Tehran University of Medical Sciences Journal of Pharmaceutical Care 2322-4630 2 1 2015 10 11 27 31 EN Ebrahim Salehifar Associate Professor of Clinical Pharmacy, Faculty of Pharmacy, Thalassemia Research Center, Mazandaran University of Medical Sciences, Sari, Iran. Javad Ghaffari Associate Professor of Pediatrics, Subspecialist in Asthma and Allergy, BoaliSina Hospital, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran. Shahram Ala Associate Professor of Clinical Pharmacy, Faculty of Pharmacy, Pharmaceutical Research Center, Mazandaran University of Medical Sciences, Sari, Iran. Fatemeh Moghimi PharmD, Department of Clinical Pharmacy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran. 2015 10 11 2015 10 11 Backgrounds: All of Long-acting β2-agonists are beneficial in maintenance treatment of asthma but their use in relieving acute asthma attacks is not well known. The aim of this study was to compare rapid bronchodilatory effects of Salmeterol and Formoterol in patient with moderate to severe asthma. Methods: It was a randomized, double blind, cross-over study on 60 patients with moderate to severe asthma. Patients randomly received 50 micrograms of salmeterol or 18 micrograms of formoterol  and  after  one-week  washed  out  period  exchanged  their  medications. All  patients undergone spirometry for four times (before receiving the drugs, as well as 3, 30 and 60 minutes after drug inhalation) and Forced Expiratory Volume in 1 second (FEV1), Forced Vital Capacity (FVC), FVC percentage predicted value, FEV1/FVC, Peak Expiratory Flow Rate (PEFR) and PEFR percentage predicted value were measured. Results: Both medications could significantly increase FEV1/FVC and PEFR at 3, 30 and 60 minutes after inhalation (P<0.001 compared to baseline).Three minutes after inhalation of salmeterol and formoterol, FEV1 increased by 8.7% and 12.2% respectively. Formoterol was associated with more increase in the amounts of FEV1 compared to Salmeterol. Conclusion: This study showed that fromoterol has a more rapid onset of bronchodilating action compared with salmeterol at 3 minutes after inhalation. Both agents had significant increases in FEV1/FVC and PEFR compared to baseline with no significant differences between two drugs. https://jpc.tums.ac.ir/index.php/jpc/article/view/40 https://jpc.tums.ac.ir/index.php/jpc/article/download/40/40