Blood dendritic cells and DC-poietins in systemic lupus erythematosus

Dendritic cells (DCs) control immunity and tolerance. Hence, we surmised that systemic lupus erythematosus (SLE), a systemic autoimmune disease with autoreactive T and B cells, might be due to alterations in DC homeostasis. Taken together, our results demonstrate profound alterations of DCs and DC-poietins homeostasis in SLE. Elevated levels of interferon-alpha (IFN) in serum of SLE patients coexist with decreased numbers of cells producing IFN-alpha, i.e., plasmacytoid dendritic cells (PDCs). Decreased numbers of circulating DCs correlate with increased levels of soluble tumor necrosis factor (TNF) receptors, thus suggesting the potential role of TNF pathway in the observed DC alterations. Finally, increased FMS-like tyrosine kinase 3-ligand (FLT3-L) and its correlation with soluble TNF receptors suggest a physiologic response to compensate low DC numbers. Although IFN-alpha remains at the center of immunologic aberrations in SLE, it remains to be determined whether increased shedding of soluble TNF receptors could also be ascribed to IFN-alpha.

Population pharmacokinetics and use of Monte Carlo simulation to evaluate currently recommended dosing regimens of ciprofloxacin in adult patients with cystic fibrosis

Pharmacodynamic data on ciprofloxacin indicate that a target area under the concentration-time curve from 0 to 24 h (AUC(0-24))/MIC ratio of >or=125 is necessary to achieve optimal bactericidal activity for the treatment of gram-negative pneumonia. The purpose of this prospective study was to (i) develop a pharmacokinetic (PK) model to be utilized for therapeutic drug monitoring (TDM) of ciprofloxacin and (ii) evaluate current ciprofloxacin dosing regimens for pneumonias in cystic fibrosis (CF) patients. Twelve adult CF patients received a single 400-mg dose of IV ciprofloxacin. Six blood samples were obtained over a 12-h interval. Serum drug concentrations were determined by high-pressure liquid chromotography and were fitted to one- and two-compartment models by using NPEM2. Ciprofloxacin MIC data for Pseudomonas aeruginosa were obtained from 1,213 CF patients enrolled in a large clinical trial. A Monte Carlo simulation was performed to estimate the fractional attainment of an AUC(0-24)/MIC ratio of >or=125. A two-compartment model best describes the serum drug concentration data. The mean fitted PK parameter values are volume of distribution in the central compartment, 0.29 liter/kg; volume of distribution at steady state, 1.1 liters/kg; total clearance, 0.34 liter/h/kg; distributional clearance, 0.89 liter/h/kg; half-life at alpha phase, 0.16 h; and half-life at beta phase, 2.9 h. The overall fractional attainment of achieving an AUC(0-24)/MIC ratio of >or=125 against P. aeruginosa isolates with ciprofloxacin (400 mg every 12 h [q12h] and 8 qh) were 10 and 30%, respectively. A clinical breakpoint MIC of <0.5 microg/ml for susceptibility is suggested, based on an examination of the fractional attainment of the AUC(0-24)/MIC target at each MIC. The recommended doses of 400 mg q8h or q12h may be inadequate to treat an acute pulmonary exacerbation when given alone. The poor and variable AUC(0-24)/MIC ratios support the use of TDM to monitor and adjust the dosage to optimize the efficacy of ciprofloxacin therapy in these patients.

Increased frequency of pre-germinal center B cells and plasma cell precursors in the blood of children with systemic lupus erythematosus

We have analyzed the blood B cell subpopulations of children with systemic lupus erythematosus (SLE) and healthy controls. We found that the normal recirculating mature B cell pool is composed of four subsets: conventional naive and memory B cells, a novel B cell subset with pregerminal center phenotype (IgD(+)CD38(+)centerin(+)), and a plasma cell precursor subset (CD20(-)CD19(+/low)CD27(+/++) CD38(++)). In SLE patients, naive and memory B cells (CD20(+)CD38(-)) are approximately 90% reduced, whereas oligoclonal plasma cell precursors are 3-fold expanded, independently of disease activity and modality of therapy. Pregerminal center cells in SLE are decreased to a lesser extent than conventional B cells, and therefore represent the predominant blood B cell subset in a number of patients. Thus, SLE is associated with major blood B cell subset alterations.

Estimation of creatinine clearance in patients with metastatic ovarian cancer

The authors evaluated the predictive performance of four methods used to estimate creatinine clearance (Cl(cr)) in patients with metastatic ovarian cancer. Methods described by Cockcroft and Gault, Jelliffe, and two equations derived from cancer patients by Robinson and Tsubaki, were evaluated. Estimated Cl(cr) values obtained by each method using actual weight (ABW), ideal weight (IBW) and lower of ABW and IBW were compared with measured values determined by a 12- or 24-hour urine collection for 14 patients enrolled in a controlled clinical trial. The mean prediction errors (ME) and mean absolute errors (MAE) were calculated to evaluate the bias and precision, respectively, of each method. The relationship between predicted and measured Cl(cr) is poor (r = 0.38 to 0.54). Cockcroft and Gault using ABW (p = 0.21), Robinson using ABW (p = 0.44), and Jelliffe (p = 0.17) were equally unbiased predictors of measured Cl(cr). All other methods significantly underestimated measured Cl(cr). All methods appeared to be equally imprecise (p<0.05). The use of standard equations for estimating Cl(cr) in patients with ovarian cancer is predictive of the measured 24-hour value. The use of oncology specific equations does not improve the accuracy or precision of these estimates.

