Subcutaneous Absorption Kinetics and Local Tissue Distribution of Interferon and Other Solutes

Abstract

Abstract The subcutaneous absorption and consequent tissue distribution of interferon g was studied in an anaesthetized rat model. Interferon g showed a biphasic disappearance profile from a solution in a subcutaneous absorption cell. Both the initial rapid distribution phase and slower removal phase followed first order kinetics. The steady-state clearance of interferon g from the cell was 1·41 ± 0·38 × 10−3 mL min−1, and the absorption half-life (t½) was 3·8 ± 1·1 h (n = 4). Noradrenaline did not significantly alter either the clearance or absorption of interferon g (1·18 ± 0·44 × 10−3 mL min−1  P > 0·05, absorption t½ 4·96 ± 1·9 h, P > 0·05). Given that the clearance of smaller solutes, such as tritiated water, is significantly reduced when noradrenaline is coadministered, it is suggested that interferon g is removed via the lymphatic system rather than by the local blood supply. The amount of interferon g recovered in the plasma, urine and muscle is minimal relative to other solutes where the recovery is almost complete.