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PubMedDate not supplied

Stability of cefazolin sodium and metronidazole at 8 degrees C for use as an i.v. admixture.

The stability of cefazolin 1 g in metronidazole 500 mg/100 mL at 8 degrees C was studied for use as an IV admixture. The commercially available injection of cefazolin sodium 1 g vial was diluted to 5 mL with 0.9% sodium chloride injection and added to metronidazole 500 mg/100 mL. Following dilution of 2 mL to 100 mL with water, 1-mL aliquots were transferred to glass vials, refrigerated at 8 degrees, and assayed for cefazolin and metronidazole concentration at 0, 1, 2, 4, 8, 12, 24, 36, 48, and 72 hours after preparation. The concentration of cefazolin and metronidazole was determined by a stability-indicating high-performance liquid chromatographic method. The range of concentration was determined to be within 5% of the 0-hour mean concentration. Over the 72-hour period, the mean concentration of cefazolin at all assay times was within 98.4 to 101.0% of the initial concentration. The mean concentration of metronidazole at each assay time was 96.9 to 104.9% of the initial concentration. Cefazolin sodium 10 mg/mL and metronidazole 5 mg/mL, prepared by adding reconstituted cefazolin to a glass bottle of metronidazole ready-to-use solution, were stable for 72 hours when stored at 8 degrees C.

Cefazolin↗

PubMed1985

Intraoperative serum and tissue activity of cefazolin and cefoxitin.

We determined the intraoperative serum and wound-muscle concentrations of cefazolin and cefoxitin in 40 patients who were undergoing cholecystectomies. The study employed an open-label design in which all of the patients randomly received cefazolin sodium (20 mg/kg) or cefoxitin sodium (30 mg/kg) intravenously while the patient was in the ward ("on call") or with the induction of anesthesia. Multiple blood and wound-muscle samples were collected intraoperatively and assayed for their cephalosporin concentrations. Considerable differences in intraoperative serum and tissue concentrations between antibiotics were apparent; there were usually higher levels of cefazolin. In all of the patients who received cefazolin sodium, the antimicrobial was detectable in wound tissue at wound closure, while it was detectable in 86% and 38% of patients who received cefoxitin sodium with anesthesia and on call, respectively. Because cefoxitin has a much shorter elimination half-life than cefazolin it seems prudent to administer the agent as close to the start of the operation as possible, and readminister the agent every two to three hours until the wound is closed. For cefazolin, on-call administration appears to be acceptable, with readministration not required for at least four hours.

Abdominal Muscles↗

PubMedDate not supplied

Single dose cefazolin prophylaxis for postcesarean infections: before vs. after cord clamping.

The objective of this study was to test the hypothesis that 1 g of cefazolin administered preoperatively is no more effective than the same dose administered after cord clamping in preventing postcesarean infectious morbidity. Ninety consecutive laboring subjects undergoing cesarean delivery at > or = 37 weeks gestation were randomized by computer to receive 1 g of cefazolin intravenously preoperatively or after cord clamping in a double-blinded, placebo-controlled study. The 2 groups were compared for differences in maternal and neonatal demographics, and intrapartum and operative characteristics associated with postcesarean infection. Primary maternal outcome variables were endometritis or wound infection. Secondary outcomes included intra-abdominal abscess formation, septic pelvic thrombophlebitis, pneumonia, or urinary tract infection. Neonatal outcomes included sepsis screens, sepsis, pneumonia, and meningitis. Subjects were followed 6 weeks postoperatively for late complications. Subjects receiving cefazolin preoperatively or after cord clamping had similar maternal and neonatal demographics, and intrapartum and operative characteristics. One patient in the former group experienced both endometritis and wound infection. In the latter group, 2 wound infections and 1 case of endometritis occurred (P = 0.35). There were no secondary maternal infections. Two infants treated for pneumonia and 2 other infants readmitted with febrile illnesses were born to mothers receiving cefazolin preoperatively. Overall, 8 neonates were evaluated for suspected sepsis and all had negative studies. Six of these infants' mothers received cefazolin preoperatively (P = 0.28). In conclusion, 1 gram of cefazolin preoperatively is no more effective than the same dose administered after cord clamping in preventing postcesarean infectious morbidity, but is associated with a trend toward increased suspected sepsis in the newborn. However, this trend may be related to differences between the study groups' risk factors for infection.

Bacterial Infections↗

PubMed1988

Interindividual changes in volume of distribution of cefazolin in newborn infants and its prediction based on physiological pharmacokinetic concepts.

