[Simultaneous determination of sixteen antibiotics in human urine with ultra performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To develop a method for simultaneous determination of sixteen antibiotics in human urine by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). METHODS: With Piperacillin as an internal standard, the target antibiotics in urine samples were enriched and purified by Oasis HLB solid phase extraction (SPE) cartridges, then separated in a ZORBAX SB-C18 column with a gradient elution of mobile phase of 0.1% formic acid water and acetonitrile, finally analyzed with multiple reaction monitoring (MRM) mode. RESULTS: The limits of detection (LOD) for these sixteen antibiotics were in the range of 0.05-10.0 ng/mL and the limits of quantification (LOQ) in the range of 0.25-20.0 ng/mL. Within the related linear range, the related coefficient (r) of sixteen antibiotics were all more than 0.995. Accuracies for these antibiotics were ranged from 82.0%-119.3%, the within-day precision were less than 13.9%. CONCLUSION: The developed method is sensitive, specific and appropriate for the analysis of antibiotics in forensic toxicology and therapeutic drugs monitoring.

A highly sensitive and rapid assay for protein determination in human urine and penicillin using a Rayleigh light-scattering technique with benzeneazo-8-acetylamino-1-naphthol-3,6-disulfonic acid sodium salt.

A simple and sensitive method was conducted for the determination of trace amounts of proteins with benzeneazo-8-acetylamino-1-naphthol-3,6-disulfonic acid sodium salt (azophloxine, AP) using a Rayleigh light-scattering (RLS) technique. At pH 2.60 and in the presence of an emulsifier OP microemulsion, the RLS of AP can be greatly enhanced by proteins, owing to the interaction between AP and protein. The enhanced intensity is proportional to the concentration of proteins. Four proteins, including bovine serum albumin (BSA), human serum albumin (HSA), lysozyme (Lys) and gamma globulin (gamma-G) have been tested. For example, the linear range of BSA was 0 - 0.06 microg mL(-1) with detection limits of 2.38 ng mL(-1). The method was applied to the analysis of protein in human urine and penicillin samples with satisfactory results. The relative standard deviation was in all instances less than 4.0%, and the recovery was in the range of 97.5 - 104%.

Simultaneous determination of carvedilol and ampicillin sodium by first-derivative fluorometry in the presence of human serum albumin.

A sensitive and selective method for the simultaneous determination of carvedilol and ampicillin sodium (AS) in the presence of human serum albumin (HSA) is described. The maximum emission wavelengths of carvedilol and AS are at 357 nm and 426 nm with excitation at 254 nm, respectively. The first-derivative peaks of carvedilol and AS were at 337 nm and 398 nm, respectively. The linear-regression equations of the calibration graphs of carvedilol and AS were C = 0.0001H - 0.0063 and C = 1.530H - 43.84; the correlation coefficients were 0.9990 and 0.9986, respectively. The detection limits were 1 ng ml(-1) for carvedilol and 23 microg ml(-1) for AS, respectively. The effects of the pH, the stability of carvedilol and AS and foreign ions on the determination of carvedilol and AS were examined. The recoveries of carvedilol and AS were measured. This method is simple and can be used for the determination of carvedilol and AS in human serum and urine samples with satisfactory results.

Determination of veterinary antibiotics in bovine urine by liquid chromatography-tandem mass spectrometry.

A follow-up of antibiotics (tetracyclines, fluoroquinolones, cephalosporins, penicillins and amphenicols) in the bovine urine is important for two reasons: to understand if they are still present in organism, and whether their occurrence in urine might be considered as an environmental risk. A validated HPLC-MS/MS method (Decision 2002/657/EC) for antibiotics determination in bovine urine was developed. CCα and CCß were in the range of 0.58-0.83 and 0.55-1.1 ng mL(-1), respectively. Recoveries were 92-108%, with inter-day repeatability below 12%. Analysis of bovine urine revealed frequent presence of tetracyclines, which was related with animal's age. The cause, most presumably, might be found in different therapeutic protocols applied for veal calves and young bulls enrolled in this study. Most abundant was oxytetracycline with highest level in veal calves (1718 ng mL(-1)) vs. young bulls (2.8 ng mL(-1)). Our results indicate the necessity of antibiotics monitoring in bovine urine before animals undergo further processing in the food industry.

Oral penicillin prophylaxis in children with imparied splenic function: a study of compliance.

