Ceftriaxone Levels Research Articles

Impact of Social Restrictions During COVID-19 on the Aquatic Levels of Antimicrobials and Other Drugs in Delhi.

The relative contribution of factors responsible for the environmental exposure of active pharmaceutical ingredients (APIs) is of interest for appropriate remedial measures. This study was carried out to evaluate the post-lockdown levels of APIs in water resources, in comparison to our previously published study from 2016. The environmental levels of 28 drugs from different classes were analyzed in surface water (Yamuna River), aquifers, and leachate samples collected from 26 locations in Delhi-NCR using the previously validated liquid chromatography-mass spectrometry (LC-MS/MS) methods. In addition, the prevalence of antimicrobial resistance in coliforms isolated from targeted surface water samples was also studied. This study revealed that more than 90% of APIs, including antibiotics, decreased drastically in both surface water and aquifers compared to our previous data. Selected samples subjected to antimicrobial resistance (AMR) analysis revealed the presence of cephalosporin-resistant coliform bacteria. Tracing cephalosporins in the surface and drain water samples revealed the presence of ceftriaxone in the drain and water samples from Yamuna River. Higher levels of ceftriaxone in landfill leachate were also found, which werefound to be associated with coliform resistanceand indicatethe un-segregated disposal of medical waste into landfills. Social restrictions enforced due to COVID-19 resulted in a drastic decrease in antimicrobials and other APIs in aquatic water resources. Increased ceftriaxone and cephalosporin resistance was seen in coliform from surface water and drain, indicating the possibility of hospital waste and treatment-related drugs entering Yamuna River. Enforcement of the regulations for the safe disposal of antibiotics at hospitals and preliminary disinfection of hospital sewage before its inflow into common drains might help minimize the spread of antibiotic resistance in the environment.

Emergence and Genomic Characterization of Neisseria gonorrhoeae Isolates with High Levels of Ceftriaxone and Azithromycin Resistance in Guangdong, China, from 2016 to 2019.

Currently, antibiotic resistance (especially ceftriaxone and azithromycin dual resistance) in Neisseria gonorrhoeae is the main obstacle affecting the efficacy of treatment. As analysis of drug sensitivity, molecular features, and dissemination of dual-resistant strains is important for gonococcal prevention and control, MIC, genotyping, and genome analysis were conducted to reveal the molecular characteristics and phylogeny of N. gonorrhoeae isolates. During 2016 to 2019, 5 out of 4,113 strains were defined as dual-resistant clones, with ceftriaxone MICs of 0.25 to ≥1 mg/L and azithromycin MICs of 2 to ≥2,048 mg/L. In particular, two strains with a ceftriaxone MIC above 0.5 mg/L were characterized as penA-60.001 FC428-related clones, and two isolates with a high-level azithromycin MIC above 1,024 mg/L featuring a 23S rRNA mutation were identified. Furthermore, phylogenetic analysis confirmed that the dual-resistant strains were closer to the evolutionary origin of F89 in France, global FC428-related clones, and high-level dual-resistant clones in Australia and the United Kingdom. Dual-resistant strains, including FC428-related clones and high-level azithromycin-resistant clones, have circulated in Guangdong, China. The ability of laboratories to perform real-time drug susceptibility and genetic analyses should be strengthened to monitor the spread of threatening strains. IMPORTANCE Here, we report five sporadic dual-resistant isolates, including FC428-related ceftriaxone-resistant clones with MICs of ≥0.5 mg/L and high-level azithromycin resistance with MICs of ≥1,024 mg/L. This study highlights that dual-resistant clones with the same evolutionary origin as FC428, A2735, and F89 have circulated in Guangdong, China, which suggests that the capacity for antibiotic resistance testing and genome analysis should be strengthened in daily epidemiological surveillance.

Ceftriaxone-induced Encephalopathy: A Pharmacokinetic Approach.

