Quantification of cefaclor in human plasma using SIL-IS LC-ESI-MS/MS for pharmacokinetics study in healthy Chinese volunteers.

A steady, high-efficiency, and precise liquid chromatography-electrospray ionization-tandem mass spectrometry method was established and validated using cefaclor-d5 as the stable isotope-labeled internal standard for quantification of cefaclor in human plasma. One-step protein precipitation was applied to extract human plasma samples using methanol as precipitant. An Ultimate XB C18 column (2.1 × 50.0 mm, 5.0 µm) was used to achieve chromatographic separation. Mobile phases of gradient elution were an aqueous solution containing 0.1% formic acid (mobile phase A) and an acetonitrile solution containing 0.1% formic acid (mobile phase B). Electrospray ionization in positive-ion mode was applied to detect under multiple reaction monitoring mode. Target fragment ion pairs of cefaclor and stable isotope-labeled internal standard, respectively, were m/z 368.2 → 191.1 and m/z 373.2 → 196.1. Linear range of this method was between 20.0 and 10,000.0 ng/ml, with coefficient of determination (R2 ) >0.9900. Seven concentrations of quality control samples were used: 20.0 ng/ml (lower limit of quantitation), 60.0 ng/ml (low quality control), 650 ng/ml (middle quality control), 5000 ng/ml (arithmetic average middle quality control [AMQC]), 7500 ng/ml (high quality control), 10,000 ng/ml (upper limit of quantification), and 40,000 ng/ml (dilution quality control [DQC]). The method was validated for selectivity, lower limit of quantitation, linearity, accuracy, precision, recovery, matrix effect, dilution reliability, stability, carryover, and incurred sample reanalysis. This stable isotope-labeled internal standard liquid chromatography-electrospray ionization-tandem mass spectrometry approach has been successfully applied to study the pharmacokinetics of cefaclor dry suspension among healthy Chinese volunteers.

HPLC method development and validation for the determination of Cefaclor in human plasma.

Cefaclor was analyzed in the human plasma by developing a simple, precise and accurate assay method which was then validated for its accuracy, specificity and precision. The mobile phase comprised of a mixture of sodium 1-pentanesulfonate, water, triethylamine and methanol. Phosphoric acid was used to adjust the pH to 2.5±0.1. The flow rate was maintained at 1.5ml/min and the wavelength was set at 265 nm. A C-18 HPLC, column 5um particle size, L x 1.D. 25cm x 4.6mm (Supelcosil) was utilized for chromatographic separation. The retention time of Cefaclor was found to be 17min. This method was validated for selectivity, accuracy, precision, repeatability, reproducibility, recovery, linearity, and stability. Calibration curves were found linear were in the range of 0.39µg/ml to50µg/mland the coefficient of correlation (R2) was found to be 0.999. Hence, this method has been found useful for the determination of Cefaclor in plasma.

Determination of cefaclor by UPLC-MS-MS for a Chinese pharmacokinetic study.

A novel method has been developed for the determination of cefaclor in human plasma by ultra-performance liquid chromatography combined with tandem mass spectrometry (UPLC-MS-MS). The plasma was treated by a single step of protein precipitation with acetonitrile. The chromatographic separation was performed on a Waters Acquity UPLC BEH C18 (2.1 × 100 mm, 1.7 µm) with a gradient mobile phase consisting of 0.1% formic acid and acetonitrile at a flow rate of 0.4 mL/min. The analyses were conducted by multiple reaction monitoring using the precursor-to-product combinations of m/z 367.5 → 173.8 (cefaclor) and m/z 454.1 → 160.3 (internal standard). Validation results indicated that the lower limit of quantification was 2 ng/mL and the assay exhibited a linear range of 2-10,000 ng/mL. Quality control samples (5, 200 and 5,000 ng/mL) in five replicates from three different runs of analysis demonstrated an intra-assay precision (relative standard deviation) of 3.7-10.7%, an inter-assay precision of 5.8-8.9%, and an overall accuracy of < 15%. A sensitive and specific method for quantifying cefaclor in human plasma has been devised and successfully applied to a pharmacokinetic study.

Pretreatment of plasma samples by a novel hollow fiber centrifugal ultrafiltrate device for the determination of cefaclor concentrations in human plasma.

