Concentrations Of Ceftizoxime Research Articles

Effects of herbal extract of Ocimum sanctum as supportive therapy with intravenous ceftriaxone in experimentally induced staphylococcal chronic mastitis in goat

The protective effects of Ocimum sanctum leaf juice as supportive therapy in induced chronic staphylococcal mastitis were evaluated with intravenous ceftriaxone injection in lactating goats. Chronic mastitis was induced after 30days of intracisternal inoculation of 2000 c.f.u. of Staphylococcus aureus (J 638) into the left teat of the udder in two Groups of goats (Group I and Group II). Group I mastitic goats received only ceftriaxone injection i.v. at 20mg/kg at 4days intervals two times, whereas Group II mastitic goats were given fresh undiluted O. sanctum leaf juice at 5ml/kg orally for consecutive 14days with intravenous ceftriaxone injection at 20mg/kg at 7days intervals two times. In the animals receiving O. sanctum leaf juice, the plasma concentration of ceftriaxone increased to 0.11±0.03μg/ml, 33.93±1.54μg/ml, 1.62±0.17μg/ml, 0.70±0.09μg/ml and 0.19±0.03μg/ml vs control at 48, 216, 240, 264 and 288h with an increased concentration of ceftizoxime i.e., 0.26±0.03μg/ml,0.58±0.05μg/ml, 0.85±0.02μg/ml,1.26±0.04μg/ml, 2.82±0.04μg/ml, 1.96±0.04μg/ml, 0.67±0.02μg/ml vs below detectable level in control Group at 72, 216, 240, 264, 288, 312 and 336h, respectively. Further, the concentration of its metabolite i.e., ceftizoxime increased to 4.08±0.18μg/ml and 0.80±0.18μg/ml at day 4 and 6, respectively in milk from a below detectable level and milk concentration of both ceftriaxone and ceftizoxime increased in both halves of the udder at different time in Group II goats. No S. aureus colony was seen in milk at 96h post treatment in Group II goats. O. sanctum leaf juice (0.05ml) decreased the minimum inhibitory concentration of ceftriaxone (3μg/ml) and ceftizoxime (1μg/ml) to 0.5μg/ml for both the drugs against inoculated S. aureus. O. sanctum treatment significantly reduced the alkaline phosphatase activity along with an increase in lactoperoxidase activity maintaining normal reduced glutathione level with intravenous ceftriaxone therapy. The findings proved that O. sanctum leaf juice has significant bioenhancing and antioxidant activities which can be used as supportive therapy in staphylococcal chronic mastitis in goat.

Disposition kinetics of ceftizoxime in acute mastitis in Murrah buffaloes

Acute mastitis was induced by inoculation of Staphylococcus aureus in 6 buffaloes. Ceftizoxime was administrated intravenously @25 mg/kg to evaluate pharmacokinetics of ceftizoxime in mastitic buffaloes. The maximum mean plasma concentration of ceftizoxime was recorded at 0.08 h in healthy buffaloes which was followed by decreased plasma concentration of 23.53 ± 0.84 µg/ml at 1 h and persisted up to 24 h. Mean values of t½ß were 5.86 ± 0.18 and 8.42 ± 0.58 h in healthy and induced mastitic buffaloes, respectively. Mean Vdarea value of 1.10 ± 0.06 L/kg in healthy buffaloes was increased significantly. The maximum mean milk concentration of ceftizoxime at 2 h (73.34 ± 4.35 µg/ml) in lactating buffaloes decreased gradually till 12 h (31.31 ± 5.66 µg/ml) and persisted up to 96 h (1.57 ± 0.20 µg/ml). So, ceftizoxime can be used for treatment of staphylococcal mastitis in buffaloes.

Modification of the Electrode Surface by Ag Nanoparticles Decorated Nano Diamond‐graphite for Voltammetric Determination of Ceftizoxime

AbstractA modified glassy carbon electrode with a film of nano diamondgraphite nano mixture decorated with Ag nanoparticles (AgNPsNDG/GCE) was constructed and used for sensitive voltammetric determination of ceftizoxime (CFX). Morphology of AgNPsNDG/GCE has been examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Experimental variables such as deposited amount of the modifier suspension, pH of the supporting electrolyte and accumulation potential and time were optimized by monitoring of CV and LSV responses of CFX. The results illustrate that AgNPsNDG/GCE exhibits an excellent electrocatalytic effect in the electro‐oxidation of CFX that leads to a considerable improvement in the corresponding anodic peak current. This also allows the development of a highly sensitive voltammetric sensor for the determination of CFX in pharmaceutical and clinical samples. Under the optimum conditions, the modified electrode showed a linear response to the concentration of CFX in the range of 0.02–7 µM with detection limit of 6 nM. The prepared modified electrode has some remarkable electrochemical properties such as simple preparation, high sensitivity, excellent repeatability and reproducibility and long‐term stability.

