8-iso PGE2 isopropyl ester is a more lipophilic form of the free acid, 8-iso PGE2. Prostaglandin esters have enhanced lipid solubility compared to their parent compounds. They are generally hydrolyzed to the free acid upon in vivo administration, making the esters useful prodrugs. In general, the C-1 esters of prostaglandins show greatly diminished agonist activity in vitro compared to the parent free acids.