[Evaluation of Patient Adherence to Anastrozole Therapy for Breast Cancer].

PURPOSE: There are many reports that describe the effectiveness of aromatase inhibitors as endocrine therapy after breast cancer surgery. However, there are few detailed evaluations of patient adherence to anastrozole(ANA)therapy. Here, we evaluated the adherence to ANA therapy in postoperative patients with primary breast cancer. METHODS: We investigated 102 postoperative patients with primary breast cancer without distant metastasis, who received ANA at JCHO Kyusyu Hospital. We calculated the medication continuation rate and disease-free survival at 5 years from the initiation of medication. The reasons for medication discontinuation and alternative drug therapy after ANA therapy discontinuation were also investigated. Re- sults: The 5-year continuation rate of ANA treatment alone was 79%(81/102). The rate of all patients who continued ANA treatment, including 9 who changed to other drugs, was 88%(90/102). The most frequent ANA discontinuation reasons were progressive disease(8 cases), arthritis(5 cases), and nausea(3 cases). The disease-free survival rate was 92%(94/102), and the overall survival rate was 97%(99/102). CONCLUSION: ANA showed a high continuation rate. Adherence of ANA in postoperative patients with breast cancer was well maintained, even when the treatment was changed to other drugs due to adverse events.

Determination of digoxin clearance in Japanese elderly patients for optimization of drug therapy: a population pharmacokinetics analysis using nonlinear mixed-effects modelling.

BACKGROUND: Optimal use of digoxin in the elderly population requires information about the drug's pharmacokinetics and the influence of various factors on the drug's disposition. However, because of sampling restrictions, it is often difficult to perform traditional pharmacokinetic studies in elderly patients. OBJECTIVE: This study was conducted to determine the apparent total clearance of digoxin from serum after oral administration (CL/F) and to establish the role of patient characteristics in estimating doses of digoxin for elderly patients (age ≥65 years), using routine therapeutic drug monitoring data. METHODS: Analyses of the pharmacokinetics of digoxin were conducted using the nonlinear mixed-effects modelling (NONMEM®) software, a computer program designed to analyse pharmacokinetics in study populations by allowing pooling of data. Steady-state data (140 observations) obtained by routine therapeutic drug monitoring following repeated oral administration of digoxin in 94 hospitalized elderly patients (age ≥65 years) were analysed to establish the role of patient characteristics in estimating doses of digoxin for elderly patients. RESULTS: Estimates generated by NONMEM® indicated that digoxin CL/F was influenced by the demographic variables of total bodyweight (TBW), serum creatinine (SCr), age (AGE), presence of congestive heart failure (CHF), concomitant administration of the calcium channel antagonists (calcium channel blockers [CCBs]: verapamil, diltiazem or nifedipine), sex (SEX) and elderly clearance factor (trough serum concentration of digoxin; [C(trough)] θ). The full version of the final NONMEM® model was where CCB is 1 for concomitant administration of a CCB and is 0 otherwise; CHF is 1 for patients with CHF and is 0 otherwise; SEX is 0 for male and is 1 for female; and the elderly clearance factor C(trough)-0.180 is 1 for digoxin C(trough) <1.7 ng/mL. CONCLUSIONS: We developed a new model for elderly patient dosing of digoxin with good predictive performance. Clinical application of the findings of the present study to patient care may permit selection of an appropriate initial digoxin maintenance dose, thus enabling the clinician to achieve a desired therapeutic effect. However, the digoxin dosage regimen should be based on an appraisal of the individual patient's clinical need for the drug.

Population pharmacokinetic investigation of digoxin in Japanese infants and young children.

To establish the role of patient characteristics in estimating doses of digoxin for infants and young children using routine therapeutic drug monitoring data, the steady-state blood-level data (n = 245) after repetitive oral administration in 117 hospitalized infants and young children were analyzed using nonlinear mixed effects modeling (NONMEM), a computer program designed for analyzing drug pharmacokinetics in study populations through pooling of data. Analysis of the pharmacokinetics of digoxin was accomplished using a 1-compartment pharmacokinetic model. Estimates generated by NONMEM indicated that the clearance of digoxin (CL/F; L/h) was influenced by the following demographic variables: total body weight (TBW), presence of congestive heart failure (CHF), and infant-young children clearance factor (trough serum concentration of digoxin; Conc). These influences could be modeled by the equation CL/F (L/h) = 0.302 · TBW (kg)¹·¹7 · 0.905(CHF) · Conc (trough serum digoxin concentration >1.7 ng/mL)⁻°·54°; F = 0.754, where CHF is 1 for presence of congestive heart failure, 0 otherwise; F is bioavailability, 1 for elixirs, 0.754 for powders; and Conc⁻°·54° is 1 for digoxin concentration <1.7 ng/mL. Clinical application of the model to patient care may permit selection of an appropriate initial maintenance dose, thus enabling the clinician to achieve the desired therapeutic effect. However, the digoxin dosage regimen for the individual patient should be based on a careful appraisal of his or her clinical need for the drug.

Pharmacoepidemiologic detection of calcium channel blocker-induced change on digoxin clearance using multiple trough screen analysis.

Nonlinear mixed effects modeling was used to estimate the effects of digoxin-calcium channel blockers (verapamil, diltiazem, nifedipine) in 336 serum levels gathered from 172 patients (104 male and 68 female) receiving oral digoxin as hospital in-patients. The final model describing digoxin clearance (CL) was CL (l/day)=(87.9+2.71C(cr))0.872(CCB)0.880(CHF)0.937(SPI)0.854(DFAC), where C(cr) is the estimated creatinine clearance (ml/min); CCB=1 for concomitant administration of calcium channel blockers and CCB=zero otherwise; CHF=1 for the patients with congestive heart failure and CHF=zero otherwise; SPI=1 for concomitant administration of spironolactone and SPI=zero otherwise; DFAC=1 for administration of a half-tablet of digoxin and DFAC=zero otherwise. Concomitant administration of calcium channel blockers resulted in a 13% decrease in digoxin relative clearance.