Determination of Cefalothin and Cefazolin in Human Plasma, Urine and Peritoneal Dialysate by UHPLC-MS/MS: application to a pilot pharmacokinetic study in humans.

An ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the analysis of cefazolin and cefalothin in human plasma (total and unbound), urine and peritoneal dialysate has been developed and validated. Total plasma concentrations are measured following protein precipitation and are suitable for the concentration range of 1-500 µg/mL. Unbound concentrations are measured from ultra-filtered plasma acquired using Centrifree(®) devices and are suitable for the concentration range of 0.1-500 µg/mL for cefazolin and 1-500 µg/mL for cefalothin. The urine method is suitable for a concentration range of 0.1-20 mg/mL for cefazolin and 0.2-20 mg/mL for cefalothin. Peritoneal dialysate concentrations are measured using direct injection, and are suitable for the concentration range of 0.2-100 µg/mL for both cefazolin and cefalothin. The cefazolin and cefalothin plasma (total and unbound), urine and peritoneal dialysate results are reported for recovery, inter-assay precision and accuracy, and the lower limit of quantification, linearity, stability and matrix effects, with all results meeting acceptance criteria. The method was used successfully in a pilot pharmacokinetic study with patients with peritoneal dialysis-associated peritonitis, receiving either intraperitoneal cefazolin or cefalothin. Copyright © 2015 John Wiley & Sons, Ltd.

Determination of unbound cephalothin in rat blood by on-line microdialysis and microbore liquid chromatography.

A method of analysis for the determination of unbound cephalothin in rat blood has been developed. The method was fully automated using an on-line microdialysis procedure. A microdialysis probe was inserted into the jugular vein/right atrium of male Sprague-Dawley rats to examine the unbound cephalothin level in the rat blood after cephalothin administration (50 mg/kg, i.v.). Dialysates were directly input to a liquid chromatographic system using an on-line injector. Samples were eluted with a mobile phase containing methanol-acetonitrile-100 mM monosodium phosphate (pH 5.0) (20:20:60, v/v). The UV wavelength was set at 254 nm for monitoring the analyte. Using the retrograde method, at infusion concentrations of 1 and 5 microg/ml of cephalothin, the in vivo microdialysis recoveries were 48.4+/-4.5% and 52.9+/-4.7% for the rat blood (n=6). Intra- and inter-assay accuracy and precision of the analyses were < or = 10% in the range of 0.01 through 10 microg/ml. Pharmacokinetic parameters were calculated from the recovery corrected dialysate concentrations of cephalothin versus time data. The results suggest that the pharmacokinetics of unbound cephalothin in blood fitted best to the two-compartmental model following cephalothin administration (50 mg/kg, i.v.).

Analysis of binary mixtures of cephalothin and cefoxitin by using first-derivative spectrophotometry.

A method for the analysis of two-component mixtures of cephalothin and cefoxitin using zero-crossing first-derivative spectrophotometry is described. This technique permits the quantification of these drugs with closely overlapping spectral bands without any separation step. Linear calibration graphs of first-derivative values at 235.00 and 236.75 nm for cephalothin and cefoxitin, respectively, with negligible intercepts were obtained versus concentration in the range 4.0-32.0 micrograms ml-1 for both antibiotics. This paper presents a systematic examination of the experimental data by applying an exhaustive statistical analysis to demonstrate the validity of the method. The results of the determination of these antibiotics in mixtures of injectable dosage forms are also presented, together with their determinations in physiological serum and glucosed physiological serum.

Whole-blood platelet aggregation, buccal mucosa bleeding time, and serum cephalothin concentration in dogs receiving a presurgical antibiotic protocol.

Whole-blood platelet aggregation (using the impedance method) and adenosine triphosphate (ATP) release, buccal mucosal bleeding time (BT), and serum cephalothin concentration were measured in 21 adult female Beagles before (PRE) and 1 hour (1 HR) after IV administration of cephalothin (22 mg/kg). A second injection of cephalothin (22 mg/kg) was given 3 hours after the first, and blood samples were obtained 1 hour (4 HR, 4 hours after the first injection) and 3 hours (6 HR, 6 hours after the first injection) after the second injection. Samples of jugular blood were obtained from each dog, using citrate as an anticoagulant. A platelet count was obtained for each sample. Platelet aggregation and ATP released from the aggregating platelets were measured within 1 hour of sample collection, using a whole-blood aggregometer. Adenosine diphosphate (ADP) and collagen were used as aggregating agents. Aggregation was measured over 6 minutes for each aggregating agent; ATP release in response to collagen, but not to ADP, was measured over the same period. For 1 HR samples, there was a significant (P < 0.01) reduction from PRE values in the ability of platelets to aggregate in response to ADP. Bleeding time was determined, using a published procedure, with each dog as its own control. Bleeding time during the same period was found to be significantly increased over PRE values for 1 HR (P < 0.01) and 6 HR (P < 0.02) samples. There was no significant difference between BT for 1 HR and 4 HR samples.(ABSTRACT TRUNCATED AT 250 WORDS)

[Data averaging in pharmacokinetic analysis: the population pharmacokinetics of cephalothin and cefazolin]. / Usrednenie dannykh pri farmakokineticheskom analize: populiatsionnaia farmakokinetika tsefalotina i tsefazolina.

