Vancomycin dosing chart for use in patients with renal impairment.
ABSTRACT A new vancomycin dosing chart for use in patients with impaired renal function is described. The chart has been adapted from a previously published nomogram, based on a linear relationship between vancomycin clearance and creatinine clearance. Doses are designed to achieve an average steady-state serum concentration of approximately 15 mg/L. Use of the chart necessitates first measuring or estimating the patient's body weight and creatinine clearance. The chart provides the advantages of generating an exact dose and dosing interval, as well as being somewhat easier to use than the original nomogram. Predicted average steady-state serum concentrations resulting from the dosing chart range from 12.1 to 18.2 mg/L, with a mean of 15.0 mg/L.
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ABSTRACT: This study investigated vancomycin therapeutic drug monitoring (TDM) and issues related to patient management. Questionnaires were distributed to 310 participants in the UK National External Quality Assessment Scheme (NEQAS) for Antibiotic Assays. The response rate was 57.4%. The majority (76%) had an 'in-house' assay service based, almost exclusively, in the microbiology department, and a fluorescence polarization immunoassay (FPIA) was used by 97%. Almost half (48.7%) had an assay service available for 24 h/day, 7 days/week and 92.7% expected same-day results. The majority (80%) had issued guidelines for vancomycin use. A 12 hourly initial dosing regimen was used by 89%. Trough assay samples were taken <10 min before the dose by 91.5%. For post-dose assay samples, 44% took a sample at 1 h, 28% at 2 h and the remainder at 'other' times. For trough target ranges, 93% quoted <10 mg/L or 5-10 mg/L. There was no consensus with regard to post-dose assay sample times and 23 ranges were quoted. The majority (74.4%) regarded a trough level of >or=10 mg/L as 'toxic' but 13 concentrations were quoted as toxic post-dose measurements. In conclusion, there was a wide variability and poor consensus with regard to post-dose vancomycin assay sampling times, target ranges and what constituted a toxic level.Journal of Antimicrobial Chemotherapy 12/2002; 50(5):713-8. · 5.34 Impact Factor
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ABSTRACT: Intrauterine growth retardation (IUGR) results in substantial decrease in nephron number and renal and hepatic organ mass in experimental animals and newborn infants. Because the liver and the kidneys are the major organs for drug biotransformation and elimination, any decrease in their size and function may lead to impaired metabolism and elimination of drugs in newborns with IUGR. Our objective was to test the hypothesis that IUGR results in prolonged renal elimination of vancomycin in newborns. Small for gestational age (SGA) infants (n = 20) were matched with appropriate for gestational age (AGA) infants (n = 123). Steady state peak and trough serum concentrations were used to calculate vancomycin clearance (Cl), volume of distribution (Vd) and half-life (t(1/2)) for each subject. Pharmacokinetic profiles were compared between groups. Overall, Cl, Vd and t(1/2) of vancomycin were the same between groups. However, stratification showed decreased Cl in those SGA versus AGA newborns 3-4 weeks old and in those newborns with a postconceptional age of 27-29 weeks. There was no difference in Vd, normalized for weight, between SGA and AGA babies. The half-life of vancomycin was similar across most groups but was prolonged in SGA newborns aged 3-4 weeks. Vancomycin Cl differs between SGA and AGA newborns. This difference is greatest early in life and normalizes between groups after the fourth week of life or after 29 weeks postconceptionally. Normalized Vd is similar between SGA and AGA newborns. The elimination of vancomycin is comparable between SGA and AGA infants, except before the fifth week of life, when SGA newborns may eliminate the drug more slowly. Specific vancomycin dose recommendations for SGA versus AGA neonates may therefore be justified during the first month of life.The Pediatric Infectious Disease Journal 12/2005; 24(11):979-83. · 3.57 Impact Factor
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ABSTRACT: The aim of this study was to evaluate retrospectively the importance of a Bayesian pharmacokinetic approach for predicting vancomycin concentrations to individualize its dosing regimen in 18 critically ill patients admitted to intensive care units following cardiothoracic surgery. The possible influence of some coadministered drugs with important haemodynamic effects (dopamine, dobutamine, frusemide) on vancomycin pharmacokinetics was assessed. Vancomycin serum concentrations were measured by fluorescence polarization immunoassay. Vancomycin dosage regimens predicted by the Bayesian method (D(a)) were compared retrospectively with Moellering's nomogram-based dosages (D(M)) to assess possible major differences in vancomycin dosing. D(a) values were similar to D(M) in 10 patients (D(a) approximately D(M) group) (20.52 +/- 8.40 mg/kg/day versus 18.81 +/- 7.24 mg/kg; P = 0.15), whereas much higher dosages were required in the other eight patients (D(a) > D(M) group) (26.78 +/- 3.01 mg/kg/day versus 18.95 +/- 3.41 mg/kg/day; P < 0.0001) despite no major difference in attained vancomycin steady-state trough concentration (C(min ss)) (9.22 +/- 1. 33 mg/L versus 8.99 +/- 1.26 mg/L; = 0.75) or estimated creatinine clearance (1.23 +/- 0.49 mL/min/kg versus 1.21 +/- 0.24 mL/min/kg; P = 0.95) being found between the two groups. The ratio between D(a) and D(M) was significantly higher in the D(a) > D(M) group than in the D(a) approximately D(M) group (1.44 +/- 0.18 versus 1.10 +/- 0. 21; P < 0.01). In four D(a) > D(M) patients the withdrawal of cotreatment with haemodynamically active drugs was followed by a sudden substantial increase in the vancomycin C(min ss) (13.30 +/- 1. 13 mg/L versus 8.79 +/- 0.87 mg/L; P < 0.01), despite no major change in bodyweight or estimated creatinine clearance being observed. We postulate that these drugs with important haemodynamic effects may enhance vancomycin clearance by inducing an improvement in cardiac output and/or renal blood flow, and/or by interacting with the renal anion transport system, and thus by causing an increased glomerular filtration rate and renal tubular secretion. Given the wide simultaneous use of vancomycin and dopamine and/or dobutamine and/or frusemide in patients admitted to intensive care units, clinicians must be aware of possible subtherapeutic serum vancomycin concentrations when these drugs are coadministered. Therefore, therapeutic drug monitoring (TDM) for the pharmacokinetic optimization of vancomycin therapy is strongly recommended in these situations.Journal of Antimicrobial Chemotherapy 03/2000; 45(3):329-35. · 5.34 Impact Factor