A simple and sensitive liquid chromatographic technique for the determination of cefotetan disodium in human plasma and its application in a pharmacokinetic study.

A simple and sensitive liquid chromatographic method was developed for quantification of cefotetan disodium (CTT), a semi-synthetic cephamycin antibiotic, in human plasma. CTT and the internal standard chloramphenicol were extracted from plasma by a simple one-step protein precipitation with 35% (v/v) perchloric acid. Separation was carried out on a reverse-phase C18 column with a mobile phase of acetonitile-water containing 0.5% (v/v) phosphoric acids (20:80, v/v) at a flow rate of 1.0 mL/min. The column effluent was monitored by UV detection at 300 nm. The column temperature was maintained at 40°C. This method demonstrated good linearity in the range of 0.525-300.0 µg/mL, with correlation coefficients greater than 0.99. The limit of quantification (LOQ) was 0.525 µg/mL in human plasma. Intra- and inter-day precisions were less than 6.63% in terms of relative standard deviation (RSD). The accuracy, when expressed by the bias, ranged from 0.57% to 4.04%. The mean extraction recovery of CTT was higher than 40.94%. The method was found to be precise, accurate, and specific for CTT quantitative analysis, and was successfully applied for a pharmacokinetic study of CTT after a single intravenous dose of 1.0 g of CTT in healthy Chinese subjects.

Pharmacokinetics and tolerability of intravenous cefotetan disodium for injection in healthy Chinese volunteers: A randomized, open-label, single- and multiple-dose study.

BACKGROUND: Cefotetan disodium for injection is a semisynthetic cephamycin antibiotic that exerts its bactericidal effects by inhibition of cell-wall synthesis. Despite being widely used in the treatment of various infections, little information is available on the pharmacokinetic properties of cefotetan disodium in Chinese subjects. OBJECTIVES: This study evaluated the pharmacokinetics of single and multiple intravenous doses of a generic formulation of cefotetan disodium in healthy Chinese volunteers. The effect of sex on the pharmacokinetics of cefotetan disodium was evaluated as a secondary objective. METHODS: In this open-label, dose-escalating study, subjects were randomized to receive a single dose of cefotetan disodium 0.5, 1.0, or 2.0 g administered as a 1-hour intravenous infusion. Those allocated to the 1.0-g dose continued into the multiple-dose phase, in which they received 1.0 g BID for 7 consecutive days. During the single-dose phase, blood samples were collected at regular intervals from 0 to 15 hours after drug administration and were analyzed using a validated HPLC method. During the multiple-dose phase, blood samples were obtained before drug administration on days 5, 6, and 7 to determine the C(min) at steady state; on day 7, blood samples were also collected from 0 to 15 hours after drug administration. Tolerability was assessed based on physical examinations, vital signs, laboratory tests (hematology, biochemistry, hepatic and renal function, and urinalysis), and subject interviews. RESULTS: Three groups, each consisting of 5 men and 5 women, were enrolled in the single-dose phase. The mean (SD) age of subjects was 23.2 (2.2) years (range, 19-30 years). Their mean weight was 57.0 (6.3) kg (range, 46.4-72.0 kg), and their mean height was 1.66 (0.08) m (range, 1.48-1.81 m). After intravenous administration of single doses of 0.5, 1.0, and 2.0 g, the cefotetan disodium C(max) was 35.01 (6.98), 76.67 (10.52), and 154.33 (27.17) mg/L, respectively; the AUC0₋15(h) was 145.35 (18.36), 307.45 (33.07), and 746.09 (103.07) mg · h/L; the AUC0₋(∞) was 171.51 (20.61), 347.25 (44.20), and 843.84 (131.13) mg · h/L; the t(1/2) was 5.80 (1.29), 4.91 (1.15), and 5.04 (1.26) hours; the CL was 2.96 (0.41), 2.92 (0.39), and 2.42 (0.39) L/h; and the V(d) was 24.55 (5.19), 20.37 (3.66), and 17.30 (3.52) L. After administration of multiple doses, the cefotetan disodium C(max,ss) was 80.53 (10.04) mg/L; the C(mix,ss) was 11.00 (4.04) mg/L; the AUC(ss) was 347.92 (50.04) mg · h/L; the steady-state plasma concentration was 28.99 (4.17) mg/L; the t(1/2) was 6.24 (2.52) hours; the CL was 2.32 (0.64) L/h; and the Vd was 19.19 (4.58) L. No significant differences in pharmacokinetic parameters were noted by sex in the multiple-dose phase. Cefotetan disodium appeared to be well tolerated. CONCLUSIONS: In these healthy Chinese subjects, the cefotetan disodium AUC and C(max) increased in a dose-proportional manner, whereas the t(1/2) was independent of dose. The pharmacokinetic properties of cefotetan disodium were linear at doses of 0.5 to 2.0 g. After multiple doses, the pharmacokinetic parameters of cefotetan disodium were consistent with those after single doses. At the doses studied, cefotetan disodium appeared to be well tolerated in these healthy volunteers.