The purpose of this study was to investigate factors affecting the volume of distribution of cefazolin (a beta-lactam antibiotic) in newborn infants with bacterial infections, and to propose a method for predicting the volume of distribution at steady state per body weight (Vdss/BW). Cefazolin and tobramycin (an aminoglycoside) were simultaneously given to newborn infants (aged 2 to 28 d), and plasma concentration-time data were analyzed on the basis of model-independent moment analysis. The Vdss/BW values ranged from 0.212 to 0.373 L/kg for cefazolin and from 0.384 to 0.541 L/kg for tobramycin. The unbound fraction of cefazolin in plasma (fp) fluctuated widely, from 0.22 to 0.83, among patients. The Vdss/BW value for cefazolin was characterized by both large extracellular water volume and a remarkable change in fp, and could be predicted as a function of fp using physiological pharmacokinetic concepts. Moreover, interindividual changes in the unconjugated bilirubin:albumin molar ratio were predominantly responsible for the individual variation in the fp values of cefazolin in newborn infants.

Blood Proteins↗

PubMed1991

In vitro activity of flomoxef and cefazolin in combination with vancomycin.

207 clinical isolates from strains of patients from the University Children's Hospital of Kiel were investigated for their in vitro activity with the agar dilution method against flomoxef and cefazolin (alone and partially in combination with vancomycin). Staphylococci were also tested with other cephalosporins (cefoxitin, cefamandole, cefotaxime, cefotetan and latamoxef). Flomoxef and cefazolin always acted more vigorously on staphylococci than the other cephalosporins. Resistance of Staphylococcus aureus strains against flomoxef and cefazolin did not occur but was found in 15 and 5 of 98 Staphylococcus epidermidis strains, respectively. Enterococcus faecalis strains were always resistant against both drugs; Streptococcus faecium strains were only moderately sensitive. Combined testing of flomoxef or cefazolin with vancomycin showed synergism in almost all staphylococcal strains. Synergism was stronger when S. epidermidis strains were only weakly sensitive to or resistant against flomoxef and cefazolin in comparison to highly sensitive strains. Flomoxef (or cefazolin) acted synergistically in combination with vancomycin on E. faecalis and S. faecium with the exception of two strains of E. faecalis which showed an additive effect of both drugs.

Cefazolin↗

PubMed1999

An additional dose of cefazolin for intraoperative prophylaxis.

We examined the pancreatic tissue concentrations of cefazolin in ten patients undergoing pancreatectomy, and determined the optimal intraoperative time to deliver a repeat dose of cefazolin. An intravenous bolus dose of 1 g cefazolin was administered at the time of skin incision. Peripheral blood, subcutaneous adipose tissue, and peritoneal samples were obtained intraoperatively every hour for 4 h after the antibiotic was first administered, and pancreatic tissue samples were obtained at the time of pancreatectomy. To determine adequate tissue levels of cefazolin, minimum inhibitory concentrations (MIC) were measured for four bacterial species, namely 360 isolates of methicillin-sensitive Staphylococcus aureus (MSSA), 204 isolates of Klebsiella pneumoniae, 314 isolates of Escherichia coli, and 30 isolates of Streptococcus spp. The antibiotic concentrations in adipose tissue and peritoneum 3 h after the administration of cefazolin were lower than the MIC80 for K. pneumoniae, E. coli, and Streptococcus spp. Most pancreatic tissue samples showed antibiotic concentrations greater than the MIC80 for these bacterial species; however, those from four patients complicated by severe chronic pancreatitis, massive intraoperative bleeding, or obesity showed concentrations lower than the MIC80. Thus, we recommend that a second dose of cefazolin be given 3 h after the first administration to maintain adequate levels of antibiotic activity.

Aged↗

PubMed1980

Serum cefazolin levels during cardiopulmonary bypass.

This study was done to assess the adequacy of a regimen using cefazolin as a prophylactic antibiotic for patients undergoing open-heart operation. At the time of the preoperative medication, adult patients received 1 gm of cefazolin intramuscularly, and pediatric patients were given a dose of 20 mg per kilogram of body weight. Group I consisted of 10 adults undergoing a variety of cardiac procedures. The mean serum cefazolin level after institution of cardiopulmonary bypass was 27.36 micrograms/ml (range, 13.1 to 40.3 micrograms/ml). This level remained fairly stable throughout cardiopulmonary bypass. Group II consisted of 10 pediatric patients undergoing cardiac procedures for repair of a variety of congenital anomalies. The mean serum cefazolin level after institution of cardiopulmonary bypass was 20.01 micrograms/ml (range, 11.4 to 28.9 micrograms/ml) and remained stable for the duration of the procedure. In both groups perfusion pressure, urinary output, and body temperature did not seem to have any influence on these levels. It is concluded that the administration of one dose of cefazolin intramuscularly before operation results in an adequate and stable serum cefazolin level in patients undergoing cardiopulmonary bypass for up to three hours, possibly longer.

