Stabilní farmaceutický prostredek obsahující bicyklickou slouceninu obecného vzorce I a acylglycerol, bicyklická sloucenina a zpusob stabilizace této slouceniny a dále farmaceutický prostredek obsahující bicyklickou slouceninu. Výhodnými slouceninami vzorce I jsou 7-[(1R,3R,6R,7R)-3-(1,1-difluorpentyl)-3-hydroxy-2-oxabicyklo[4,3,0]nonan-8-on-7-yl]heptanová kyselina vzorce 1 a 7-[(1R,6R,7R)-3-[(3S)-1,1-difluor-3-methylpentyl]-3-hydroxy-2-oxabicyklo[4,3,0]nonan-8-on-7-yl]heptanová kyselina vzorce 2.In the present invention, there is disclosed stable pharmaceutical composition containing a bicyclic compound of the general formula I and acyglycerol, further the bicyclic compound of the general formula I and stabilization process of the compound, and further a pharmaceutical composition in which the bicyclic compound is comprised. Preferred compounds of the general formula I are 7-[(1R,3R,6R,7R)-3-(1,1-difluoropentyl)-3-hydroxy-2-oxabicyclo[4,3,0]nonan-8-on-7-yl]heptanoic acid of the general formula 1 and 7-[(1R,6R,7R)-3-](3S)-1,1-difluoro-3-methylpentyl]-3-hydroxy-2-oxabicyclo[4,3,0]nonan-8-on-7-yl]heptanoic acid of the general formula 2.
