Penetration of ceforanide and cefamandole into the right atrial appendage, pericardial fluid, sternum, and intercostal muscle of patients undergoing open heart surgery

Plasma vs heart tissue concentration in humans - literature data analysis of drugs distribution

Little is known about the uptake of drugs into the human heart, although it is of great importance nowadays, when science desires to predict tissue level behavior rather than to measure it. Although the drug concentration in cardiac tissue seems a better predictor for physiological and electrophysiological changes than its level in plasma, knowledge of this value is very limited. Tissue to plasma partition coefficients (Kp) come to rescue since they characterize the distribution of a drug among tissues as being one of the input parameters in physiologically based pharmacokinetic (PBPK) models. The article reviews cardiac surgery and forensic medical studies to provide a reference for drug concentrations in human cardiac tissue. Firstly, the focus is on whether a drug penetrates into heart tissue at a therapeutic level; the provided values refer to antibiotics, antifungals and anticancer drugs. Drugs that directly affect cardiomyocyte electrophysiology are another group of interest. Measured levels of amiodarone, digoxin, perhexiline and verapamil in different sites in human cardiac tissue where the compounds might meet ion channels, gives an insight into how these more lipophilic drugs penetrate the heart. Much data are derived from postmortem studies and they provide insight to the cardiac distribution of more than 200 drugs. The analysis depicts potential problems in defining the active concentration location, what may indirectly suggest multiple mechanisms involved in the drug distribution within the heart. Copyright © 2015 John Wiley & Sons, Ltd.

Concentration of cefamandole in plasma and tissues of patients undergoing cardiac surgery: the influence of different cefamandole dosage

OBJECTIVE

To develop an improved regimen of antibiotic prophylaxis in cardiac surgery, three antibiotic prophylactic regimens for patients scheduled to have elective cardiothoracic surgery involving a median sternotomy were evaluated.

DESIGN

A prospective, randomized, unblinded study.

SETTING

A university teaching hospital.

PARTICIPANTS

Sixty-nine men scheduled for elective coronary artery bypass grafting (CABG) with extracorporeal circulation (ECC) were included in the study.

INTERVENTIONS

The patients were selected at random to receive 2 g of cefamandole (CM) at induction of anesthesia (group 1, n = 24), or 2 g of CM at the beginning of anesthesia followed by an additional dose (2 g) immediately after onset of cardiopulmonary bypass (CPB) (group 2, n = 22), or 4 g of CM just at the initiation of anesthesia (group 3, n = 23). Samples from the mammary artery, sternum, and plasma were obtained at various intervals after injection of the antibiotic (10 minutes intravenously) to compare antibiotic levels, assayed for CM concentrations, with high-pressure liquid chromatography (HPLC) and plasma bactericidal activity as well as infectious complications in these sites as a function of time for the three groups.

MEASUREMENTS AND MAIN RESULTS

There were no significant differences in biometric data, duration of hospitalization, or management of cardiopulmonary bypass, including urinary tract drainage and infusion volume. The mean plasma t1/2 (distributive or alpha-phase) before bypass was 51.7 +/- 16.7 minutes for group 1 and 2 patients and 54.9 +/- 15.9 minutes for group 3 patients. CM plasma values were significantly higher in group 2 (170.3 +/- 105.8 micrograms/mL) than in groups 1 and 3 (111.8 +/- 42.2 micrograms/mL, 101.2 +/- 57.2 micrograms/mL) at the end of bypass periods (p < 0.05). The antibiotic contents of mammary artery and sternum samples of group 2 (15.6 +/- 4.7 micrograms/mL, 9.5 +/- 4.7 micrograms/mL) were significantly higher after completion of CPB compared with group 1 (5.7 +/- 1.9 micrograms/mL, 3.8 +/- 2.9 micrograms/mL) and group 3 (6.3 +/- 3.5 micrograms/mL, 3.6 +/- 1.8 micrograms/mL) (p < 0.05). There were no significant differences in distribution of micro-organisms among the three groups, but two patients of groups 1 and 3 with plasma and tissue CM levels below minimal inhibitor concentration (MIC90) for Hemophilus influencea, E coli, Proteus ssp and Klebsiella ssp after completion of CPB, respectively, developed a pneumonia postoperatively caused by Hemophilus influencea (1), E coli (1) and Klebsiella ssp (2) (p < 0.05).

CONCLUSIONS

It would be preferable to infuse the antibiotic shortly before the operative procedure. However, to keep tissue and plasma CM values more than MIC90 for common pathogens during the time period studied, a second infusion of 2 g of CM administered after onset of CPB suggests better protection against the risk of microbial infections. Therefore, the findings might be important for the choice of antibiotic prophylaxis, particularly for high-risk patients.

