MacKichan J J, Dobrinska M R, Welling P G, Wagner J G
Clin Pharmacol Ther. 1977 Nov;22(5 Pt 1):609-14. doi: 10.1002/cpt1977225part1609.
An example from the literature has been used to demonstrate errors involved in calculating drug clearance by inappropriate use of the apparent drug distribution volume Vdext. The Vdext is always an overestimate of the true volume of distribution in a multicompartment system, and the degree of overestimation in using it to calculate clearance for such a system will increase as renal function increases. Drug dosages calculated on the basis of overestimated clearance values may give rise to overdosage in normal individuals, or therapeutic failure in severely uremic patients. Problems associated with the use of an oversimplified pharmacokinetic model for clearance calculations are discussed, together with the concept of model-independent calculations.
文献中的一个例子被用来证明，通过不恰当地使用表观药物分布容积Vdext来计算药物清除率所涉及的错误。在多室系统中，Vdext总是对真实分布容积的高估，并且在使用它来计算此类系统的清除率时，高估程度会随着肾功能的增加而增大。基于高估的清除率值计算出的药物剂量可能会导致正常个体用药过量，或导致严重尿毒症患者治疗失败。文中讨论了使用过于简化的药代动力学模型进行清除率计算所涉及的问题，以及与模型无关的计算概念。