新生児, 未熟児におけるCeftizoximeの基礎的・臨床的検討

Ceftizoxime (CZX), one of the fifth group in cephem-antibiotics classified by Fujii, was administrated intravenously with a one shot dose of 20 mg/kg to neonates and low birth weight infants with ages ranged 4-21 day old and plasma and urinary concentrations and urinary recovery rates of the drug were determined. Clinical, prophylactic and bacteriological effects of CZX were evaluated and adverse reactions and effects on laboratory test values due to this drug were studied in 22 neonates and low birth weight infants (0-76 day old) consisting of 16 cases with various bacterial infections including presumptive cases of bacterial infections and 6 cases with prophylactic administration against infectious diseases. An average CZX daily dose of 55.3 mg/kg was given once or divided into 2-4 times daily (twice: 16 cases, 3 times: 3 cases, 4 times: 2 cases) through intravenous one shot administration for 6 days on the average. The results obtained are summarized as follows. 1. Neonates and low birth weight infants were classified into 3 groups by age: 4-7, 8-14, 15-21 day old. Plasma peak levels of CZX were observed at an average of 5 minutes after administration in all 3 groups with mean values of 58.3, 74.9 and 76.9 micrograms/ml, respectively, and the 4-7 day old-group showed a lower value than with other 2 groups. Mean values of AUC were 218.9, 221.0 and 197.0 micrograms.hr/ml, respectively, and no notable difference was observed within each group. Mean values of half-lives of CZX were 3.61, 2.72 and 2.37 hours, respectively, and the younger group tended to have the longer value. 2. Urinary concentrations of CZX ranged 10.9-1.190 micrograms/ml in all of the 3 groups during 0-2, 2-4, 4-6, 6-8 hours after administration. Mean values of urinary recovery rates during 8 hours of the 3 age-groups were 60.1, 68.7, 56.7%, respectively. The oldest group showed the lowest mean value because one of the cases had the lowest value of 34.5% for an unknown reason. 3. Clinical effect of CZX in 16 cases with various bacterial infections and presumptive bacterial infections was evaluated with an efficacy rate of 87.5%. The prophylactic effect was recognized in all 6 cases that were given CZX to prevent infectious diseases. 4. The bacteriological effect was evaluated in only one case with an infection due to Escherichia coli, which was eradicated by the treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Study on Concentration of Ceftizoxime in Blood and Hematoma in Total Hip Replacement

Study on Concentration of Ceftizoxime in Blood and Hematoma in Total Hip Replacement

Involvement of MRP4 (ABCC4) in the Luminal Efflux of Ceftizoxime and Cefazolin in the Kidney

The purpose of the present study was to investigate the role of multidrug resistance-associated protein 4 (MRP4) in the tubular secretion of cephalosporin antibiotics. Most of the injectable cephalosporins have an inhibitory effect on the ATP-dependent uptake of [(3)H]dehydroepiandrosterone sulfate by membrane vesicles expressing hMRP4, whereas cephaloridine, cefsulodin, and cefepime do not. Aminocephalosporins have a weak inhibitory effect. Significant ATP-dependent transport of ceftizoxime (K(m), 18 microM), cefazolin (K(m), 80 microM), cefotaxime, and cefmetazole has been observed only in the membrane vesicles expressing hMRP4. Ceftizoxime and cefazolin were given by a constant intravenous infusion to wild-type and Mrp4(-/-) mice. The steady-state plasma concentrations of ceftizoxime and cefazolin were unchanged in Mrp4(-)(/)(-) mice. The urinary recovery of ceftizoxime was significantly reduced in Mrp4(-/-) mice, whereas it was unchanged for cefazolin. The kidney-to-plasma concentration ratio of ceftizoxime and cefazolin was increased 2.0- and 2.7-fold in Mrp4(-/-) mice, respectively; thus, the renal clearance with regard to the kidney concentration was reduced in Mrp4(-/-) mice, to 7.5 and 34% of the corresponding control values, respectively. These results suggest that Mrp4 is involved in the tubular secretion of ceftizoxime and cefazolin, in concert with basolateral uptake transporters.