We report a case of ceftriaxone-induced encephalopathy correlated with a high concentration of the drug in cerebrospinal fluid (CSF). Cephalosporin neurotoxicity is increasingly reported, especially in association with fourth-generation cephalosporins. The factors influencing CSF concentration are plasma concentration, liposolubility, ionization, molecular weight, protein binding and efflux. In our patient, high levels of ceftriaxone (27.9 mg/l) were found in CSF. β-Lactam-associated neurotoxicity is mainly due to similarities between GABA and the β-lactam ring. Because of differences in CSF/plasma ratios and blood–brain barrier efflux among patients, plasma drug monitoring cannot be used to estimate CSF concentration. As far as we know, this is the first reported case of ceftriaxone-induced encephalopathy associated with a high CSF concentration.LEARNING POINTSCeftriaxone dose adjustment and clinical surveillance are strongly recommended in patients with renal failure.Measuring ceftriaxone cerebrospinal fluid concentration could be useful for confirming ceftriaxone-induced encephalopathy.

"Effect of Subinhibitory Concentrations of Some Antibiotics and Low Doses of Gamma Radiation on the Cytotoxicity and Expression of Colibactin by an Uropathogenic Escherichia coli isolate".

Colibactin and cytotoxic necrotizing factor 1 (Cnf 1) are cyclomodulins secreted by uropathogenic E. coli. In this study, uropathogenic E. coli expressing colibactin and Cnf 1 was exposed to antibiotics subMICs and gamma radiation to investigate their effects on its cytotoxicity and expression of colibactin. The test isolate was exposed to three subMIC levels of levofloxacin, ciprofloxacin, trimethoprim/sulfamethoxazole and ceftriaxone and irradiated with gamma rays at 10 and 24.4Gy. The cytotoxicity for either antibiotic or gamma rays treated cultures was measured using MTT assay and the expression of colibactin encoding genes was determined by RT-PCR. Treatment with fluoroquinolones nearly abolished the cytotoxicity of E. coli isolate and significantly downregulated clbA gene expression at the tested subMICs (P ≤ 0.05) while trimethoprim/sulfamethoxazole treated cultures exerted significant downregulation of clbA and clbQ genes at 0.5 MIC only (P ≤ 0.05). Ceftriaxone treated cultured exhibited reduction in the cytotoxicity and insignificant effects on expression of clbA, clbQ and clbM genes. On contrast, significant upregulation in the expression of clbA and clbQ genes was observed in irradiated cultures (P ≤ 0.05). Fluoroquinolones reduced both the cytotoxicity of UPEC isolate and colibactin expression at different subMICs while ceftriaxone at subMICs failed to suppress the expression of genotoxin, colibactin, giving an insight to the risks associated upon their choice for UTI treatment. Colibactin expression was enhanced by gamma irradiation at doses resembling these received during pelvic radiotherapy which might contribute to post-radiotherapy complications.

Pharmacokinetic-pharmacodynamic comparison of ceftriaxone regimens in acute cholangitis

The most important factors determining the prognosis of patients with acute cholangitis (AC) are prompt biliary drainage and appropriate choice of antibiotics. This study was performed to evaluate whether dividing the number of doses based on the PK-PD theory contributes to better clinical outcome in the management of acute cholangitis. We measured ceftriaxone levels in blood and bile in 21 cases diagnosed with moderate-to-severe AC. Eleven cases were administered 2 g of ceftriaxone once-daily (group A) and 10 cases were given 1 g of ceftriaxone twice-daily (group B). The theoretical effect of ceftriaxone was evaluated by pharmacokinetic–pharmacodynamic (PK–PD) parameters. Clinical efficacy was evaluated by body temperature, white blood cell count and serum levels of C-reactive protein. Minimum level of ceftriaxone in serum (in mg/L) in groups A and B at 24 h after the first dose was 9.1 and 9.2, whereas that in bile was 2.9 and 2.5, respectively. The minimum inhibitory concentration (MIC) of ceftriaxone for all isolated bacteria was below the minimum serum and biliary concentration of ceftriaxone 24 h after the first administration (except for Enterococcus species). The MIC for isolated bacterial strains was <16 mg/L, which is the PK–PD breakpoint for ceftriaxone at 2 g/day. Both regimens showed clinical efficacy and did not contradict the effect predicted based on PK–PD.

Study to Compare Blood Levels of Ceftriaxone Given by Suppository or Injection.

Study to Compare Blood Levels of Ceftriaxone Given by Suppository or Injection.

Effect of sublethal concentrations of ceftriaxone on antibiotic susceptibility of multiple antibiotic-resistant Salmonella strains.