One measure used to prevent overwhelming sepsis due to Streptococcus pneumoniae in children with defective splenic function is oral penicillin prophylaxis. However, a frequently cited argument against this approach is the likelihood of poor compliance. Compliance was studied by examining urine specimens for penicillin by the Sarcina lutea disc diffusion technique in 22 surgically asplenic children, two patients following bone marrow transplantation, and 38 infants and young children with sickle cell disease. Multiple specimens (mean 3.5 per patient) were examined in 43 of the children. Overall, 125/188 (66%) of the urine samples contained penicillin, indicating compliance within the previous 12 to 24 hours. Compliance tended to improve on subsequent clinic visits. These relatively good results were attributed to an intensive educational program in which repetitive efforts are made to counsel patients and parents about the risks of life-threatening infection. Poor compliance should no longer be invoked as a reason not to study the efficacy of prophylactic penicillin in functionally or surgically asplenic subjects.

Pharmacokinetics of temocillin in volunteers.

The pharmacokinetics of temocillin, a new semisynthetic parenteral penicillin, were studied in 10 healthy volunteers. Doses of 0.5, 1.0, and 2.0 g were administered by intravenous bolus injection at weekly intervals, and serum and urine samples were assayed by an agar diffusion method. Mean peak serum concentrations were: 77.9 (+/- 28.4) mg/L (0.5 g), 160.8 (+/- 58.2) mg/L (1.0 g), and 236.1 (+/- 93.3) mg/L (2.0 g), with serum concentrations still being measurable after 12 hours for all doses [7.9 (+/- 3.7) mg/L, 12.9 (+/- 5.2) mg/L, 14.8 (+/- 6.3) mg/L]. According to a 2-compartment open model, the mean terminal half-lives of 0.5, 1.0, and 2.0 g doses were 5.2 (+/- 0.3), 5.0 (+/- 0.2), and 5.0 (+/- 0.2) hours, respectively. The total volume of distribution averaged 0.15 (+/- 0.01), 0.17 (+/- 0.01), and 0.24 (+/- 0.01) L/kg bodyweight, respectively, mean renal clearances were 18.5 (+/- 3.2), 19.6 (+/- 5.0), and 29.8 (+/- 2.6) ml/min, respectively, and the area under the serum concentration time curve (AUC) was 344.1 (+/- 18.7), 573.3 (+/- 27.8), and 784.5 (+/- 47.1) mg X h/L, respectively. At 74 (+/- 12.9)%, the 24-hour urinary recovery was highest for the low dose, followed by 68.1 (+/- 6)% for the 2.0 g dose, and 66.1 (+/- 16.8)% for the 1.0 dose. No untoward side effects were recorded. Thus, temocillin appears to be a penicillin with a prolonged half-life and high AUC.

Quantification of temocillin biliary excretion and gallbladder bile concentration in healthy subjects.

The techniques of duodenal perfusion with polyethylene glycol as a nonabsorbable marker, and cholescintiscan using 99Tc HIDA as a gallbladder bile marker, were used to measure the total duodenal output and gallbladder bile concentration of temocillin after administration of an intravenous bolus injection to each of 6 healthy subjects. We carried out 8 studies. 3 with 0.5g temocillin and 5 with 1g temocillin. The plasma half-life of temocillin was 177 (+/- 25) minutes [mean (+/- SD)] and 196 (+/- 29) minutes with the 0.5g and 1g doses, respectively. Urinary excretion accounted for 38% of the total dose given during the study period of 6 hours, and total biliary excretion was recorded as 2.2% of the given dose for both doses. The mean concentration of temocillin in gallbladder bile was 314.7 (+/- 273.2) mg/L after the 0.5g dose and 474.5 (+/- 307.3) mg/L after 1g dose. It was concluded that temocillin is highly concentrated in the normal gallbladder in man.

Temocillin. Summary of safety studies.

Temocillin is a novel injectable beta-lactam antibiotic designed for parenteral use. It is active against the majority of Gram-negative bacteria and is stable to a wide range of beta-lactamases. Disposition and metabolic studies on temocillin in animals and man demonstrate that the drug is well distributed throughout the body tissues and will cross the placenta. The major route of elimination is via the kidney (89%) where the drug is excreted unchanged as parent compound, mainly by the glomerular filtration of unbound temocillin. A full toxicological safety evaluation programme has been completed and includes acute, subacute and chronic toxicology in rat and dog, and reproductive and mutagenicity studies. Temocillin was well tolerated in animals at dosages of up to 1000 mg/kg and appears to be without any potential hazard for man in dosages which are well in excess of the proposed therapeutic dose.

