*Review* **Digital Twins in Pharmaceutical and Biopharmaceutical Manufacturing: A Literature Review**

#### **Yingjie Chen 1, Ou Yang 2, Chaitanya Sampat 2, Pooja Bhalode 2, Rohit Ramachandran 2 and Marianthi Ierapetritou 1,\***


Received: 6 August 2020; Accepted: 31 August 2020; Published: 2 September 2020

**Abstract:** The development and application of emerging technologies of Industry 4.0 enable the realization of digital twins (DT), which facilitates the transformation of the manufacturing sector to a more agile and intelligent one. DTs are virtual constructs of physical systems that mirror the behavior and dynamics of such physical systems. A fully developed DT consists of physical components, virtual components, and information communications between the two. Integrated DTs are being applied in various processes and product industries. Although the pharmaceutical industry has evolved recently to adopt Quality-by-Design (QbD) initiatives and is undergoing a paradigm shift of digitalization to embrace Industry 4.0, there has not been a full DT application in pharmaceutical manufacturing. Therefore, there is a critical need to examine the progress of the pharmaceutical industry towards implementing DT solutions. The aim of this narrative literature review is to give an overview of the current status of DT development and its application in pharmaceutical and biopharmaceutical manufacturing. State-of-the-art Process Analytical Technology (PAT) developments, process modeling approaches, and data integration studies are reviewed. Challenges and opportunities for future research in this field are also discussed.

**Keywords:** digital twin; Industry 4.0; pharmaceutical manufacturing; biopharmaceutical manufacturing; process modeling
