[Antiphiogistic drugs. Sudies on the pharmocokinetics of anti-inflammatory agents].

The kinetic behaviour of radioactively labeled acetylsalicylic acid (ASA), phenylbutazone (PBZ), indometacin and dexamethasone in rabbits with knee joints experimentally inflamed can be summarized as follows: 1. Under control (non-inflammation) conditions as well as during inflammation, subthreshold doses of 14C-ASA intravenously (i.v.) administered were eliminated from the blood in a fast and slow biphasis process. The changes of the concentration in the perfusion fluid were very similar compared to the changes in the blood. However, they were enhanced during experimentally induced synovitis. 2. Subthreshold does of 3H-phenylbutazone i.v. administered were eliminated from the blood like 14C-ASA in a biphasic process. During an experimentally produced inflammation of the joints, the blood level decreased rapidly. The concentration of radioactivity in the perfusion fluid was very low. 3. In constrast, 3H-indometacin injected like ASA and PBZ in subtherapeutic dosage diappeared from the blood in a threephasic process. The uptake into both the normal and the inflamed synovial space was biphasic. Under both conditions the perfusion fluid contained low concentrations of the drug. 4. 3H-dexamethasone (subtherapeutic dosage) displayed a biphasis fall of concentration in the blood: a fast first phase and a slower second phase. With inflammation of the kneejoint, the elimination was characterized by a three-phase slope and was significantly faster compared with control animals. While the alterations of ASA and indometacin level in the perfusion fluid were corresponding to the decrease of the blood concentration, the uptake of dexamethasone into the synovial space did not show any change. 5. Under control conditions. 3H-dexamethasone (subthreshold doses) injected intraariculary was rapidly detectalbe in the blood. However, systemic absorption was considerably faster under inflammation conditions; the blood level was lower than following administration of 3H-dexamethasone into the normal knee-joint, the distribution from which was not uniform. After pretreating the animals with high does of hydrocortisonacetate, the i.v. application of 3H-dexamethasone was followed by a delayed first phase of the biphasis process of elimination. 6. Autoradiographic studies revealed 14C-ASA to be accumulated in the synovial fluid under normal conditions and in the periaricular connective tissue under inflammation conditions.