||PGE1 is the theoretical cyclooxygenase metabolite of dihomo-γ-linolenic acid (DGLA), but it is virtually undetectable in the plasma of normal humans or other animals. Its pharmacology includes vasodilation, hypotension, and anti-platelet activities. The IC50 of PGE1 for the inhibition of ADP-induced human platelet aggregation is 40 nM. The vasorelaxant and anti-hypertensive effects of PGE1 are used to treat male erectile dysfunction and to provide emergency vasodilation of the patent ductus arteriosus in infants whose cardiac anomalies require pulmonary shunting for survival. In human males, the intracavernosal effective dose range for PGE1 is 2 to 80 µg, and the transurethral range is 125 to 1,000 µg.