Half-life and elimination rate constant are determined by both clearance and volume of distribution.半衰期和消除速率常数既受清除率的影响，也受分布容积的影响。

Question

BlackTom AI · Accepted Answer

ke = CL / Vd, and t1/2 = ln2 / ke = (ln2 · Vd) / CL, so both clearance and volume of distribution determine the elimination rate constant and half‑life.

1) Relevant knowledge points and concepts
- Clearance (CL) is the volume of plasma completely cleared of drug per unit time (L/h).  
- Volume of distribution (Vd) is a proportionality relating amount of drug in body to plasma concentration (L).  
- Elimination rate constant (ke) is the first‑order fractional rate of loss (h−1).  
- Half‑life (t1/2) is the time for plasma concentration to fall by half for first‑order kinetics.

2) Step‑by‑step reasoning
- For a one‑compartment, first‑order model, the rate of elimination is proportional to concentration: dC/dt = −ke·C.  
- Clearance relates to ke by the definition CL = ke · Vd (because rate = CL · C = ke · Vd · C). Rearranging gives ke = CL / Vd.

3) Calculations and intermediate steps
- ke = CL / Vd.  
- t1/2 = ln2 / ke. Substitute ke: t1/2 = ln2 / (CL / Vd) = ln2 · Vd / CL.  
- Using ln2 ≈ 0.693: t1/2 = 0.693 · Vd / CL.

4) Why the correct answer is correct
- The algebra shows ke depends directly on CL and inversely on Vd, and t1/2 is proportional to Vd and inversely proportional to CL. Thus changing either CL or Vd will change ke and t1/2 (e.g., increased CL → larger ke → shorter t1/2; increased Vd → smaller ke → longer t1/2).

5) Why the other option (False) is incorrect
- Answering False would claim ke and t1/2 are independent of CL or Vd, which contradicts the derived relationships ke = CL/Vd and t1/2 = 0.693·Vd/CL. Those formulas directly show dependence on both parameters.

6) Conclusion
- Therefore the statement is True, which matches the provided answer.

Half-life and elimination rate constant are determined by both clearance and volume of distribution.半衰期和消除速率常数既受清除率的影响，也受分布容积的影响。判断题

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