Drug delivery

Lore & Background

Drug delivery encompasses a range of methods and technologies designed to transport pharmaceutical compounds to their intended sites of action, with the goal of optimizing therapeutic efficacy and safety while improving patient convenience. A key defining characteristic is the modification of a drug's pharmacokinetics and specificity through the combination of the drug with excipients, carriers, and medical devices that control its distribution and activity in the body. Enhancing bioavailability and prolonging the duration of action are essential strategies, particularly for managing chronic diseases. Research also emphasizes safety for those administering the medication; for instance, microneedle patches have been developed to minimize the risk of needlestick injuries. The field is closely linked to, yet distinct from, dosage form and route of administration. The route of administration is the path a drug takes to enter the body—such as oral, parenteral, transdermal, nasal, or ocular—while the dosage form is the physical presentation of the drug, like tablets, capsules, patches, or injectable solutions. A single route can accommodate multiple forms; the oral route, for example, can involve tablets, capsules, or liquid suspensions. Modern drug delivery expands these possibilities through novel and hybrid approaches, including nanoparticles, liposomes, microneedles, and hydrogels. Since the approval of the first controlled-release formulation in the 1950s, research into new delivery systems has progressed, driven partly by the high cost of developing new drugs; a 2013 review found the cost of developing a delivery system was only 10% of the cost of developing a new pharmaceutical. Other factors include the increasing prevalence of chronic and infectious diseases and a greater understanding of pharmacology. Current efforts focus on controlled-release formulations, targeted delivery, nanomedicine, drug carriers, 3D printing, and the delivery of biologic drugs.

Reader's Guide

Since the approval of the first controlled-release formulation in the 1950s, research into new delivery systems has progressed, while new drug development has declined. A 2013 review found the cost of developing a delivery system was only 10% of the cost of developing a new pharmaceutical. Factors driving this shift include the high cost of drug development, increasing prevalence of chronic and infectious diseases, and a greater understanding of pharmacology and pharmacokinetics. Current efforts include controlled-release formulations, targeted delivery, nanomedicine, drug carriers, 3D printing, and biologic drug delivery. Nanotechnology offers advantages such as precise targeting and increased drug potency, though concerns exist about potential tumor development and environmental harm. Targeted drug delivery aims to avoid host defenses and circulate to the intended site, using carriers like liposomes and nanogels. Microneedle patches deliver drugs painlessly through the skin and could enable home treatment, but remain expensive and not easily accessible. Controlled-release formulations maintain steady drug levels, reducing dosing frequency and side effects, and are especially useful for chronic conditions. Nanoparticle-based systems can respond to biological cues like pH to release drugs at tumor sites, improving effectiveness while protecting healthy cells.

Did You Know?

• The first controlled-release formulation was Dexedrine, approved in the 1950s.
• A 2013 review found the cost of developing a drug delivery system was only 10% of the cost of developing a new pharmaceutical.
• Microneedle patches can deliver vaccines or medications such as insulin without pain, but are very expensive and not easily accessible.
• Nanoparticles may contribute to the development of tumors in other parts of the body, according to some studies.