Evaluation of Amikacin Pharmacokinetics and Pharmacodynamics for Optimal Initial Dosing Regimen.

Amikacin has been one of the important antimicrobial agents against Gram-negative pathogens. However, there is discrepancy regarding the amikacin initial dosage, with some reports recently recommending ≥25 mg/kg and others the conventional dosage (15-20 mg/kg). Hence, we evaluated the optimal initial dosing regimen of amikacin. Pharmacokinetic (PK) parameters were estimated using a population PK analysis. The pharmacodynamic (PD) target was a ratio of ≥8 between the concentration achieved 1 h after beginning the infusion (C peak) and the minimal inhibitory concentration (MIC) of the liable bacteria. Based on the population PK parameters, we simulated individual C peak for several dosing regimens by Monte Carlo method and analyzed the C peak/MIC ratio for MICs from 0.5 to 32 µg/mL. This study included 35 infected patients (25 males), with a median (range) age and body weight of 70 (15-95) years and 49.5 (32.5-78) kg, respectively. A two-compartment model was used, and total body clearance (CL) significantly correlated with creatinine clearance, and volume of distribution (V d) with body weight. Regarding the probability to achieve a C peak/MIC of ≥8, the 15 mg/kg regimen was sufficient to achieve the PK/PD target in ≥90% of patients for a MIC of 4 µg/mL or less. The cumulative fraction of response in Pseudomonas aeruginosa was that 76% of patients achieved a C peak/MIC of 8 with the amikacin dosage of 15 mg/kg/day. We suggest that the 15-mg/kg once-daily dosage of amikacin be recommended as the initial dosage. As its maintenance dosage, the 15 mg/kg/day amikacin dosage is needed for a MIC of ≤4 µg/mL, and amikacin monotherapy for a MIC of ≥8 µg/mL should be avoided.

Assessment of optimal initial dosing regimen with vancomycin pharmacokinetics model in very low birth weight neonates.

INTRODUCTION: Pharmacokinetic of vancomycin in very low birth weight neonates showed big variety, and limited data were available due to very minor population. These facts make it difficult to adjust its optimal initial dosage. Therefore, this study was to develop optimal dosing regimen of vancomycin in very low birth weight neonates. METHODS: Between 2010 and 2015, low birth weight neonates (≤1500 g) were included in a population pharmacokinetics analysis. Based on the pharmacokinetic parameters we estimated, we simulated individual blood concentrations of vancomycin and evaluated the probability of its pharmacokinetics/pharmacodynamics (PK/PD) target attainment, such as 24-h area under the concentration-time curve (AUC24)/MIC (≥400) and blood trough concentration (10-20 µg/mL), as primary measure for several dosing regimens by Monte Carlo simulation method. RESULTS: Ten patients were prescribed vancomycin and detected its blood concentrations as routine pharmacy practice to adjust the dosage. A one-compartment model was used and clearance significantly correlated with serum creatinine and the volume of infusion. In this model, vancomycin dose at 10 mg/kg three times a day (TID) was predicted to result 86.7% of neonates for an MIC of 1 µg/mL achieving AUC/MIC of ≥400 and 30.6% of the neonates for an MIC of 2 µg/mL. Moreover, the probability of reaching the target trough concentration was 70.5% for patients treated with vancomycin 10 mg/kg TID. DISCUSSION: We recommended vancomycin 10 mg/kg TID as initial dosage regimens for low birth weight neonates infected with the pathogens showed MIC of ≤1 µg/mL.

A Cost-Effectiveness Analysis of Gemcitabine plus Cisplatin Versus Gemcitabine Alone for Treatment of Advanced Biliary Tract Cancer in Japan.

OBJECTIVES: This study assessed the cost-effectiveness of combination treatment with gemcitabine and cisplatin compared to treatment with gemcitabine alone for advanced biliary tract cancer (BTC) in Japan. METHODS: A monthly transmitted Markov model of three states was constructed based on the Japan BT-22 trial. Transition probabilities among the health states were derived from a trial conducted in Japan and converted to appropriate parameters for our model. The associated cost components, obtained from a receipt-based survey undertaken at the Aichi Medical University Hospital, were those related to inpatient care, outpatient care, and treatment for BTC. Costs for palliative care and treatment of adverse events were obtained from the National Health Insurance price list. We estimated cost-effectiveness per quality-adjusted life year (QALY) at a time horizon of 36 months. An annual discount of 3 % for both cost and outcome was considered. RESULTS: The base case outcomes indicated that combination therapy was less cost-effective than monotherapy when the incremental cost-effectiveness ratio (ICER) was approximately 14 million yen per QALY gained. The deterministic sensitivity analysis of the ICER revealed that the ICER of the base case was robust. A probabilistic analysis conducted with 10,000-time Monte Carlo simulations demonstrated efficacy at the willingness to pay threshold of 6 million yen per QALY gained for approximately 33 % of the population. CONCLUSION: In Japan, combination therapy is less cost-effective than monotherapy for treating advanced BTC, regardless of the statistical significance of the two therapies. Useful information on the cost-effectiveness of chemotherapy is much needed for the treatment of advanced BTC in Japan.

