Attached
In most volume of distribution (Vd)
determinations the drug partitioned in to
erythrocytes (Cery) occupying 45% of blood
volume is disregarded. The Vd
determinations can be erroneous on two
accounts. The first is the indiscriminate
reference to plasma (CP) , whdle blood (Cb)
or serum (Cs) concentrations. The second is
when Cery values are not considered in
calculations. Isolated erythrocytes were
incubated in plasma water (Cpw) represented
by physiological saline drug solutions, the
Cpw, Cery and Cb values were experimentally
determined in vitro. Aberrations to the Vd
determinations are demonstrated using both
theoretically and practically determined
values o f Cpw, Cery and Cb. Widely varying
Vd values 125 L to 2.55 L resulted when Cp
data alone is used while the values differed
marginally from 4.56 L to 5.53 L when Cb
values were used for two setting using same
amount of drug.
