LSF, a chiral metabolite of pentoxifylline, acts as a potent anti-inflammatory agent. (S)-LSF is the pharmacologically inactive optical enantiomer of (R)-LSF, the biologically active isomer. When metabolized by isolated human liver cells, pentoxifylline is exclusively reduced to (S)-LSF in the cytosol, while reduction in liver microsomes is 85% stereoselective in favor of (S)-LSF formation. Thus, pentoxifylline is an inefficient prodrug for the delivery of therapeutically relevant lisofylline.