Cephalothin and cefazolin pharmacokinetics was studied in cats after intravenous administration in doses of 20 and 75 mg/kg. The antibiotic serum concentrations were determined microbiologically. It was shown that the antibiotic pharmacokinetics within the above dose ranges was linear. The data on the antibiotic pharmacokinetics were described by bioexponential equations. Various methods for estimating population pharmacokinetic parameters were compared. Two approaches were used in estimating the population parameters: (1) averaging of individual concentrations followed by determining a single set of the parameters (naive pooled data approach) and (2) calculating of the parameters for an individual concentration/time set followed by the parameter averaging (two-stage approach). With the use of every approach the geometric mean of the parameters was calculated along with the arithmetic one. When the two-stage approach was used the population parameters were estimated with two procedures: averaging of the hybrid parameters (macroconstants) and averaging of the microconstants. Estimation of the population parameters as a geometric mean of the individual parameters, proved to be the most preferable approach.

The utility of diffusion chambers as models for the description of drug disposition.

Tissue cages were employed to explore the diffusion processes of several cephalosporins into extravascular fluids. Concentrations of cefotaxime in serum and in subcutaneous chambers increased proportionally to the amount of the drug injected. Administration of single equal doses of cephalothin, cephaloridine and cefotaxime resulted in different concentration-time courses in the serum and in diffusion chambers. These observations suggest that diffusion chambers are linked to the tissue at the implantation site. None of the classical compartmental approaches can be applied to evaluate the kinetics of drug diffusion into tissue cages. Correlations of total or non-protein bound drug concentrations in tissue cages to those in the peripheral compartment assumed concentration and time dependent diffusion processes. No specific diffusion constant based on the law of Fick could be derived for the diffusion chambers used in this study. Concentration-time courses in serum and interstitial fluid can be simultaneously evaluated according to pharmacokinetic-pharmacodynamic models. Based on the equation describing the effect site this model can be used to simulate drug concentrations in tissue cages by varying the dose size or the dose interval.

Pharmacokinetics and protein binding of cefazolin and cephalothin in patients with cirrhosis.

The effects of liver disease on the pharmacokinetics and protein binding of cefazolin and cephalothin were studied in patients with cirrhosis, chronic active hepatitis or normal liver function. The T1/2 and mean residence time of cefazolin were significantly shorter in cirrhosis. Cephalothin clearance was decreased by cirrhosis. Plasma protein binding of cefazolin, but not cephalothin was significantly reduced in cirrhosis. It is suggested that no dose reduction is necessary for either drug in severe hepatic impairment.

Serum bactericidal titer as a predictor of outcome in endocarditis.

A study was conducted in 89 rabbits with experimental aortic valve endocarditis caused by three different strains of Staphylococcus aureus to determine whether there was a correlation between the peak serum bactericidal titer of the four drugs tested and the vegetation titer. After four days of therapy both the rabbits with and those without sterile vegetations had median peak bactericidal titers of 1 : 8. The mean vegetation titers did not correlate with the mean bactericidal titers. The serum bactericidal test does not measure the relative rate of killing of the bacteria by the drugs. Although the test remains clinically useful for documentation of bactericidal activity, the minimum level of activity necessary for the test to serve as a predictor of outcome remains to be defined.

Antibiotic prophylaxis for cardiovascular surgery. Efficacy with coronary artery bypass.

Two hundred twenty patients were randomly assigned to receive either ceforanide or cephalothin as perioperative antibiotic prophylaxis during cardiovascular surgery. More infections were seen among cephalothin recipients (8 deep, 32 total) than among ceforanide recipients (1 deep, 17 total). Among patients who had only coronary artery bypass grafting, more cephalothin recipients had infection than did ceforanide recipients (19 of 82 as opposed to 7 of 83; p = 0.001; relative risk, 2.7; 95% confidence interval, 1.22 to 6.18). The difference between the two regimens was attributable to fewer blood, wound, and urinary tract infections. Among patients who had other procedures, there was no difference in the efficacy of the two regimens. Cephalothin recipients who developed wound or blood stream infections had lower antibiotic levels in their atrial appendages than recipients not developing such infections (p = 0.02). If one assumes that cephalothin does not increase the risk of infection, then these data show that antibiotic prophylaxis prevents infection after coronary artery bypass surgery, and, in the dosages used, that ceforanide is superior to cephalothin.

Binding of cefalotin to human serum albumin.

Binding of cefalotin to human serum albumin was studied in vitro by equilibrium dialysis and the quantitative measurement of cefalotin was made by fluorimetric assay. The binding rate of cefalotin to human serum albumin found to be 61,1%. The determination of drug binding parameters showed a large number of binding sites (n = 9.36) and a moderate affinity (K = 3898 M-1).

Mechanism of cefoxitin and cephalothin interference with the Jaffé method for creatinine.

