Impact of a target drug monitoring program on the usage of clindamycin

The use of parenteral clindamycin at the Health Sciences Centre had not been amendable to traditional cost containment strategies. Clindamycin was targeted through a Target Drug Monitoring (TDM) Program to improve its appropriate use. A retrospective audit was conducted to serve as a baseline. In the concurrent phase, the TDM pharmacist reviewed and assessed clindamycin cases based on approved criteria. Those cases which failed to meet the criteria were targeted in order to convert clindamycin to alternative agents. The concurrent TDM program reviewed 339 cases of clindamycin over a 32-week period, of which 76 cases (22.4%) failed to meet the criteria and were targeted. Of the 76 recommendations, 48 (63.2%) were accepted. Cost-avoidance due to direct intervention was approximately $16,000 annualized compared to $28,000 estimated from the retrospective audit. Fiscal year-end antibiotic usage indicated a dramatic decline (32%) in clindamycin use. Net savings of $37,600 were attributed to modification of physician prescribing. The TDM program was successful in identifying areas of inappropriate clindamycin use and correcting them by direct interaction with the prescriber(s).

Eliminating needless testing in intensive care--an information-based team management approach

OBJECTIVE

To determine if the application of an information-based management system in adult intensive care units (ICU) can produce sustained decreases in the use of laboratory resources and costs.

DESIGN

Interventional study with prospective data collection on consecutive patients admitted during three time periods.

SETTING

A 10-bed adult surgical ICU and an eight-bed adult medical ICU in a tertiary care hospital.

PATIENTS

All patients admitted to an ICU during a 7-month baseline period (n = 647), a 1-yr intervention period (n = 1236), and a 2-yr follow-up period (n = 2349).

INTERVENTIONS

Using a management database to track the use of 123 laboratory investigations during the baseline period, nine frequently ordered investigations (determination of blood gases, glucose, potassium, electrocardiogram, chest radiograph, sodium, chloride, complete blood count with differential, and serum osmolality) were targeted for reduction. Specific policies were developed by a multidisciplinary committee within the ICU to reduce the utilization of these laboratory, radiology, and cardiology tests. The policies were applied to all patients admitted during the 1-yr intervention period and during the 2-yr follow-up period.

MEASUREMENTS AND MAIN RESULTS

A 25% reduction was observed in the frequency of all 123 monitored tests during the intervention period. The most dramatic reductions occurred in the nine targeted tests (range 19% to 46%) (p < .001). There were significant reductions in only 13 of the untargeted 114 investigations during this period. Potential annual cost savings were > $150,000 Canadian. No increases in ICU mortality rate, length of stay, or cost of medication were observed, and the reductions in the frequency of targeted tests were maintained during the 2-yr follow-up period.

CONCLUSIONS

Application of an information-based multidisciplinary management system in the ICU can produce marked and sustained reductions in unnecessary testing in a cost-effective manner. Although rationing of intensive care services may be necessary, reducing needless testing can be a safe and effective cost-containment strategy in the ICU.

Distribution of cyclosporin G (NVa2 cyclosporin) in blood and plasma

We report here on the distribution of cyclosporin G (CsG), an analog of cyclosporin A, in whole blood. CsG has a temperature-dependent distribution between erythrocytes (RBCs) and plasma. After 30 min at 37 degrees C, the plasma/whole blood and plasma/RBC ratios were relatively constant (0.7-0.8) up to CsG at 1000 micrograms/L. At 5000 micrograms/L, this ratio increased to 1.0-1.1 for plasma/whole blood and 1.7 for plasma/RBC. The primary CsG metabolites GM1 and GM9 were sequestered within RBCs to a greater extent than was the parent drug. In whole blood, approximately 2% of CsG was bound to granulocytes, 6% to lymphocytes, and 50-55% to RBC, and 35-40% was found in the plasma fraction. The free fraction of the drug as determined by ultracentrifugation was 5-6% and 13-17% of total drug at 37 and 4 degrees C, respectively. In plasma the drug was primarily associated with high-density lipoprotein (50-60%) and to a lesser degree with low-density (20-30%) and very-low-density (10%) lipoproteins.

