High tolerance of and removal of cefazolin sodium in single-chamber microbial fuel cells operation

Single-chamber microbial fuel cells (MFCs) have been shown to be a promising approach for cefazolin sodium (CFZS)-contaminated wastewater treatment, in terms of electricity production, high CFZS tolerance and effective CFZS removal. MFCs exposed to CFZS loadings up to 100 mg L^-1, produced stable power of 18.2 ± 1.1 W m^-3 and a maximum power of 30.4 ± 2.1 W m^-3, similar to that of CFZS-free MFCs (stable power 19.4 ± 0.8 W m^-3 and maximum power 32.5 ± 1.6 W m^-3), notwithstanding a longer acclimitisation MFC activation. More anodophilic genera (i.e. Acinetobacter, Stenotrophomonas, Lysinibacillus) and antibiotic-resisting genera (i.e. Dysgonomonas) were enriched in CFZS acclimitised anodes. Both the thickness of biofilms and the duration of CFZS acclimitisation were essential for the development of high CFZS tolerance (e.g. 450 mg L^-1). The inhibition of MFCs by CFZS was reversible. The present MFCs generated a CFZS removal rate of 1.2-6.8 mg L^-1 h^-1 without any apparent inhibition of electricity production.

Stability of drug additives in peritoneal dialysis solutions in a new container

OBJECTIVE

To evaluate the stability of gentamicin, tobramycin, netilmycin, vancomycin, cefazolin, unfractionated heparin, and low molecular weight heparin when added to four different peritoneal dialysis (PD) solutions [Extraneal (Baxter Healthcare, Castlebar, Ireland); Physioneal, Nutrineal, and Dianeal (Baxter Healthcare, Grosotto, Italy)] in new, non-PVC Clear-Flex containers.

MEASUREMENTS

Gentamicin, tobramycin, netilmycin, vancomycin, cefazolin, unfractionated heparin, and low molecular weight heparin were injected into separate bags of PD solution. Samples were withdrawn at predefined sampling times and the concentration of each drug was analyzed using high-performance liquid chromatography (for gentamicin, tobramycin, vancomycin, and cefazolin), or bioassay (for netilmycin, gentamicin, and tobramycin in Nutrineal), or coagulation methods (heparins).

RESULTS

Netilmycin, vancomycin, cefazolin, and heparin in Physioneal, Nutrineal, Extraneal, and Dianeal were stable for at least 24 hours at 25 degrees C and for an additional 4 hours at 37 degrees C. Gentamicin in Nutrineal, Extraneal, and Dianeal was stable for at least 24 hours at 25 degrees C and for an additional 4 hours at 37 degrees C; gentamicin in Physioneal was stable for less than 24 hours at 25 degrees C. Tobramycin in Nutrineal and Extraneal was stable for at least 24 hours at 25 degrees C and for an additional 4 hours at 37 degrees C; tobramycin in Physioneal and Dianeal was stable for less than 24 hours at 25 degrees C.

Quantitation of vancomycin and its crystalline degradation product (CDP-1) in human serum by high performance liquid chromatography

The delayed clearance of vancomycin results in accumulation of vancomycin crystalline degradation product, CDP-1, in the bodies of renally impaired patients. The 2 isomers, CDP-1-M (major) and CDP-1-m (minor), of CDP-1 are antibiotically inactive but cross-react with some immunoassays that use polyclonal antibodies resulting in falsely elevated results. A high performance liquid chromatographic (HPLC) method was developed to quantitate vancomycin and CDP-1 in the serum of renal patients. After solid phase extraction of 200 microliters serum, the separation of vancomycin, the 2 isomers of CDP-1 and the internal standard (cefazolin) was accomplished by gradient HPLC on a reversed phase C18 column with detection at 210 nm. Linearity was established from 1 to 25 and 25 to 100 micrograms ml-1 vancomycin and 1 to 25 micrograms ml-1 CDP-1. Coefficients of variation for vancomycin and CDP-1 were 3.3-8.6% (n = 10) and 2.8-5.2% (n = 8).

Stability of cefazolin sodium in various artificial tear solutions and aqueous vehicles

The stability of cefazolin sodium reconstituted in four artificial tear solutions, two acetate buffer solutions, phosphate buffer solution, and 0.9% sodium chloride injection was studied. Cefazolin was reconstituted in Tearisol, Isopto Tears, Liquifilm Forte, and Liquifilm Tears; acetate buffer solution at pH 4.5 and pH 5.7; phosphate buffer solution at pH 7.5; and 0.9% sodium chloride injection. The solutions were stored at 4 degrees C, 25 degrees C, and 35 degrees C for seven days. All of the solutions were inspected for particulates, turbidity, color, and odor. Five assay determinations on each of three samples of each formulation were performed using a stability-indicating high-performance liquid chromatographic assay. Cefazolin stability was influenced primarily by pH and storage temperature. Reconstitution of cefazolin sodium in the alkaline tear solutions Isopto Tears and Tearisol and in phosphate buffer solution resulted in particulate and color formation at 25 degrees C and 35 degrees C. Turbidity was noted after cefazolin sodium was reconstituted in Isopto Tears. No color or precipitate formation was evident after seven days at 25 degrees C and 35 degrees C in the formulations of acidic pH containing Liquifilm Tears, Liquifilm Forte, 0.9% sodium chloride injection or acetate buffer solution as the vehicles. The extent of degradation of cefazolin was substantially higher in the formulations of alkaline pH than in those of acidic pH at 35 degrees C and 25 degrees C. All of the formulations retained more than 90% of their initial concentration when stored at 4 degrees C. Cefazolin sodium, when reconstituted in artificial tear solutions with an acidic pH, is stable for up to three days at room temperature.