The aim of this study was to determine whether sublethal concentrations of ceftriaxone could alter antibiotic resistance patterns in Salmonella strains. Three multiple antibiotic-resistant Salmonella isolates and the control strain ATCC 13076 were subjected to induction experiments by stepwise increases in sublethal concentrations of ceftriaxone. Sublethal levels of ceftriaxone induced antibiotic resistance but not control Salmonella isolates to ceftriaxone and to other antibiotics. After 100 generations in 2 months when the antibiotic stress was removed, only one isolate (Salmonella Typhimurium 11202) maintained the induction changes in antibiotic resistance phenotype (tetracycline from resistance to sensitive and ampicillin from sensitive to resistance). Consistent with its stable phenotypic resistance changes, expression of the tetracycline and β-lactam resistance-related genes tetA and blaTEM were>10-fold down- and upregulated, respectively. Moreover, this strain had increased mRNA levels of efflux pump associated genes acrB and tolC and the SOS response regulator lexA and downregulation of the porin gene ompC. We found no overt changes in plasmid profiles before and after resistance induction. In all, sublethal concentrations of ceftriaxone induced alterations in Salmonella isolates to multiple antibiotics and some of them kept stable maintenance. The increased blaTEM expression may pose a potential danger for new generation β-lactam antibiotics.

Ceftriaxone pharmacokinetics by new simple and sensitive ultra-high-performance liquid chromatography method

Ceftriaxone is a cephalosporin antibiotic with a potent antimicrobial activity and excellent penetration in most body fluids such as pleural, peritoneal, spinal and brain. These facts contribute to the application of ceftriaxone in the treatment of bacterial peritonitis, an abdominal disorder in veterinary medicine, with potential risk of death. The determination of ceftriaxone levels in plasma and peritoneal fluid may be used to assess the pharmacokinetic profile at various instances of administration and allows observing if the concentrations needed are being achieved. Therefore a method was developed and validated for the determination of ceftriaxone in plasma and peritoneal fluid which after was applied in a pharmacokinetic profile study. The bioanalytical method validation was performed according to widely acceptable experiments. Two horses were used as a model of the method applicability; ceftriaxone was intraperitoneally administered to these animals as a single dose. The plasma and peritoneal fluid analysis were performed using an UHPLC system in reverse phase chromatography mode in fully validated conditions. The methods have shown linearity between 0.49 and 500μg/mL for plasma, and between 0.24 and 500μg/mL for peritoneal fluid. The quantitative analysis of ceftriaxone in these matrices allows monitoring of the therapy. This method showed improved sensitivity as well as the quantitation in peritoneal fluid.

Superiority of Ceftriaxon to Cefazolin in a Rat Model of Obstructive Jaundice: An Experimental Study

ABSTRACTObjective: The objective of this study was to evaluate the serum and bile concentrations of cefazolin and ceftriaxone at the third and sixth hours in an experimental obstructive jaundice model and to identify the rate of excretion of these antibiotics into the bile. Material and methods: Thirty-two Wistar albino rats were used in this study. The bile and serum levels of cefazolin were measured at the third hour in the A1 group and at the sixth hour in the A2 group, with cefazolin administered as 5 mg/rat; while the bile and serum levels of ceftriaxone were studied at the third hour in the B1 group and at the sixth hour in the B2 group, with ceftriaxone administered as 5 mg/rat. Results: After 3 hr of cefazolin administration, the serum concentration in the A1 group reached a mean of 1.8 μg/ml, while the bile concentration was 90% of the serum concentration, with a mean of 1.6 μg/ml; whereas in the B1 group, the third-hour serum concentration of ceftriaxone was 18.6 μg/ml, while the bile concentration was found to be as high as 330% of this level, i.e., 56 μg/ml. The serum value of cefazolin decreased to 1.4 μg/ml in the A2 group and ceftriaxone decreased to 3.7 μg/ml in the B2 group at the sixth hour. Conclusions: Although the excretory level of cefazolin and ceftriaxone into the bile reaches therapeutic doses, the duration for which these levels are above those required for bactericidal activity is short. Ceftriaxone is better concentrated in the serum and bile than cefazolin.