Pathophysiology and treatment of psoriasis

The pathogenesis and treatment of psoriasis are reviewed. Psoriasis is characterized by defects in the normal cycle of epidermal development that lead to epidermal hyperproliferation, altered maturation of skin cells, and vascular changes and inflammation. The condition typically manifests as areas of thickened, flaky, silvery white and reddened skin that may hurt, itch, and bleed. Biochemical markers of psoriasis are changes in levels of keratins, keratinocyte transglutamase, migration inhibitory factor-related protein, skin-derived antileukoproteinase, involucrin, small protein rich protein 2, filaggrin, and cytokines. Types of psoriasis that may be clinically encountered include plaque psoriasis, guttate psoriasis, erythrodermic psoriasis, and pustular psoriasis. Psoriasis is believed to be genetically linked but can also be triggered by mechanical, ultraviolet, and chemical injury; various infections; prescription drug use; psychological stress; smoking; and other factors. Topical treatment of psoriasis is usually the first line of therapy. Topical treatments consist of emollients and keratolytic agents, anthralin, coal tar, corticosteroids, vitamin D3 analogues, topical retinoids, and topical psoralens plus ultraviolet A (UVA) light. In patients who do not respond adequately to topical therapy, oral or injectable therapy, such as oral retinoids, methotrexate, cyclosporine, tacrolimus, and oral psoralens plus UVA light, may be warranted. Patients receiving systemic treatments should be carefully monitored for adverse effects and drug-drug interactions. Drug therapy is the mainstay of the treatment of psoriasis. The potential adverse effects and interactions necessitate vigilant monitoring.

Stability of Ranitidine Hydrochloride with Cefazolin Sodium, Cefbuperazone Sodium, Cefoxitin Sodium and Cephalothin Sodium during Simulated Y-Site Administration

The compatibility and stability of ranitidine hydrochloride when comixed with four cephalosporins (cefazolin sodium, cefoxitin sodium, cephalothin sodium and cefbuperazone sodium) during simulated Y-site injection were studied. The mixtures were prepared by mixing equal volumes (2 mL) of ranitidine hydrochloride (1mg/mL) and each tested cephalosporin (20 mg/mL) in a 10 mL glass test tube. All study mixtures were prepared in triplicate and stored at room temperature under normal fluorescent room lighting. The physical appearaance and pH of each mixture were recorded; the chemical stability of each drug was immediatedly determined by stability-indicating high-performance liquid chromatography from samples stored for up to four hours after mixing. Stability was defined as the retention of more than 90% of the initial concentration of each drug. Visual inspection revealed no color or clarity change and the pH changes were less than 0.2 pH units in the tested mixtures for cefazolin and cefoxitin: however, there were significant pH changes for cefbuperazone and cephalothin after four hours of storage. Ranitidine retained greater than 90% of its original concentration within the tested period in the mixture with 20 mg/mL of each tested cephalosporin, except for cephalothin (86.6% of control). In the presence of 10 mg/mL cephalothin, however, ranitidine retained greater than 90% for four hours. Meanwhile, all four cephalosporins retained greater than 90% of their original concentrations for up to four hours in the mixture with ranitidine. From the results obtained, it is clear that ranitidine solution may be coadministered with a solution of either cefazolin, cefoxitin or cefbuperazone during Y-site administration for up to four hours after mxining. On the other hand, since ranitidine with cephalothin (20 mg/mL) fell below 90%, the amount of cephalothin should not exceed 10 mg/mL when coadminstered with ranitidine solution.

Citrobacter urinary tract infections in children

BACKGROUND

Citrobacter species have been described as the etiologic agents in cases of bacteremia, meningitis, diarrhea and brain abscess, but little is known of their role as a cause of urinary tract infections in children. The purpose of this study was to define the role of Citrobacter species in pediatric urinary tract infections.

METHODS

The project consisted of a retrospective chart review of microbiologic and medical records of patients younger than 18 years of age with urine cultures positive for Citrobacter species during a 3-year period.

RESULTS

Thirty-four patients with 37 infections were included in the review. The average patient age was 6.9 years (range, 1 month to 18 years) and 71% were female. Fifty-six percent of the patients had urinary tract/renal anomalies or neurologic impairment and 26% represented nosocomial infections. Thirty-seven percent of patients were asymptomatic at the time of diagnosis, whereas 63% complained of at least one of the following findings: gastrointestinal symptoms; dysuria; fever; incontinence; penile/vaginal discharge; frequency; flank pain; and hematuria. Twenty-six of the isolates were Citrobacter freundii and 11 were Citrobacter koseri. Blood cultures were obtained in 9 patients and all were negative for Citrobacter isolates.

CONCLUSIONS

Although it is uncommon Citrobacter can cause urinary tract infections in the pediatric population, which occur more frequently in children with underlying medical conditions. It appears that treatment similar to that of other gram-negative enteric organisms is the most prudent approach to these children until more information can be gathered.

Five-day Stability of Vinorelbine in 5% Dextrose Injection and in 0.9% Sodium Chloride Injection at Room Temperature

The stability of vinorelbine tartrate in 5% dextrose injection or 0.9% sodium chloride injection stored in polyvinyl chloride minibags was studied. Vinorelbine was diluted to concentrations of 0.5 mg/mL or 2 mg/mL in the above vehicles, and the solution was placed at room temperature and exposed to constant fluorescent lighting. Three bags were prepared for each concentration and solution and each bag was assayed for vinorelbine concentration by stability-indicating high-performance liquid chromatography at 0, 24, 48, 96, and 120 hours. Each solution was inspected for clarity, color and precipitation. Throughtout the study, the mean concentration of vinorelbine remaining was more than 94% of the initial concentration in both vehicles. No precipitation, color change or haziness was seen. Vinorelbine, at concentrations of 0.5 mg/mL or 2 mg/mL in 5% dextrose injeciotn or 0.9% sodium chloride injection, was stable for at least 120 hours at room temperature under fluorescent lighting.

Compatibility and stability of ranitidine hydrochloride with six cephalosporins during simulated y-site administration

The purpose of this project was to determine the visual compatibility and stability of ranitidine hydrochloride in admixtures during simulated Y-site administration with six individual cephalosporins: ceftizoxime sodium, cefuzonam sodium, cefoperazone sodium, cefmenoxime hydrochloride, moxalactam disodium and flomoxef sodium. Dilutions of ranitidine hydrochloride 1 mg (as the free base)/mL were prepared in 0.9% sodium chloride injection. Two milliliters of the ranitidine solution (1mg/mL) was mixed with 2mL of each cephalosporin (20 mg/ml) in 10 mL glass test tubes. Concentrations of each drug were determined by stability-indicationg high-performance liquid chromatographic assay methods following zero, one, two, and four hours after mixing. All six cephalosporins retained greater than 95% of their original concentrations for four hours in the admixture with ranitidine. Ranitidine retained greater than 95% of its original concentration for four hours in the admixture with four of the tested cephalosporins and apporximately 90% with moxalactam and flomoxef. Solutions containing ranitidine may be coadministered with solutions either ceftizoxime, cefuzonam, cefoperazone or cefmenoxime via Y-injection site over four hours. While the ranitidine concentration may be reduced to near 90% after four hours with moxalactam and flomoxef, the tested antibiotics were not affected in the presence of ranitidine over four hours.