Considerations in dosage selection for third generation cephalosporins

Pharmacokinetic parameters of third generation cephalosporins vary widely, requiring different dosage regimens and adjustment methods for each agent. Although their antibacterial spectrum favours their usage in infections caused by aerobic Gram-negative organisms, due to their limited post-antibiotic effect against these organisms, dosage regimens should ensure that free drug concentrations at the site of infection remain above the minimum inhibitory concentration for as much of the dosage interval as possible in patients with normal host defence mechanisms and for the entire dosage interval in immunocompromised patients. Altered protein binding encountered in various disease states can affect both microbiological and pharmacokinetic properties especially for drugs with high protein binding. Since the concentrations at the site of action are often different from those in serum, a higher or lower range of dosages needs to be selected depending on the target site. Decreased renal function affects the elimination of most third generation cephalosporins, whereas the presence of hepatic disease does not generally necessitate dosage adjustment. Because of the complex age-related physiological changes in paediatric and elderly patients, dosage should be adjusted on the basis of the reported pharmacokinetic data in these populations. The usual recommended dose may or may not be optimal in a given condition depending on the complex interactions between pharmacokinetic, microbiological and other host factors.

A comparative study of cefamandole and ceftriaxone as prophylaxis in cardiac surgery

We compared the prophylactic use of cefamandole and ceftriaxone in 40 patients undergoing elective cardiac surgery. Postoperative wound infection occurred in one and two patients, respectively, in each group (n.s.), and bronchial superinfection in one patient in each group. In 12 additional patients drug concentrations in plasma and pericardial fluid were measured at different times following the administration of ceftriaxone. Plasma and pericardial fluid concentrations of ceftriaxone were above the minimal inhibitory concentration of susceptible microorganisms for up to 24 h after intravenous administration. We conclude, firstly, that the incidence of infection after cardiac surgery is low with both cefamandole and ceftriaxone prophylaxis. Secondly, efficient plasma and pericardial fluid levels of ceftriaxone last for up to 24 h after intravenous administration.

Antimicrobial prophylaxis of experimental endocarditis caused by Staphylococcus epidermidis

Using two different strains of Staphylococcus epidermidis in a rat model of experimental endocarditis, we examined the prophylactic efficacy of cefamandole (200 mg/kg/dose), cefazolin (200 mg/kg/dose), nafcillin (200 mg/kg/dose), and vancomycin (20 mg/kg/dose). In vitro susceptibility testing demonstrated that both test strains were resistant to methicillin and cefazolin and susceptible to cefamandole and vancomycin. A 10(6) cfu inoculum was used for both strains, an inoculum which produced endocardial infections in greater than 90% of rats. Initial doses of each antibiotic were given 45 min to 1 h prior to bacterial challenge and were followed by six additional doses of each antibiotic administered subcutaneously every 6 h. The efficacy rates of cefamandole (84.0%) and cefazolin (70.8%) were exactly the same for rats infected with either S. epidermidis strain. Similar efficacy rates were seen in rats infected with either strain and treated with vancomycin (94.4% and 86.7%). Unlike the other three drugs, the efficacy of nafcillin was quite different in rats challenged with the two strains (62.5% and 38.5%, p = 0.19). It appears that cefamandole and cefazolin may have considerable prophylactic efficacy against certain infecting strains of methicillin-resistant, coagulase-negative staphylococci when relatively large doses of cephalosporins are administered subcutaneously in this animal model.

Cefamandole prophylaxis for cardiovascular surgery: a dosage comparison

For more than a decade, studies have indicated that antibiotic dosing immediately before and for a short time after surgery is effective in reducing the incidence of infectious complications of open-heart operations. At our institution we have used cefamandole, because of its broad spectrum of activity against bacteria common to the skin and respiratory system and its low toxicity. However, in response to more recent studies that threw doubt on the ability of the recommended dosing regimen (1.0 g given intravenously every six hours for three days) to maintain adequate intraoperative levels of cefamandole in heart tissue, we undertook an evaluation of a dosage of 2.0 g given intravenously every 6 hours for two days. This was a randomized study of 211 successive, evaluable, open-heart surgery patients who had no concurrent infections or cephalosporin allergy. Postoperatively, there were eight surgery-related infections (3.9%) and eight nosocomial infections in the 2.0-g dose group, compared with seven surgery-related infections (3.5%) and seven nosocomial infections in the 1.0-g dose group. These differences were not statistically significant. Tissue levels and cardiopulmonary bypass pump time were not risk factors for infection. We conclude that the 2.0-g doses over two days are no more effective than the 1.0-g doses over three days. However, when administration fees are considered, in a cost comparison, the 2.0-g dosing regimen is more economical than the 1.0-g regimen.

Ceforanide. A review of its antibacterial activity, pharmacokinetic properties and clinical efficacy

