TISSUE DISTRIBUTION AND ANTI-INFLAMMATORY ACTIVITY OF CORTICOSTEROIDS INCORPORATED IN LIPID EMULSION

Dexamethasone palmitate was incorporated into a lipid emulsion (Intralipid, Intralipos) and was injected into rats, and its distribution in the organs and tissues and its antiinflammatory effects were compared to those of free dexamethasone disodium phosphate. The distribution patterns of [3H]dexamethasone were markedly different between the 2 preparations in 3 h after i.v. administration. Dexamethasone palmitate given as a lipid emulsion showed a much higher concentration in the blood, spleen and inflamed tissues (carrageenan edema); dexamethasone sodium phosphate had a high concentration in the muscles. The antiinflammatory activity of both preparations given i.v. was evaluated by using the preformed carrageenan granuloma pouch method. The antiinflammatory activity of lipid emulsion dexamethasone was 5.6 times as potent as an equivalent amount of free dexamethasone. Corticosteroids which are incorporated in lipid emulsions may be taken up by the RES and some inflammatory cells much more than are free corticosteroids; thus, they have a stronger antiinflammatory activity. The [human] clinical use of lipid emulsion corticosteroids for certain types of diseases is suggested.