Propylene glycol enhances anti-inflammatory effects of phenylbutazone.

1. The interference of propylene glycol with anti-inflammatory effects of phenylbutazone was investigated. 2. Inhibitory effect of phenylbutazone on both carrageenin-induced edema and the cotton pellet granuloma was increased when propylene glycol was used as solvent. 3. Propylene glycol given alone inhibited carrageenin-induced edema and pleurisy, as well as granulomatous tissue formation. 4. Some pharmacokinetic parameters of phenylbutazone were also changed by propylene glycol administered simultaneously. 5. These results suggest that propylene glycol probably increases the anti-inflammatory effect of phenylbutazone by summation and by raising the plasma half-life and the distribution volume of phenylbutazone.