THE RADIOIMMUNOASSAY AND THE PHARMACOKINETICS OF PERUVOSIDE AND NERIIFOLIN

Antibodies with high affinity and specificity were produced by six-month immunization of rabbits with BSA-peruvoside conjugate emulsified wit Freunds adjuvant. The titer of the antisera was measured to be 800 when using ³H-neriifolin (1 Ci/mmol) as the labelled antigen. Competition experiments showed that cross-reaction of the antiperuvoside sera with neriifolin was complete, but was little with cerberin (20%), digoxin (0.4%) and corticosterone (<0.2%). Sensitivity of the method in measuring neriifolin was at least 0.3 ng. The coefficients of variance within-assay and between-assays were 5.2～6.5% and 5.1～10.7%, respectively.After intravenous injection of peruvoside or neriifolin, the plasma concentration-time curve was shown to fit a two compartment open model with the following pharmacokinetic parameters: neriifolin T1/2α=11 min, T1/2β=6.79 h, vd=6.78 L/kg and CL=0.69 L/h/kg; peruvoside T1/2α=8 min, T1/2β=2.13 h, vd=3.94 L/kg and CL=1.28 L/h/kg. After oral administration of peruvoside, neriifolin and neriperside, absorption was shown to be rapid with peak blood levels at 52 min, 34 min and 15 min respectively. The bioavailability of peruvoside, neriifolin and neriperside was found to be 29.5%, 35.6% and 27.1% respectively.