for cephradine and 31% for cefazolin). Half-lives of both drugs were significantly shorter during compared with after pregnancy (mean change 26% for cephradine and 35% for cefazolin). Consequently, total body clearance was increased during pregnancy. A significant negative correlation between length of gestation and total clearance per kg bodyweight was seen for cephradine. The bioavailability of oral cephradine did not differ significantly during compared with after pregnancy. It is concluded that the dosage of both cefazolin and cephradine should be increased when treating infections in pregnant women in order to obtain the same antibacterial effect as when treating non-pregnant women.

Application of moment analysis in assessing rates of absorption for bioequivalency studies

Moment analysis was utilized in the evaluation of equivalency between test and reference formulations with respect to the rate of absorption for four drugs having different pharmacokinetic characteristics. A confidence interval technique was applied to compare the three relevant absorption parameters, that is, peak plasma concentration (Cmax), time to peak plasma concentration (tmax), and mean absorption time (MAT). Equivalence in the absorption rate of drugs was found to be best evaluated by the combined use of MAT, tmax, and Cmax. Use of these parameters for assessing equivalency requires careful interpretation of the results of statistical analysis as well as appropriate consideration of efficacy and safety issues for individual drugs. In addition, the statistical moment method proves to be useful in the assessment of bioequivalency, particularly for drugs with multiple absorption maxima.

Bone levels of cephradine and cefuroxime after intravenous administration in patients undergoing total hip replacement

A randomised, comparative study is reported of single intravenous doses of cephradine 2 g or cefuroxime 1.5 g given as prophylactic cover for total hip replacements in 40 patients. The serum and bone levels of cephalosporin achieved were higher in the cephradine treated group in proportion to the higher dose employed. Both agents provided adequate bone levels on average, cephradine 25.34 mcg/g, cefuroxime 17.39 mcg/g, although bone penetration was more variable with cefuroxime.

Comparative pharmacokinetics of cefamandole, cefuroxime and cephradine during total hip replacement

Serum, bone and tissue levels of the three cephalosporins, cefamandole, cefuroxime and cephradine were determined in 60 patients given a single 1 g dose intravenously before total hip surgery and two similar doses at 8 h intervals. The levels achieved were comparable for all three antibiotics, hence the choice of prophylactic antibiotic for total hip replacement should be guided by the pathogens causing infection and cost of the antibiotic.

CAPD peritonitis: a prospective randomized trial of oral versus intraperitoneal treatment with cephradine

In a prospective randomized clinical trial 84 peritonitis episodes were treated with cephradine, either orally or intraperitoneally. No difference in treatment outcome between both groups could be demonstrated. In episodes caused by susceptible micro-organisms a good response was seen in 82% in the oral and 82% in the intraperitoneal groups. These clinical findings were supported by the demonstration of adequate cephradine concentrations in serum and dialysate after oral as well as after intraperitoneal administration. Altogether cephradine was given orally or intraperitoneally in 88 episodes of peritonitis as drug of first choice. In 52 a complete cure was obtained, in 36 another antibiotic was subsequently needed as soon as bacterial susceptibility was known. No patient deteriorated appreciably during the delay between the start of cephradine and the switch to another antibiotic. Of the 36 episodes 14, caused by methicillin-resistant Staphylococcus epidermidis, responded well initially to cephradine but relapsed later. Change to another antibiotic effected a complete recovery in all 14 cases. Of the remaining 22 episodes, 14 were cured by the other antibiotic, in eight the catheter had to be removed. Aminoglycosides could be avoided except for ten of the episodes. During peritonitis CAPD was continued, in 71% of the cases on an outpatient basis. Mortality due to peritonitis was absent. We conclude that oral cephradine can be used as drug of first choice in the initial treatment of CAPD peritonitis, because a good initial response was obtained in 66 (52 + 14) i.e. 75% of 88 episodes. However, complete cure by cephradine alone was achieved in only 60%.(ABSTRACT TRUNCATED AT 250 WORDS)

[Study on the transfer of cefroxadine to human tears]

