Multivariate optimization methods for in-situ growth of LDH/ZIF-8 nanocrystals on anodized aluminium substrate as a nanosorbent for stir bar sorptive extraction in biological and food samples.

In-situ growth of zeolite imidazolate frameworks (ZIFs) on the surface of layered double hydroxides (LDHs) for preparation of porous nanocomposites is a favorable strategy to design potential materials in separation fields. In this research, nanoporous Zn-Al LDH/ZIF-8 composite was prepared by in-situ growth of ZIF-8 on the Zn-Al LDH surface. The nanocomposite was applied for stir bar sorptive extraction and detection of benzylpenicillin (penicillin G, PEN G). Characterizations of the nanocomposite were performed by various techniques, including Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and thermogravimetric differential thermal analysis. An optimized strategy based on response surface methodology was combined with high performance liquid chromatography analysis. Under the optimized conditions, the limit of detection and quantification obtained were 0.05 and 0.15 µg l-1, respectively. The good validation criteria results allowed the method to be used in the quantification of PEN G in real samples.

Comparison of Lateral Flow Assay, Kidney Inhibition Swab, and Liquid Chromatography-Tandem Mass Spectrometry for the Detection of Penicillin G Residues in Sow Urine.

Sows (n = 126) were administered penicillin G; urine, collected at slaughter, was screened by kidney inhibition swab (KIS; 4 h testing time) and then stored at -80 °C (∼1200 days) until analysis by lateral flow assay (LF, ∼5 min testing time) and tandem quadrupole LC-MS/MS (TQ) analysis. The stability of penicillin in urine during storage was verified using TQ analyses. Quantitative results were well-correlated (R2 = 0.98) with only a ∼10% decrease in penicillin concentration during the 3-year storage period. KIS retesting of stored samples returned results consistent with the original analyses. Lateral flow assay results were highly correlated with the KIS and TQ results. A KIS positive sample, which was not confirmed by TQ or LF, was assayed by Triple-TOF LC-MS to determine the cause of the apparent false positive. This study suggests LF can be used to quickly and efficiently screen for penicillin G residues before slaughter.

Anionic metabolic profiling of urine from antibiotic-treated rats by capillary electrophoresis-mass spectrometry.

A recently developed capillary electrophoresis (CE)-negative-ionisation mass spectrometry (MS) method was used to profile anionic metabolites in a microbial-host co-metabolism study. Urine samples from rats receiving antibiotics (penicillin G and streptomycin sulfate) for 0, 4, or 8 days were analysed. A quality control sample was measured repeatedly to monitor the performance of the applied CE-MS method. After peak alignment, relative standard deviations (RSDs) for migration time of five representative compounds were below 0.4 %, whereas RSDs for peak area were 7.9-13.5 %. Using univariate and principal component analysis of obtained urinary metabolic profiles, groups of rats receiving different antibiotic treatment could be distinguished based on 17 discriminatory compounds, of which 15 were downregulated and 2 were upregulated upon treatment. Eleven compounds remained down- or upregulated after discontinuation of the antibiotics administration, whereas a recovery effect was observed for others. Based on accurate mass, nine compounds were putatively identified; these included the microbial-mammalian co-metabolites hippuric acid and indoxyl sulfate. Some discriminatory compounds were also observed by other analytical techniques, but CE-MS uniquely revealed ten metabolites modulated by antibiotic exposure, including aconitic acid and an oxocholic acid. This clearly demonstrates the added value of CE-MS for nontargeted profiling of small anionic metabolites in biological samples.

Quantification of sub-nanomolar levels of Penicillin G by differential pulse adsorptive stripping voltammetry.

A novel selective and sensitive method is developed for determination of Penicillin G by Differential Pulse Adsorptive Stripping Voltammetry (DPAdSV). Penicillin G gave well-resolved diffusion-controlled cathodic peaks at -0.42 and -0.584 V, respectively (vs Ag/AgCl) in pH 7.50 of borate buffer. Optimal conditions were obtained as pH 7.50, accumulation potential of -0.2 V (vs Ag/AgCl), accumulation time of 120 s, and scan rate of 100 mV/s. Under the optimized conditions, a linear calibration curve was established for the concentration of Penicillin G in the range of 0.007-2.13 µg/ml with a detection limit of 0.000717 µg/ml. The procedure was successfully applied to the determination of Penicillin G in various medicine and biological samples. The relative standard deviation of the method at 0.05 and 0.5 µg/ml Penicillin G, for 10 runs, was 2.55% and 2.06%, respectively.