Plasma pharmacokinetics and milk levels of ceftriaxone following single intravenous administration in healthy and endometritic cows

Pharmacokinetics and milk levels of ceftriaxone were studied in healthy and endometritic cows following single intravenous administration. The drug was detected up to 8 h of dosing in plasma of healthy and endometritic cows and the drug disposition followed three-compartment open model. The values of Vd(area), AUC, t(1/2beta), Cl(B), MRT and P/C ratio were 0.50 +/- 0.19 L.kg(-1), 62.2 +/- 23.3 microg.ml(-1).h, 1.02 +/- 0.07 h, 0.30 +/- 0.09 L.kg(-1).h(-1), 1.55 +/- 0.25 h and 0.52 +/- 0.27, respectively, in healthy and 1.55 +/- 0.52 L.kg(-1), 37.0 +/- 17.1 microg.ml(-1).h, 1.56 +/- 0.25 h, 0.56 +/- 0.14 L.kg(-1).h(-1), 2.14 +/- 0.34 h and 1.44 +/- 0.60, respectively, in endometritic cows. The drug was detected in milk for 36 h after administration. For MIC(90) of 0.5 microg.ml(-1) the most appropriate dosage for ceftriaxone, would be 9.0 mg.kg(-1) repeated at 6 h intervals for the treatment of endometritis in cows.

In vitro and in vivo Methods to Measure the Ceftriaxone Distribution into the Rat Tail Intervertebral Disc

To characterize the pathway of ceftriaxone penetration into intervertebral discs, rat-tail discs were collected and immersed in a ceftriaxone solution for an in vitro study. For this in vivo experiment, plasma and tail discs were collected 30 min after ceftriaxone administration (463.2 mg/kg, equal to 500 mg/kg disodium salt, iv). The ceftriaxone levels in the plasma and discs were determined with HPLC by a reversed-phase C18 column and a mobile phase of methanol and a 10 mM K(2)HPO(4) solution (pH 6.7) (21:79, v/v). The results indicate that ceftriaxone was undetectable by the in vitro model. The concentrations of ceftriaxone in plasma and in intervertebral discs were 147.4 ± 21.2 and 4.0 ± 1.7 µg/mL (as disodium salt), respectively. Our results suggest that a sufficient blood supply is required for the passive diffusion of ceftriaxone into intervertebral discs. The concentration ratio of ceftriaxone in intervertebral disc-to-plasma was about 2.7% at 30 min after ceftriaxone disodium administration (500 mg/kg, iv).

Influence of assay methodology on the measurement of free serum ceftriaxone concentrations.

The influence of assay methodology on the measurement of the active free fraction of ceftriaxone in plasma was determined. The free fraction was measured by three methods: agar diffusion bioassay, precipitation of plasma protein with methanol followed by high-performance liquid chromatography (HPLC) of the supernatant, and ultrafiltration of plasma followed by HPLC of the filtrate. In human serum, the free ceftriaxone levels were significantly lower (P = 0.03) when measured on ultrafiltrates compared to the other two methods. This difference disappeared when dolphin serum was studied. After ultrafiltration, human serum was shown, by Scatchard plot analysis, to have two ceftriaxone binding sites. Species differences were also demonstrated. Hence, in humans, determination of free plasma ceftriaxone varies with the assay method employed.

Comparative pharmacokinetics of ceftriaxone after periincisional and intravenous administration in patients undergoing abdominal surgery

The advantages of the preoperative periincisional infiltration (ppi) of ceftriaxone in the prophylaxis of surgical wound infections over the preoperative intravenous injection (piv) has been demonstrated by comparing the pharmacokinetics of the two routes of antibiotic administration and the clinical results. The study was conducted in 36 patients undergoing abdominal surgery. Eighteen of them received a 2 g ceftriaxone piv (group A) and the rest a similar dose by ppi (group B). The peak time, peak plasma concentration and the bioavailability for the ppi route were respectively 1.19±0.24 h, 96.9±3.8 μg/ml and 0.68±0.07. After piv, a typical bioexponential decline of plasma ceftriaxone levels from 256.7±37.5 μg/ml (0.5 h) to 15.7±7.5 μg/ml (24 h) was observed. Tissue and wound fluid antibiotic levels of patients from group B (range: for tissues 95–1850 μg/g, for fluid 62–1342 μg/ml) were much higher than for group A (range: for tissues 18–150 μg/g, for fluid 35–160 μg/ml). Adequate for chemoprophylaxis antibiotic plasma levels were measured in both patient groups 24 h post operatively (group A: 15.7±7.5 μg/ml, group B: 12.4±4.5 μg/ml). No wound infections or other complications were noted in group B. In contrast, three cases of wound infections and one case of pneumonia were observed in group A.