Stability of Milrinone Lactate in 5% Dextrose Injection and 0.9% Sodium Chloride Injection at Concentrations of 400, 600, and 800 micrograms/mL

Milirone lactate is a phosphodiesterase inhibitor that is used in the acute phase of congestive heart failure. It is available in ready-to-use intravenous piggybacks at a concentration of 200 micrograms/mL and in 10-mL and 20-mL vials at a concentration of 1 mg/mL. The stability of milrinone lactate at highter concentrations of 400, 600, and 800 micrograms/mL in 5% dextrose injection and 0.9% sodium chloride injection was studied. The solutions were prepared in polyvinyl chloride bags and aliquots of 10mL were withdrawn initially and after one, three and seven days at room and refrigerator temperatures under normal light. The aliquots were stored at -20 deg C and analyzed for potency using a high-performance liquid chromatography proceure. Both intraday and interday variations of the external standard were less than 4%. Stablility was defined as 90% or greater of the original concentration remaining. Milrinone lactate prepared in either 5% dextrose injection or 0.9% sodium chloride injection at concentrations of 400, 600, and 800 micrograms/mL is stable at room or refrigerated temperature for 14 days.

Stability of Milrinone Lactate 200 micrograms/mL in 5% Dextrose Injection and 0.9% Sodium Chloride Injection

The stability of milrinone lactate 200 microgram/mL in either 5% dextrose injection or 0.9% sodium chloride injection was studied. The solutions were prepared in polyvinyl chloride bags and aliquots of 10 mL were withdrawn at times zero, one, three, seven and 14 days at room (20 to 25 deg C) and refrigerated (2 to 8 deg C) temperatures. The samples were then stored at -20 deg C and analyzed for potency using a stability-indicating high-performance liquid chromatography assay procedure. Stability was defined as 90% or greater of the original concentration remaining. Samples were inspected visually and no color change, haziness or precipitation was observed at any time during the study. Milrinone lactate 200 micrograms/mL mixed in either 5% dextrose injection or 0.9% sodium chloride injection is stable at room or refrigerated temperatures for 14 days.

Pharmacokinetics of aztreonam in critically ill surgical patients

The pharmacokinetics of aztreonam in critically ill surgical patients with serious gram-negative infections were studied. Blood samples were taken before and at 30 minutes, 2.5 hours, and 5 hours after a dose of aztreonam 2 g i.v. every six hours. All patients had received at least two aztreonam doses before the dosage interval being studied. Aztreonam concentrations were measured by high-performance liquid chromatography. Aztreonam's pharmacokinetics, the severity of illness, and patient outcomes were examined. A total of 28 patients with 111 serum aztreonam concentrations were included in the analysis. The patients were young (mean age, 35 years) and predominantly male. The mean APACHE II score was 19.3, and 22 patients had sepsis. Four patients died. The mean volume of distribution (V) of 0.35 L/ kg was nearly twice the previously reported steady-state value for healthy volunteers (0.18 L/kg) and was highly variable. A slightly higher than normal mean V, 0.22 L/ kg, was seen in a subset of six patients whose infection occurred earlier in their intensive care and who had lower APACHE II scores. While with some antibiotics the elevated V would imply difficulty in achieving therapeutic drug levels, 99 (89%) of the 111 concentrations were at or above the in vitro susceptibility breakpoint of 8 micrograms/mL. Despite observations of markedly increased and highly variable V in critically ill surgical patients, a standard dosage of aztreonam was usually sufficient to maintain adequate serum drug levels.

Pharmacokinetics of meropenem in animals, healthy volunteers, and patients

Meropenem is a carbapenem antibiotic that appears to be widely distributed in tissues and is eliminated by both excretion and metabolism. Approximately 70% of meropenem is excreted via the kidneys, thus dosage adjustments are required for patients with renal impairment. The pharmacokinetic parameters for meropenem are similar to those for imipenem/cilastatin, with the exception of meropenem's smaller volume of distribution. The urinary recovery of meropenem is as high as that of imipenem in combination with cilastatin, an inhibitor of renal dehydropeptidase. Therefore, unlike imipenem, meropenem can be used without dehydropeptidase inhibitors to obtain a consistently high concentration in the urine without nephrotoxic effects.

Factors associated with antihypertensive prescribing

OBJECTIVE

To investigate factors associated with treatment approaches to hypertension, a major risk factor for coronary heart and cerebrovascular disease and significant healthcare problem in the US. The study reports on three cross-sectional national surveys of patient-physician encounters.

POPULATION

Visits were selected for adults with hypertension diagnoses from the National Ambulatory Medical Care Surveys, which represent office encounters during a given year. Years of observation included 1989, 1990, and 1991.

METHODS

Multiple variable logistic regression was used to identify predisposing need, enabling, and health utilization characteristics associated with whether the visit resulted in a prescription of an antihypertensive. Additionally, the association of these visits with combination therapy is determined.

RESULTS

For each of the 3 years, 69-75% of the encounters were associated with a prescription for drugs to treat hypertension. Prescribing is consistent with current literature demonstrating decreasing reliance on diuretics and beta-blockers, and increasing reliance on calcium antagonists. Combination therapy decreased as a percentage of prescriptions in 1990 and 1991. Variables associated with receiving an antihypertensive prescription included predisposing characteristics (patient age > 65 y), need characteristics (diagnosis of congestive hear failure [CHF]), and health utilization characteristics (physician specialty, previous diagnosis of hypertension). The most significant variables associated with combination therapy were predisposing characteristics (patient age > 65 y), need (CHF diagnosis, diagnosis of hypertension with end organ involvement), and health utilization characteristics (physician specialty).

CONCLUSIONS

These national estimates reinforce previous regional data regarding the categories of hypertension medications used. Patient visits involving multiple diagnoses, cardiologists, or patients older than 65 years, are more likely to generate prescriptions for combination antihypertensive therapy.