Quantification of penicillin G during labor and delivery by capillary electrophoresis.

In this study, a capillary electrophoresis (CE) method was developed as a means to measure levels of penicillin G (PCN G) in Group B Streptococcus (GBS) positive pregnant women during labor and delivery. Volunteers for this developmental study were administered five million units of PCN G at the onset of labor. Urine, blood, and amniotic fluid samples were collected during labor and post delivery. Samples were semi-purified by solid-phase extraction (SPE) using Waters tC18 SepPak 3cc cartridges with a sodium phosphate/methanol step gradient for elution. Capillary electrophoresis or reversed-phase high-performance liquid chromatography (RP-HPLC) with diode-array absorbance detection were used to separate the samples in less than 30 min. Quantification was accomplished by establishing a calibration curve with a linear dynamic range. The tC18 SPE methodology provided substantial sample clean-up with high recovery yields of PCN G ( approximately 90%). It was found that SPE was critical for maintaining the integrity of the separation column when using RP-HPLC, but was not necessary for sample analysis by CE where no stationary phase is present. Quantification results ranged from millimolar concentrations of PCN G in maternal urine to micromolar concentrations in amniotic fluid. Serum and cord blood levels of PCN G were below quantification limits, which is likely due to the prolonged delay in sample collection after antibiotic administration. These results show that CE can serve as a simple and effective means to characterize the pharmacokinetic distribution of PCN G from mother to unborn fetus during labor and delivery. It is anticipated that similar methodologies have the potential to provide a quick, simple, and cost-effective means of monitoring the clinical efficacy of PCN G and other drugs during pregnancy.

Pharmacokinetics of penicillin g in very-low-birth-weight neonates.

Data on the pharmacokinetics (PKs) of penicillin G (PEN) in neonates date back to the 1970s and do not include data for very-low-birth-weight (VLBW) neonates. The aim of this study was to describe the steady-state PKs and to establish an optimal regimen for the dosing of PEN in neonates with gestational ages of less than 28 weeks and birth weights of less than 1,200 g. Two PEN dosing regimens were studied: 50,000 IU (30 mg)/kg of body weight every 12 h (q12h) (group 1; n = 9) and 25,000 IU (15 mg)/kg q12h (group 2; n = 9). Samples for PK analysis were drawn before the injection of PEN and at 2 and 30 min and 1.5, 4, 8, and 12 h after intravenous injection of the third to eighth PEN doses. The PEN concentration was measured by a high-performance liquid chromatography with UV detection technique. The median peak and trough concentrations of PEN were 147 mug/ml (lower and upper quartiles, 109 and 157 mug/ml, respectively) and 7 mug/ml (lower and upper quartiles, 5 and 13 mug/ml, respectively) after administration of the dose of 50,000 IU and 59 mug/ml (lower and upper quartiles, 53 and 78 mug/ml, respectively) and 3 mug/ml (lower and upper quartiles, 3 and 4 mug/ml, respectively) after administration of the dose of 25,000 IU. The PEN half-life (median and lower and upper quartiles for group 1, 3.9 h and 3.3 and 7.0 h, respectively; median and lower and upper quartiles for group 2, 4.6 h and 3.8 and 5.6 h, respectively) was longer in VLBW neonates than in adults and term infants. PEN renal clearance correlated with creatinine clearance (R(2) = 0.309596; P = 0.038). Only a median of 34% (lower and upper quartiles, 28 and 37%, respectively) of the administered dose was excreted in urine within the following 12 h. We conclude that in VLBW infants a PEN dose of 25,000 IU (15 mg)/kg q12h is safe and sufficient to achieve serum concentrations above the MIC(90) for group B streptococci for the entire dosing interval.