Cost analysis of using premixed frozen versus hospital-reconstituted cefazolin sodium injection

The costs of preparing cefazolin sodium 1-g small-volume injections (SVIs) by each of two reconstitution methods were compared with the costs of using premixed frozen cefazolin SVIs at two hospitals. Both hospitals routinely used premixed cefazolin 1-g SVIs. Each converted to its previous reconstitution system for approximately two weeks. One hospital used a once-weekly "batch" system, and the other hospital used the twice-daily "extemporaneous" system. Pharmacist and technician time involved in both systems was determined using time-and-motion methods. A total of 40 preparation cycles of 10 SVIs each were monitored to determine labor costs. Hospital purchase-contract prices were used for determining material costs per SVI, and waste was calculated based on the number of SVIs that could not be recycled. The total time required for preparation of 10 cefazolin 1-g SVIs by each method was comparable (6.2 minutes for the batch method, 5.8 minutes for the extemporaneous method); labor costs contributed minimally to overall costs of each reconstituted SVI. Approximately 5% of reconstituted SVIs were wasted in each system. The conversion to premixed cefazolin SVIs resulted in an annual cost increase of more than $5000 at each hospital, compared with the reconstitution methods. However, subjective evaluations indicated that use of the premixed admixtures resulted in increased efficiency of i.v. preparation by allowing pharmacy personnel to devote more time to other labor-intensive duties. The results of this study allowed the pharmacies to negotiate more equitable prices for premixed cefazolin sodium injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Antiepileptic effects of a calcium antagonist (nimodipine) on cefazolin-induced epileptogenic foci in rabbits

The epileptogenic properties of cefazolin (CFZ) were utilized to induce an electrophysiological pattern of epilepsy in the rabbit. CFZ, cortically applied in different concentrations (2 or 4%), produced epileptic activity in a degree proportional to the concentration of the substance. In this experimental epilepsy model, we evaluated the effects of increasing doses (0.025, 0.05, and 0.1 mg/kg i.v.) of the calcium antagonist nimodipine (Bay e 9736). In the evaluation of nimodipine effects, the spike-and-wave burst frequency per minute was taken into account. These data were compared with those of placebo-treated (Bay e 9736 control test) control groups and statistically evaluated by two-tailed t test. In 2% CFZ-induced epilepsy, nimodipine at the 0.025- and 0.05-mg/kg doses did not produce significant changes in the EEG pattern. A statistically significant reduction (p less than 0.001) in epileptic activity was observed at the 0.1-mg/kg nimodipine dose. This reduction was seen first in the contralateral focus leads and persisted for the entire time of observation. In the more intense epileptic form (4% CFZ), nimodipine at the doses employed did not induce noteworthy EEG modifications. These data indicate that nimodipine exerts an antiepileptic effect. The possible mechanisms involved in this activity of a calcium antagonist are discussed.

Epileptogenic activity of cephalosporins in rats and their structure-activity relationship

The epileptogenic properties of 10 cephalosporins and penicillin G were compared by intraventricular application to rats. At doses greater than 32 micrograms per head, cefazolin provoked tremendous seizure signs, a spike-and-wave complex appeared in close succession for more than 30 min, and severe convulsions were observed repeatedly. Reactions to cefotiam, ceftezole, and cephaloridine were almost equal to reactions to penicillin. No epileptogenic signs were observed on EEGs, and no behavioral symptoms were observed after administration of 1,000 micrograms of cephalexin and cephradine per head. Reactions to cephapirin, cefmetazole, cephalothin, and ceftizoxime exhibited less marked epileptogenic features; activity was diminished in that order on EEGs and in behavioral signs. Compounds substituted with two different heterocyclic rings at position 7 (R1) and position 3 (R2) of 7-aminocephalosporanic acid were potent in producing epileptogenic signs both on EEGs and in behaviors. Compounds substituted with a heterocyclic ring at either position of 7-aminocephalosporanic acid were less potent. Compounds such as ceftizoxime, cephalexin, and cephradine, substituted at R2 with small groups, were almost incapable of producing epileptogenic activity. This may indicate that the substitution of a heterocyclic ring at position 3 will provoke the convulsive actions.

