11-trans Leukotriene D4 (11-trans LTD4) is a C-11 double bond isomer of LTD4. LTD4 undergoes slow temperature-dependent isomerization to 11-trans LTD4 during storage. 11-trans LTD4 retains about 10-25 % of the potency for contraction of guinea pig ileum, trachea and parenchyma compared to LTD4. It exhibits an ED50 ranging between 12-60 nM for contraction of guinea pig trachea.