Persistence of cefotetan on red blood cells.

BACKGROUND: Cefotetan can cause severe immune hemolytic anemia that may persist long after the drug is discontinued. To study the binding of cefotetan to RBCs, patients who received cefotetan were followed and tested for the presence of antibody to cefotetan. STUDY DESIGN AND METHODS: Patients receiving cefotetan were identified from pharmacy and nursing records. Blood samples obtained for routine hematology tests were analyzed. Cefotetan binding to patients' RBCs was tested using a previously characterized high-titer anticefotetan serum by gel technique. To determine the minimum amount of drug necessary for binding to occur, RBCs were incubated with serial dilutions of cefotetan at pH 7.4. RESULTS: Sixty patients receiving 1 to 25 g i.v. (median, 2 g) of cefotetan were followed for 1 to 123 days (median, 18 days). All were initially positive, for cefotetan on RBCs. Positivity persisted for up to 98 days after the last dose of drug. Fifteen patients became negative during follow-up. The first negative sample occurred at Day 30 to 123. Using the midpoint between the last positive and first negative to estimate of the duration of positivity, we estimate that cefotetan remains RBC-bound for 16.5 to 92 days (median, 67.5 days). During the follow-up period, five patients developed anticefotetan detectable in the serum. Twenty patients receiving other cephalosporin antibiotics showed no specific reactivity of their RBCs with anticefotetan. In vitro studies showed a minimum necessary drug concentration of 1 micromol/L at physiologic pH, which was not significantly altered by RBC pretreatment with ficin, sialydase, or DTT. CONCLUSIONS: Cefotetan is tightly bound to RBCs after intravenous administration and remains detectable for weeks after the last dose. Antibodies to cefotetan may occur in about 8 percent of patients receiving the drug. The minimum necessary concentration for RBC binding is low compared to an estimated plasma concentration of 240 micromol/L from a single i.v. dose of 1 g.

Clinical pharmacokinetics of cefotetan.

Cefotetan is a 7-alpha-methoxy beta-lactam. A long serum half-life and resistance to beta-lactamase hydrolysis have made cefotetan an attractive chemotherapeutic agent, and the results of clinical trials worldwide have demonstrated its efficacy in a wide variety of clinical situations. Cefotetan can be administered intravenously (bolus or infusion) or intramuscularly with lidocaine (lignocaine) 0.5%. Mean peak plasma concentrations are almost linearly related to dose. The volume of distribution is between 8 and 13L and is not different from other cephalosporins. No accumulation is seen after repeated doses and no metabolite has been detected in either plasma or urine. Total body clearance is 1.8 to 2.9 L/h. Renal clearance accounts for about 64 to 84% of a dose, and 75% of a dose is excreted in the urine within 24 hours. The plasma elimination half-life is between 3 and 4 hours after intravenous and intramuscular doses. Half-life is considerably prolonged in patients with renal impairment (up to 10 hours). Cefotetan concentrations are likely to be active against susceptible bacteria in most tissues and body fluids. Breast milk and cerebrospinal fluid concentrations are low. The recommended dosage is 1g every 12 hours, increasing to 2g in severe infections and 3g in life-threatening infections. In surgical prophylaxis, a single dose of 2g is given with the induction of anaesthesia; an additional dose of 2g may be administered 12 hours later. In children over 6 months, the recommended dosage is 30 mg/kg given 12-hourly. In patients with a creatinine clearance of 10 to 40 ml/min (0.6 to 2.4 L/h), the dose is halved or the dosage interval is doubled. When creatinine clearance is less than 10 ml/min (0.6 L/h), the dose is quartered or the dosage interval quadrupled.

Pharmacokinetics and tissue penetration of single-dose cefotetan used for antimicrobial prophylaxis in patients undergoing colorectal surgery.

