Leucine as an excipient in spray dried powder for inhalation

• Published in: Drug discovery today 2021-10, Vol.26 (10), p.2384-2396
• Main Authors: Alhajj, Nasser, O'Reilly, Niall J., Cathcart, Helen
• Format: Article
• Language: English
• Subjects: Administration, Inhalation; Aerosols; Drug Development - methods; Drug Stability; Dry Powder Inhalers; Excipients - chemistry; Humans; Leucine; Leucine - chemistry; Particle engineering; Pharmaceutical Preparations - administration & dosage; Pharmaceutical Preparations - chemistry; Powders; Regulatory considerations; Spray drying
• ISSN: 1359-6446; 1878-5832
• DOI: 10.1016/j.drudis.2021.04.009

[Display omitted] •Leucine physicochemical properties and spray drying behavior.•Formulation and processing parameters controlling leucine functionalities.•Functionalities of leucine in spray dried powder for inhalation.•Leucine applications in spray dried small molecule drugs and biopharmaceuticals.•Leucine regulatory consideration. Leucine is a promising excipient with several applications in the development of inhalable spray-dried powder of high- and low-dose drugs. The addition of leucine has exhibited significant enhancing effects on the aerosolization and physical stability of the produced particles. Here, we focus not only on the applications of leucine in inhalable spray-drying powders, but also on the underlying mechanisms by which the formulation and processing parameters dictate the behavior of leucine during the drying process and, therefore, its functionalities within the dried powder. Additionally, we highlight the current regulatory status of leucine. Such insights are important for more efficient utilization of leucine in the future, both for dry powder inhaler formulations and other pharmaceutical applications.