Leukotriene D4 is one of the leukotrienes. Its functions in the body are bronchoconstriction, vasoconstriction, contraction of smooth muscle, and increasing vascular permeability. Other leukotrienes that function in a similar manner are leukotrienes C4 and E4. Pharmacological agents that inhibit the function of these leukotrienes are leukotriene receptor antagonists (e.g. Zafirlukast, montelukast) and are useful for asthmatic individuals.