The pharmacokinetics and tissue penetration of cefotetan were studied after a single injection of 2 g given intravenously for antimicrobial prophylaxis to 16 consecutive patients undergoing colorectal surgery. Concentrations in tissue greater than or equal to the MIC for 90% of the main pathogens tested were considered adequate. The elimination half-life at beta phase was 4.6 +/- 1.4 h, the total body clearance was 0.75 +/- 0.19 ml/kg/min, and the volume of distribution was 260 +/- 71 ml/kg. At the time of incision (33 +/- 16 min after the injection), cefotetan concentrations were 14.2 +/- 7 micrograms/g in abdominal-wall fat, 16.4 +/- 1 micrograms/g in epiploic fat, and 163 +/- 62 mg/liter in serum. At the time of surgical anastomosis (151 +/- 54 min), cefotetan concentrations were 33.3 +/- 6 micrograms/g in the colonic wall and 73 +/- 34 mg/liter in serum. Upon closure of the abdomen (216 +/- 76 min), cefotetan concentrations were 6.3 +/- 3 micrograms/g in abdominal-wall fat, 6.1 +/- 4 micrograms/g in epiploic fat, and 64 +/- 38 mg/liter in serum. Cefotetan tissue penetration was 10% into abdominal and epiploic fat and 46% into the colonic wall. Levels in tissue were compared with the MIC for 90% of the most frequently encountered pathogenic germs (Staphylococcus aureus, Bacteroides fragilis, and Escherichia coli). Adequate concentrations in tissue were obtained up to anastomosis but not upon closure. The authors therefore recommend the injection of an additional dose of 1 g before closure in order to ensure optimal efficacy throughout the surgical procedure.

Fatal immune hemolytic anemia due to cefotetan.

In the first death associated with immune hemolytic anemia due to cefotetan, the patient developed hemolytic anemia and renal failure, dying 12 days after the beginning of 1 week's cefotetan therapy. The patient's serum contained strong antibodies reacting with cefotetan-treated red cells (RBCs) and with uncoated RBCs in the presence of cefotetan; a much weaker, drug-independent antibody was also detected. Three-days before the patient's death, the antibody reacting with cefotetan-coated RBCs rose to a titer of 262,144; the titer of the antibody to uncoated RBCs, in the presence of cefotetan, rose to 2048; the titer of the drug-independent antibody remained at 4.

Severe immune-mediated hemolytic anemia secondary to treatment with cefotetan.

Severe acute hemolytic anemia developed in a woman following treatment with multiple antibiotics for possible postpartum uterine infection. On admission, the hemoglobin was 5 g per dL (50 g/L), the reticulocytes were 35 percent (0.350), the direct antiglobulin test was strongly positive for IgG and C3d (mixed fields), and the indirect antiglobulin test was negative. Serologic studies revealed antibody to cefotetan that reacted by both the immune complex and the drug adsorption mechanisms. Before the diagnosis of cefotetan-related immune hemolysis was made, all medications had been discontinued, and the patient received 4 units of red cells and a short course of adrenocorticosteroids. Recovery was prompt and complete.

Tissue distribution of cefotetan in patients with Crohn's disease.

Concentrations of cefotetan in the intestinal wall of patients with Crohn's disease were investigated with the method of tissue homogenates with the aim to evaluate the effects of inflammation on tissue distribution. Twenty-four patients who underwent surgery were treated with a 2-gram single dose of cefotetan intravenously before the operation. The mean tissue levels in inflamed intestinal wall were constantly higher than in normal wall, but the difference was statistically significant only in samples taken more than 2 h after cefotetan administration (31.0 +/- 17.8 vs 14.7 +/- 11.4 mg/kg; p less than 0.05). The mean residence time was 284.3 min for inflamed tissue and 123.9 min for normal. The areas under the curve were significantly higher in inflamed wall than in normal, with mean values of 4,789 and 3,020.2 mg/l.h, respectively (p less than 0.05). Inflammation seems to facilitate the penetration of cefotetan into the intestinal wall of patients with Crohn's disease but above all, it increases the mean residence time in inflamed tissue.

Prediction of the pharmacokinetics of cefodizime and cefotetan in humans from pharmacokinetic parameters in animals.

