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Biomedical subjects

J C Rotschafer

Publications and source records attributed to J C Rotschafer.

At least 73 records · Page 4Linked to original sources
PubMed1986

The clinical utility of a published nomogram to predict aminoglycoside nephrotoxicity.

Moore and colleagues recently published a nomogram for predicting the risk of aminoglycoside nephrotoxicity. This study was undertaken to evaluate the clinical usefulness of this nomogram. The nephrotoxicity risk scores of 61 patients were determined using parameters suggested by Moore et al. Thirteen patients (21%) could not be scored because their initial creatinine clearances exceeded the upper limit of the nomogram. Six patients (9.8%) developed nephrotoxicity (defined as a greater than or equal to 50% decrease in creatinine clearance). In five of these patients in whom risk scores could be determined, the scores were estimated at 14% or less. Twenty patients had risk scores of 10% or more (four patients, greater than or equal to 50%) without developing nephrotoxicity. These results demonstrate that this nomogram may have limited clinical application in predicting patients likely to develop aminoglycoside nephrotoxicity.

Adolescent↗
PubMed1984

Pain syndromes associated with cancer. Achieving effective relief.

Pain occurs frequently in patients with cancer and, if uncontrolled, may lead to depression, deep anxiety, insomnia, and progressive mental and physical deterioration. Pain can be effectively relieved in the majority of cases by balanced use of pharmacologic agents and other treatment modalities, including surgery, chemotherapy, and radiation therapy. A thorough evaluation of the patient's complaints and an accurate diagnosis of the causes and mechanism of pain are mandatory for the formulation of an effective and individualized treatment plan. Continuing emotional support is essential to the relief of suffering in patient and family.

Analgesics↗
PubMed1984

Effect of decreased renal function on the pharmacokinetics of ceftazidime.

The pharmacokinetics of ceftazidime after a 1-g bolus dose were studied in 11 subjects, with creatinine clearances ranging from 113 to 6 ml/min. Concentrations of ceftazidime in serum were determined by microbiological assay. These data were fitted to a two-compartment open model, and pharmacokinetic parameters were calculated. Correlation of ceftazidime clearance with creatinine clearance was excellent (r = 0.99).

Adult↗
PubMed1983

Clinical use of a one-compartment model for determining netilmicin pharmacokinetic parameters and dosage recommendations.

To determine netilmicin pharmacokinetic parameters and to evaluate the use of a one-compartment pharmacokinetic model, 32 patients receiving netilmicin for suspected gram-negative sepsis were enrolled in our study protocol. Dose and dosage interval for each patient were determined by one-compartment pharmacokinetic analysis of six postinfusion netilmicin serum samples (0.16, 0.33, 0.5, 1, 2, and 3 h) measured by radioimmunoassay. In patients with a normal serum creatinine, mean (+/- SD) half-life and distribution volume were 1.9 +/- 1.1 h and 0.2 +/- 0.8 L/kg, respectively. The average daily dose and mean days of therapy were 5.1 +/- 1.9 mg/kg/day for 7.3 +/- 2.8 days. Serum creatinine changes of greater than 0.5 mg% occurred in 2 of 28 (7%) patients. Substantial variability in half-life and distribution volume occurred in patients. Initial dosages of 5-7 mg/kg/day in divided dosages seem appropriate for adult patients with normal renal function. Monitoring of serum levels and adjustment of dose and dosage interval are necessary to maintain therapeutic antibiotic concentrations. As with other aminoglycosides, the one-compartment pharmacokinetic model proved to be an acceptable method for measuring netilmicin pharmacokinetic parameters and individualizing therapy.

Adolescent↗
PubMed1983

Observed differences in gentamicin pharmacokinetic parameters and dosage recommendations determined by fluorescent polarization immunoassay and radioimmunoassay methods.

Radioimmunoassay (RIA) and fluorescent polarization immunoassay (FPI) methods for quantitative gentamicin serum concentration assay have been shown to be comparable. The purpose of this study was to determine if serum concentration-time data from the same patients assayed by RIA and FPI would provide the same estimates for half-life, elimination rate constant, distribution volume, drug clearance, and gentamicin dose. A total of 99 pre-and postinfusion serum samples were obtained from 30 patients. Samples were divided and assayed by RIA or FPI, and the resultant serum concentration-time data were fitted to a standard one-compartment model. The correlation between the two assay methods was 0.99 (p less than 0.005). A mean difference of 10% was seen in distribution volume, gentamicin clearance, and gentamicin dose from quantitative data from the two methods. These differences were significant (p less than 0.01). Although the two methods appear to be interchangeable, based on in vitro comparison, differences in calculated pharmacokinetic parameters resulted in significant differences in dose recommendations.

Adolescent↗
PubMed1983

Comparison of radioimmunoassay and fluorescent polarization immunoassay for quantitative determination of vancomycin concentrations in serum.

A new fluorescent polarization immunoassay (Abbott Laboratories, Diagnostics Division, North Chicago, Ill.) was compared with a standard radioimmunoassay (American Diagnostics Corp., Newport Beach, Calif.) in 34 patients being treated with vancomycin. A total of 123 serum samples were divided and quantitatively analyzed for vancomycin by both assay methods. The results obtained indicated that the two assay methods are comparable (y = 1.01x - 0.81; r = 0.99).

Fluorescence Polarization↗
PubMed1982

Gentamicin dosing errors with four commonly used nomograms.

