Prostaglandin I2 is an unstable prostanoid which, through the ‘I prostanoid’ (IP) receptor, inhibits platelet aggregation and promotes vasodilatation in pulmonary vascular beds. AFP 07 is a 7,7-difluoroprostacyclin derivative that acts as a selective and highly potent agonist for the IP receptor (Ki = 0.561 nM). AFP 07 shows weaker affinity for EP receptors, with Ki values of > 100 nM for EP1-3 and > 10 nM for EP4. In piglet and rabbit saphenous veins, which express both IP and EP4, the EP4 antagonist AH 23848 reduces AFP 07-mediated relaxation, suggesting that AFP 07 activates EP4 as well as IP, particularly when both receptors are present.