A comparative study to determine the transfer of cefroxadine (CXD), an oral cephem antibiotic, to the human tears was undertaken using cephalexin (CEX) as the control drug. The mean tear levels of 250 mg each of CXD and CEX after oral administration in 6 volunteers were equally peaked at 0.26 micrograms/ml with CXD after 1 to 2 hours and with CEX after 2 hours. The changes of tear levels were also equal for both drugs. The ratios between the tear and the blood levels at 2 hours after oral administration were almost equal with 4.1% for CXD and 3.7% for CEX. From the above evidence it has been confirmed that the both drugs were equivalent with regard to the concentration profiles in human tears after oral medication.

The transfer of cephradine across the placenta

The transfer of maternally administered cephradine (1 g given intravenously) to the fetal circulation and amniotic fluid was investigated in 2 pregnant patients undergoing fetoscopy. Cephradine was detected in fetal serum between 23 and 72 minutes after injection and was present in therapeutic concentrations. Fetal serum levels appeared to peak at approximately 40-50 min. Amniotic fluid levels were rising during the sampling period of 97 min. Cephradine is transferred across the placenta and appears to be a suitable antibiotic for use in selected obstetric patients when penetration of the fetal compartment is desirable.

Relationship between pharmacokinetics and bioavailability of cefroxadine (CGP 9000) and renal function

The pharmacokinetics and bioavailability of cefroxadine were studied in 15 patients with different renal functions after administration of 0.5 g as oral capsules and as intravenous infusions. Microbiological assays by agar diffusion and high-pressure liquid chromatography may both be used for this agent since no metabolite can be found. The bioavailability is near 100% of the oral dose regardless of renal function. Urinary recovery varied from about 50% in renal glomerular filtration rates (GFR) of less than 7 ml/min to nearly 100% in normal renal function. The serum concentrations, serum elimination half-life and total body clearance were significantly influenced by reduced renal function. Nonrenal elimination occurred in reduced renal function; the maximum serum elimination half-life was 24.6 h. Dose modifications according to renal function are suggested with from three doses/24 in normal renal function to one dose/24 h in patients with GFR of 10 ml/min. The relative distribution volume corresponded to approximately 30% of the body weight. Tubular secretion of cefroxadine took place. The concentrations in urine remained above 32 mg/l for 12 h in all subjects regardless of renal function.

Antibacterial effects of cefroxadine, cephalexin and cephradine in a new in vitro pharmacokinetic model

A pharmacokinetic model has been developed, by means of which all possible time courses of the concentrations of antibiotics in the plasma of treated individuals can be exactly simulated in vitro without diluting the test organism and affecting the growth curves. Equieffective concentrations in the system corresponded to the plasma concentrations in man produced by cefroxadine in a single oral dose of 250 mg and cephalexin and cephradine in a single oral dose of 500 mg.

Determination of cefsulodin, cefotiam, cephalexin, cefotaxime, desacetyl-cefotaxime, cefuroxime and cefroxadin in plasma and urine by high-performance liquid chromatography

Closely related methods for the determination of several cephalosporins in plasma and urine are described. Deproteinized plasma or diluted urine is directly injected on a RP-8 or RP-18 bonded-material column. Chromatography is performed either in the reversed-phase or the ion-pair mode. The limits of sensitivity range from 0.4 to 2 mumol of cephalosporins per liter of plasma, and from 20 to 100 mumol per liter of urine. The sensitivity may be improved two to five times by using precolumn loading, direct sample clean-up and automatic injection. The stability of the cephalosporins in plasma, urine and water and the reproducibility and accuracy of the methods are reported.

Pharmacokinetics of cefroxadin (CGP 9000) in man

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.