Distribution of cyclosporin G (NVa2 cyclosporin) in blood and plasma

We report here on the distribution of cyclosporin G (CsG), an analog of cyclosporin A, in whole blood. CsG has a temperature-dependent distribution between erythrocytes (RBCs) and plasma. After 30 min at 37 degrees C, the plasma/whole blood and plasma/RBC ratios were relatively constant (0.7-0.8) up to CsG at 1000 micrograms/L. At 5000 micrograms/L, this ratio increased to 1.0-1.1 for plasma/whole blood and 1.7 for plasma/RBC. The primary CsG metabolites GM1 and GM9 were sequestered within RBCs to a greater extent than was the parent drug. In whole blood, approximately 2% of CsG was bound to granulocytes, 6% to lymphocytes, and 50-55% to RBC, and 35-40% was found in the plasma fraction. The free fraction of the drug as determined by ultracentrifugation was 5-6% and 13-17% of total drug at 37 and 4 degrees C, respectively. In plasma the drug was primarily associated with high-density lipoprotein (50-60%) and to a lesser degree with low-density (20-30%) and very-low-density (10%) lipoproteins.

Pharmacokinetics of rapamycin: single-dose studies in the rabbit

The pharmacokinetics of rapamycin was investigated in five New Zealand white rabbits following intravenous administration of 0.05 and 0.5 mg/kg rapamycin in a randomized crossover fashion. Whole blood concentrations of rapamycin were analyzed by high-performance liquid chromatography (HPLC). Model-dependent and -independent parameters were calculated. The volume of distribution at steady state and total body clearance increased significantly as the dose increased. Rapamycin pharmacokinetics appear to be nonlinear. The whole blood volume of distribution, especially at the higher dose, indicated distribution out of the blood component. The drug is not cleared rapidly, with a terminal half-life of > 13 hours as calculated by model-independent parameters. The 24-h whole blood trough concentrations of the drug are well within the analytical range of the HPLC procedure. This should permit trough level monitoring for therapeutic range studies involving the drug.

The effect of food on cyclosporine absorption

The high lipophilicity of cyclosporine A (CsA) and the importance of bile for its absorption suggest that food may alter the absorption of CsA. Food has been reported to have varied effects on the absorption of CsA. Study methodology may explain the conflicting reports. Factors which were not well controlled in these studies include time post transplant, fat and caloric content of a meal, the inherent gastric emptying pattern of a patient, and concurrent disease processes which may alter gastric emptying. Based on available information, patients should be instructed to take their CsA consistently in relation to the timing and composition of meals in order to minimize absorption variability.

Diltiazem overdose: pharmacokinetics of diltiazem and its metabolites and effect of multiple dose charcoal therapy

We describe a 38 year-old female who ingested 900 mg of diltiazem. She experienced hypotension, bradycardia and heart block but responded well to supportive care that included normal saline infusion and vasopressors. Calcium administration was not beneficial. Serial plasma concentrations of diltiazem, N-demethyldiltiazem and desacetyldiltiazem were quantified. By comparing the elimination half-life for diltiazem with historical controls, it is concluded that multiple dose charcoal therapy was not beneficial for our patient.

Pharmacokinetics and biotransformation of the cyclosporine metabolite M-17 in the rabbit

The monohydroxylated cyclosporine (CsA) metabolite M-17 was isolated from bile of human liver transplant recipients by preparative HPLC. The structure and purity of the metabolite were confirmed by fast atom bombardment-mass spectroscopy and proton NMR. The isolated metabolite was administered iv to three rabbits at a dose of 1.0 mg/kg with the following mean pharmacokinetic parameters being determined: half-life (t1/2B) 2.22 hr, volume of distribution (Vss) 1.44 liters/kg, and clearance 11.07 ml/min/kg. These are not significantly different from those obtained for CsA. In bile and urine obtained from rabbits administered M-17, the CsA metabolites M-8, M-18, and M-26 were found, indicating that M-17 is further metabolized. The latter data support the proposed biotransformation pathways for M-17.