Abstract: Prostane derivatives of the formula ##STR1## wherein R.sub.1 is OR.sub.2 or NHR.sub.3 ;R.sub.2 is hydrogen, C.sub.1-10 alkyl, C.sub.4-10 cycloalkyl, C.sub.6-10 aryl, or a 5 or 6 membered heterocyclic ring having 1-3 hetero atoms selected from O, N and S;R.sub.3 is the residue of a hydrocarbon carboxylic or sulfonic acid of 1-15 carbon atoms;W is (a) an OH-substituted methylene group, (b) a ##STR2## wherein the OH-groups in (a) or (b) can be in the .alpha.- or .beta.-position, or (c) such a group wherein the H atom of the OH group is replaced by the residue of a hydrocarbon carboxylic or sulfonic acid of 1-15 carbon atoms or by a conventional etherifying OH-blocking group;R.sub.4 is OH or hydroxy whose H atom is replaced as defined for W; andR.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10 and R.sub.11 each independently is hydrogen or alkyl of 1-5 carbon atoms; or R.sub.9 and R.sub.10 together represent a direct bond; and, when R.sub.11 is alkyl, R.sub.