LC/MS/MS measurement of penicillin G in bovine plasma, urine, and biopsy samples taken from kidneys of standing animals.

Methods for the measurement of penicillin concentration in bovine plasma, kidney and urine were developed and validated. Detection was based on liquid chromatography/tandem mass spectrometry (LC/MS/MS). Phenethecillin was used as an internal standard. Plasma was extracted with acetonitrile using a method with a calculated limit of quantitation (LOQ) of 12 ng/mL. Kidney samples were homogenized in water and acetonitrile, then cleaned up on C18-bonded silica SPE cartridges. The LOQ of this procedure was 10 ng/g. Urine samples were diluted, filtered, and analyzed directly. The LOQ of this procedure was 63 ng/mL. The overall accuracy for plasma was 103% with coefficient of variation (CV) of 3%; for kidney, 96% and 11%, respectively, and for urine, 98% and 4%, respectively. These methods were applied to the analysis of plasma, urine, and kidney biopsy samples taken from standing animals that had been dosed with penicillin.

Comparison of microbial growth inhibition screening assays with high-pressure liquid chromatography for detection of experimentally incurred penicillin G residues in calves.

Twelve calves were fed milk replacer containing 3.33 ppm penicillin G for one feeding, and 12 calves were fed the medicated milk replacer once daily at a rate of 12% of their body weight for 14 days. Two calves served as controls. Calves were slaughtered 4 to 13 hours after being fed. Kidney, liver, muscle, and urine samples were assayed for penicillin by high-pressure liquid chromatography (HPLC). Penicillin G was not detected in any muscle samples and concentrations of penicillin exceeded the tolerance level (0.05 microg/g) in kidney or liver tissue from 13 of 24 treated-calf carcasses examined by HPLC. The Live Animal Swab Test identified all 13 carcasses with violative drug residues. Using kidney as the test matrix, the Swab Test on Premises identified 10 of 13 carcasses with violative drug residues, while the Calf Antibiotic Sulfa Test identified seven of 13 carcasses with violative residues.

Quantification of penicillin-G and procaine in equine urine and plasma using high-performance liquid chromatography.

A rapid and sensitive method for the extraction and quantification of penicillin-G and procaine in horse urine and plasma samples has been successfully developed. The method involves the use of solid-phase extraction (SPE) for penicillin-G, liquid-liquid extraction (LLE) for procaine, and high-performance liquid chromatography (HPLC) for the quantification of penicillin-G and procaine. The new method described here has been successfully applied in the pharmacokinetic studies of procaine, penicillin-G and procaine-penicillin-G administrations in the horse.

The tubular excretion of benzylpenicillin in patients with cystic fibrosis.

1. The tubular excretion of benzylpenicillin (BP) was investigated in six volunteers with cystic fibrosis. 2. The volunteers received a continuous infusion of BP at increasing infusion rates in order to maintain constant plasma concentrations at three different levels. Blood and urine samples were taken every 30 min. Sufficient urinary flow was ensured by a saline infusion (500 ml h-1). 3. The renal clearance of BP was calculated for the non-protein bound fraction of the drug. 4. Tubular clearance and tubular excretion rate were estimated from the renal clearance of the antibiotic minus the glomerular filtration rate; the latter was considered to be equal to creatinine clearance. 5. The data were analysed according to a Scatchard plot and values for ECu50 and maximal tubular excretion rate were calculated. The mean value of ECu50 was 89 +/- 24 (mg l-1 +/- s.d.) and that for the maximal tubular excretion rate was 2603 +/- 714 (mg h-1 +/- s.d.). The latter value was significantly less than that found in a previous study of healthy volunteers, but the ECu50 was similar. 6. It is concluded that the tubular excretory capacity for BP is decreased in patients with cystic fibrosis in direct relation to their low body weight.

Urine concentrations of five penicillins following oral administration to normal adult dogs.