[Fundamental and clinical studies of cefroxadine in pediatric field (author's transl)]

Fundamental and clinical studies on cefroxadine (CXD) were carried out, and we have obtained the following results. (1) Sensitivity distribution: As for the sensitivity distribution in S. aureus, the peak was within the ranges from 3.13 to 6.25 microgram/ml in the inoculum size of 10(9) CFU/ml, the distribution was less than or equal to 0.1 to 50 microgram/ml in the inoculum size of 10(6) CFU/ml, with the peak at 1.56 to 6.25 microgram/ml. In S. pyogenes, the sensitivity distribution ranged between less than 0.1 and 1.56 microgram/ml, with the peak at 0.1 microgram/ml in the inoculum size of 10(9) CFU/ml. In the inoculum size of 10(6) CFU/ml, however, the all strains were distributed within the ranges of 0.1 to 0.78 microgram/ml, and the growth of 49 out of 54 strains (91%) was inhibited at less than or equal to 0.1 microgram/ml. In E. coli, the sensitivity peak was at 25 to 50 microgram/ml in the inoculum size of 10(8) CFU/ml, and 5 strains (9.3%) were detected with greater than 100 microgram/ml. Of the 5 strains, 1 strain showed cross tolerance with CEX, the remaining 4 strains was at 50 microgram/ml and at 25 microgram/ml in 2 strains each. In the case of inoculum size of 10(6) CFU/ml, the sensitivity distribution was all within the ranges from 0.78 to 12.5 microgram/ml, except for 1 strain at 100 microgram/ml, with the peak being within the ranges from 3.13 to 12.5 microgram/ml. As for the above 100 microgram/ml-strain, it was showing cross tolerance with CEX. (2) Serum concentration: CXD was administered at a dose level of 10 mg/kg and 20 mg/kg between meals to 5 children, and CXD concentration in their serum was measured. In the group of the 10 mg/kg administration: average 30 minutes value; 8.7 microgram/ml, 1 hour value; 9.15 microgram/ml, 2 hours value; 7.4 microgram/ml, 3 hours value; 2.85 microgram/ml, 4 hours value; 1.0 microgram/ml and 6 hours value; 0.32 microgram/ml, with half-life of 0.88 hours. In the group of the 20 mg/kg administration: average 30 minutes value; 11.7 microgram/ml, 1 hour value; 16.8 microgram/ml, 2 hours value; 10.7 microgram/ml, 3 hours value; 8.15 microgram/ml, 4 hours value; 3.33 microgram/ml, 6 hours value; 1.22 microgram/ml, with half-life of 1.03 hours. A significant interrelation in dose response was observed between the 2 groups. (3) CLINICAL RESULTS: Clinical investigation were held in 29 cases (47 boys and 32 girls). Their diseases comprised of 2 acute pharyngitis, 28 acute purulent tonsillitis, 11 scarlet fever, 3 cervical purulent lymphadenitis, 14 acute bronchitis, 7 acute pneumonia, 11 urinary tract infection and 3 skin soft tissue infection. The drug was effective in 74 out of the 79 cases (93.7%). Causative organism was proved in 60 out of the 79 cases. Fifty-five cases (91.7%) were observed bacterial disappearance or reduction in the 60 cases. Side effects were observed in a total of 3 cases (3.8%), i.e. 2 cases of abnormal values in the laboratory findings (an eosinophilia and/or an elevation of the GPT readings) and 1 case of manifestation of exanthema.

[Clinical evaluation of cefroxadine dry syrup in pediatric field (author's transl)]