Meropenem versus tobramycin with clindamycin in the antibiotic management of patients with advanced appendicitis

BACKGROUND

Meropenem (MP), a new carbapenem antibiotic, has excellent antimicrobial activity against the enteric flora commonly encountered in acute appendicitis. Although similar to imipenem, it may have clinical advantages.

STUDY DESIGN

We compared patients with advanced appendicitis (gangrenous or perforated) treated with 1,000 mg MP every eight hours with those given the combination of tobramycin 5 mg/kg/day at eight hour intervals and clindamycin 900 mg every eight hours. Both treatments were given intravenously. Patients were randomized to either group of the double-blind study.

RESULTS

Of 129 evaluable cases, 63 received MP and 66 received both tobramycin and clindamycin (T/C). The two groups were similar in age, sex, and severity of disease. The mean number of days of postoperative fever (MP = 3.1 +/- 1.7 SD compared to T/C = 4.4 +/- 2.2 SD, p < or = 0.01), days of antibiotic therapy (MP = 6.1 +/- 1.6 SD compared to T/C = 7.3 +/- 2.2 SD, p = 0.01), and therefore hospital stay (MP = 8.0 +/- 3.5 SD compared to T/C = 9.4 +/- 2.6 SD, p < 0.01) were significantly better for patients treated with MP. No difference was found between the numbers of failures in each group (MP = 5 compared to T/C = 6).

CONCLUSIONS

This study demonstrates a small but significant reduction (approximately one day) in post-operative fever, duration of antibiotic treatment, and hospital stay for patients treated with MP compared to those treated with T/C.

Stability of granisetron hydrochloride in a disposable elastomeric infusion device

The stability and sterility of granisetron hydrochloride in 5% dextrose injection or 0.9% sodium chloride injection when stored in a disposable elastomeric infusion device were studied. Granisetron was diluted to 0.02 mg/mL (as the hydrochloride salt) in 5% dextrose chloride injection. The solution was placed in the drug reservoir of a disposable elastomeric infusion device and refrigerated at 4 degrees C for 14 days. A total of eight pumps were prepared, four containing granisetron 0.02 mg/mL in 5% dextrose injection and four containing granisetron 0.02 mg/mL in 0.9% sodium chloride injection. The solutions were assayed for granisetron concentration by stability-indicating high-performance liquid chromatography at 0 hours, 24 hours, 48 hours, 7 days, and 14 days. Each solution was inspected for clarity, color, and precipitation, and sterility testing was performed. Throughout the study, the mean concentration of granisetron remaining was more than 92% of the initial concentration both in 5% dextrose injection and in 0.9% sodium chloride injection. Individual solutions in 0.9% sodium chloride injection consistently maintained more than 90% of the initial drug concentration for only seven days. No microbial growth was detected. No precipitation, color change, or haziness was seen. Granisetron 0.02 mg/mL (as the hydrochloride salt) was stable and free of microbial growth in 0.9% sodium chloride injection for up to 7 days and stable and free of microbial growth in 5% dextrose injection for up to 14 days when stored at 4 degrees C in a disposable elastomeric infusion device.

Piperacillin-tazobactam pharmacokinetics in patients with intraabdominal infections

STUDY OBJECTIVE

To determine the appropriate compartmental and noncompartmental pharmacokinetic parameters for intravenous piperacillin and tazobactam.

DESIGN

Sequential selection of patients entered into a randomized, open-label clinical efficacy trial.

SETTING

Los Angeles County-University of Southern California Medical Center.

PARTICIPANTS

Sequential sample of 18 patients admitted for intraabdominal infections and consented into a comparative antibiotic trial.

INTERVENTIONS

Patients received piperacillin 4 g plus tazobactam 500 mg by intravenous intermittent infusion every 8 hours.

MEASUREMENTS AND MAIN RESULTS

The estimated noncompartmental pharmacokinetic parameters (mean +/- SD) for piperacillin and tazobactam, respectively, were as follows: maximum concentration in plasma 218.7 +/- 48.9 micrograms/ml and 27.8 +/- 9.1 micrograms/ml; half-life 1.07 +/- 0.22 hours and 1.00 +/- 0.27 hours; elimination rate constant 0.67 +/- 0.13 hr-1 and 0.73 +/- 0.18 hr-1; area under the concentration-time curve from zero hour to infinity 288.5 +/- 71.25 mg.hr/L and 36.3 +/- 9.55 mg.hr/L; total plasma clearance 14.75 +/- 3.93 L/hour and 14.78 +/- 4.39 L/hour; renal clearance 5.69 +/- 1.94 L/hour and 7.85 +/- 3.37 L/hour; volume of distribution at steady state 21.00 +/- 4.18 L and 22.47 +/- 8.27 L; and mean residence time 1.72 +/- 0.29 hours and 1.79 +/- 0.35 hours.

CONCLUSION

Our findings were similar to those in other surgical patient models. The two-compartmental model best described piperacillin and tazobactam disposition in our patients. Bayesian analyses of the two-compartment models of piperacillin and tazobactam were able to predict trough, peak, and 2-hour postadministration levels without bias.

Pharmacoeconomics of piperacillin/tazobactam and imipenem/cilastatin in the treatment of patients with intra-abdominal infections

Costs involved in using piperacillin 4 g/tazobactam 500 mg, given as intermittent intravenous infusions every 8 hours, were compared with those for imipenem/cilastatin 500 mg, given as intermittent intravenous infusions every 6 hours, for the treatment of patients with gangrenous or perforated appendicitis. A total of 88 patients were included in our cost analyses: 42 patients in the piperacillin/tazobactam group and 46 patients in the imipenem/cilastatin group. Durations (mean +/- SD) of antibiotic therapies were 7.8 +/- 3.3 days and 7.1 +/- 2.6 days for the piperacillin/tazobactam and imipenem/cilastatin groups, respectively. No statistical significance was found for the difference in duration of therapy (P = 0.376). Total drug treatment costs were $538.83 +/- $385.33 for the piperacillin/tazobactam group and $687.66 +/- $345.37 for the imipenem/cilastatin group. This difference in treatment cost was statistically significant (P = 0.0001). The need for laboratory tests and the use of other medications were not different between the two groups. Total hospital-days charges were higher for the piperacillin/tazobactam group ($18,339.76 +/- $6090.38) compared with the imipenem/cilastatin group ($16,150.00 +/- $5088.60) (P = 0.052). These findings suggest that length of hospital stay should be the economic focus of antibiotic therapy.

