BASIC PHARMACOKINETICS
生體可用率 77%, 經肝臟轉換成 penciclovir, 血漿半衰期 2.1~2.7 小時, 食物不影響吸收率(空腹或飯後服用都可以)
Famciclovir is well absorbed, featuring an oral bioavailability of 77 percent [7]. Prompt first-pass metabolism in the intestine and liver results in conversion to penciclovir. A 500 mg dose of famciclovir yields peak penciclovir levels of 2.7 to 4 mg/L, with a plasma half-life of 2.1 to 2.7 hours. Food has no clinically important effect upon these levels [2].
感染單純皰疹病毒 herpes simplex 的細胞, 細胞內 penciclovir 半衰期10-20 小時, 感染帶狀皰疹病毒 varicella zoster virus 的細胞內半衰期 7-14 小時,相較於半衰期僅不到一小時的 acyclovir, 服用 famvir 一天三次即可.
A key feature of penciclovir is a prolonged intracellular half-life of penciclovir triphosphate: 10 to 20 hours in herpes simplex virus-infected cells, and 7 to 14 hours in varicella zoster virus-infected cells. In comparison, the intracellular half-life of acyclovir triphosphate is one hour or less [2]. As a result, famciclovir requires less frequent dosing.
排出主藥經過腎臟, 因此腎功能不良 (CCR<60) 需減量 ., 血液透析可移除 penciclovir
排出主藥經過腎臟, 因此腎功能不良 (CCR<60) 需減量 ., 血液透析可移除 penciclovir
慢性穩定性肝病不需減量. 但目前缺乏失償性肝功能不良的研究.
Excretion is primarily renal, and dose reduction is recommended in patients with impaired renal function (creatinine clearance under 60 mL/min) [1,2]. Penciclovir is removed by hemodialysis [1]. Well-compensated chronic liver disease does not require dose modification, but pharmacokinetic studies in patients with poorly compensated hepatic insufficiency have not been performed [1].
Excretion is primarily renal, and dose reduction is recommended in patients with impaired renal function (creatinine clearance under 60 mL/min) [1,2]. Penciclovir is removed by hemodialysis [1]. Well-compensated chronic liver disease does not require dose modification, but pharmacokinetic studies in patients with poorly compensated hepatic insufficiency have not been performed [1].
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