Gender difference in letrozole pharmacokinetics in rats
Abstract
"AIM:
To study gender difference in letrozole (Letr) pharmacokinetics in rats.
METHODS:
Letr concentrations in plasma and tissues were determined after ig administration of Letr 2 mg/kg. Recoveries of Letr in urine and feces were also analyzed.
RESULTS:
Marked gender differences were found 6 h after ig Letr 2 mg/kg, the plasma concentrations of Letr in male rats were significantly (P < 0.01) lower than those in female rats. For example, at 24, 36, 48, and 72 h after administration, plasma concentrations in female rats were about 3.3, 5.6, 10.5, and 7.4-fold of that of male rats, respectively. AUC value of Letr in male was only about one-third of that in female rats. Estimated terminal phase half-lives (T1/2) were 10.5 and 40.4 h, respectively. In female rats, cumulative excreted fractions of Letr in urine and feces were 5.8% +/- 1.4% and 6.6% +/- 1.1% within 120 h after administration, respectively, but in male rats, the excreted fractions of Letr in urine and feces were only 1.30% +/- 0.59% and 0.87% +/- 0.31%. Letr concentrations in female rat tissues were significantly (P < 0.01) higher than those in male rat tissues 24 h after administration.
CONCLUSION:
There are marked gender differences in Letr pharmacokinetics in rats."
Keywords:
To study gender difference in letrozole (Letr) pharmacokinetics in rats.
METHODS:
Letr concentrations in plasma and tissues were determined after ig administration of Letr 2 mg/kg. Recoveries of Letr in urine and feces were also analyzed.
RESULTS:
Marked gender differences were found 6 h after ig Letr 2 mg/kg, the plasma concentrations of Letr in male rats were significantly (P < 0.01) lower than those in female rats. For example, at 24, 36, 48, and 72 h after administration, plasma concentrations in female rats were about 3.3, 5.6, 10.5, and 7.4-fold of that of male rats, respectively. AUC value of Letr in male was only about one-third of that in female rats. Estimated terminal phase half-lives (T1/2) were 10.5 and 40.4 h, respectively. In female rats, cumulative excreted fractions of Letr in urine and feces were 5.8% +/- 1.4% and 6.6% +/- 1.1% within 120 h after administration, respectively, but in male rats, the excreted fractions of Letr in urine and feces were only 1.30% +/- 0.59% and 0.87% +/- 0.31%. Letr concentrations in female rat tissues were significantly (P < 0.01) higher than those in male rat tissues 24 h after administration.
CONCLUSION:
There are marked gender differences in Letr pharmacokinetics in rats."