A simple sample preparation method was developed by using a centrifugal ultrafiltration (CF-UF) device with hollow fiber (HF) for the determination of cefaclor in plasma by HPLC. Samples were placed into a homemade device, which was consisted of a glass tube and a U-shaped hollow fiber. The filtrate was withdrawn from the hollow fiber into a syringe after centrifugation and 20 µL was directly injected into the HPLC for analysis. The HPLC method had a linear calibration curve in the concentration range of 6.00×10(-2)-30.7 µg mL(-1)(r=0.9996). The limit of detection (LOD) and limit of quantitation (LOQ) were 0.02 and 0.06 µg mL(-1), respectively. The intra and inter-day precisions (RSD) were 1.7%, 1.2%, 1.0% and 3.6%, 2.5%, 1.9%, respectively, for three concentrations. Assay accuracy was higher than 99.2% and the absolute recovery was 86.8-92.5%. It is feasible to use this novel and low cost device for sample pretreatment for the analysis of cefaclor in plasma.

Effects of cranberry juice on pharmacokinetics of beta-lactam antibiotics following oral administration.

Cranberry juice consumption is often recommended along with low-dose oral antibiotics for prophylaxis for recurrent urinary tract infection (UTI). Because multiple membrane transporters are involved in the intestinal absorption and renal excretion of beta-lactam antibiotics, we evaluated the potential risk of pharmacokinetic interactions between cranberry juice and the beta-lactams amoxicillin (amoxicilline) and cefaclor. The amoxicillin-cranberry juice interaction was investigated in 18 healthy women who received on four separate occasions a single oral test dose of amoxicillin at 500 mg and 2 g with or without cranberry juice cocktail (8 oz) according to a crossover design. A parallel cefaclor-cranberry juice interaction study was also conducted in which 500 mg cefaclor was administered with or without cranberry juice cocktail (12 oz). Data were analyzed by noncompartmental methods and nonlinear mixed-effects compartmental modeling. We conclude that the concurrent use of cranberry juice has no significant effect on the extent of oral absorption or the renal clearance of amoxicillin and cefaclor. However, delays in the absorption of amoxicillin and cefaclor were observed. These results suggest that the use of cranberry juice at usual quantities as prophylaxis for UTI is not likely to alter the pharmacokinetics of these two oral antibiotics.

A comparative study of capillary zone electrophoresis and pH-potentiometry for determination of dissociation constants.

Acidity constants of six cephalosporin antibiotics, cefalexin, cefaclor, cefadroxil, cefotaxim, cefoperazon and cefoxitin are determined using capillary zone electrophoresis (CZE) and pH-potentiometric titrations. Since CZE is a separation method, it is not necessary for the samples to be of high purity and known concentration because only mobilities are measured. The effect on determination of dissociation constants of different matrices (serum, 0.9% NaCl, fermentation matrix) was examined. The advantages of CZE can be utilized in those fields where potentiometry has limitations (sample quantity, solubility, purity, simultaneous determinations), although pK(a) values that are close to each other can be determined by potentiometry with more accuracy.

The effect of four different types of food on the bioavailability of cefaclor.

This randomized, open-label, balanced, five-treatment, five-period, five-sequence, single-dose and crossover pharmacokinetic study assessed the effect of different types of food on the bioavailability of cefaclor in 18 healthy male volunteers. A single dose of cefaclor, 250-mg capsule was administered at five occasions: after overnight fasting, after two vegetarian (high-fat and low-fat) diets and two non-vegetarian (high-fat and low-fat) diets. Serial blood samples were collected upto 8 h post dose. Serum cefaclor concentrations were determined by a validated HPLC method. AUC values were not significantly affected by food intake, but the T(max) was prolonged and C(max) was decreased, depending on the type of meal. The non-vegetarian diets affected the rate of absorption of cefaclor more than the vegetarian diets. The least decrease in C(max) was produced by low-fat vegetarian diet, while the maximum decrease was produced by high-fat non-vegetarian diet. The results of this study indicate that while the rate of absorption of cefaclor is significantly decreased, the extent of absorption and the rate of elimination are not significantly decreased in the presence of food. As compared to high-fat non-vegetarian diet, the time above MIC50 concentration was significantly increased by low-fat vegetarian diet. The implications of these findings for the large vegetarian Indian population are considerable.

Determination of cefaclor in human plasma by a sensitive and specific liquid chromatographic-tandem mass spectrometric method.

A sensitive and specific liquid chromatographic-tandem mass spectrometric method is described for the determination of cefaclor in human plasma. The plasma samples were treated by two sample preparation procedures, i.e. protein precipitation (PPT) and solid-phase extraction (SPE). The pretreated samples were analyzed on a C(18) HPLC column interfaced with a triple quadrupole tandem mass spectrometer. Positive electrospray ionization (ESI) was employed as the ionization source. The analyte and internal standard ampicillin (for PPT) or cefetamet (for SPE) were detected by use of selected reaction monitoring (SRM) mode. The lower limit of quantitation obtained as a result of the PPT procedure was 100 ng/ml. The intra- and inter-run precision, calculated from quality control (QC) samples was less than 12% for cefaclor. The accuracy as determined from QC samples was within +/-3% for the analyte. The SPE procedure could provide the lower limit of quantitation of 2 ng/ml. The precision and accuracy were measured to be below 7.1% and between -3.6% and 1.1%, respectively, for all QC samples. The method was applied for the evaluation of the pharmacokinetic profiles of cefaclor sustained-release formulation.