Determination of piperacillin and mezlocillin in human serum and urine by high-performance liquid chromatography after derivatisation with 1,2,4-triazole.

High-performance liquid chromatographic methods have been developed for the determination of piperacillin and mezlocillin in human serum and urine samples. The methods involve ultrafiltration of samples followed by reaction with 1.5 M 1, 2, 4-triazole and 0.5 x 10(-3) M mercury (II) chloride in solution (pH 8.50) at 50 degrees C for 15 min. The resulting products were separated on a C18 column following stabilisation in an eluent containing sodium thiosulphate. They were detected at 323 nm for both penicillins. The methods have been applied to assays applied to assays of these penicillins in human serum and urine samples. The procedures, which permit the determination of penicillin concentration down to 0.1 microgram m1-1 in serum and 1 microgram m1-1 in urine samples, are specific to intact penicillins without interference from corresponding penicilloates [see J. Haginaka et al., Anal. Sci. 1 (1985) 73]. At concentrations of 1-500 micrograms ml-1 for each compound, the within- and between-day precisions were 1.8-4.8 and 3.7-6.9, respectively. The accuracy was ca. 100% for all samples assayed.

Pharmacokinetics of ampicillin and methoxymethyl ester of hetacillin in dogs.

Concentrations of ampicillin and the methoxymethyl ester of hetacillin were measured in plasma, prostatic fluid, and spinal fluid of dogs receiving ampicillin or the hetacillin ester by continuous intravenous infusion. The ratios of ampicillin in prostatic fluid relative to plasma levels were higher after dosing with the hetacillin ester. Pharmacokinetic parameter values were consistent with urinary excretion characteristics. Ready diffusion of the ester across biological membranes may facilitate eradication of pathogenic organisms in prostatic and spinal fluids.

Identification of the active metabolites of the isoxazolylpenicillins by means of mass-spectrometry.

Electron-impact mass-spectrometry of the methyl esters of the isoxazolylpenicillins and of their active metabolites showed the latter to be formed from their parent compounds by hydroxylation of the 5-methyl group.

Effect of the hydroxyl group of the p-hydroxyphenyl moiety of aspoxicillin, a semisynthetic penicillin, on its pharmacokinetic property.

The serum concentrations, urinary and biliary excretions of six penicillin derivatives including aspoxicillin (ASPC) were studied in rats and the correlation between the values of pharmacokinetic parameters thus obtained and the Rm values measured by means of reversed phase TLC were analyzed. Among the penicillins studied, the hydrophilicity of amoxicillin was the highest (the lowest Rm value), which was followed by those of ASPC, ampicillin, p-hydroxypiperacillin, dehydroxyaspoxicillin and piperacillin in descending order. These Rm values were then correlated with the AUC values at 20 mg/kg of dosing, giving the results that more hydrophilic penicillins having a hydroxyl group show higher serum concentrations as well as greater AUC values. The studies of correlation between the Rm values and the urinary or biliary excretion revealed that hydrophilic penicillins were almost excreted into urine, but more hydrophobic ones were mainly eliminated into bile. From the above results, a hydroxyl group introduced to the phenyl group of ASPC was considered to have a role that increases the hydrophilicity of ASPC, giving higher and longer persistency of the serum levels and increasing the excretion of drugs into urine.

Fluorimetric determination of ampicillin by use of non-toxic catalysts. Estimation of beta-lactamase activity and parameters.