Comparison of Plasma and Free Tissue Levels of Ceftriaxone in Rats by Microdialysis

Ceftriaxone has a very high plasma protein binding (up to 98%) that is saturable and decreases with higher concentrations. This high protein binding results in high concentrations in plasma that are frequently related to the anti-infective activity. However, because only the free fraction of the drug is pharmacologically active and most of the infections are located in the tissues, it is more relevant to evaluate unbound concentrations in the interstitial space. Plasma and tissue pharmacoki-netics of ceftriaxone in rats after single intravenous administration were investigated at two different concentrations (50 and 100mg/kg). Both plasma and tissue samples were taken simultaneously from the same animal and analyzed by reversed-phase high-performance liquid chromatography. Free tissue levels in the thigh muscle were measured by microdialysis. The concentration in plasma is much higher than the free concentration in tissue. After determination of nonlinear protein binding by microdialysis and including these parameters in the pharmacokinetic model, it is possible to predict free concentrations in the interstitial space from plasma levels for any given dose.

Concentrations of ceftriaxone (1,000 milligrams intravenously) in abdominal tissues during open prostatectomy

Ceftriaxone concentrations in abdominal tissues were evaluated at different stages of open prostatectomy. Ceftriaxone was administered as antibiotic prophylaxis, and 15 consecutive patients were given a single dose of ceftriaxone (1,000 mg intravenously in 1 min) 30 min before surgery. Ceftriaxone concentrations in tissue were determined at three stages of the surgical procedure; upon the opening of the abdominal cavity, during the prostatectomy, and upon the closure of the abdominal cavity. Samples of the following tissues or sample were assayed: epiploic and abdominal-wall fat; Retzius' space, bladder, and prostate tissue; and urine. During the different stages of the surgical procedure, for all patients, and in the different tested tissues, ceftriaxone concentrations greater than or equal to the cutoff point (4 micrograms/g of tissue) were measured. The highest concentrations were obtained in the bladder (43 +/- 18 micrograms/g) and in the prostate (35 +/- 18 micrograms/g). In fatty tissues, concentrations were between 13 +/- 5 and 22 +/- 8 micrograms/g. All patients (15 of 15) had ceftriaxone levels in tissue greater than the MICs for the potential pathogens (Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis). In conclusion, during open prostatectomy and after the use of a single dose of ceftriaxone (1,000 mg), high antibiotic levels were obtained throughout the surgical procedure in the tissues potentially involved in postoperative infection.

Analysis of ceftriaxone and ceftazidime distribution in cerebrospinal fluid of and cerebral extracellular space in awake rats by in vivo microdialysis.

In vivo microdialysis was used to estimate the extracellular concentrations of ceftazidime and ceftriaxone, two expanded-spectrum cephalosporins commonly used in the treatment of bacterial meningitis, in two brain regions (the right corpus striatum and the left lateral ventricle_ of awake, freely moving rats. Antibiotics were administered by constant intravenous infusion at 18 mg/h until steady-state levels were reached. Ceftriaxone levels measured at the steady state in the extracellular space of the corpus striatum (0.80 +/- 0.17 micrograms/ml) were statistically equivalent to those obtained in the cerebrospinal fluid of the lateral ventricle (0.71 +/- 0.15 micrograms/ml). The ratios of these levels in the brain to the steady-state levels in plasma were 0.5 +/- 0.1% for both regions. The postinfusion concentrations of ceftriaxone in the brain declined monoexponentially, with an elimination half-life similar to that obtained in plasma. However, the mean antibiotic concentration of ceftazidime in the striatum (2.2 +/- 0.4 micrograms/ml) was lower (P < 0.001) than that in the lateral ventricle (3.8 +/- 0.5% and 4.0 +/- 1.8%, respectively) were higher than those obtained with ceftriaxone. Moreover, the half-life of ceftazidime elimination from plasma was lower than that obtained in the two brain regions. It was concluded that the in vivo microdialysis technique yields useful data on antibiotic distribution in the extracellular space of the brain, that the distribution may not be homogeneous, and that the decay of postinfusion concentrations in the brain may be different from the decay of postinfusion concentrations in plasma.

