Prostanoids are described of the formulae ##STR1## (and the salts thereof) in which: X is cis or trans--CH.dbd.CH-- or CH.sub.2 CH.sub.2 --;R.sup.1 is C.sub.1-7 alkyl terminated by --COOR.sup.10 where R.sup.10 is H, C.sub.1-6 alkyl or aralkyl;Y is a saturtaed heterocyclic amino group; andR.sup.4 is thienylalkyl or furanylalkyl in which the ring may be substituted.These compounds inhibit blood platelet aggregation and have bronchodilatory action, and may be formulated for use as anti-asthmatics and antithrombotic agents.