Pharmacokinetics and penetration into tissue fluid of ceftizoxime in normal and hyperthermic sheep

The pharmacokinetics of ceftizoxime was studied in six sheep before and after inducing hyperthermia using Escherichia coli endotoxin. Sheep implanted subcutaneously with cages of non-reactive material for collecting tissue cage fluid (TCF) were used to conduct two trials. In Trial 1 animals with normal basal temperature (normal sheep (NS)) were given intravenous (i.v.) and intramuscular (i.m.) monodoses of ceftizoxime (20 mg/kg BW) at 1 week interval. One and 5 weeks later (Trial 2) each sheep were injected 1 μg/kg BW of endotoxin to produce hyperthermia (hyperthermic sheep (HS)) previously to i.v. administration (HSi.v.) and i.m. (HSi.m.) of ceftizoxime (20 mg/kg BW), respectively. Serum and TCF samples were collected over 6 h post-administration. Ceftizoxime concentrations in serum and TCF were determined by a microbiological assay. The concentrations in serum and TCF of ceftizoxime were analyzed through compartmental and non-compartmental models. Rectal temperature were significantly incremented in all animals during Trial 2. The half-time and constant of elimination in serum of ceftizoxime in NSi.v. ( t 1/2 = 1.1 ± 0.4 h; λ z = 0.7 ± 0.2 h −1) were statistically different those observed in HSi.v. ( t 1/2 = 1.4 ± 0.4 h; λ z = 0.5 ± 0.2 h −1). The constants of distribution in NSi.v. and HSIV were 5.1 ± 4.6 and 4.1 ± 3.4 h −1, respectively. The time to reach the maximum concentrations in TCF was latter ( p < 0.05) in NS ( t max = 2.3 ± 0.7 h) than in HS ( t max = 1.3 ± 0.6 h). After i.m. administration in NS the absorption half-life (0.12 ± 0.19 h) was latter ( p < 0.05) than in HS (0.06 ± 0.007 h) with greater areas under the curve (AUC in NS = 65.4 ± 20.8 and AUC in HS = 34.7 ± 7.5 (μg/ml) h). The maximum value of concentration in serum ( C max) and AUC in TCF were greater ( p < 0.05) in NS ( C max = 46.1 ± 10.6 μg/ml and AUC = 84.4 ± 17.4 (μg/ml) h) as compared to same HS ( C max = 27.0 ± 12.9 μg/ml and AUC = 47.9 ± 3.9 (μg/ml) h). The concentrations of ceftizoxime in TCF after i.v. and i.m. in NS and HS were elevated during a 6 h period after administration. The bioavailability of ceftizoxime in NS (101.6 ± 59.9%) and HS (87.4 ± 63.3%) was suitable for its use by the i.m. route.

去たん剤併用時のＣＺＸのし骨蜂巣粘膜移行

Ceftizoxime and ambroxol were administered in combination to patients with chronic sinusitis, who required surgical treatment. The transfer of ceftizoxime in combination with ambroxol into the ethmoid cell mucosa was compared to that of ceftizoxime alone. Ethmoid cell mucosal concentrations of ceftizoxime 90-120 minutes after intravenous administration of 1g of ceftizoxime alone ranged from 0.21 to 14.3μg/g. Plasma concentrations ranged from 9.51 to 31.6μg/ml, and the tissue distribution rate (ethmoid cell mucosal c./plasma c.) was 31%. When ambroxol was administered in combination with ceftizoxime, ethmoid cell mucosal concentrations of ceftizoxime ranged from 1.04 to 9.66μg/g. Plasma concentrations ranged from 6.7 to 33.5μg/ml, and the tissue distribution rate was 38%. In patients administered ceftizoxime alone, the tissue distribution rates of ceftizoxime were comparatively variable. The mean distribution rates however, were nearly the same in both groups. On the basis of these findings, it was concluded that the concentrations of ceftizoxime in the ethmoid cell mucosa and the plasma were scarcely affected even when ceftizoxime was administered in combination with ambroxol. Ethmoid cell mucosal concentrations and plasma concentrations of ceftizoxime are typically maintained at MIC80 values for period of 4 hours or more, in the treatment of various clinical isolates including organisms causing respiratory infection. This suggests that the therapeutic effects of ceftizoxime can be obtained clinically even when it is used alone. Concomitant use of ambroxol is however, considered to be useful supplemental therapy since the antibacterial activity of ceftizoxime is supported by the improvements in sinusitis induced by ambroxol.

