Answer Explanation: Many manifestations of inflammation can be attributed in part to leukotrienes. Medications categorized as leukotriene antagonists or modifiers such as montelukast (Singulair) block the synthesis or action of leukotrienes and prevent signs and symptoms associated with asthma. Diphenhydramine prevents histamines effect on smooth muscle. Albuterol sulfate relaxes smooth muscle during an asthma attack. Epinephrine relaxes bronchial smooth muscle but is not used on a preventative basis.