Adult↗

PubMed1998

Biodegradable polyanhydride devices of cefazolin sodium, bupivacaine, and taxol for local drug delivery: preparation, and kinetics and mechanism of in vitro release.

The overall objective was to design and evaluate biodegradable implants for local drug delivery in clinical conditions and/or diseases described below, which are currently treated with systemic administration of drugs. Local delivery of cefazolin is desired in conditions such as osteomyelitis, soft-tissue infection and for prevention of post-surgical infections. Similarly, implanting a biodegradable device loaded with taxol in the cavity created by tumor resection will provide high local concentrations of taxol killing the malignant cells which may have survived the surgery, thus preventing metastasis and regrowth of the tumor and also prevent the systemic side effects of taxol. Prolonged reversible nerve blockade required in a number of clinical situations involving acute or chronic pain such as post-surgical pain following herniorrhaphy and thoracotomy can be achieved with local delivery of bupivacaine. Therefore, disk-shaped implants of polyanhydride, P(FAD-SA, 50:50 w/w), loaded with 10% w/w of cefazolin sodium, taxol and bupivacaine were prepared and evaluated for content uniformity and in vitro release characteristics for the above mentioned local drug delivery applications. All of cefazolin sodium was released in 14 days while 90% bupivacaine was released in 35 days. In striking contrast, taxol was released very slowly, and only 15% taxol was released in 77 days. The overall release appeared to be following first order kinetics, and the initial linear profile was fitted to zero order kinetics to obtain release parameters. Since cefazolin is highly water soluble and bupivacaine is moderately water soluble, compared to taxol which is extremely lipophilic, the aqueous solubility of the incorporated drug appeared to influence in release characteristics. Very good correlation was observed between release parameters (Ao, ko) and the solubility and intrinsic dissolution rate (IDR) of drugs suggesting that the hydrophilic/hydrophobic nature of the drug influences its release from polyanhydride devices. Since polyanhydrides are believed to undergo pure surface erosion, release of the incorporated drug should be independent of its physicochemical properties, however the results presented in this study suggest otherwise. Therefore, P(FAD-SA, 50:50 w/w) may not be undergoing surface erosion, and the diffusion and dissolution properties of the drug in addition to erosion characteristics of the polyanhydride appear to play a role in drug release. Implants prepared and evaluated in this study released cefazolin, bupivacaine and taxol for a prolonged duration of time; however, depending upon the desired duration of release, an appropriate polyanhydride will have to be selected. For example, taxol was released so slowly that a more hydrophilic polyanhydride may have to be selected to release all the drug in a shorter period of time to be of any therapeutic use. Cefazolin implants released the drug for a sufficient duration for osteomyelitis and soft-tissue infection but the release was more prolonged than required for prevention of post-surgical wound infection.

Anesthetics, Local↗

PubMed1994

High-performance liquid chromatographic assay of cefazolin in rat tissues.

A rapid, sensitive and reproducible high-performance liquid chromatographic (HPLC) assay for cefazolin in rat tissues was developed. Tissue samples were homogenized in distilled water, acidified with 8.5% phosphoric acid, and centrifuged. Cefazolin was isolated from the supernatant by solid-phase extraction on C18 cartridges. The eluate containing cefazolin and internal standard, cephalexin, was injected onto a reversed-phase C18 column and eluted with a mobile phase of 23% methanol in 0.02 M sodium phosphate monobasic (pH 5.0) and detected with UV absorbance at 270 nm. Recoveries of cefazolin were 33.7 +/- 2.5%, 45.4 +/- 2.1%, and 42.9 +/- 1.0% from liver, spleen and lung, respectively. The calibration curves for cefazolin were established at 0.5-1500 micrograms/g in spleen, 0.1-250 micrograms/g in liver and 0.1-75 micrograms/g in lung. The assay was reproducible with within-day and between-day variations of 1-2 and 1-4%, respectively. Application of the assay for tissue distribution of cefazolin in liposomal targeting study was demonstrated.

