(+)-D-threo-PDMP is a ceramide analog and is one of the four possible stereoisomers of PDMP . (+)-D-threo-PDMP is an inhibitor of glucosylceramide synthase. It inhibits glucosylceramide synthase by 50% when used at a concentration of 5 μM in an enzyme assay. (+)-D-threo-PDMP is the active component of racemic DL-threo-PDMP .