Ceftizoxime use in trauma celiotomy: pharmacokinetics and patient outcomes.

Seriously injured patients undergo vigorous resuscitation upon arrival at the emergency department and through the immediate perioperative period. Although resuscitation leads to volume loading and fluid shifts, drug dosing and dosing intervals are often not altered to account for changes in total body volume or circulatory volume. To address this, a prospective study of pharmacokinetics of ceftizoxime in 53 injured adults who underwent emergency celiotomy was conducted. Further, the relationship between serum ceftizoxime concentrations and infectious outcomes was evaluated. Per protocol, injured adults undergoing emergency celiotomy received prophylactic ceftizoxime treatment according to standard dosing regimens. Of the patients, 6 (11.5%) experienced postoperative infections and had lower peak serum ceftizoxime levels in the recovery room than patients not experiencing infection. For severely injured adults with extensive blood loss or undergoing lengthy operations requiring rigorous volume resuscitation, doses of ceftizoxime, and indeed all antibiotics, may need to be increased beyond conventional standards to minimize infectious complications.

Differential protein binding of ceftizoxime in cord versus maternal serum

Ceftizoxime concentrations are higher in cord blood and amniotic fluid than in maternal blood. More avid binding to fetal serum proteins is a suggested mechanism. We measured ceftizoxime protein binding in fetal and maternal blood and documented significantly less protein binding to fetal proteins (21.9% vs 57.8%).

Population Pharmacokinetics of Ceftizoxime in Premature Newborns

The population pharmacokinetic parameters of ceftizoxime were determined in 50 premature newborns less than 1 week of age (birth weight = 1.8 +/- 0.6 kg) with a clinical diagnosis of suspected sepsis. Each infant received ceftizoxime 25 mg/kg every 12 h intravenously over 30 min for a total of 6 doses. Serum concentrations of ceftizoxime were assayed by HPLC at 0.5, 1, 2.5 and 11.5 h or at 0.5, 1.5, 4.5 and 11.5 h after the first and the sixth dose. A total of 184 serum concentrations following the first dose and 160 following the sixth dose were fit separately and then collectively to a one-compartment model using NONMEM. The separately estimated parameters were not significantly different between the first and the sixth dose. The final parameter estimates were 27.1 ml/h/kg, 333 ml/kg and 8.5 h for clearance, volume of distribution and half-life, respectively. Other factors including gestational and postnatal age were not associated with alterations in ceftizoxime clearance. That the large variability in clearance was decreased from a coefficient of variation of 80 to 50% warrants dosing premature infants on the basis of body weight. The results of this study suggest that 25 mg/kg ceftizoxime every 12 h appears to be an appropriate dosing regimen for premature neonates.

Efficacy of Ceftizoxime in the Treatment of Severe Bacterial Infections in Patients with Cirrhosis

Bacterial infections, particularly spontaneous bacterial peritonitis and bacteraemia, are a frequent complication in cirrhotic patients (Rimola et al. 1986). These infections are predominantly caused by Enterobacteriaceae, although a significant proportion are caused by other organisms, particularly Gram-positive cocci. Even when appropriate treatment is given, spontaneous bacterial peritonitis and bacteraemia in cirrhosis are associated with a high mortality rate. Because of the severity of these infections, antibiotic therapy must be initiated empirically, without any knowledge of causative organisms and their in vitro susceptibility. In a randomised controlled study in the empirical treatment of severe infections in cirrhosis, Felisart et al. (1985) observed that cefotaxime was more effective than ampicillin + tobramycin and concluded that cefotaxime should be considered as the first-choice antibiotic in this situation. However, because of the short halflife of cefotaxime, frequent administration is required (Carmine et al. 1983); in the Felisart study, for example, cefotaxime was administered at a dosage of 2g every 4 hours. In the present investigation we therefore evaluated the efficacy of ceftizoxime, a third generation cephalosporin with a similar antibacterial spectrum to that of cefotaxime but with a more prolonged half-life (Richards & Heel 1985), in a series of cirrhotic patients with severe bacterial infections. Additionally, serum and ascitic fluid ceftizoxime concentrations were determined in these patients.