A fluorescence assay based on the use of biological reducing agents as catalysts rather than heavy metal ions has been developed for estimation of ampicillin concentrations. The assay is based on the conversion of ampicillin to its penicilloate, by treatment with sodium hydroxide, then neutralization, dilution with 0.5 M acetate buffer at pH4 and heating for 30 min at 100 degrees C in the presence of ascorbic acid (0.5 mg) and EDTA (50 microM). Reduced glutathione, cysteine and N-acetylcysteine also catalysed the development of fluorescence. A practical sensitivity range of 0.5-50 microM ampicillin was used. The assay was used to estimate ampicillin in some biological solutions to which the antibiotic has been added. Milk, blood serum, trypticase soy broth and nutrient broth containing 25 microM antibiotic assayed at 18.5, 21.7, 16.5 and 14.7 microM, respectively, with standard deviations between 1.2 and 0.7%. The low results were attributed to binding of some ampicillin by proteins or peptides which were removed by pretreatment. Urine containing 5 mM ampicillin assayed at 4.97 mM with a standard deviation of 3%. A modification of the procedure was used to measure beta-lactamase activity against ampicillin in several organisms in a fixed time assay. Kinetic parameters of a commercial beta-lactamase preparation from Bacillus cereus could also be determined by an additional modification. In both instances a correction was required for the intrinsic fluorescence of ampicillin remaining in the solution. The preparation examined had a Michaelis constant (Km) of 0.32 mM, a maximum velocity (Vmax) of 5398 micromol ampicillin hydrolysed mg(-1) min(-1), an apparent catalytic constant (Kcat, turnover number) of 20,220 s(-1) and a Kcat/Km ratio of 0.63 x 10(7) M(-1) s(-1). The major advantage of using this assay technique is that toxic metals are not used in the development of fluorescence so it is more environmentally acceptable. The technique is useful for examining beta-lactamase activity against ampicillin and might be useful for pharmaceutical products-for determining available therapeutic levels and for monitoring the activity of penicillin acylase against the penicilloate of ampicillin.

Biliary excretion of piperacillin.

1. The excretion of piperacillin sodium in bile was studied after intravenous injection of 2 g (n = 5) and 4 g (n = 7). All patients had undergone cholecystectomy and exploration of the common bile duct for cholelithiasis. Bile, serum and urine concentrations were measured by a microbiological technique. 2. Peak concentrations of piperacillin were found in bile at 150 minutes after 4 g and at 210 minutes after 2 g. 3. Both the concentration of piperacillin in bile at the end of a 6 1/2 hour study and the calculated mean bile concentration of piperacillin were above the minimum inhibitory concentration (MIC) of this drug for organisms commonly found in acute biliary tract infections. We believe piperacillin may be useful in the management of such conditions.

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).

Pharmacokinetics of penicillin G procaine versus penicillin G potassium and procaine hydrochloride in horses.

OBJECTIVE: To compare the pharmacokinetics of penicillin G and procaine in racehorses following i.m. administration of penicillin G procaine (PGP) with pharmacokinetics following i.m. administration of penicillin G potassium and procaine hydrochloride (PH). ANIMALS: 6 healthy adult mares. PROCEDURE: Horses were treated with PGP (22,000 units of penicillin G/kg of body weight, i.m.) and with penicillin G potassium (22,000 U/kg, i.m.) and PH (1.55 mg/kg, i.m.). A minimum of 3 weeks was allowed to elapse between drug treatments. Plasma and urine penicillin G and procaine concentrations were measured by use of high-pressure liquid chromatography. RESULTS: Median elimination phase half-lives of penicillin G were 24.7 and 12.9 hours, respectively, after administration of PGP and penicillin G potassium. Plasma penicillin G concentration 24 hours after administration of penicillin G potassium and PH was not significantly different from concentration 24 hours after administration of PGP. Median elimination phase half-life of procaine following administration of PGP (15.6 hours) was significantly longer than value obtained after administration of penicillin G potassium and PH (1 hour). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that i.m. administration of penicillin G potassium will result in plasma penicillin G concentrations for 24 hours after drug administration comparable to those obtained with administration of PGP Clearance of procaine from plasma following administration of penicillin G potassium and PH was rapid, compared with clearance following administration of PGP.

Study on fluorescent property of degrading products of piperacillin and its analytical application.

The fluorimetric property of the degrading products of piperacillin has been studied in detail. The studies on degrading pH, degrading time, detection alkalinity and other corresponding analytical parameters of acid degradation have been made. Then fluorometry of piperacillin was established by producing its stable fluorescent products. The detection limit for acid degradation analytical method is 2.34 ng/ml, the linear range is 7.80-4.0 x 10(2) ppb. The analytical sensitivity, precision and stability of degrading products of acid degradation are satisfactory, which has been used for the determination of the trace piperacillin in human serum and urine with satisfactory results.

Penicillin prophylaxis in children with sickle cell disease in Brent.