Animals↗

PubMed2001

Delayed hypersensitivity to cefazolin: report on a case involving lymphocyte transformation studies with different cephalosporins.

BACKGROUND: A cell-mediated immunopathogenic mechanism has been demonstrated in only a few cases of cutaneous reactions to systemically administered cephalosporins. OBJECTIVE: The aim was to investigate the pathogenic mechanism of a maculopapular rash experienced by a subject during cefazolin therapy. METHODS AND RESULTS: Prick, intradermal, and patch tests were carried out using penicillin determinants, ampicillin, amoxicillin, cefazolin, cephalothin, cefuroxime, ceftazidime, and ceftriaxone. Those tests for penicillin G and its determinants, as well as for ampicillin and amoxicillin, were negative. The patient displayed patch-test and delayed intradermal-test positivity to all the cephalosporins tested. No specific immunoglobulin E antibodies were found for penicillins or cefazolin. The lymphocyte-transformation-test results were negative for all the penicillins tested and showed a positive concentration-effect curve for cefazolin, ceftazidime, and ceftriaxone at concentrations up to 50 microg/mL. At 100 microg/mL the responses decreased with all the cephalosporins tested. Challenges with penicillin G and amoxicillin were well tolerated, but the challenge with cefazolin was positive. CONCLUSIONS: The data of this case demonstrate delayed hypersensitivity to cefazolin. Patch tests and delayed-reading intradermal tests can be a simple and effective means of diagnosing this type of reaction. Both in vivo and in vitro studies indicate that the responses were directed toward a determinant shared by all cephalosporins, but not by penicillins. The concentration of the cephalosporins used for the in vitro lymphocyte stimulation was critical, because at the concentrations normally used to test other beta-lactams the response decreased. This phenomenon may be attributable to an immunosuppressive, rather than toxic, effect.

Adult↗

PubMedDate not supplied

Hemolysis induced by cefazolin and cephalothin in a patient with penicillin sensitivity.

A patient with penicillin sensitivity, who had never received a cephalosporin antibiotic previously, developed anemia and spherocytosis following the administration of cefazolin. Hemolysis abated when the drug was discontinued on the fourth day, and recurred on day six when cephalothin therapy was begun. IgG and complement components were present on the patient's erythrocytes, and IgG antibodies in her serum reacted with normal red blood cells which had been coated with benzylpenicillin, cefazolin or cephalothin. Antibodies to cephalothin-coated red blood cells were removed partially by incubating her serum with either benzylpenicillin or cefazolin. Complement-fixing IgG antibodies which reacted with red blood cells coated by cefazolin, cephalothin, and benzylpenicillin were considered to be responsible for hemolysis during the administration of cefazolin and, subsequently, cephalothin. The patient recovered completely following discontinuation of antibiotics, transfusion of red blood cells, and treatment with glucocorticoids. It is concluded that hemolysis may occur during therapy with cefazolin, as well as cephalothin, and may develop rapidly in a patient with penicillin sensitivity.

Adult↗

PubMed2003

Prospective randomized study comparing amoxicillin-clavulanic acid with cefazolin as antimicrobial prophylaxis in laparotomic gynecologic surgery.

BACKGROUND: To compare amoxicillin-clavulanic acid with cefazolin as ultra-short-term prophylaxis in laparotomic gynecologic surgery. MATERIALS AND METHODS: A prospective randomized study was conducted to compare two antimicrobial regimens in surgical prophylaxis of laparotomic surgery. Patients were randomly allocated to receive amoxicillin-clavulanic acid (2.2 g) [Group A] or cefazolin (2 g) [Group B] as a single dose 30 min before surgery. Each patient was assessed daily until discharge to evidence febrile status and the presence of infections at the operative site, urinary tract, and respiratory tract. RESULTS: In the amoxicillin-clavulanic acid (Group A) and cefazolin (Group B) groups, overall 346 and 352 patients, respectively, were evaluable for prophylactic efficacy at hospital discharge. Infectious complications were infrequent in both arms. Febrile morbidity occurred in 21 (6.1%) and 26 (7.4%) patients, respectively, in the amoxicillin-clavulanic acid and cefazolin groups. Wound infection and urinary tract infection were also higher, but not significantly in the cefazolin group (0.5% vs. 1.1% and 2.0% vs. 2.5%, respectively). There was one respiratory tract infection (0.2%) in Group B, and no septic death in either groups. CONCLUSION: Ultra-short-term prophylaxis with both amoxicillin-clavulanic acid and cefazolin is safe in elective laparotomic gynecologic surgery.