Comparative study of pharmacokinetics and serum bactericidal activity of ceftizoxime and cefotaxime

Single 2-g intravenous doses of ceftizoxime (CZX) and cefotaxime (CTX) were given over 30 min to 10 adult volunteers in a crossover manner on two separate occasions. Concentrations of CZX, CTX, and the primary metabolite of CTX, desacetylcefotaxime (dCTX), in serum, suction-induced-blister fluid, and urine were determined by high-pressure liquid chromatography. Pharmacokinetic parameters were estimated by using an extended least-squares modeling program (MKMODEL). CZX exhibited a half-life in serum (2.05 h) longer than that of CTX (1.43 h) but comparable to that of dCTX (2.02 h). The percentage of penetration in blister fluid, estimated by area under the curve ratios, was significantly higher for CZX (164.4%) than for CTX (60.8%). Serum bactericidal activity, determined for volunteer samples at 1, 6, 8, and 12 h after patients were dosed, against clinical isolates of the Bacteroides fragilis group, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, and Morganella morganii were significantly higher for CZX than those for CTX against members of the family Enterobacteriaceae at all times. Serum bactericidal titers against B. fragilis were also higher for CZX than for CTX at 1 h postinfusion. Neither CZX nor CTX exhibited any bactericidal activity at any other time against the B. fragilis group. In conclusion, the serum bactericidal activity of CZX was greater and more-prolonged than that of CTX against tested strains in spite of the in vitro synergistic contribution of dCTX to CTX, equal serum elimination half-lives of dCTX and CZX, and similar antibacterial activity and similar instability under microbiological testing for CZX and CTX.

Ca&lt;SUP&gt;2+&lt;/SUP&gt;またはMg&lt;SUP&gt;2+&lt;/SUP&gt;存在下でのβ-ラクタム剤によるグラム陰性菌臨床分離株のスフェロプラスト形成

Induction to cell wall-deficient bacteria has been suggested to be a cause of intractable and opportunistic infection after chemotherapy. Spheroplast formation by beta-lactam antibiotic in not so high osmotic pressure was investigated in six species of gram-negative bacteria. Some species of gram-negative bacteria were induced to form spheroplast at a high rate by 1:10 concentration of ceftizoxime in the presence of Ca2+ or Mg2+. Especially in 38% of Proteus mirabilis and P. vulgaris, more than 40% of the original cells were induced to form spheroplast by ceftizoxime in a medium supplemented with 40 mM Ca2+. The same formation rate was also found in 22% of Serratia marcescens. Formation rates in the drug sensitive strains of S. marcescens were enhanced as the drug concentration increased. Ca2+ was more effective in spheroplast formation than Mg2+.

Steady-state cord and amniotic fluid ceftizoxime levels continuously surpass maternal levels

As part of our management protocol for preterm premature rupture of membranes, ceftizoxime and tocolysis were used to prolong the latent period and prevent or treat concomitant infection. Ceftizoxime was selected for this protocol based on its physiochemical properties, which favor placental transfer of the drug. Patients achieving steady-state pharmacodynamics (more than three doses of the drug) were considered eligible for study. Ceftizoxime levels were determined by reverse-phase high-pressure liquid chromatography. All levels measured after the first hour of treatment were indicative of the relative concentration of ceftizoxime in the fetal and amniotic fluid compartments when compared with the maternal compartment. Mean (+/- SEM) ceftizoxime levels were 11.96 + 2.35 micrograms/ml in maternal serum, 24.54 +/- 4.78 micrograms/ml in cord serum, and 43.45 +/- 4.97 micrograms/ml in amniotic fluid. Based on its broad antibacterial activity and its high concentration in fetal blood and amniotic fluid, ceftizoxime appears to be an ideal agent for treatment of the intrauterine environment.

Synergism of cephalosporins at subinhibitory concentrations and polymorphonuclear leukocytes on phagocytic killing of Escherichia coli and its mode of action.