Comparative target site pharmacokinetics of immediate- and modified-release formulations of cefaclor in humans.

Optimal dosing of beta-lactam antibiotics aims at maximizing the time at which drug levels in the interstitial space fluid (ISF)--the fluid that surrounds the causative microorganisms at the target site--exceed the minimal inhibitory concentration (MIC). One potentially attractive strategy to achieve this goal is to administer antibiotics as oral sustained-release formulations. The present study was designed to test the hypothesis that sustained-release formulations could lead to a more suitable pharmacokinetic profile in the ISF at the relevant target site. For this purpose, time versus cefaclor concentration profiles attained in the ISF were measured following administration of two formulations, an immediate- (500 mg IR) and a modified-release formulation in two different doses (500 mg MR and 750 mgMR) in a three-way crossover study of healthy male volunteers (n = 12). For the measurement of unbound cefaclor concentrations in the ISF of human skeletal muscle, the in vivo microdialysis technique was employed. For all three formulations, unbound cefaclor concentration in the ISF closely followed individual plasma concentration profiles in a dose-dependent pattern, with ISF to unbound plasma ratios ranging from 0.67 to 0.73. The mean residence time was found to be significantly longer for the MR formulations versus the IR formulation. The data of the present study indicate that time above MIC values at the target site can be substantially prolonged if an antibiotic is administered as a sustained-release product.

Evaluation of oral antimicrobial agent levels in tooth extraction sites.

OBJECTIVE: The purpose of this study was to evaluate various oral antimicrobial agent levels in tooth extraction sites. STUDY DESIGN: The concentration of dental alveolar blood in extraction wounds after the oral administration of talampicillin (500 mg), cefaclor (500 mg), cefteram pivoxil (200 mg), cefuroxime axetil (250 mg), cefdinir (200 mg), and ofloxacin (100 mg) was determined in 338 patients and was assessed on the basis of its antimicrobial activity against Streptococcus isolated in odontogenic infections. RESULTS: The percentage of patients whose concentrations exceeded the minimum inhibitory concentration for 90% of Streptococcus was 62.5% to 100% for talampicillin at 30 to 360 minutes, 0% to 12.5% for cefaclor at 30 to 360 minutes, 18.2% to 100% for cefteram pivoxil at 30 to 480 minutes, 50% to 100% for cefuroxime axetil at 30 to 480 minutes, 0% to 50% for cefdinir at 16 to 290 minutes, and 0% to 40% for ofloxacin at 30 to 480 minutes. CONCLUSION: These results indicate that talampicillin, cefteram pivoxil, and cefuroxime axetil have minimum inhibitory concentration levels for 90% of Streptococcus in tooth sockets.

Determination of cefaclor by selective sample enrichment/clean-up on silica gel bonded polyelectrolyte in ion-exchange column chromatography.

A silica gel-bound cationic polyelectrolyte, poly[N-chloranil N,N,N',N'- tetramethylethylene diammonium dichloride], modified as ion-exchanger capable of molecular recognition of beta-lactam antibiotic, was used in solid phase extraction through column chromatography for a sample clean-up and enrichment of analyte from a dilute solution. The optimum and selective sorption conditions for a model antibiotic, cefaclor, were established. The high selectivity of polymer at pH 9.5 and flow rate as high as 5 ml/min were observed for the quantitative sorption of cefaclor. The desorption by 0.1 N HCl at flow rate of 0.1 ml/min and subsequent heating at 80 degrees C for 2 h allowed the antibiotic to be detected as corresponding oxazolone form in UV-spectrophotometric and differential pulse adsorptive stripping voltammetric measurements. The potential of the suggested approach was illustrated by estimating cefaclor in urine and blood plasma samples.

Cefaclor concentration in radicular granuloma after a single oral administration.

1. Cefaclor concentrations in radicular granuloma and serum in nonfasting patients after a single oral administration of 500-mg cefaclor were assayed. 2. The mean peak concentrations in radicular granuloma and serum were 2.57 mcg/g and 7.41 mcg/ ml, respectively. The mean ratio of granuloma/serum concentration at the peak time was 0.35. 3. All cefaclor concentrations in radicular granuloma at the peak time exceeded the minimal inhibitory concentration for 90% of oral streptococci (1 mcg/ml) isolated from odontogenic infection.

Cefaclor concentration in pus from abscess caused by odontogenic infection after a single oral administration.