Feasibility of Non-contrast-enhanced MR Angiography Using the Time-SLIP Technique for the Assessment of Pulmonary Arteriovenous Malformation.

PURPOSE: The purpose of this study was to evaluate the diagnostic performance of non-contrast-enhanced magnetic resonance angiography with time-spatial labeling inversion pulse (time-SLIP MRA) in the assessment of pulmonary arteriovenous malformation (PAVM). METHODS: Eleven consecutive patients with 38 documented PAVMs underwent time-SLIP MRA with a 3-tesla unit. Eight patients with 25 lesions were examined twice, once before and once after embolotherapy. The lesions were divided into two groups-initial diagnosis (n = 35) and follow-up (n = 28)-corresponding to untreated and treated lesions, respectively, and were evaluated separately. To evaluate the initial diagnosis group, two reviewers assessed image quality for visualization of PAVMs by using a qualitative 4-point scale (1 = not assessable to 4 = excellent). The location and classification of PAVMs were also evaluated. The results were compared with those from digital subtraction angiography. For evaluation of the follow-up group, the reviewers assessed the status of treated PAVMs. Reperfusion and occlusion were defined respectively as visualization or disappearance of the aneurysmal sac. The diagnostic accuracy of time-SLIP MRA was assessed and compared with standard reference images. Interobserver agreement was evaluated with the κ statistic. RESULTS: In the initial diagnosis group, time-SLIP MRA correctly determined the PAVMs in all but one patient with one lesion who had image degradation due to irregular breath. Image quality was considered excellent (median = 4) and the κ coefficient was 0.85. Additionally, both readers could correctly localize and classify the PAVMs on time-SLIP MRA images with both κ coefficient of 1.00. In the follow-up group, the sensitivity and specificity of time-SLIP MRA for reperfusion of PAVMs were both 100%, and the κ coefficient was 1.00. CONCLUSION: Time-SLIP MRA is technically and clinically feasible and represents a promising technique for noninvasive pre- and post-treatment assessment of PAVMs.

Pharmacists contribute to the improved efficiency of medical practices in the outpatient cancer chemotherapy clinic.

RATIONALE, AIMS AND OBJECTIVES: Outpatient cancer chemotherapy is increasing with the development of anticancer agents, and roles of medical staff are becoming more and more important in cancer chemotherapy. We showed here roles of pharmacists with experience in oncology and evaluated outcomes of their activities in medical practices in cancer chemotherapy clinic. METHODS: Two pharmacists were newly assigned to the outpatient cancer chemotherapy clinic, where they were in charge of verification of prescription orders, mixing of anticancer injections, monitoring adverse drug reactions, implementation of supportive care and provision of information about cancer chemotherapy to medical staff and patients. The number of patients, amounts of mixing of anticancer injections and hospital revenue were compared before and after assignment of pharmacists. Management of chemotherapy-induced nausea and vomiting in breast cancer patients receiving the combination chemotherapy with anthracycline and cyclophosphamide were also compared. RESULTS: Pharmacists spent 75 hours per month in patient education and adverse drug reactions monitoring, which led to the reduction of the workload of physicians. As a consequence, the number of outpatients and the resultant hospital revenue markedly increased. In addition, facilitation of proper use of anti-emetic drugs led to the improved control of chemotherapy-induced nausea with reducing the cost for anti-emesis by 16%. CONCLUSIONS: Pharmacists contributed to the improved efficiency of medical practices.

Nutritional screening with Subjective Global Assessment predicts hospital stay in patients with digestive diseases.

OBJECTIVE: Nutritional status is an important factor that determines hospital stay, and the Subjective Global Assessment (SGA) is a candidate tool for nutritional screening on admission. However, the significance of the SGA has not been evaluated well in the ward for digestive diseases. We conducted the present study to test whether the SGA predicts hospital stay of these patients. METHODS: Two hundred sixty-two patients with digestive diseases were consecutively enrolled between July 2004 and April 2005. They consisted of 145 males and 117 females and included 110 patients with cancer. Disease category was gastrointestinal in 94, hepatic in 111, and biliary/pancreatic in 57. The SGA was performed by a certified dietician. Effects of SGA and other nutritional parameters on hospital stay were examined by simple and multiple regression analysis. RESULTS: Among tested variables, simple regression analysis identified the SGA, disease category, presence of malignancy, serum albumin level, percent triceps skinfold thickness, and percent arm muscle circumference as significant predictive parameters for hospital stay. Multiple regression analysis revealed that the SGA had the best predictive power, followed by the presence of malignancy and disease category. CONCLUSION: The SGA is a simple and reliable predictor for hospital stay in patients with digestive diseases.