Stability of piperacillin sodium-tazobactam sodium and ranitidine hydrochloride in 0.9% sodium chloride injection during simulated Y-site administration

The stability of piperacillin sodium plus tazobactam sodium and ranitidine hydrochloride in 0.9% sodium chloride injection during simulated Y-site administration was studied. Triplicate test solutions of piperacillin 40 mg/mL plus tazobactam 5 mg/mL (as the sodium salts) or piperacillin 80 mg/mL plus tazobactam 10 mg/mL (as the sodium salts) were mixed 1:1 with ranitidine 0.5 and 2.0 mg/mL (as the hydrochloride salt). The solutions were stored at 23 degrees C, and samples were removed at zero, one, two, and four hours for measurement of drug concentration by stability-indicating high-performance liquid chromatography. At the time of sampling and before any dilution, each sample was visually inspected for color and precipitation, and pH was determined. At all sampling times, the concentrations of piperacillin, tazobactam, and ranitidine were > 90% of initial concentrations. There were no substantial changes in pH or color. Tazobactam 5 mg/mL (as the sodium salt) and ranitidine 0.5 and 2 mg/mL (as the hydrochloride salt) in 0.9% sodium chloride injection were stable for up to four hours during simulated Y-site administration. Piperacillin 80 mg/mL plus tazobactam 10 mg/mL (as the sodium salts) and ranitidine 0.5 and 2 mg/mL (as the hydrochloride salt) were stable for up to four hours during simulated Y-site administration.

A randomized study of cefepime versus the combination of gentamicin and mezlocillin as an adjunct to surgical treatment in patients with acute cholecystitis

In patients with acute cholecystitis, antibiotics are used as an adjunct to cholecystectomy to reduce the incidence of postoperative septic complications thought to be related to bactibilia. Combinations of penicillins, or cephalosporins or aminoglycosides, or both, are often used. Cefepime is a fourth-generation cephalosporin with excellent activity against gram-positive and gram-negative bacteria, including Pseudomonas species. It has a prolonged serum half-life, allowing twice-daily dosing, and is not nephrotoxic. This study was undertaken to determine whether or not cefepime was as effective as the combination of gentamicin and mezlocillin in patients with acute cholecystitis. One hundred and forty-nine patients were randomized, two to one, to receive cefepime or gentamicin and mezlocillin. Cefepime was given intravenously at 2 grams every 12 hours; gentamicin, 1.0 to 1.5 milligrams per kilograms every eight hours, and mezlocillin, 3 to 4 grams every four to six hours. All patients underwent cholecystectomy. Bile cultures were obtained, and concentrations of cefepime in blood, bile, peritoneal fluid and gallbladder were determined in a subset of patients. There were 56 evaluable cefepime-treated and 34 evaluable gentamicin and mezlocillin-treated patients. Bactibilia was present in 17 of 56 cefepime-treated patients (30.4 percent) and ten of 34 gentamicin and mezlocillin-treated patients (29.4 percent). Enterococci were recovered in six cefepime-treated patients. Clinical and bacteriologic responses were similar for the cefepime-treated and gentamicin and mezlocillin-treated groups, with one failure in each group, a wound infection in a patient receiving cefepime and a subhepatic abscess in a patients receiving gentamicin and mezlocillin. Other measures of outcome, such as the number of days of fever, days nothing by mouth, days of hospitalization and days of antibiotic therapy were similar in both groups. Cefepime, with every 12 hour dosing, achieved extremely high concentrations in all tissues assayed at the time of the operation, a mean of eight hours after administration. Adverse clinical events were similar in both treatment groups. Cefepime is as effective as gentamicin and mezlocillin in preventing septic complications after cholecystectomy for acute cholecystitis. Cefepime requires fewer doses, does not require drug monitoring, is not associated with nephrotoxicity and may therefore prove to be a cost-effective alternative to combination therapy that uses an aminoglycoside.

A clinical comparison of cefepime and metronidazole versus gentamicin and clindamycin in the antibiotic management of surgically treated advanced appendicitis

Many antibiotics and antibiotic combinations are used for the treatment of peritonitis because of advanced (gangrenous or perforated) appendicitis. An aminoglycoside combined with an antianaerobe antibiotic is one standard treatment, but there is concern about the potential nephrotoxicity of the aminoglycoside and the necessity for monitoring aminoglycoside blood levels. Cefepime, a new broad-spectrum cephalosporin with a prolonged serum half-life, has excellent activity against gram-positive and gram-negative bacteria, including Pseudomonas aeruginosa. Its spectrum of activity is similar to the aminoglycosides, but it has less potential for inducing renal injury. A double-blind, randomized study compared cefepime, 2 grams every 12 hours IVPB plus metronidazole 0.5 grams every eight hours IVPB (C/M) with gentamicin 1.5 milligrams per kilograms of IVPB plus clindamycin 0.9 grams q eight hours IVPB (G/C), administered up to 14 days, in 96 surgically treated patients with gangrenous or perforated appendicitis. Fifty patients had advanced appendicitis (nine gangrenous and 41 perforated) in the C/M group and 46 patients (six gangrenous and 40 perforated) in the G/C group. The mean number of days of postoperative fever (C/M, 4.4 +/- 2.7 versus G/C, 5.0 +/- 2.2), postoperative hospitalization (C/M, 2.0 +/- 1.9 versus G/C, 2.0 +/- 2.1) and antibiotic therapy (C/M, 6.3 +/- 1.9 versus G/C, 6.9 +/- 1.9) was similar in the two treatment groups. There were 11 treatment failures (C/M, three; G/C, eight; p = 0.13), six of which were probably a result of enterococci. No deaths occurred. Our study results show that the efficacy of cefepime plus metronidazole is equivalent to that of clindamycin plus gentamicin.

