Drug delivery

Lore & Background

Drug delivery is closely linked with dosage form and route of administration, though the terms are distinct. The route of administration refers to the path by which a drug enters the body—such as oral, parenteral, or transdermal—while the dosage form is the physical form of the drug, such as tablets, capsules, patches, or injectable solutions. The same route can accommodate multiple dosage forms; for example, the oral route may involve tablets, capsules, or liquid suspensions. Modern drug delivery continues to expand possibilities through novel and hybrid approaches.

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.