Adult↗

PubMed2002

Vancomycin versus cefazolin prophylaxis for cardiac surgery in the setting of a high prevalence of methicillin-resistant staphylococcal infections.

OBJECTIVE: This study was undertaken to compare the efficacy of vancomycin prophylaxis with that of cefazolin in preventing surgical site infections in a tertiary medical center with a high prevalence of methicillin-resistant staphylococcal infections. METHODS: All adult patients (> or = 18 years) scheduled for cardiac surgery requiring sternotomy were randomly assigned to receive vancomycin (1 g every 12 hours) or cefazolin (1 g every 8 hours). Prophylaxis was started during the induction of anesthesia and continued for only 24 hours. Patients were followed up for at least 30 days (1 year for those receiving a cardiac implant). Surgical site infections were stratified according to the National Nosocomial Infections Surveillance System risk index. RESULTS: Of the 885 patients included in the study, 452 received vancomycin and 433 received cefazolin. The overall surgical site infection rates were similar in the two groups (43 cases in the vancomycin group, 9.5%, vs 39 cases in the cefazolin group, 9.0%, P =.8). Superficial and deep incisional surgical site infection rates were also similar in the two groups. There was a trend toward more frequent organ-space infections and infections with beta-lactam-resistant organisms among patients receiving cefazolin, but this trend did not reach statistical significance. In contrast, surgical site infections caused by methicillin-susceptible staphylococci were significantly more common in the vancomycin group (17 cases, 3.7%, vs 6 cases, 1.3%, P =.04). The durations of postoperative hospitalization and the mortalities were similar in the two groups. CONCLUSIONS: This trial suggests that vancomycin and cefazolin have similar efficacy in preventing surgical site infections in cardiac surgery.

Adult↗

PubMedDate not supplied

Effect of cefazolin on aminotransferase activity in the rat.

Cefazolin given sc to male rats in daily doses of 0.5-2 g per kilogram of body weight significantly decreased alanine aminotranferase activity in serum, liver, kidney, heart, and brain 2-4 wk from the beginning of the treatment. Serum aspartate aminotransferase was also reduced, but serum alkaline phosphatase and tissue pyruvate decarboxylase activities remained unaltered. In female rats, daily sc administration of cefazolin at 0.1-1 g/kg also brought about a dose-related reduction of alanine and aspartate aminotransferase activities, which reached statistical significance at high dose levels. The effect of cefazolin at low concentrations was partly reversed by administration of pyridoxal in vivo. Paradoxically, at higher dose levels pyridoxal potentiated the action of cefazolin on serum aminotranferases. The low enzyme activities were elevated by subsequent addition of pyridoxal 5'-phosphate in vitro. Similar results were obtained when rats were treated with isoniazid at daily oral doses of 200 mg/kg; administration of pyridoxal completely restored alanine aminotransferase activity to the normal level within 2 wk. Cefazolin was metabolized in vivo, resulting in some metabolites that probably possessed a hydrazine group, since positive reactions were obtained with p-dimethylaminobenzaldehyde and Fast Blue B salt. The potentiation of decreased aminotransferase activity by pyridoxal indicated, however, some dissimilarity in the effect between isoniazid and cefazolin.

Alanine Transaminase↗

PubMed2002

Once-daily intravenous cefazolin plus oral probenecid is equivalent to once-daily intravenous ceftriaxone plus oral placebo for the treatment of moderate-to-severe cellulitis in adults.

A once-daily regimen of cefazolin (2 g intravenously [iv]) plus probenecid (1 g by mouth) was compared with a once-daily regimen of ceftriaxone (1 g iv) plus oral placebo in a randomized, double-blind equivalence trial of home-based therapy for moderate-to-severe cellulitis in adults. For the assessable recipients of cefazolin-probenecid (n=59) and ceftriaxone-placebo (n=57), clinical cure occurred at the end of treatment in 86% and 96% (P=.11), respectively, and was maintained at 1 month of follow-up in 96% and 91% (P=.55), respectively. The mean number of treatment doses (+/-standard deviation) given was similar in the 2 treatment arms (6.97+/-2.6 for cefazolin-probenecid and 6.12+/-2.1 for ceftriaxone-placebo; P=.06). The median antibiotic trough concentrations were 2.35 microgram/mL for cefazolin and 15.45 microgram/mL for ceftriaxone. Patients in the 2 treatment arms were similar with regard to overall rates of adverse reaction (P=.15), but nausea was more common among those in the cefazolin-probenecid arm (P=.048). The once-daily regimen of cefazolin-probenecid is a cheap, practical, and effective treatment option for moderate-to-severe cellulitis, and it avoids the need to use third-generation cephalosporins in most patients.

