Phenothiazine Levels in Plasma and Red Blood Cells

Comparison of plasma, venous and capillary blood levels of piperaquine in patients with uncomplicated falciparum malaria

“…This could partially explain the inter-individual variability of the relationship shown here. For certain drugs, such as neuroleptics, the red cell concentrations have been reported to correlate better with therapeutic effects or dose than plasma concentrations [4, 8, 26]. …”

The Effects of Haematocrit, Plasma Protein Concentration and Temperature of Drug-containing Blood In-vitro on the Concentrations of the Drug in the Plasma

“…Although only free drug in plasma is pharmacologically active, therapeutic schedules being evaluated are often based on the total drug concentration in serum or plasma. In addition to plasma proteins, erythrocytes are known to bind certain drugs, such as phenytoin (Sherwin et al 1976), cyclosporin A (Lemaire & Tillement 1982), chlorpromazine (Bickel 1975;Casper et al 1980), nicardipine (Urien et al 1985) and amiodarone (Maling et al 1989). It has recently been reported that, with increasing haematocrit values, the plasma concentration of cyclosporin A (Rosano 1985) and busulfan (Ehrsson & Hassan 1984) decreased, whereas cephalosporin levels increased (Derendorf 1987), without any change in total drug concentration in whole blood.…”