Comparison of four experimental techniques for studying drug absorption kinetics in the anesthetized rat in situ.

Theophylline absorption kinetics were determined using in situ perfusion techniques. The objectives of this study were to obtain information on the effective permeability constant (ke) of theophylline and its variance during the course of an experiment, and to study the dependence of ke on the experimental technique used. Four in situ intestinal perfusion techniques were compared in the rat: single-pass perfusion, recirculating perfusion, oscillating perfusion, and the closed loop method.

Immunological measurements on the disappearance of creatine kinase MM from the circulation.

Both a two-site immunoradiometric assay and a two-site enzyme-linked immunosorbent assay for creatine kinase MM are described. Linearity, reproducibility and cross-reactivity of the assays are satisfactory. Creatine kinase MM incubated in a pH-controlled serum matrix loses its activity, but has its antigenic determinants affected as well.