Comparison of aminoglycoside pharmacokinetics in Asian, Hispanic, and Caucasian patients by using population pharmacokinetic methods

A population pharmacokinetic model for aminoglycosides was developed from 24 Hispanic, 16 Asian, and 22 Caucasian patients. A nonparametric expectation maximization algorithm for population modeling was used. With this one-compartment model, the parameters were the slope of the apparent volume of distribution versus weight (VS) and the slope of the elimination rate constant versus the creatinine clearance rate (KS). The mean VS (+/- standard deviation) was not different at 0.264 (+/- 0.05), 0.248 (+/- 0.055), and 0.260 (+/- 0.080) liter/kg of body weight for Asian, Hispanic, and Caucasian populations, respectively (P > 0.10). The KS means +/- standard deviations were 0.00424 +/- 0.00129, 0.00404 +/- 0.00160 and 0.00394 0.00103 [h(ml/min/1.73 m2)]-1 +/- for Hispanic, Asian, and Caucasian populations, respectively. Again, there was no statistical difference among the groups (P > 0.10). In conclusion, there are no differences in aminoglycoside pharmacokinetics among Asian, Hispanic, and Caucasian patients.

Stability of paclitaxel with ondansetron hydrochloride or ranitidine hydrochloride during simulated Y-site administration

The stability of paclitaxel with either ondansetron hydrochloride or ranitidine hydrochloride during simulated Y-site injection at room temperature was studied. Triplicate test solutions of paclitaxel 0.3 and 1.2 mg/mL were admixed 1:1 with ondansetron 0.03 and 0.3 mg/mL (as the hydrochloride salt) or ranitidine 0.5 and 2.0 mg/mL (as the hydrochloride salt). Also, paclitaxel 1.2 mg/mL was admixed 1:1:1 with ondansetron 0.3 mg/mL and ranitidine 2.0 mg/mL. The solutions were stored in glass containers at room temperature, and samples were removed at zero, one, two, and four hours for immediate assay. At the time of the assay and before any dilution, each sample was visually inspected for clarity, color, and precipitation, and the pH was determined. Drug concentrations were measured by stability-indicating high-performance liquid chromatographic procedures. Throughout the study, more than 90% of the initial concentrations of paclitaxel, ondansetron, and ranitidine remained in the solutions. No precipitates, color changes, or haziness was seen. The changes in pH were minor. Paclitaxel in concentrations of 0.3 and 1.2 mg/mL was stable when mixed with either ondansetron (0.03 or 0.3 mg/mL, as the hydrochloride salt) or ranitidine (0.5 or 2.0 mg/mL, as the hydrochloride salt) and stored in glass containers for four hours. Paclitaxel 1.2 mg/mL was also stable when mixed with both ondansetron 0.3 mg/mL and ranitidine 2.0 mg/mL and stored in glass containers for four hours.

Cefepime: a new fourth-generation cephalosporin

The chemistry, pharmacology, antimicrobial spectrum, pharmacokinetics, clinical efficacy, adverse effects, and dosage of cefepime are reviewed. Fourth-generation cephalosporins, such as cefepime, have a quaternary nitrogen that is positively charged at the 3-position, providing the properties of a zwitterion. A 2-aminothiazolyl-acetamido group in the side chain at the 7-position with an alpha-oxyimino substitution may enhance stability against beta-lactamases by preventing the enzymes' approach to the main nucleus. Cefepime may exert its antimicrobial effect by attaching to specific penicillin-binding proteins, disrupting cell-wall synthesis. Cefepime has good activity against gram-positive organisms, such as Staphylococcus aureus, and gram-negative organisms, such as Pseudomonas aeruginosa. Cefepime is not active in vitro against Enterococcus faecalis, Clostridium difficile, and methicillin- and cefazolin-resistant Staph. aureus. Cefepime's activity against gram-negative organisms is similar to that of most third-generation cephalosporins. The agent has poor activity against Bacteroides species. The most common mechanism of resistance to cefepime is the excess production of beta-lactamases. Maximum peak plasma concentrations are two to three times higher after i.v. administration than after intramuscular administration. In healthy adults, the volume of distribution is 13-22 L and the elimination half-life is 2-2.3 hours. Clinical studies show that cefepime is as effective as cefotaxime or ceftazidime in patients with infections of the lower respiratory tract, skin and skin structures, urinary tract, or female reproductive system. Cefepime reduces fever as effectively as ceftazidime or piperacillin plus gentamicin in neutropenic patients. The most common adverse effects of cefepime are headache (2.4%), nausea (1.8%), rash (1.8%), and diarrhea (1.7%). Depending on creatinine clearance, the dosage of cefepime is 1000-2000 mg i.v. every 8-24 hours for life-threatening infections and 500-2000 mg i.v. every 12-24 hours for severe infections. Cefepime's clinical efficacy is comparable to that of ceftazidime and cefotaxime.

Pharmacokinetics of meropenem in patients with intra-abdominal infections

Noncompartmental and compartmental analyses of meropenem disposition in patients receiving 1-g intravenous intermittent infusions every 8 h were performed. Twelve patients (one woman and 11 men) participated in the meropenem pharmacokinetic analysis. Operative findings included perforated appendicitis (five patients), gangrenous appendicitis (five patients), peri-appendical abscess (one patient), and gunshot wound to the abdomen (one patient). The most common associated adverse drug reactions to meropenem were diarrhea and increased liver enzymes. The estimated noncompartmental pharmacokinetic parameters, mean +/- standard deviation, are as follows: maximum drug concentration in plasma, 47.58 +/- 17.59 micrograms/ml; half-life, 1.04 +/- 0.19 h; elimination rate constant, 0.68 +/- 0.12 h-1; area under the concentration-time curve from 0 h to infinity, 57.5 +/- 20.12 micrograms x ml/h; total plasma clearance, 315.40 +/- 71.94 ml/min; renal clearance, 136.7 +/- 89.20 ml/min; volume of distribution at steady state, 26.68 +/- 6.88 liters; and mean residence time, 1.47 +/- 0.28 h. The two-compartment model best described meropenem disposition in our patients. Our findings differed from estimates for healthy volunteers possibly because of the physiologic changes as a result of surgery. Our findings suggest that meropenem (1,000 mg) administered intravenously every 8 h provides adequate concentrations for most intra-abdominal infections.

