The inhalation therapy is one of the oldest drug delivery methods known. The significance of inhalation can be understood notably through its remarkable history. The goals of this review are to explore the pulmonary drug delivery, its significant relevance and various advantageous properties, particularly due to the physiology of the lungs. The drug delivery into the lungs can be provided by several inhalation instruments presently accessible on the market such as nebulizers, MDIs, and DPIs. Supplementary devices suchlike spacers for instance are also available in order to optimize the therapy results. The efficiency of these devices depends on several parameters of the formulation used, as well as its deposition in the lungs. Therefore, this review focuses on the meticulous testing performed on both the formulation and the device carrying it in the interest of insuring safety, quality, and efficacy of the final product. Ultimately, the pulmonary drug delivery represents a substantially advantageous alternative route of administration to obtain a systemic effect as well. This review aims to the better understanding of the development of pulmonary dosage forms and its complex process which requires extensive considerations and thorough optimization