Phospholipid bilayer permeability of beta-lactam antibiotics

Liposomes containing penicillinase or cephalosporinase were prepared from the phospholipids of Escherichia coli. After free beta-lactamase was inactivated by clavulanic acid or penicillanic acid sulfone followed by separation of inactivated enzyme and inhibitor from liposomes by gel filtration, the permeability of these liposomes to ampicillin, cefazolin and cephaloridine was estimated by measuring the hydrolysis of these antibiotics by the entrapped enzymes. The permeability parameter C (minute-1 microM lipid-1) of ampicillin, cefazolin and cephaloridine was calculated to be 2.35 X 10(-4), 0.33 X 10(-4) and 0.52 X 10(-4), respectively. The lipid bilayer permeability of these antibiotics was also measured by using the liposomes containing these antibiotics. About half of the initially entrapped ampicillin was released from the liposomes within 80 minutes, while no significant release of cefazolin and cephaloridine could be detected during the same period. These results clearly indicates that the lipid bilayer membrane is more permeable to ampicillin than cefazolin and cephaloridine, and they are consistent with the observations of Sawai et al., who showed that ampicillin was a more effective antibacterial drug than cefazolin and cephaloridine against the porin-deficient mutants.

Microwave thawing of frozen minibag admixtures

An efficient system is described for the preparation of high volume minibag admixtures e.g. cefazolin. The system includes use of bulk reconstitution, freezing and microwave thawing techniques; special admixture dosage forms; and, the use of technical staff. The system can be utilized in any centralized, intravenous, admixture service where the workload is demanding for existing staff.

Cost containment through restriction of cephalosporins

The effect of a program designed to reduce hospital drug costs by limiting the selection of injectable cephalosporins and promoting the rational use of the selected agents was studied. Cefazolin sodium was chosen as the primary injectable cephalosporin, and guidelines for proper dosing were approved. Strict guidelines for the use of cephapirin sodium, cefamandole nafate, and cefoxitin sodium were also adopted; cephalothin sodium was deleted from the formulary. Clinical pharmacists reviewed all cephalosporin orders and consulted with prescribers whose orders did not conform to the guidelines. Total cephalosporin purchases for the first fiscal year of the program were $64,914, a decrease of $55,715 or 46.2% from the previous year's total of $120,629. Cost per patient day for cephalosporins decreased from $0.921 to $0.519 (43.6%) over the same period. The number of milligrams of cephalosporins used per patient day decreased from 398.16 to 178.77 (55.1%), while the number of patient days decreased by only 4.45% during the same interval. The estimated annual cost of monitoring the program was $1500. This program demonstrates that substantial cost savings can be achieved if guidelines for the use of injectable cephalosporins are clearly outlined and strictly enforced.

Intravenous antibiotic therapy at home

Many patients who are hospitalized for intensive intravenous (IV) antibiotic therapy of serious infections are not disabled. Following a short period of treatment in the hospital and after their medical problem has stabilized, these patients can safety receive IV antibiotics at home. Patients who had osteomyelitis or infective endocarditis were selected for this study. Utilizing an IV nurse team, patients were instructed in the administration of the antibiotic. They returned to the hospital every 48 hours to have their IV catheter changed and to receive a new supply of antibiotic. There was a substantial monetary saving with each treatment course (at least $1,600 per patient), and, in addition, the patients were much more comfortable at home and some returned to work or to school.

Nocardicin A, a new monocyclic beta-lactam antibiotic V. In vivo evaluation

Nocardicin A is a new monocyclic beta-lactam antibiotic which provides a potent therapeutic effect in mice experimentally infected with gram-negative bacilli. When given subcutaneously to mice, the therapeutic effect of the drug was stronger than had been anticipated from in vitro studies. Nocardicin A was more potent in therapeutic effect than carbenicillin against infections due to Pseudomonas aeruginosa, Proteus mirabilis, Pr. vulgaris, Pr. rettgeri and Pr. inconstans, and was similar in effect to carbenicillin against infections due to Escherichia coli in mice. In addition, nocardicin A proved to be active against infections due to Serratia marcescens and other organisms resistant to beta-lactam antibiotics. When nocardicin A was given subcutaneously to mice, blood and hepatic levels of the drug were higher than those of carbenicillin.

Residues in antibiotic preparations, i: scanning electron microscopic studies of surface topography

The surface characteristics of residues obtained from several commercial antibiotic products were studied using scanning electron microscopy. The photomicrographs showed the presence of particulates possessing crystalline or amorphous properties with particle sizes ranging from 1 mum to several mum. Small, well-defined, granular crystalline particulates seemed to predominate in residues of products which were processed under optimum pH conditions. Coalescing or aggregating of small crystalline particles (1-10mum) to form larger masses was interpreted as a sign of instability of the antibiotic. Most of the penicillin and semisynthetic penicillins produced residues that were characterized as amorphous, flaky, bulky and of no distinct shape. Such structures were attributed to the drying of gelatinous particulates. The possible sources and causes of the occurrence of these particulates are discussed. It appears that in many of the products the particulates are product-related rather than process-related, and subtle degradation may be involved. Advice is given to practitioners regarding the preparation, storage and administration of these products.