[en] Summary: Dry powder inhalers (DPIs) have been well established and recognized for the delivery to the lungs. It provides better drug stability, less irritable, easy to use with deep penetration of drugs in the lungs. Budesonide (BDS) and formoterol fumarate dihydrate (FFD) indicated in pulmonary diseases. The main aim of the study is to evaluate BDS, FFD and their marketed DPIs product in Pakistan were compare in quality and performance with the reference product. The particle size distribution and aerodynamic characterization were analyzed by laser diffraction and multi stage liquid impinger, respectively. The particle density and delivered dose uniformity were also determined. HPLC was also used for the qualitative and quantitative estimation of BDS and FFD along with its marketed products. Laser diffraction particle size analyzer revealed Dv50 53.27 to 56.34 µm having surface area 1815 to 2304 cm3/g. The percentages of emitted dose (%ED) and fine particle fraction (%FPF) was found 98.19 to 99.23% and 31.57 to 34.87%, respectively. The mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) were calculated 2.62 to 2.89 µm and 1.99 to 2.54, correspondingly. The quantitative assay of BDS and FFD in all the commercial DPIs and reference product were well within the pharmacopeial limit i.e. 97.26 to 101.36%. The average of ten units results of delivered dose uniformity for BSD and FFD were also found in the range i.e. 97.97 to 103.19% and 98.48 to 104.41 %, respectively. The results of evaluation of parameters of DPIs like Dv50, %ED, %FPF, MMAD, GSD has shown compliance with the pharmacopeial standards. It is concluded that the all DPIs of BDS/FFD marketed in Pakistan has revealed conformance with the standard of pharmacopoeia and meet the requirements of drug regulatory authority of Pakistan. (author)