Penicillin G, penicillin V, ampicillin, hetacillin, and amoxicillin were administered separately per os to clinically normal adult dogs of both sexes at 8-hour intervals for five consecutive 8-hour test periods. All urine was collected from each dog during each test period and was assayed for antimicrobial activity. Daily doses of the antimicrobics used were as follows: penicillin G, 110,000 U/kg of body weight; penicillin V, 77 mg/kg; ampicillin, 77 mg/kg; hetacillin, 77 mg/kg; and amoxicillin, 33 mg/kg. Mean 8-hour urine concentrations (+/- 1 SD) were as follows: penicillin G, 294 +/- 210 U/ml; penicillin V, 148 +/- 98 micrograms/ml; ampicillin, 309 +/- 55 micrograms/ml; hetacillin, 300 +/- 156 micrograms/ml, and amoxicillin 201 +/- 93 micrograms/ml. Among the three antimicrobials administered at the same daily dosage, ie, penicillin V, ampicillin, and hetacillin, the mean urine concentrations of penicillin V were significantly lower (P < 0.01) than were concentrations of ampicillin and hetacillin. The mean urine concentrations of the latter two did not differ significantly (P > 0.05).

Penicillin G or ampicillin for oral treatment of canine urinary tract infections.

Penicillin G or ampicillin was administered orally to 144 dogs with urinary tract infections. The daily dosage of penicillin G ranged from 110,000 to 165,000 U/kg (50,000-75,000 U/lb), and the dosage of ampicillin varied from 77 to 110 mg/kg (35-50 mg/lb). The daily dose of each antibiotic was divided into 3 or 4 doses and given at approximately 8- or 6-hour intervals for 10 to 14 days. Response to treatment, based on results of urine culture, varied from no response for infections caused by Pseudomonas spp to 100% response for those caused by Staphylococcus aureus and Streptococcus spp. About 50% of infections caused by Escherichia coli were eliminated, as were about 80% of those due to Proteus mirabilis. Mean concentrations of penicillin G and ampicillin in urines collected at 6-hour intervals after oral administration to clinically normal adult dogs were approximately 350 microgram/ml for both drugs when each was given individually in daily dosages (divided QID) of 55 mg/kg (25 mg/lb). The minimum inhibitory concentration of penicillin G for a number of the bacteria isolated from the urine of the infected dogs was compared with the results of the clinical trials and to the minimum inhibitory concentration of a larger number of urinary bacterial isolates.

Antimicrobial prophylaxis in patients with rhinorrhea or otorrhea: a double-blind study.

A controlled double-blind study was performed on patients with injury to the head and face which had caused rhinorrhea or otorrhea. The patients were treated, at the time of the admission to the hospital, with penicillin (20 mega-units daily) or a placebo. A total of 52 patients was studied, 26 in each treatment group. Meningitis developed in one patient in the placebo group. Staphylococcus epidermidis (sensitive to penicillin) was the causative pathogen in this patient who also had a retained intraventricular foreign body. The frequency of extra-neurological infections and of asymptomatic pulmonary bacterial colonization was similar in both groups, but frequency of asymptomatic bacteriuria was higher in the placebo-treated patients.

Pharmacokinetics of sulbenicillin, a new broad-spectrum semisynthetic penicillin.

In a pharmacolinetic study on a new semisynthetic penicillin, alpha-sulfobenzylpenicillin, sulbenicillin, serum level, serum half-life, apparent distribution volume, renal clearance, urinary excretion, and metabolism were determined after a 4-gm intravenous dose and compared to that of carbenicillin in 5 patients with normal renal function. In the case of sulbenicillin, the mean serum concentration at 1 hr was 157 plus or minus 25 mug/ml, the mean serum half-life was 70 plus or minus 10 min, the renal clearance was 95 plus or minus 25 ml/min, and the total urinary recovery after 24 hr was about 80% of the dose. The only metabolite detected in the urine was the penicilloic acid derivative, in an amount usually less than 5% of the dose. Serum values, serum half-live, renal clearances, and excretion pattern did not differ significantly from that of carbenicillin. In 8 patients with decreased renal function (creatinine clearance less than 50 ml/min) there was an inverse correlation between creatinine clearance and serum half-life.

Penicillin clearance in diabetic children.

The clearance of crystalline penicillin G was found to be significantly higher in children in the early period of diabetes than in age-matched healthy controls. The therapeutic importance of the finding is emphasized.