Asthma meds. Neither formoterol nor salmeterol has "addictive properties". Both are long-acting bronchodilators (open small airways) used in conjunction with an inhaled corticosteroid to control asthma. They are related to albuterol, a short-acting bronchodilator. If your asthma is not adequately controlled w/ formoterol, see your pcp or pulmonologist for meds adjustment.
Similar. Both formoterol and salmeterol are long-acting beta2-adrenergic agonists (laba), which have similar side effect profiles, including cardiac and central nervous system stimulation. Neither one should have any serious addictive potentials when used for asthma/copd control. But as either one can act as a central nervous system stimulant, there is certainly a potential for addiction and misuse.