Sequential Levels of Ceftriaxone in Intervertebral Disc Removed As Part of Scoliosis Surgery

A single intravenous loading dose of 1 g ceftriaxone was injected at different intervals before surgery for correction of spinal scoliosis. Serum and concomitant disc samples were obtained and assay was performed using high-pressure liquid chromatography. Data showed that the antibiotic levels in intervertebral disc space reached 3.5 mcg/mg, which is above the minimum inhibitory concentration for most of the relevant pathogens, as early as 1 hour after intravenous administration. These therapeutic levels were maintained for more than 5 hours, an accepted period for most spinal surgical procedures.

A single daily dose of ceftriaxone for bacterial meningitis in adults: experience with 84 patients and review of the literature.

Although the pharmacokinetics of ceftriaxone allows its administration in a single daily dose, this practice is not standard in the treatment of bacterial meningitis. Herein, we review our experience and that of other investigators with this mode of therapy. We used a single daily dose of ceftriaxone (50 mg/[kg.d]; maximum, 4 g/d) for the treatment of bacterial meningitis in 84 adult patients. Meningitis was due to Neisseria meningitidis in 34 cases, to Streptococcus pneumoniae in 25, to Escherichia coli in three, to Klebsiella pneumoniae in two, to Haemophilus influenzae in two, to viridans streptococci in two, and to an unknown agent in 16. Eleven patients died, for an overall mortality of 13%; therapy failed in three additional cases. The mean trough levels of ceftriaxone in cerebrospinal fluid was 3.5 micrograms/mL; the median trough bactericidal titer at this site was 1:128. Both our experience and that in the literature suggest that a single daily dose is optimal when ceftriaxone is used for the treatment of bacterial meningitis.

Effects of macro- and microcirculatory functions on ceftriaxone concentrations in tissues of patients with stage IV peripheral arterial occlusive disease.

The objective of the study was to determine the ceftriaxone levels achievable within lesions (toe or forefoot area) in patients with septic gangrene and to investigate the relationship between macro- and microcirculatory parameters and antibiotic concentration. Fifteen patients with severe chronic peripheral occlusive disease received an intravenous injection of 2 g of ceftriaxone. Antibiotic levels in venous and capillary blood and in an exudative part of the lesion were measured. Macrocirculatory functions were assessed by Doppler sonography, plethysmography, and angiography; microcirculatory functions were assessed by quantitative capillaroscopy and fluorescence video microscopy. The mean antibiotic concentrations measured between 4 and 8 h after injection were 92 +/- 26 micrograms/ml in venous blood and 84 +/- 46 micrograms/ml in capillary blood. The concentration in tissue reached its maximum 4 h after injection; the average concentration at between 2 and 8 h was 95 +/- 55 micrograms/ml. Only dynamic capillary parameters showed significant (P < 0.01) correlations to antibiotic levels in tissue. Significantly (P < 0.01) higher levels in tissue were observed in patients with adequate microcirculatory functions (138 +/- 48 micrograms/ml) than in patients with poor microcirculatory function (51 +/- 26 micrograms/ml). Microcirculatory dysfunction appears to be the limiting factor for tissue antibiotic levels. However, even those patients with poor microcirculatory function showed tissue antibiotic levels that were above the MICs for the pathogens most frequently isolated from gangrenous lesions. Therefore, intravenous application was found to be adequate and additional measures such as intra-arterial therapy or Bier's occlusion are basically unnecessary. Our finding that microcirculatory function is the limiting factor for the tissue antibiotic concentration is corroborated by computations based on a three-compartment model.

Determination of ceftriaxone in aqueous humor and serum samples of differential-pulse adsorptive stripping voltammetry.

Differential-pulse adsorptive stripping voltammetry was used to determine ceftriaxone in serum and aqueous humour samples. The method involved extraction of the ceftriaxone from serum samples with an Amberlite XAD-2 column followed by elution with methanol. The recovery was 97.6% with a relative standard deviation of 3.3% at a ceftriaxone concentration of 90.9 microg 1(-1). Peak currents of ceftriaxone were measured with a hanging mercury drop electrode at -0.78 V versus an Ag-AgCl reference electrode in pH 3.0 Britton-Robinson buffer. The calibration graph was linear from 0.02 to 1300 microg 1(-1). The method was applied to cataract cases and ceftriaxone levels were measured in aqueous humour and serum samples from patients who had received 1 or 2 g of ceftriaxone intravenously. Aqueous humour was added to the polarographic cell directly. The amounts of ceftriaxone in the aqueous humour and serum samples with respect to time were measured. The pharmacokinetic profiles for 1 and 2 g were compared.