Patient description: The patient is a 15-year-old boy with asthma diagnosed a year ago. He presents with shortness of breath, chest tightening and cough. According to his mother, he didn't respond to the usual corticosteroid inhaler. He was admitted to the emergency department with diagnosis of severe asthma exacerbation. He is a candidate for general corticosteroid therapy. Spirometry revealed a forced expiratory volume in the first second (FEV1) of 60% of the predicted. His past medical history is non-significant. His family history is significant for asthma in his mother and his uncle. He used to be treated with combination of inhaled corticosteroids and Zafirlukast.

Clinical trial eligibility criteria: eligible ages (years): 12.0-999.0,  Asthma Best pre-bronchodilator forced expiratory volume in 1 second (FEV1) of 40 to 85% of their predicted normal value. 2. Current Asthma Therapy: Patients must have a short-acting β2-agonist (for rescue use) for a minimum of 8 weeks before the Screening Visit (SV) and a low-dose inhaled corticosteroid (ICS). The low-dose ICS may be either as ICS monotherapy or as an ICS/long-acting beta agonist (LABA) combination. The ICS component of the patient's asthma therapy should be stable for a minimum of 1 months before providing consent. 3. Reversibility of Disease: Patients must have at least 15% reversibility (all patients) and at least a 200 mL increase from baseline FEV1 (patients age 18 and older) within 30 minutes after 2 to 4 inhalations of albuterol/salbutamol at the SV. Note: Patients who do not qualify for the study due to failure to meet reversibility will be permitted to perform a retest once within 7 days. 4. Patients must provide written informed consent/assent. For minor patients (ages 12 to 17 years, or as applicable per local regulations), the written ICF must be signed and dated by the parent/legal guardian and the written assent form must be signed and dated by the patient (if applicable). Note: Age requirements are as specified by local regulations. 5. Outpatient >= 12 years of age on the date of consent/assent. In countries where the local regulations permit enrollment of adult patients only, patients must be 18 years of age and older. 6. Asthma diagnosis: The patient has a diagnosis of asthma as defined by the National Institutes of Health (NIH). The asthma diagnosis has been present for a minimum of 3 months and has been stable (defined as no exacerbations and no changes in asthma medication) for at least 30 days. 7. The patient is able to perform acceptable and repeatable spirometry. 8. The patient is able to perform peak expiratory flow (PEF) with a handheld peak flow meter. 9. The patient is able to use a MDI device without a spacer device and a MDPI device. 10. The patient is able to withhold (as judged by the investigator) his or her regimen of ICS or study drug, and rescue medication for at least 6 hours before the SV and before all treatment visits. 11. The patient/parent/legal guardian/caregiver is capable of understanding the requirements, risks, and benefits of study participation, and, as judged by the investigator, capable of giving informed consent/assent and being compliant with all study requirements. 12. SABAs: All patients must be able to replace their current SABA with albuterol/salbutamol HFA MDI inhalation aerosol for the duration of the study. 13. Female patients may not be pregnant, breastfeeding, or attempting to become pregnant other may apply, please contact the investigator for more information  A history of a life-threatening asthma exacerbation (an asthma episode that required intubation and/or was associated with hypercapnea, respiratory arrest, or hypoxic seizures). 2. The patient is pregnant or lactating, or plans to become pregnant during the study period or for 30 days after the study. 3. The patient has participated as a randomized patient in any investigational drug study within 30 days of the SV. 4. The patient has previously participated as a randomized patient in a study of Fp MDPI or FS MDPI. 5. The patient has a known hypersensitivity to any corticosteroid, salmeterol, or any of the excipients in the study drug or rescue medication formulation (ie, lactose). 6. The patient has been treated with any known strong cytochrome P450 (CYP) 3A4 inhibitors (eg, azole antifungals, ritonavir, or clarithromycin) within 30 days before the SV. 7. The patient has been treated with any of the prohibited medications during the prescribed (per protocol) washout periods before the SV. 8. The patient currently smokes or has a smoking history of 10 pack years or more (a pack year is defined as smoking 1 pack of cigarettes/day for 1 year). The patient must not have used tobacco products within the past year (eg, cigarettes, cigars, chewing tobacco, or pipe tobacco). 9. The patient has a culture-documented or suspected bacterial or viral infection of the upper or lower respiratory tract, sinus, or middle ear that has not resolved at least 2 weeks before the SV. 10. The patient has a history of alcohol or drug abuse within 2 years preceding the SV. 11. The patient has had an asthma exacerbation requiring systemic corticosteroids within 30 days before the SV, or has had any hospitalization for asthma within 2 months before the SV. 12. Initiation or dose escalation of immunotherapy (administered by any route) is planned during the study period. However, patients on stable immunotherapy may be considered for inclusion. 13. The patient has used immunosuppressive medications within 4 weeks before the SV. 14. The patient is unable to tolerate or unwilling to comply with the appropriate washout periods and withholding of all applicable medications. 15. The patient has untreated oral candidiasis at the SV. Patients with clinical visual evidence of oral candidiasis who agree to receive treatment and comply with appropriate medical monitoring may enter the study. 16. The patient has a history of a positive test for human immunodeficiency virus (HIV), active hepatitis B virus, or hepatitis C infection. 17. The patient is either an employee or an immediate relative of an employee of the clinical investigational center. 18. A member of the patient's household is participating in the study at the same time. However, after the enrolled patient completes or discontinues participation in the study, another patient from the same household may be screened. 19. The patient has a disease/condition that in the medical judgment of the investigator would put the safety of the patient at risk through participation or that could affect the efficacy or safety analysis if the disease/condition worsened during the study other may apply, please contact the investigator for more information