Application of freeze-drying in the development of oral drug delivery systems

ABSTRACT

Introduction: With continual focus on oral drug delivery systems (ODDS), the role of freeze-drying becomes increasingly valuable. While freeze-drying is fundamentally a desiccation process, the advantageous material properties attributed to freeze-drying extend far beyond the preparation of stable pharmaceutical products. The formulation and process variables are important considerations as they affect the final freeze-dried product characteristics. It is of interest to expound on the principles and effects of freeze-drying in the hope of introducing novel products for applications in the development of ODDS.

Areas covered: In this review, basic principles, general formulation and process variables associated with freeze-drying will be covered. The application of freeze-drying in 3 areas: modification of active ingredients, development of novel freeze-dried excipients and development of freeze-dried final dosage forms will be discussed.

Expert opinion: As a pharmaceutical unit operation, freeze-drying has created new dimensions in the area of oral drug delivery, where the properties of the drugs, excipients and characteristics of the final solid dosage form can be modified by the freeze-drying process. With the emergence of new applications, the role of freeze-drying technology in ODDS is indeed a relevant and promising one.

KEYWORDS:

• Freeze-drying
• pharmaceutical applications
• formulation
• excipients
• oral drug delivery systems

Article highlights

• Freeze-drying may be applied as a pharmaceutical unit operation to modify the properties of the active ingredient or develop novel excipients for oral drug delivery systems.

• The porosity conferred by freeze-drying is advantageous in enhancing the mechanical properties of the API or excipient for tablet compaction.

• The formulation flexibility conferred by the freeze-drying process is highly attractive as it enables a wide range of materials to be employed.

• With a suitable container system, freeze-drying may produce final oral solid dosage forms such as tablets and films.

• Freeze-drying process parameters are important considerations in achieving desired product quality attributes and high drying efficiency.

This box summarizes key points contained in the article.

Declaration of interest

The authors were supported by GEA-NUS Pharmaceutical Processing Research Laboratory, National University of Singapore. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.