Clinical evaluation was carried out on cefroxadine dry syrup (containing 100 mg of cefroxadine per 1 g) for child use, and the following results were obtained. 1. Serum levels: Peak serum levels at 1 hour after single administration of CXD 100 mg (9.1 mg/kg) to a 4-year old child (11kg) and 300 mg (12.8 mg/kg) to a 8-year old child (23.5 kg) were 20.32 microgram/ml and 18.75 microgram/ml, respectively. They declined to 0.78 microgram/ml and 0.88 microgram/ml respectively after 6 hours and to undetectable levels after 8 hours. Half-life was 1 hour and 1.2 hours, respectively. CXD has shown the same concentration pattern as CEX, except for the fact that serum levels were peaked after 30 minutes and not detectable after 6 hours. 2. Clinical responses: CXD was administered, for 7 days, to 33 children with scarlet fever in the dosage of greater than or equal 20 approximately less than 60 mg/kg/day (7 children in greater than or equal to 20 approximately 30 mg/kg/day, 21 in greater than or equal to 30 approximately less than 40 mg/kg/day and 5 in greater than or equal to 40 approximately less than 60 mg/kg/day). Clinical responses were excellent in 19 cases and good in 14 cases, with an efficacy rate of 100%. All strains of group A Streptococcus isolated from the pharynx of 22 children were eradicated within 24 hours. In 1 case each of acute pharyngitis, acute tonsillitis, acute laryngotracheitis and staphylococcal scalded skin syndrome, the dosage of greater than or equal to 30 approximately less than 45 mg/kg/day produced a 100% good clinical response and eliminated the causative pathogens. 3. Side effect: Only 2 cases of eosinophilia were observed in hematologic study as well as in hepatic and renal function tests before and after administration.

[Study of cefroxadine in pediatrics regarding clinical efficacy and serum levels (author's transl)]

Basic and clinical evaluations of cefroxadine were carried out in children, and the following results were obtained. 1. Cefroxadine 20 mg/kg was administered to 9 children with heart disease for the prophylaxis against infections before undergoing cardiocatheterization and cardioangiography, and serum levels were determined. Peak levels reached after 30 minutes in 4 of the 9 cases, with a mean peak level of 22.5 mcg/ml and after 1 hour in 5 cases, with a mean peak level of 16.2 mcg/ml. Half life was 3.1 hours in the former group in a 6-hour blood sampling (1.04 hours in a 2-hour sampling) while in the latter group it was 1.37 hours. 2. Clinical responses were evaluated in 56 children comprising 23 cases of pharyngitis, 8 of tonsillitis, 13 of scarlet fever, 10 of urinary tract infections and 2 of impetigo. Fifty of these cases had excellent and good responses showing a efficacy rate of 89.3%. 3. From 42 of the cases, 43 strains were isolated as causative organisms. Major organisms included 27 strains of S. pyogenes, 9 of E. coli and 3 of S. aureus. As for bacteriological responses, all strains were eradicated. 4. No severe side effects were observed except for diarrhea of 1 cases and eosinophilia of 2 cases. Furthermore, no children refused to take cefroxadine dry syrup.

[Clinical evaluation of cefroxadine dry syrup in children (author's transl)]

Clinical efficacy of cefroxadine dry syrup, a new oral cephalosporin antibiotic, was evaluated in children, and the following results were obtained. 1. Three children were given a single oral dose of about 10 mg/kg of the drug when fasting, and its blood concentrations were determined. Blood concentrations were maximum at 30 approximately 60 minutes, i.e., 16.9 approximately 18.2 microgram/ml, and markedly low at 4 hours. 2. Thirty-six patients with the following diseases were tested with 23.1 approximately 44.4 mg/kg/day of the drug in 3 to 4 divided doses; 21 patients with lacunar tonsillitis, 2 with tonsillitis, 1 with scarlet fever, 4 with bronchitis and tonsillitis, 2 with cystitis, 4 with pyelonephritis, 1 with impetigo and 1 with probable Mycoplasma pneumonia. An overall efficacy rate in 35 patients excluding the last mentioned case was 91.4%, i.e., excellent in 20, good in 12 and poor in 3, and an eradication rate of the causative organisms was 88.9%. 3. Adverse reactions noted were diarrhea in 1 patient, eruption and diarrhea in 1 transient neutropenia in 1, eosinophilia in 3 and an elevation of GOT and GPT in 1. None were significant. 4. Taste and flavor of the drug was considered to be well palatable to children. 5. Taking into consideration of the results of fundamental evaluation of the drug, cefroxadine dry syrup is considered to be a potent new antibiotic in children, and the recommended dose will be 10 mg/kg 3 to 4 times a day.

