Pharmacokinetics of liposomal and free dexamethasone phosphate in rats. (a) A dose of 4 mg/kg liposomal dexamethasone phosphate (DXM-P) (open squares) or free DXM-P (diamonds) was injected intravenously into rats, and the appearance of the converted dexamethasone (DXM) was monitored in plasma. In a separate experiment, radiolabelled liposomal DXM-P (triangles) was injected into rats and their pharmacokinetics was followed using 14C-1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). (b) Integrity of liposomal DXM-P. Radiolabelled liposomal DXM-P was injected as in (a) and the additional aqueous phase marker 3H-inuline was analysed. The resulting 3H/14C ratio was plotted with respect to the initial ratio. The constant ratio indicates high carrier integrity in the circulation. Error bars indicate standard deviations.