Administration, Oral↗

PubMed2006

Comparison of routine prophylaxis with vancomycin or cefazolin for femoral neck fracture surgery: microbiological and clinical outcomes.

OBJECTIVE: To assess the impact of antibiotic prophylaxis on the emergence of vancomycin-resistant strains of Enterococcus faecium, Enterococcus faecalis, and Staphylococcus aureus and the incidence of surgical site infection (SSI) after vancomycin or cefazolin prophylaxis for femoral neck fracture surgery. DESIGN: Prospective cohort study. SETTING: A hospital with a high prevalence of methicillin-resistant S. aureus (MRSA) carriage. PATIENTS: All patients admitted with a femoral neck fracture from March 1, 2004 through February 28, 2005 were prospectively identified and screened for MRSA and vancomycin-resistant (VRE) carriage at admission and at day 7. Deep incisional and organ/space SSIs were also recorded. RESULTS: Of 263 patients included in the study, 152 (58%) received cefazolin and 106 (40%) received vancomycin. At admission, the prevalence of MRSA carriage was 6.8%; it was 12% among patients with risk factors and 2.2% among patients with no risk factors (P=.002). At day 7 after surgery, there were 6 patients (2%) who had hospital-acquired MRSA, corresponding to 0.7% in the cefazolin group and 5% in the vancomycin group (P=.04); none of the MRSA isolates were resistant to glycopeptides. The rate of VRE carriage at admission was 0.4%. Three patients (1%) had acquired carriage of VRE (1 had E. faecium and 2 had E. faecalis); all 3 were in the cefazolin group (2% of patients) and none in the vancomycin group (P=.27). Eight SSIs (3%) occurred, 4% in the cefazolin group and 2% in the vancomycin group (P=.47). CONCLUSIONS: This preliminary study demonstrates that cefazolin and vancomycin prophylaxis have similar impacts on the emergence of glycopeptide-resistant pathogens. Neither MRSA infection nor increased rates of SSI with other bacteria were observed in the vancomycin group, suggesting that a larger multicenter study should be initiated.

Aged, 80 and over↗

PubMed1975

The biliary excretion of cefazolin.

The biliary excretion of cefazolin was studied by perfusion of isolated rabbit livers. Under these conditions, 6.7 percent of the amount of cefazolin added to the circulating blood was excreted in bile, and concentrations of drug in bile were significantly higher than concentrations in serum. Biliary excretion of cefazolin was also studied in humans after the intravenous administration of 500 mg of the drug. In 10 normal subjects, maximal concentrations of cefazolin (17.10 plus or minus 8.5 mug/ml) in the fluid obtained by duodenal tubing were attained 1-2 hr after administration of cefazolin. Concentrations were similar in bile collected by external drainage from five cholecystectomized patients (maximal levels, 14.0 plus or minus 4.7 mug/ml) 1-2 hr after injection. Assays during cholecystectomy showed that 1 hr after injection, cefazolin levels were much higher in common duct bile (31 plus or minus 11 mug/ml) than in gallbladder bile (5 plus or minus 2 mug/ml).

Animals↗

PubMed1976

Protein binding and concentrations of cephaloridine and cefazolin in serum and interstitial fluid of dogs.

Percentages of free and protein-bound cefazolin and cephaloridine in serum and interstitial fluid of dogs were determined by ultrafiltration and microbiologic assay. The percentages of cephaloridine and cefazolin bound to protein in serum were 10% and 80%, respectively. In interstitial fluid accumulating within tissue-embedded polypropylene capsules, 29% of cefazolin was bound to protein, and cephaloridine was unbound. Both antibiotics rapidly penetrated the interstitial fluid and attained measurable levels 5 min after intravenous administration. Levels of total cefazolin in the interstitial fluid were generally higher than those of cephaloridine; however, concentrations of free cephaloridine in the fluid exceeded the levels of free cefazolin after the first 15 min. Binding of anitbiotics by serum proteins does not restrict such agents to the intravascular space, since a highly protein-bound compound has been shown to penetrate interstitial fluid as readily as one that is minimally bound. It should be noted, however, that this penetration may be due primarily to the slow rate of binding of cefazolin to serum proteins.

Animals↗