OBJECTIVE: To assess compliance with oral penicillin prophylaxis in children with sickle cell disease and identify possible reasons for poor compliance. DESIGN: Closed questionnaires given to parents of children with sickle cell disease and general practitioners in Brent. Urine samples from 23 children were tested for penicillin. SETTING: Paediatric haematology clinic, Central Middlesex Hospital, and general practices in Brent. SUBJECTS: 50 children (aged less than or equal to 16) attending clinic with sickle cell disease over six months (33 HbSS, 12 HbSC, five HbS beta thalassaemia). 30 general practitioners: 15 with the greatest number of patients with sickle cell disease on the Brent register; 15 selected randomly from family practitioner committee's list. MAIN OUTCOME MEASURES: Reported compliance with and awareness of importance of penicillin prophylaxis. Results of urine tests for penicillin. RESULTS: 31 parents claimed that their children received penicillin every day and 19 that they received it most days (greater than or equal to 5 days a week). Penicillin was detected in only 10 of 23 urine samples tested. Parents and doctors seemed not to appreciate the importance of treatment: only eight parents were aware of the risk of death if penicillin were discontinued, and 16 doctors were unaware that regular penicillin prophylaxis prevents pneumococcal septicaemia and death in these children. CONCLUSIONS: Education for families with children with sickle cell disease must be improved. Specialised information and training are needed for doctors working in areas with a high prevalence of the disorder.

[Pharmacokinetics of azlocillin in chronic renal failure and hemodialysis patients]. / Pharmacocinétique de l'azlocilline chez l'insuffisant rénal chronique et l'hémodialysé.

The pharmacokinetics of azlocillin were studied in 16 patients with varying degrees of renal impairment (creatinine clearance Ccr ranging from 0 to 52 ml/min/1.73 m2) and on and off sessions in 4 of these patients on periodical haemodialysis. A single dose of azlocillin 80 mg/kg was given by intravenous infusion over 30 min. Maximum concentrations in the sera of patients with renal impairment were the same as in normal subjects, ranging from 300 to 400 micrograms/ml. The elimination half-life (t 1/2) increased as renal function deteriorated, with values of 1.11 h in subjects with healthy kidneys to 5.66 h in patients with Ccr less than 15 ml/min (maximum 8.38 h). The apparent volume of distribution (Vd) was unchanged in patients with renal impairment but was significantly increased in patients on haemodialysis. The mean percentage of the dose administered excreted in the urines decreased from 60-70% in normal subjects to about 11% in patients with severe renal failure, but urinary concentrations remained above therapeutic levels. The extra-renal elimination of azlocillin was unmodified by renal impairment. Azlocillin is easily removed by dialysis: t 1/2 values between and during 6 h sessions of haemodialysis were 6.55 h and 2.81 h respectively, corresponding to a 45.8% extraction on the dialyser. These results are comparable to those found in the literature and can be used as a basis for adjusting azlocillin dosage to the degree of renal function.

[Clinical pharmacokinetics of azlocillin]. / Pharmacocinétique clinique de l'azlocilline.

The pharmacokinetics of azlocillin have been studied in healthy subjects and in patients, in children and in adults, using different doses, either single or repeated. Following intravenous injection of doses ranging from 1 to 5 g, plasma concentrations increase in relation to dosage. Maximum concentrations at the end of an injection or infusion average 100-200 micrograms/ml with 1 g and 400-500 micrograms/ml with 5 g. Azlocillin has a low degree of plasma protein binding: 30% to 40% depending on concentrations. Its volume of distribution is approximately 0.2 l/kg. Tissue distribution has been studied by various authors: with a 2 to 5 g dose, therapeutically active concentrations have been found in a variety of tissues, including bronchial secretions, bone, etc. Azlocillin crosses the placenta; the ratio of maternal to foetal plasma concentrations is 0.50. Azlocillin undergoes little metabolic degradation and its metabolites (penicilloates) amount to less than 15% of the dose administered. Most of the drug is excreted by the kidneys, 50% to 70% of the dose injected being recovered in the 24 h urines; the remainder is excreted in the bile, and biliary concentrations may be as high as 15-fold the corresponding plasma concentrations. Azlocillin is rapidly cleared. Its plasma half-life varies from 45 to 75 min according to different authors. The fact that it increases slightly with dosage suggests the kinetics of the drug might be dose-dependent. In view of the intervals between doses, this is certainly not of therapeutic importance. Total and renal clearance values are 150-200 ml/min and 100-140 ml/min respectively. In patients with renal impairment azlocillin is eliminated more slowly, with a half-life of up to 6-10 h when creatinine clearance is below 5 ml/min. The reduced urinary excretion may partly be compensated for by increased biliary excretion. The proportion of drug removed by haemodialysis is 40-50%. Azlocillin excretion is slowed down in children under 3 months of age, with half-lives of 4.5 h, 3.0 h and 2.0 h respectively in prematures, neonates and infants.