2004 年 30 巻 4 号 p. 261-265
The bioavailability of digoxin is known to differ between tablets and powders. To evaluate this difference in clinical practice, serum concentrations were compared between inpatients who received tablets (tablet group) and those who received a powder (powder group). For the powder, the quantity packaged by an automatic packaging machine and that on removal from the package were measured.
The C/D (concentration/dose/body weight) in the powder group was significantly less than that in the tablet group when classified according to Ccr (creatinine clearance) and age. The difference in C/D increased with age, and, as compared with the tablet group, there was a 42.2 % greater decrease in C/D in the powder group for those over 80 years old. After removal from the package, the quantity of powder was about 6.1% less than it than that packaged by the automatic packaging machine. In a study using volunteers that was also performed, the powder losses stemming from packaging were 7.3% and 18.0% in young people and the elderly, respectively.
These results suggest that the difference in C/D between tablets and the powder stemmed not only from the difference in their bioavailabilities but also from losses arising during preparation and at the time of taking the powder.