Four methods for calculating gentamicin sulfate dosage requirements were evaluated in 96 patients and compared with an individualized method. The pharmacokinetic parameters of gentamicin were determined from serum concentration time data and used to calculate individualized dosage regimens. Doses were determined in each patient using the "predictive methods" (Sarubbi-Hull, Dettli, "rule of eights," and Chan). Resultant serum concentrations were calculated from doses arrived at by each method. These dosing methods resulted in a large proportion of patients with subtherapeutic or potentially toxic concentrations, or both. The Dettli and Chan methods produced therapeutic concentrations in more patients than the Sarubbi-Hull and rule of eights methods. Desired therapeutic concentrations were attained in significantly more patients with the individualized method than with the predictive methods, and, in addition, larger doses were required. The use of predictive dosage methods should be followed with serum concentration determinations and dosage adjustment to ensure therapeutic concentrations early in treatment.

Adolescent↗
PubMed1982

Gentamicin pharmacokinetics in 1,640 patients: method for control of serum concentrations.

The pharmacokinetics and dosage requirements of gentamicin were studied in 1,640 patients receiving treatment for gram-negative infections. A wide interpatient variation in the kinetic parameters of the drug occurred in all patients and in patients who had normal serum creatinine or normal creatinine clearance. The half-life ranged from 0.4 to 32.7 h in 331 patients who had normal creatinine clearance. The factors related to the elimination rate constant were creatinine clearance, age, distribution volume, weight, gender, and hematocrit. The daily dose necessary to obtain therapeutic serum concentrations ranged from 0.5 to 25.8 mg/kg in patients with normal serum creatinine and from 0.7 to 25.8 mg/kg in patients with normal creatinine clearance. In 13 patients (0.9%), a significant change in base-line serum creatinine (greater than or equal to 0.5 mg/dl) occurred during or after treatment, which may have been gentamicin-associated toxicity. Overt cochlear or vestibular toxicity did not occur in these patients. The method of individualizing dosage regimens provided a clinically useful means of rapidly attaining therapeutic peak and trough serum concentrations.

Adolescent↗
PubMed1982

Pharmacokinetics of vancomycin: observations in 28 patients and dosage recommendations.

Studies of the pharmacokinetics of vancomycin were conducted in a group of 28 patients with serious staphylococcal infection. Serum specimens were collected before and on 11 occasions after vancomycin administration. Serum concentration time data were fitted to a biexponential equation, using nonlinear regression analysis. A prolonged distribution phase with a half-life of 0.5 +/- 0.3 h (standard deviation) and a central component volume of 9.0 +/- 4.0 liters were demonstrated. Wide interpatient variation was observed in the terminal half-life which ranged from 3 to 13 h (mean, 6 h) and in the distribution volume which ranged from 14 to 111 liters (mean, 39 liters). A correlation of 0.45 (Pearson product moment correlation coefficient) was found between vancomycin clearance and creatinine clearance. Multiple regression analyses demonstrated that 50% of the variance (R2) in the terminal half-life and vancomycin clearance could be explained on the basis of renal function, volume of distribution, age, weight, and sex. These observations suggest that adults with normal renal function should receive an initial dosage of 6.5 to 8 mg of vancomycin per kg intravenously over 1 h every 6 to 12 h. After 24 h, and through the period of therapy, trough and peak serum vancomycin concentrations should be monitored, and the dose and dosage interval should be changed to produce the desired peak (30 to 40 micrograms/ml) and trough (5 to 10 micrograms/ml) levels.

Adolescent↗
PubMed1982

Comparison of radioimmunoassay and enzyme immunoassay methods in determining gentamicin pharmacokinetic parameters and dosages.

Radioimmunoassay and enzyme immunoassay methods for analysis of serum gentamicin levels have been shown to be comparable. The purpose of this study was to determine if serum concentration-time data from the same patient assayed by radioimmunoassay and enzyme immunoassay would provide the same estimates for half-life, elimination rate constant, distribution volume, drug clearance, and gentamicin dose. A total of 103 pre- and postinfusion serum samples were obtained from 32 patients. The samples were divided and assayed by radioimmunoassay and enzyme immunoassay. Serum concentration-time data were fitted to a one-compartment model, and kinetic calculations were performed using the method of Sawchuk et al. (Clin. Pharmacol. Ther. 21:362-369, 1977). While good correlation was established between the two assay methods, significant (P less than 0.05) mean differences were seen in distribution volume (25%), gentamicin clearance (15%), and half-life (11%), using the quantitative data from both methods. Because of differences noted in these pharmacokinetic parameters, significant differences were also noted in dosage calculations. We conclude that there are differences in the pharmacokinetic parameters obtained using results from the radioimmunoassay and enzyme immunoassay. These differences also translate into significant differences between dosage recommendations when individualization of the gentamicin regimen is attempted.

Adolescent↗
PubMed1980

Comparison of a radioimmunoassay and a microbiological assay for measurement of serum vancomycin concentrations.

A newly developed radioimmunoassay was used to measure the concentration of vancomycin in 137 specimens of serum from patients being treated with this antibiotic. Of these sera, 84 were also analyzed with a microbiological assay technique for vancomycin. Duplicate determinations were done with each of the techniques. Individual values and averaged values for both methods were used for statistical analyses. The correlation coefficients between all possible combinations of radioimmunoassay and microbiological assay results for the 84 sera were greater than or equal to 0.99 (P less than 0.01). Values for the regression coefficients of radioimmunoassay results on microbiological assay results ranged from 0.98 +/- 0.01 to 1.03 +/- 0.01. The mean percent deviation of radioimmunoassay versus microbiological assay results was -1.56 +/- 0.60. A one-way analysis of variance demonstrated that the use of different standard curves for each batch of specimens assayed by microbiological assay did not significantly influence the results (P = 0.07). The microbiological assay and the radioimmunoassay for measurement of serum vancomycin levels yielded essentially identical results.

Biological Assay↗