1. Cefaclor concentrations in serum and pus from abscess of odontogenic infection after a single oral administration of 500-mg cefaclor were assayed and pus concentrations were compared with minimum inhibitory concentration (MIC) of oral streptococci isolated from odontogenic infection. 2. The mean peak concentrations in serum and pus were found at identical times, 1.5 hr after administration, which were 7.22 and 0.72 micrograms/ml, respectively. 3. The mean ratio of pus:serum concentration at the peak time was 0.10. 4. Most cefaclor concentrations in pus at the peak time (seven of nine cases) exceeded the MIC for 90% of oral streptococci (0.5 micrograms/ml).

Cefadroxil concentrations in human serum, gingiva, and mandibular bone following a single oral administration.

Cefadroxil concentrations in human serum, gingiva, and mandibular bone were measured by a paper disk method following a single 500-mg oral dose. The mean peak concentrations in serum, gingiva, and mandibular bone occurred at the identical time, 3 hours, and were 12.92 micrograms/mL, 6.50 micrograms/g, and 2.67 micrograms/g, respectively. Mean cefadroxil concentration ratios of gingiva/serum and mandibular bone/serum at the peak time were 0.54 and 0.21, respectively. Mean concentrations in gingiva and mandibular bone at the peak time exceeded the minimum inhibitory concentrations for 90% of clinically isolated strains of a alpha-hemolytic streptococci.

Semi-quantitative analysis of cefaclor in human serum by capillary high performance liquid chromatography/fast atom bombardment mass spectrometry.

Capillary high performance liquid chromatography (HPLC) was combined with frit fast atom bombardment (FAB) mass spectrometry (MS) and a detailed procedure has been established for on-line analysis of cefaclor in human serum. The capillary column (0.3 mm i.d.) enabled the introduction of entire effluent to the frit interface for FAB-MS; and a special column switching device for injection and concentration enabled the injection of as large as a 500-microliters volume sample. These conditions gave much higher sensitivity than that of previous HPLC/MS system. Thus, low levels of cefaclor could be successfully identified in sera by its mass spectral measurements 2 h after its single oral administration of a 250-mg capsule in two subjects.

Cefaclor concentrations in human serum, gingiva, mandibular bone, and dental follicle following a single oral administration.

1. Cefaclor concentrations in human serum (n = 59), gingiva (n = 46), mandibular bone (n = 39), and dental follicle (n = 42) following a single oral administration of cefaclor (500 mg) were measured by the paper disk method. 2. The peak times of serum, gingiva, mandibular bone, and dental follicle were 1.5, 2, 2, and 1.5 hr, respectively. 3. The mean peak concentrations of serum, gingiva, mandibular bone, and dental follicle were 7.58 micrograms/ml, 3.71, 1.59 and 2.42 micrograms/g, respectively. 4. The concentration ratios of gingiva/serum, mandibular bone/serum, and dental follicle/serum at peak times of the tissues were 0.49, 0.18, and 0.32, respectively. 5. Mean cefaclor concentrations in gingiva, mandibular bone, and dental follicle at peak times exceeded MIC for 90% for clinically isolated strains of alpha-hemolytic Streptococci.

Pharmacokinetics of cefaclor AF: effects of age, antacids and H2-receptor antagonists.

The pharmacokinetics and bioavailability of cefaclor advanced formulation (cefaclor AF) were investigated in two studies, one comparing healthy elderly and younger volunteers and the other assessing the effects of an antacid and H2-receptor antagonist on cefaclor AF bioavailability. The pharmacokinetics of a 750 mg dose of cefaclor AF were studied in 30 subjects ranging in age from 65 to 84 years and 10 control subjects 21-45 years of age. Compared with controls, elderly subjects exhibited higher plasma concentrations of cefaclor which were attributed to lower plasma clearance. There was a strong association between age and renal function, and the plasma clearance of cefaclor was highly dependent upon renal function. Thus, elderly patients with impaired renal function had a reduced ability to eliminate cefaclor. Due to a short elimination half-life and wide therapeutic index, dosage adjustments are not necessary in patients exhibiting moderate renal dysfunction. The 15 healthy men in the second trial were crossed over to receive five treatments, including cefaclor AF (500 mg) alone, cefaclor AF with or preceded by cimetidine, cefaclor AF followed by Maalox TC and cefaclor immediate release (500 mg) alone. Cefaclor AF and immediate release cefaclor had similar bioavailability, but plasma concentrations were maintained for a longer period of time when cefaclor AF was administered. Cimetidine did not alter the bioavailability of cefaclor AF but Maalox TC, coadministered with cefaclor AF, reduced the extent of absorption. This suggests that cefaclor AF bioavailability is influenced by the antacid Maalox TC but not by H2-receptor antagonist cimetidine.