Nasal pharmaceutical formulations comprising a drug substance having a specific particle size distribution profile are disclosed herein. Such profile provides increased bioavailability, increased efficacy or prolonged therapeutic effect of the drug substance when administered intranasally. The formulations of the present invention may comprise one or more corticosteroids having a specific particle size distribution profile. In a preferred embodiment, the corticosteroid is beclomethasone or a pharmaceutically acceptable derivative thereof for the treatment of one or more symptoms of rhinitis. Preferably, the drug substance is beclomethasone dipropionate. The formulations herein may be provided as an aqueous suspension suitable for inhalation via the intranasal route.