An airflow adaptor for a breath-actuated dry powder inhaler. The airflow adaptor includes a conduit having a proximal end and a distal end, wherein the proximal end allows fluid communication from a deagglomerator outlet port to the distal end of the conduit, and wherein the airflow adaptor further includes provisions for allowing air to flow from a proximal end of the adaptor to a distal end of the adaptor independently of the airflow in the conduit when a breath induced low pressure is applied to the distal end of the airflow adaptor.