Current and future directions of drug delivery for the treatment of mental illnesses

Mental illnesses including anxiety disorders, autism spectrum disorder, post-traumatic stress disorder, schizophrenia, depression, and others exact an immense toll on the healthcare system and society at large. Depression alone impacts 21 million adults and costs over $200 billion annually in the United States. However, pharmaceutical strategies to treat mental illnesses are lagging behind drug development in many other disease areas. Because many of the shortcomings of therapeutics for mental illness relate to delivery problems, drug delivery technologies have the potential to radically improve the effectiveness of therapeutics for these diseases. This review describes the current pharmacotherapeutic approaches to treating mental illnesses as well as drug delivery approaches that have improved existing therapies. Approaches to improve drug bioavailability, provide controlled release of therapeutics, and enable drug targeting to the central nervous system (CNS) will be highlighted. Moreover, next-generation delivery approaches such as environmentally-controlled release and interval/sequential drug release will be addressed. Based on the evolving landscape of the treatment of mental illnesses, the nascent field of drug delivery in mental health has tremendous potential for growth in terms of both economic and patient impact.