Free Drug Fraction Versus Free Drug Concentration

Letter to the Editor

Sir: In their article on pharmacokinetic considerations in theelderly, DeVane and Pollock present a wealth of valuable informationfor the clinician. However, a small point needs clarification.The authors state—as do many textbooks and articles onthis subject—that an increase in plasma binding proteins in theelderly "can lead to a diminished free concentration of basicdrugs" (italics mine).