一般臨床藥物代謝動力學回顧2(1)(編輯修改稿)
2025-02-23 17:44 本頁面
【文章內容簡介】 cal Question? A 65 year old man is started on digoxin mg po qd for the treatment of congestive heart failure. If a loading dose is not given, approxi mately how long will it take for this patient to reach a steady state digoxin level? Answer to Clinical Question The halflife of digoxin is approx. 40 hours Steady state should be achieved by approximately 5 halflives. Therefore, this patient should achieve steady state digoxin levels in approxi mately 89 days. Elimination Rate Constant (ke) The fraction of drug removed per unit of time (. hour 1) Time (hours) 1 2 3 4 5 6 5 Drug Conc. (log scale) * * (Co, to) (C1, t1) ln C1 = ke t + ln Co FirstOrder Elimination Time (hours) 1 2 3 4 5 6 5 Drug Conc. (log scale) * * (Co, to) (C1, t1) slope = ke = ln C1 ln Co t1 to Elimination Rate Constant Time (hours) 1 2 3 4 5 6 5 Drug Conc. (log scale) * * (Co, to) (C1, t1) slope = ke = ln 5 ln 4 hr 0 hr Elimination Rate Constant Time (hours) 1 2 3 4 5 6 5 Drug Conc. (log scale) * * (Co, to) (C1, t1) slope = ke = hr Clinical Question? A 45 year old man is receiving gentamicin 160mg IV q 12 hr. A peak and trough level were drawn at steady state. Peak = mcg/ml 0900 Trough = mcg/ml 2023 What is this patient’s elimination rate constant (ke) and halflife? First Order Elimination conc time ke slope = ke = ln C1 ln C0 T1 T 0 * * Answer to Clinical Question ke = ln C1 ln C2 t1 t2 ke = ln ln 11 hr = R
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