Ceforanide is a 'second generation' cephalosporin administered intravenously or intramuscularly. It is similar to cefamandole and cefonicid in its in vitro superiority to 'first generation' cephalosporins against several species of Enterobacteriaceae as well as its activity against Haemophilus influenzae, including beta-lactamase-producing strains. Its activity against Staphylococcus aureus is less than that of cefamandole, cefuroxime and first generation cephalosporins. The in vitro activity against Neisseria gonorrhoeae is excellent. Pseudomonas, Acinetobacter and Serratia species, and Bacteroides fragilis are resistant, as are many strains of Proteus and Providencia species. The elimination half-life is relatively long, although shorter than that of cefonicid, and in most clinical trials ceforanide has been administered twice daily. It appeared to be comparable in therapeutic efficacy to procaine penicillin and cephazolin in the treatment of patients with community-acquired pneumonia, to cephazolin in the treatment of skin and soft tissue infections due to S. aureus or beta-haemolytic streptococci and to cefapirin in S. aureus endocarditis in parenteral drug abusers. Also, it was comparable in efficacy to cephalothin in the prophylaxis of infection in patients undergoing open heart surgery or vaginal hysterectomy, and to cephazolin in patients undergoing cholecystectomy. Thus, ceforanide is an alternative to first and certain other second generation cephalosporins in several important therapeutic and prophylactic situations. It has no advantage over other cephalosporins with regard to spectrum of antibacterial activity, but has a longer half-life than other second generation cephalosporins, except cefonicid, and can be administered according to a twice daily dosage schedule.

Aztreonam penetration into synovial fluid and bone

Eighteen patients with uncomplicated degenerative joint disease requiring joint replacement (hip or knee) were given a single 2-g intravenous dose of aztreonam over a 5-min period preoperatively. The mean concentration in synovial fluid of 83.0 +/- 9.2 micrograms/ml averaged 0.99 times the concomitant levels in serum. The mean concentration in cancellous bone of 16.0 +/- 4.3 micrograms/g averaged 0.20 times the concomitant levels in serum.

Intraoperative ceforanide pharmacokinetics and protein binding

The pharmacokinetics and protein binding of ceforanide were studied in 15 patients undergoing cholecystectomies. Each patient received ceforanide (20 mg/kg) intravenously on arrival in the operating room, after which serial blood samples were collected during the elimination phase for determination of total and free ceforanide concentrations in the serum. A high-pressure liquid chromatography assay was used, with a centrifugal filtration system for free-drug determinations. Serum concentration data for each individual were subjected to linear regression to determine the elimination rate constants (total and free drug), volumes of distribution, and systemic clearances. The mean elimination rate constants were 0.41 and 0.50 h-1 for total and free ceforanide, respectively. The mean percentage of ceforanide bound to serum protein was 87.9%. The relationship of the free ceforanide concentration to the total concentration appeared to be linear. The data were fit to double-reciprocal and half-reciprocal relationships with good agreement, showing one binding site and an association constant range of 1.6 X 10(7) to 1.9 X 10(7) at these in vivo concentrations. The mean volume of distribution and mean systemic clearance of total drug were 100 ml/kg and 45.9 ml/min per 1.73 m2, respectively. Ceforanide consistently produced higher intraoperative total drug concentrations compared with those of cefazolin and cefoxitin from similar studies.

Review of the new second-generation cephalosporins: cefonicid, ceforanide, and cefuroxime

The new second-generation cephalosporins, cefonicid, ceforanide, and cefuroxime, have recently become available. These agents are generally less active against gram-positive cocci than first-generation cephalosporins and, at best, equal to cefoxitin and cefamandole against many gram-negative bacteria. Cefuroxime, however, is the most active cephalosporin for beta-lactamase-producing Haemophilus influenzae. These newer agents have superior pharmacokinetic characteristics over cefoxitin and cefamandole. Smaller doses, longer dosing intervals and, potentially, a reduction in total drug cost may be the real advantage of these agents. Open trials and a limited number of comparative studies have documented the effectiveness of cefonicid, ceforanide, and cefuroxime in the treatment of most mild-to-serious infectious diseases, although failures with cefonicid in the treatment of staphylococcal infections have been reported. Notably, cefuroxime has received approval for the treatment of common pediatric bacterial meningitis infections. Replacement of cefamandole or cefoxitin with one of these "longer-acting" agents may be cost-beneficial; however, clinicians must be on alert for the development of bacterial resistance or decreased efficacy.

Ceforanide: antibacterial activity, pharmacology, and clinical efficacy

Ceforanide is a new cephalosporin with a longer elimination half-life than any currently available cephalosporin. Its activity is very similar to that of cefamandole, a second-generation cephalosporin, except that ceforanide is less active against most gram-positive organisms. Many coliforms, including Escherichia coli, Klebsiella, Enterobacter, and Proteus, are susceptible to ceforanide, as are most strains of Salmonella, Shigella, Hemophilus, Citrobacter and Arizona species. However, most strains of Serratia marcescens and all Pseudomonas aeruginosa are resistant to this compound. Peak serum concentrations in excess of 100 micrograms/ml are achieved after a 1 g intravenous dose. The elimination half-life of ceforanide is about 3 hrs in patients with normal renal function; this allows twice daily dosing for the majority of patients. As renal excretion amounts for 85-90% of drug elimination, the serum half-life increases to approximately 20 hours in anuric patients. Tissue penetration studies demonstrate inhibitory concentrations in cardiac tissue, bone, and joint fluid. Minor adverse effects have been reported after large doses of ceforanide. Clinical trials indicate that ceforanide is effective in the treatment of skin and soft tissue, pulmonary and urinary tract infections, bone and joint infections, and endocarditis. Ceforanide also has been shown to be as effective as cephalothin or cephaloridine when given prophylactically for vaginal hysterectomy.