Naphtidrofuryl oxalate (LS121) was orally administered to volunteers in the fasted or non-fasted state and the time courses of the serum concentration of naphtidrofuryl (LS84) and its three metabolites were determined. In case of the non-fasted state, the maximum serum concentration (
C max) decreased and the time when the
C max appeared (
T max) delayed compared to the fasted state, in all the four compounds. The area under concentration time curve calculated by the trapezoidal method using the observed data (
AUC obs or
AUC obs,
m) increased in the non-fasted state. The bioavailability of LS84 estimated by the
AUC obs devided by the calculated
AUC (
AUC cal) from the pharmacokinetic parameters in the intravenous infusion experiments which were reported in the preceding paper, were 23.0% in the non-fasted state and 20.2% in the fasted state. The
AUC obs,
m of three metabolites were larger than
AUC cal,
m calculated from the
AUC obs of LS84 according to the intravenous infusion results reported in the preceeding paper. The percentages of the
AUC of the first-pass effect were calculated by the equation that (
AUC obs,
m-
AUC cal,
m)/
AUC obs,
m, and were about 80% for three metabolites.
It was concluded that about 20% of the oral dose removed unchanged to the circulation system and the rest 80% was metabolized by the first-pass effect.
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