SUBCUTANEOUS ABSORPTION KINETICS AND LOCAL TISSUE DISTRIBUTION OF INTERFERON AND OTHER SOLUTES

The subcutaneous absorption and consequent tissue distribution of inte rferon g was studied in an anaesthetized rat model. Interferon g showe d a biphasic disappearance profile from a solution in a subcutaneous a bsorption cell. Both the initial rapid distribution phase and slower r emoval phase followed first order kinetics. The steady-state clearance of interferon g from the cell was 1.41 +/- 0.38 x 10(-3) mL min-1, an d the absorption half-life (t1/2) was 3.8 +/- 1.1 h (n = 4). Noradrena line did not significantly alter either the clearance or absorption of interferon g (1.18 +/- 0.44 x 10(-3) mL min-1, P > 0.05, absorption t 1/2 4.96 +/- 1.9 h, P > 0.05). Given that the clearance of smaller sol utes, such as tritiated water, is significantly reduced when noradrena line is coadministered, it is suggested that interferon g is removed v ia the lymphatic system rather than by the local blood supply. The amo unt of interferon g recovered in the plasma, urine and muscle is minim al relative to other solutes where the recovery is almost complete.