Drug Delivery Technologies and Future Directions

he number of products based on new drug delivery systems has significantly increased in the past few years, and this growth is expected to continue in the near future. Recent advances in the field of genomics have accelerated research of biopharmaceuticals, and today a large number of companies are busy developing proteinand peptide-based drugs. These biopharmaceuticals present challenges to drug delivery scientists because of their unique nature and difficulty in delivery through conventional routes. Therefore, future research will focus on the delivery of these complex molecules through different routes, including oral, nasal, pulmonary, vaginal, rectal, etc. This review is an update on some of the existing drug delivery technologies for oral controlled-release, delivery of large molecules, liposomes, taste masking, fast-dispersing dosage forms, and technology for insoluble drugs. Nasal, pulmonary, vaginal, and rectal routes also are briefly reviewed. In the 21st century, the pharmaceutical industry is caught between the downward pressure on prices and the increasing cost of successful drug discovery and development. The average cost and time for the development of a new chemical entity are much higher (approximately $500 million and 10–12 years) than those required to develop a novel drug delivery system (NDDS) ($20–50 million and 3–4 years). In the form of an NDDS, an existing drug molecule can get a new life, thereby increasing its market value and competitiveness and extending patent life. Limited formularies, patent expiry with subsequent entry of generic competition, and vertical integration have the entire pharmaceutical industry (approximately 350 drug delivery companies and 1000 medical device companies) focused on designing and developing new and better methods of drug delivery. There has been a significant increase in approvals of NDDSs in the past couple of years, and this is expected to continue at an impressive rate in the near future. The sale of drug delivery products is valued at more than $22 billion worldwide, and this growth is expected to continue into the present century. It is estimated that the drug delivery market will be at $120 billion by 2007. At present, there are so many existing drug delivery technologies that a total compilation is not within the scope of this article. Yet an attempt is being made to compile some of the most successfully marketed drug delivery technologies. Most of the information is derived from the Internet sites of the major drug delivery companies.