The interactions between subinhibitory concentrations of cephalosporins and polymorphonuclear leukocytes in the killing of a strain of Escherichia coli are described and an attempt is made to define the responsible mechanism. Ceftizoxime was the most potent agent tested. Pretreatment of the E. coli strain with subinhibitory concentrations of ceftizoxime increased the susceptibility to both; phagocytic killing activity of the polymorphonuclear leukocytes and bactericidal activities of the oxygen metabolites and the granule extracts. A most interesting result was the increased susceptibility of the ceftizoxime-treated E. coli to killing by beta-glucuronidase which normally is not bactericidal. It is suggested that the augmented killing could be due to bacteriolysis by beta-glucuronidase.

Susceptibility of intra- and extracellular Mycobacterium avium-intracellulare to cephem antibiotics.

Intra- and extracellular susceptibility of 35 clinically isolated Mycobacterium avium-intracellulare strains to cefotaxime (CTX), ceftizoxime (CZX), and cefoperazone was studied. MICs for 50% of the isolates in vitro were 6.25 micrograms/ml for CTX and CZX and 25 micrograms/ml for cefoperazone. A strain susceptible to CTX (MIC, 0.78 micrograms/ml) and CZX (MIC, 1.56 micrograms/ml) infected human peripheral blood mononuclear cells in the presence of 20% autologous plasma. The mycobacteria replicated exclusively in monocytes under the above culture condition. Concentrations of CZX 1- to 16-fold higher than its in vitro MIC had little effect on intracellular replication of the strain. A concentration of CTX 16-fold higher than its in vitro MIC was bacteriostatic to the mycobacteria, but CTX of lower concentrations showed no effect on intracellular replication. Thus, ineffectiveness of the cephems on the therapy of M. avium-intracellulare infection was suggested.

耳鼻いんこう科領域におけるＣｅｆｔｉｚｏｘｉｍｅ（ＣＺＸ）の組織移行に関する研究 特にけい部組織について

After the i. v. injection of 1.0g of ceftizoxime its tissue distribution was investigated in the parotid gland of 18 patients, the submandibular gland of 16, the anterior neck muscles of 18, the thyroid gland of 11, and the tongue of 6. The regression equation for each tissue concentration of ceftizoxime was found by pharmacodynamic analysis to be:Parotid gland C=15.6×e-0.353tSubmandibular gland C=16.1×e-0.396tAnterior neck muscles C=25.5×e-0.435tThyroid gland C=14.2×e-0.233tTongue C=26.8×e-0.533tIt was used to confirm ceftizoxime concentrations in the tissues. The tissue concentrations of ceftizoxime 2 hours after i. v. injection were 7.70μg/g for the parotid gland, 7.29μg/g for the submandibular gland, 10.68μg/g for the anterior neck muscles, 8.91μg/g for the thyroid gland, and 9.23μg/g for the tongue. These tissue concentrations and the antibacterial activity of ceftizoxime indicate that it is very useful in the treatment of otolaryngological infections and postoperative infections.

Activity of ceftizoxime combined with gentamicin against 100 clinical isolates of Pseudomonas aeruginosa

The effects of ceftizoxime and gentamicin alone and in combination were determined against 100 Pseudomonas aeruginosa strains. Concentrations of 32 micrograms of ceftizoxime and 8 micrograms of gentamicin per ml inhibited 22 and 43% of the strains, respectively. At concentrations of ceftizoxime and gentamicin that are readily achievable in serum, 15 strains were affected synergistically and 17 strains were affected antagonistically. Gentamicin accounted for most of the anti-P. aeruginosa activity of ceftizoxime-gentamicin combinations.

Liquid chromatographic assay of ceftizoxime in sera of normal and uremic patients.

The application of high-pressure liquid chromatography assays for cephalosporin serum concentrations is difficult in uremic patients because of interference from nondialyzable substances. We developed a high-pressure liquid chromatography method for determining the serum concentration of ceftizoxime in normal and uremic patients. The method involves protein precipitation with acetonitrile, followed by removal of the acetonitrile with dichloromethane. Separation was accomplished with a reverse-phase (C-18) column and a mobile phase of 13% acetonitrile and 2.8% acetic acid. UV detection at 310 nm was used to monitor the peaks. This assay produced a linear relationship between peak height ratio and ceftizoxime concentration from 1.5 to 100 micrograms/ml. Samples from 30 patients were assayed by this method and by a bioassay, with a good correlation of results (r = 0.9832). The method was applicable equally to normal and uremic serum samples.