[Laboratory and clinical studies cefroxadine in pediatric field (author's transl)]

Cefroxadine (CGP-9000, CXD) is an orally active cephalosporin which has been newly developed by Ciba-Geigy. Its antibacterial activity against clinically isolated organisms, absorption and excretion after oral administration and clinical responses of patients with infections were studied. Its antibacterial activity against S. aureus and K. pneumoniae was comparable to that of CEX. Against E. coli, it showed slightly stronger activity than CEX. The serum concentrations of CXD was measured in 6 patients given orally 10 mg/kg of it after meals. The peak mean serum level attained 1 hour after administration was 11.66 mcg/ml. Forty-three children with various infections (upper respiratory infections, lower respiratory infections, urinary tract infections, etc.) were given 17 approximately 46 mg/kg (averaged 28.7 mg/kg) of CXD daily. The result was excellent in 26 cases, good in 12 cases, fair in 3 cases, fair in 3 cases and poor in 2 cases, showing an effective rate of 88.4%. Side effect of transient leukopenia and elevation of S-GOT were noticed in 2 cases. However, there were no serious adverse reactions in our study. It is concluded that CXD might be effective in rather mild cases of respiratory or urinary tract infections.

[High-performance liquid chromatographic micro-assay for cefradine in biological fluids (author's transl)]

Recently, cephalosporins have been developed progressively that the clinical experiences in new cephalosporins have been reported one after another; some of them are widely used in daily medicine. The microbiological studies and other metabolic studies; i.e. absorption, distribution, and excretion, have undertaken simultaneously during the clinical trials of new antibiotics. On the other hand, the necessity of the optimum dose regimen for not only antibiotics but also other drugs has been emphasized to achieve the maximum pharmacological effects with minimal dosage or to prevent the side-effects and sequelae. In such cases, the monitoring of the blood level is essential and the drug concentration is necessary to be measured as soon as possible. The chemical assay has an advantage in this point over the bioassay, and has become available for the routine analysis recently. With cephalosporins, the blood and urine levels of cephalothin (CET), cefoxitin (CFX), cephalexin (CEX)(2,3), cefazolin (CEZ)(4), cefuroxime (CXM)(5), cephaloridine (CER)(6) and cefradine (CED)(7) determined by high-performance liquid chromatography (HPLC) have been reported. The author describes a new HPLC method using a reversed phase column which found to be applicable to the routine analysis of CED in serum and urine comparing with bioassay.

[Absorption and excretion of cefradine in healthy volunteers (author's transl)]

From experiments in which cefradine (CED) was orally administered to healthy volunteers in doses of 1,000 mg, 500 mg and successive 250 mg after meal and 500 mg in fasting condition, the following results were obtained. 1) Absorption of CED was rapid in fasting volunteers with peak serum levels at about one hour after administration. On the other hand, the absorption was delayed in non-fasting volunteers with peak serum levels at about 2 approximately 3 hours after administration. Absorbed amounts of CED were proportional to the doses with no effect of meal. 2) Maximum urinary excretion of CED was observed in 0 approximately 2 hour-urine of fasting volunteers and 2 approximately 4 hour-urine of non-fasting volunteers. Total urinary recovery of CED was about 85% in either experiment, showing no effect of meal.

Oral antibiotic therapy of skeletal infections in children

Oral and intravenous (IV) antibiotic regimens were compared in 15 children with etiologically defined osteomyelitis and/or septic arthritis. On admission all children were started on standard IV therapy; seven were changed to oral antibiotics within 72 hours and the remaining eight continued on IV therapy for four weeks. Oral antibiotic doses were adjusted to achieve a peak serum bactericidal titer of greater than or equal to 1:8 against the patient's own pathogen. All patients were treated in hospital for four weeks; therapy continued for a minimum of six weeks or until the erythrocyte sedimentation rate (ESR) fell below 20 mm/hr. The clinical course and outcome were similar in both groups. There were no treatment failures nor any relapses during a 12-month follow-up period. This prospective study supports, with controlled data, the concept that acute skeletal infections can be safely and successfully treated with carefully monitored oral therapy.