Some cepha antibiotics interfere positively in the Jaffé method for determining creatinine. The extent of this interference differs with the modification used, and its mechanism is unknown. We studied the spectrophotometric and thermodynamic properties of the reaction of picrate with creatinine and two cepha antibiotics, cefoxitin and cephalothin. The absorbance spectra of the chromophore produced by each of the three compounds when reacted with picrate were essentially identical, with an absorbance maximum at 485 nm. We determined the molar absorptivity, rate constant, and equilibrium constant for the reaction of the three compounds with picrate. The molar absorptivity was similar for creatinine and cefoxitin but about fourfold smaller for cephalothin. The rate constant and equilibrium constant for the reaction with picrate were respectively 20- and 10-fold greater for creatinine than for either of the two cepha antibiotics. Thus, these differences indicate the mechanism by which these two cepha antibiotics interfere with the Jaffé procedure for creatinine, and explain why the degree of interference depends on details of the procedure.

Intraoperative antibiotic wound irrigation.

Postoperatively, wound infections in arterial procedures may have calamitous consequences with loss of limb and of life and is associated with significant financial, physical and emotional upsets by patients. Good surgical technique carried out in a clean operating room and hospital environment has a postoperative rate of wound infection of 1 to 5 per cent. By using intermittent intraoperative antibiotic wound irrigation, the postoperative rate of wound infection can be reduced to the vanishing point, that is, 0.1 per cent.

Serum and dialyzate concentrations of intraperitoneal cephalothin in patients undergoing continuous ambulatory peritoneal dialysis.

The pharmacokinetics of cephalothin sodium were studied in seven patients with chronic renal failure undergoing continuous ambulatory peritoneal dialysis. 100 mg of cephalothin per liter dialyzate were administered intraperitoneally during nine dialysis cycles with 2 liters of dialysis fluid per cycle. Serum levels of the antibiotic, measured microbiologically during the first, fifth and ninth dwell time, revealed peak values of 3.5 +/- 1.7 mg/l, 5.6 +/- 2.2 mg/l and 5.3 +/- 2.5 mg/l, respectively. The mean concentration in the dialysis outflow was 23.6 +/- 15.6 mg/l (range: 2.0-78.7 mg/l). Intraperitoneally administered cephalothin is well tolerated. Serum levels exceeded the minimal inhibitory concentrations of most gram positive bacteria causing peritonitis in these patients.

Covalent binding of cefotaxime to human serum albumin.

The covalent binding ratio of cephalosporins (CEZ, CER, CET and CTX) to human serum albumin was examined at pH 7 and pH 10. The antibiotic equivalents were larger at pH 10 than at pH 7. The degree in the binding ratio of the 4 cephalosporins was CET greater than CER greater than CTX greater than CEZ at pH 7 and CER greater than CET greater than CTX greater than CEZ at pH 10.

[Model studies of the antibiotic release of gentamycin, tobramycin and cephalothin polymethylmethacrylate beads in vivo]. / Modellversuche zur Antibiotikaabgabe von Gentamycin-. Tobramycin- und Cephalothin-Polymethylmethacrylatkugeln in vivo.

Gentamycin-, tobramycin-, and cephalothin-polymethylmethacrylat beads were implanted into a bone cavity of the rabbit tibia. The antibiotic release of the implants was observed by measure of the antibiotic concentration of the secretion respectively of the neighbouring bone tissue in the surroundings of the beads produced by punction. An antibiotic concentration about 1 microgram/ml could be measured with gentamycin and tobramycin for 120 to 150 days and with cephalothin for 30 to 50 days in the surroundings of the beads.

Comparison of ceforanide and cephalothin prophylaxis for vaginal hysterectomies.

We compared the safety and efficacy of a six-dose regimen of cephalothin with a two-dose regimen of ceforanide for the prevention of infection after elective vaginal hysterectomy. A total of 150 patients were randomly assigned to either regimen. The overall incidence of documented pelvic infection was 5.3% and did not differ significantly between the prophylaxis groups when stratified by type of surgery. No serious adverse reactions were encountered in either group, but phlebitis was significantly more common in patients receiving cephalothin. We conclude that a two-dose regimen of ceforanide given intramuscularly is as effective as, and possibly better tolerated than, a six-dose regimen of cephalothin.

A comparison of the safety, efficacy, and distribution of ceforanide and cephalothin in coronary artery bypass graft surgery.

Antibiotic prophylaxis in open-heart operations is a widely accepted practice. Introduction of new antibiotics with differences in tissue distribution, spectrum of activity and therapeutic index prompts their evaluation as possible effective prophylactic agents. We compared the distribution, clinical efficacy, and safety of ceforanide with cephalothin as a prophylactic agent in coronary artery bypass graft (CABG) procedures. The results indicated that the intravenous administration of ceforanide at the dose of 1 gm every 12 hours for 2.5 days was equivalent to cephalothin 1 gm every 6 hours for 2.5 days. Serum, muscle, and bone concentrations of ceforanide were significantly greater than those of cephalothin. These concentrations consistently exceeded the minimal inhibitory concentration for Staphylococcus aureus, the major pathogen implicated in wound infections. No toxicty was observed with either antibiotic. Ceforanide merits consideration as a prophylactic antibiotic in CABG operations.