PDE4A and Allergy: Similarly, an association was found between violence and montelukast, a leukotriene receptor antagonist used for the treatment of bronchial asthma and allergy relief, whose adverse reactions include suicidal ideation, self-injurious behavior, agitation, aggressiveness, anxiety and irritability [17,33,34,35], as well as roflumilast, a phosphodiesterase 4 inhibitor drug (PDE4), which has been linked to suicidal ideation, suicide attempts and completed suicide [22,36].