Pharmacokinetic behavior of beta-lactam antibiotics (cefodizime and cefotetan) in humans were predicted from the animal data. Total body clearance (CLp) of these drugs in humans (weighting 65-69 kg) were successfully extrapolated from the allometric relationship between the clearance for the unbound drug in plasma and body weight (r = 0.954-1.000) with a power of 0.948-0.991 for cefodizime and 0.700-0.756 for cefotetan. We also predicted the volume of distribution at steady state (Vdss), the volume of distribution in the central compartment (V1) and the volume of distribution at beta-phase (Vd beta) of these drugs in humans from the observed human plasma unbound fraction, inasmuch as the plasma unbound fraction correlated well (r = 0.913-0.995) with the values of Vdss, V1, and Vd beta among various animal species. Based on these predicted pharmacokinetic parameters, we calculated the plasma concentration profiles of these drugs in humans and found a good agreement between the predicted and observed values. We also report here that the prediction is successful when we consider the plasma protein binding of these drugs.

Antibiotic prophylaxis in gynecological surgery.

A randomized prospective study was undertaken at the Obstetrics and Gynecology Clinic of the Catholic University of Rome in order to evaluate the effectiveness of two wide spectrum antibiotics: mezlocillin and cefotetan. Both drugs were administered 2 g i.v. 15 to 20 minutes preoperatively to allow optimal serum and tissue levels of antibiotic at the moment of bacterial innoculation. 184 patients undergoing elective gynecological surgery for nonmalignant disease were considered eligible for the study (124 pts abdominal hysterectomy, 58 pts vaginal hysterectomy). We found no statistically significant differences between the results obtained with the two drugs.

The pharmacokinetic properties of cefotetan and its relevance for prophylaxis in elective colorectal surgery.

In an open, prospective, non-randomised study involving 112 patients undergoing elective colorectal surgery, the effect of perioperative prophylaxis with cefotetan was investigated. Cefotetan (2g) was administered, pre- and intra-operatively only. Preoperative bowel preparation was done by the standardised "Würzburg Method" i.e. oral metronidazole pre and post orthograde lavage. Mucosal biopsies were obtained from the resected colon and simultaneously serum samples were taken to determine tissue and serum levels respectively. Antibiotic serum and gut mucosal levels were well in excess of the minimum inhibitory concentration (MIC90) levels of the isolated bacteria. Wound infections occurred in only 2 patients. Cefotetan was well tolerated and no adverse events were noted. In prolonged colorectal surgery, an antibiotic such as cefotetan with a long half-life is to be recommended.

Serum bactericidal activity against aerobes and anaerobes of volunteers receiving cefoxitin or cefotetan.

Six volunteers received intravenously a single 1 g dose of cefoxitin or cefotetan. The 2 groups were crossed after a week of washout. Five strains each of Escherichia coli, Klebsiella pneumoniae, Bacteroides fragilis and Bacteroides thetaiotaomicron susceptible to the administered drugs were tested for serum bactericidal activity (SBA). Blood samples were obtained before and 0.5, 3.0 and 12.0 hours after antibiotic injection. SBA was determined using microtitre procedures. Anaerobic bacteria were incubated in an anaerobic chamber. Cefotetan showed a very high SBA both against aerobes and anaerobes over the 12 hour sampling time. Cefoxitin reached satisfactory SBA values only 0.5 hours after administration.

Cefotetan: antibacterial activity against Staphylococcus aureus in the presence of human serum.

Cefotetan is a broad spectrum cephamycin antibiotic with a long serum half-life (3-4.5 h): this is explained, in part, by serum-protein-binding (SPB) of 88%. The rate of kill of Staphylococcus aureus by cefotetan was assessed in human serum or broth containing reducing concentrations of drug simulating those seen following a 1 g intravenous dose to man. Cefotetan was bactericidal in serum despite the assumed concentration of unbound drug never reaching the minimum inhibitory concentration (MIC) for the test strain. In a separate study, ceftriaxone (SPB 96%) was more active in broth (MIC 4 mg/1) than cefotetan (MIC 16 mg/1). In 100% serum the minimum bactericidal concentration (MBC) of ceftriaxone was 64 mg/1 whilst the MBC for cefotetan was 16 mg/1.

Pharmacokinetic profile of cefotetan in different clinical conditions.

The pharmacokinetic profile of cefotetan was studied in a group of hospitalized patients. The absorption of the molecule (after a single dose of 2 g/i.m.) was good and the drug was found to diffuse satisfactorily in the lungs, prostatic tissue, kidney and in the female genitalia.