Effect of antihypertensive formulation on health service expenditures

A major barrier to the management of hypertension is the extent to which patients comply with the treatment regimen. Herein we report the findings of a retrospective analysis designed to discern the relationship between antihypertensive formulation, regimen compliance and the utilization of health care services. Data for this analysis were derived from the state of South Carolina's Medicaid computer archive. The study population consisted of 1,000 randomly selected beneficiaries initially prescribed one of the following antihypertensive regimens as monotherapy: atenolol (daily); captopril (twice daily); oral clonidine (twice daily); transdermal clonidine (once a week); diltiazem (twice daily); enalapril (twice daily); metoprolol (twice daily); prazosin (twice daily); terazosin (daily); and verapamil-SR (daily). Multivariate regression analysis was used to determine the incremental influence of selected demographic characteristics, utilization of medical services prior to diagnosis for hypertension, initial antihypertensive medication, medication possession ratio for antihypertensive therapy, and the number of maintenance medications for disease state processes other than hypertension on post-period health care expenditure. Results indicate that patients initially prescribed antihypertensive medication requiring daily or weekly administration experience infrequent changes in their therapeutic regimen, far less use of concomitant therapy for blood pressure control, an increased utilization of antihypertensive medication, and a decrease in the use and cost of physician, hospital and laboratory services.

Effect of pharmaceutical formulation for antihypertensive therapy on health service utilization

A significant factor in the management of hypertension is the extent to which patients comply with the treatment regimen. A retrospective analysis was undertaken to determine the relationship between antihypertensive formulation, regimen compliance, and the utilization of health care services. Data for this analysis were derived from the state of South Carolina's Medicaid computer archive. The study population consisted of 1000 randomly selected patients initially prescribed one of the following antihypertensive regimens as monotherapy: atenolol once daily, captopril BID, oral clonidine BID, transdermal clonidine once weekly, diltiazem BID, enalapril BID, metoprolol BID, prazosin BID, terazosin once daily, and sustained-release verapamil once daily. Multivariate regression analysis was used to determine the incremental influence of selected demographic characteristics, use of medical services before diagnosis of hypertension, initial antihypertensive medication, medication possession ratio for antihypertensive therapy, and number of maintenance medications for diseases other than hypertension on post-period health care expenditures. The results indicated that patients initially prescribed antihypertensive medication requiring once-daily or once-weekly administration experienced an increased utilization of antihypertensive medication, needed fewer changes in their therapeutic regimen, and far less need for concomitant therapy for blood pressure control compared with those prescribed a BID regimen. Patients in the once-daily or once-weekly groups also used significantly fewer physician, hospital, and laboratory services (P < or = 0.05).

Chemical compatibility of cefmetazole sodium with ranitidine hydrochloride during simulated Y-site administration

The stability of cefmetazole sodium and ranitidine hydrochloride was studied under conditions simulating administration via a Y-injection site into a primary infusion line. Cefmetazole sodium was reconstituted with both 0.9% sodium chloride injection (50 mL or 100 mL) and 5% dextrose injection (50 mL) to produce premixing concentrations of cefmetazole 10 and 20 mg/mL. Ranitidine hydrochloride injection was diluted with 50 mL 0.9% sodium chloride injection to give premixing concentrations of ranitidine 1 mg/mL. To simulate Y-site administration, 2 mL of cefmetazole was mixed with 2 mL of ranitidine in a 10-mL glass test tube. All study mixtures were prepared in triplicate and stored at room temperature (22-23 degrees C) under normal fluorescent room lighting. Samples of these admixtures were inspected for visual changes and tested for pH. The concentrations of two drugs were immediately determined by stability-indicating high-performance liquid chromatographic assay methods after mixing and at 1, 2, and 4 hours. No visual changes were observed. The pH in the admixtures was influenced by concentrations of the two drugs. The pH of each single-drug solution did not change during the study period. On the other hand, the pH of any admixtures of cefmetazole and ranitidine solutions prepared with 0.9% sodium chloride or 5% dextrose injection, decreased. Cefmetazole in any of the admixtures with ranitidine retained greater than 95% of its original concentration for 4 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Stability of ranitidine hydrochloride with aztreonam, ceftazidime, or piperacillin sodium during simulated Y-site administration

The stability of ranitidine hydrochloride after being mixed with commonly used i.v. beta-lactam antibiotics and administered by simulated Y-site injection was studied. Solutions of ranitidine 1 mg/mL (as the hydrochloride salt), aztreonam 16.7 mg/mL, ceftazidime 20 mg/mL (with sodium carbonate), and piperacillin 30 mg/mL (as the sodium salt) were prepared by reconstitution in i.v. mini-bags. To simulate Y-site injection, 2 mL of ranitidine hydrochloride was mixed with 2 mL of each antibiotic in glass test tubes. These admixtures were prepared in triplicate and stored at room temperature under fluorescent light. Concentrations of each drug in each admixture were determined by stability-indicating high-performance liquid chromatography immediately and after one, two, and four hours. Aztreonam, ceftazidime, and piperacillin each retained more than 95% of the original concentration for at least four hours when mixed 1:1 with ranitidine. Ranitidine retained more than 90% of its original concentration for at least four hours when combined with each of the other drugs. Ranitidine 1 mg/mL (as the hydrochloride salt) and aztreonam 16.7 mg/mL, ceftazidime 20 mg/mL (with sodium carbonate), or piperacillin 30 mg/mL (as the sodium salt) were stable for at least four hours during simulated Y-site administration.

Determination of fluconazole in human serum by solid-phase extraction and reversed-phase high-performance liquid chromatography

A simple, rapid, and accurate reversed-phase octadecylsilyl high-performance liquid chromatographic method using solid-phase column extraction is described for measuring fluconazole in human serum. The column eluent was monitored by ultraviolet absorption at 210 nm. Fluconazole was extracted from diluted serum by adsorption on a small Bond-Elut C18 cartridge after the addition of UK48,134 as the internal standard and recovered by elution with methanol. The methanol was then evaporated to dryness and the residue reconstituted in 200 microliters of mobile phase and filtered prior to injecting an aliquot (50 microliters) onto an Adsorbosphere C18 column (4.6 x 250 mm, 5 microns particle size), using a mobile phase of 25 mM tris(hydroxymethyl)aminomethane-phosphate buffer (pH 7.0):acetonitrile (75:25, vol/vol). The retention times were 6.6 min for fluconazole and 9.0 min for the internal standard. The assay was precise, with inter- and intraassay coefficients of variation of less than or equal to 2.9% and less than or equal to 2.1%, respectively, and with good linearity (r = 1.000) in the range of 0.1 to 25 micrograms/ml. The duration of each analysis was 15 min and the minimum detectable serum concentration was 0.1 microgram/ml.

Tissue concentrations of cefepime in acute cholecystitis patients

Cefepime is a new broad-spectrum cephalosporin with activity against Staphylococcus, Streptococcus, Pseudomonas, and the Enterobacteriaceae. The purpose of this study was to measure cefepime concentrations in plasma, peritoneal fluid, bile fluid and appendix tissue in patients undergoing elective cholecystectomy. Patients were randomly assigned to receive either cefepime, 2 g intravenously in phosphate buffer (IVPB) q 12 h or gentamicin 1.5 mg/kg IVPB q 8 h plus mezlocillin 4 g IVPB q 6 h. During surgery, gall bladder tissue, plasma, peritoneal fluid, and bile fluid samples were obtained at approximately the same time. Thirty-three patients had data acceptable for analysis. Values are given as mean +/- standard deviation. The mean delta time (defined as the time between the administration of cefepime and the time the samples were obtained) was 8.58 +/- 3.53 h. The values for plasma, peritoneal fluid, bile fluid, and gall bladder tissue concentrations were 7.63 +/- 14.17 micrograms/ml, 5.66 +/- 6.80 micrograms/ml, 15.51 +/- 16.94 micrograms/ml, and 5.36 +/- 6.57 micrograms/gm, respectively. The peritoneal fluid/plasma ratio was 2.10 +/- 2.33, the bile fluid/plasma ratio was 14.44 +/- 31.99, and the gall bladder tissue/plasma ratio was 1.44 +/- 1.82. There was a significant correlation between peritoneal fluid and plasma concentration (r = 0.91, p less than 0.0005), and gall bladder tissue and plasma concentration (r = 0.90, p less than 0.0005). There was no correlation between bile fluid and plasma cefepime concentrations. The minimum inhibitory concentration (MIC) data from previous in vitro studies indicate that cefepime concentrations achieved in this patient population would be adequate against typical biliary tract pathogens.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetic population parameters for aminoglycosides in cholecystitis patients

We report the use of a new method to determine patient population pharmacokinetic parameters (nonparametric expected maximum or NPEM). Our purpose was to develop and then analyze the utility of these parameters, compared to a more traditional approach. Nineteen patients with acute cholecystitis made up the control group for defining the parameters via NPEM. The standard of practice was to use a model created from a different intraabdominal infection group (appendicitis), referred to as "surgical patient model." These two models were compared with a group of 23 patients receiving gentamicin for acute cholecystitis. We concluded that the NPEM model was superior to the surgical patient model in predicting gentamicin trough and peak levels with less bias and better precision.

Utility of a transdermal delivery system for antihypertensive therapy. Part 1

A retrospective evaluation of patient-level Medicaid claims data from two states was undertaken to discern the fiscal utility of transdermally delivered clonidine versus both the oral formulation of clonidine and oral formulations of eight other antihypertensive agents. In the first phase of our two-part study, we compared paid claims data (n = 1,135) from Florida for transdermal and oral clonidine. Multivariate regression analysis was used to evaluate the incremental impact of six variables on health-care expenditures in the first year after patients were given a diagnosis of hypertension. These variables were: age, gender, prior utilization of medical services, regimen complexity, and dosage formulation. Patients prescribed transdermal clonidine experienced a significant (p less than or equal to 0.001) increase in prescription expenditures and significant reductions in the use of physician (p less than or equal to 0.05), laboratory (p less than or equal to 0.10), and hospital (p less than or equal to 0.05) services. Moreover, savings were maximized (p less than or equal to 0.001) where multi-drug regimens incorporated the transdermal delivery system. In the second phase of our study we compared paid claims data (n = 8,894) from South Carolina for transdermal clonidine and for nine oral antihypertensive agents: atenolol, captopril, clonidine, diltiazem, enalapril, metoprolol, prazosin, terazosin, and verapamil-SR. Once again, regression analysis was used, this time to evaluate the incremental impact of five variables on health-care expenditures in the first year post diagnosis: age, gender, prior utilization of medical services, regimen complexity, and Medication Possession Ratio (MPR), an index of compliance. The data from part 2 of our study revealed that patients assigned a b.i.d. oral antihypertensive agent experienced a significant reduction (p less than or equal to 0.05) in MPR and a significant (p less than 0.05) increase in health-care expenditures when compared to patients prescribed the transdermal delivery system and to patients prescribed once-daily oral medications. These data confirm previous findings concerning the impact of complicated dosing regimens on compliance in hypertensive patients. In this two-part paper we report the data from both phases of our study.

Effect of health education in promoting prescription refill compliance among patients with hypertension

A multifactorial health-education program designed to enhance compliance with a once-daily regimen of atenolol was evaluated among 453 patients enrolled in health maintenance organizations (HMOs). The initiation of the 180-day study period was used to classify patients as either new or existing cases of hypertension. In turn, patients in these two categories were randomly assigned to a control or an experimental group. Patients assigned to the experimental groups received an enrollment kit upon exercising their initial prescription (new patients) or their first refill request (existing patients). The kit contained: a 30-day supply of atenolol; an educational newsletter about hypertension; information on nutrition and life-style changes; and an explanation of the intent and content of the program. Before the next scheduled prescription-refill date, each patient was contacted by telephone to inquire about his or her experience with the therapy and to stress the importance of adherence to the regimen. Each month thereafter, the newsletter and an enclosed prescription-refill reminder were mailed to each patient. The medication possession ratio, defined as the number of days' supply of atenolol obtained by a patient during the 180-day study period, was significantly (P less than or equal to 0.001) enhanced for the new and existing experimental groups relative to the control groups. Multiple regression analyses revealed that enrollment in the health-education program increased the number of days' supply of atenolol obtained by existing patients by 27 (P less than or equal to 0.001), and by new patients by 40 (P less than or equal to 0.001).