Drug delivery
Drug delivery involves various methods and technologies designed to transport pharmaceutical compounds to their target sites helping therapeutic effect. It involves principles related to drug preparation, route of administration, site-specific targeting, metabolism, and toxicity all aimed to optimize efficacy and safety, while improving patient convenience and compliance. A key goal of drug delivery is to modify a drug's pharmacokinetics and specificity by combining it with different excipients, drug carriers, and medical devices designed to control its distribution and activity in the body. Enhancing bioavailability and prolonging duration of action are essential strategies for improving therapeutic outcomes, particularly in chronic disease management. Additionally, some research emphasizes on improving safety for the individuals administering the medication. For example, microneedle patches have been developed for vaccines and drug delivery to minimize the risk of needlestick injuries.
Drug delivery is closely linked with dosage form and route of administration, the latter of which is sometimes considered to be part of the definition. Although the terms are often used interchangeably, they represent distinct concepts. The route of administration refers specifically to the path by which a drug enters the body, such as oral, parenteral, or transdermal. In contrast, the dosage form refers to the physical form in which the drug is manufactured and delivered, such as tablets, capsules, patches, inhalers or injectable solutions. These are various dosage forms and technologies which include but not limited to nanoparticles, liposomes, microneedles, and hydrogels that can be used to enhance therapeutic efficacy and safety. The same route can accommodate multiple dosage forms; for example, the oral route may involve tablet, capsule, or liquid suspension. While the transdermal route may use a patch, gel, or cream. Drug delivery incorporates both of these concepts while encompassing a broader scope, including the design and engineering of systems that operate within or across these routes. Common routes of administration include oral, parenteral, sublingual, topical, transdermal, nasal, ocular, rectal, and vaginal. However, modern drug delivery continue to expand the possibilities of these routes through novel and hybrid approaches.
Since the approval of the first controlled-release formulation in the 1950s, research into new delivery systems has been progressing, as opposed to new drug development which has been declining. Several factors may be contributing to this shift in focus. One of the driving factors is 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. A more recent study found the median cost of bringing a new drug to market was $985 million in 2020, but did not look at the cost of developing drug delivery systems. Other factors that have potentially influenced the increase in drug delivery system development may include the increasing prevalence of both chronic and infectious diseases, as well as a general increased understanding of the pharmacology, pharmacokinetics, and pharmacodynamics of many drugs.
Current efforts
Current efforts in drug delivery are vast and include topics such as controlled-release formulations, targeted delivery, nanomedicine, drug carriers, 3D printing, and the delivery of biologic drugs.The relation between nanomaterial and drug delivery
Nanotechnology is a broad field of research and development that deals with the manipulation of matter at the atomic or subatomic level. It is used in fields such as medicine, energy, aerospace engineering, and more. One of the applications of nanotechnology is in drug delivery. This is a process by which nanoparticles are used to carry and deliver drugs to a specific area in the body. There are several advantages of using nanotechnology for drug delivery, including precise targeting of specific cells, increased drug potency, and lowered toxicity to the cells that are targeted. Nanoparticles can also carry vaccines to cells that might be hard to reach with traditional delivery methods. However, there are some concerns with the use of nanoparticles for drug delivery. Some studies have shown that nanoparticles may contribute to the development of tumors in other parts of the body. There is also growing concern that nanoparticles may have harmful effects on the environment. Despite these potential drawbacks, the use of nanotechnology in drug delivery is still a promising area for future research.Targeted delivery
is the delivery of a drug to its target site without having an effect on other tissues. Interest in targeted drug delivery has grown drastically due to its potential implications in the treatment of cancers and other chronic diseases. In order to achieve efficient targeted delivery, the designed system must avoid the host's defense mechanisms and circulate to its intended site of action. A number of drug carriers have been studied to effectively target specific tissues, including liposomes, nanogels, and other nanotechnologies.Microneedle Patches to Deliver Drugs
Drugs are delivered via scratch size patches known as Microneedle Patches. Microneedle patches are an invention of the introduction of drugs into the skin with the help of minute needles that are not painful. The patches can deliver vaccines or medications, including insulin to diabetes patients into the blood or skin. They are easy to use and they could make people give treatments at home. However, such patches are very expensive and not easily accessible.Controlled-release formulations
Controlled or modified-release formulations are designed to deliver medications at a steady rate over time, helping maintain consistent drug levels in the bloodstream. This steady release reduced how often patients need to take their medication and minimizes the ups and downs in drug concentration that can cause side effects or lower effectiveness. These systems often take the form of matrix tablets, osmotic pumps, and reservoir-type devices, all of which use physical or chemical barriers to regulate how the drug is released. This approach is especially useful for chronic conditions such as high blood pressure, diabetes, or chronic pain, where maintaining stable therapeutic levels is key to keeping symptoms under control.The concept of controlled-release medication dates back to the 1950s, when Dexedrine became the first such formulation on the market. This era saw the introduction of transdermal patches, which deliver drugs slowly through the skin. As technology progressed, new formulations were developed to match the specific properties of different drugs. Examples include long-acting depot injections for medication like antipsychotics and hormone therapies, which remain effective for weeks or even months after a single dose.
Since the late 1990s, research has increasingly turned to nanotechnology as a way to improve controlled-released drug delivery. Nanoparticles, tiny carriers engineered at a molecular level, can protect drugs from being broken down too quickly in the body, improve how well they're absorbed, and deliver them directly to the tissues where they're needed. This targeted delivery not only reduces side effects but also helps patients stay on track with their treatments. These advances in nanotechnology are transforming the landscape of drug delivery and are emphasizing the importance of developing the next generation of CR systems.
Nanoparticle-based Controlled-Release
The use of nanotechnology into drug delivery has opened the door to new possibilities, particularly with the development of nanoparticle-based controlled-release systems. These systems are designed to deliver drugs more precisely and over longer periods of time helping with targeted sites and therapeutic effects. Tiny carriers, such as liposomes, dendrimers, and polymeric nanoparticles, can hold medication and release them at controlled rates. Some are even engineered to respond to specific conditions in the body. For instance, acidic microenvironment commonly found in tumor tissues can be used to trigger drug release at the site needed. This targeted approach helps minimize side effects by limiting exposure to the rest the body. Thus, making treatment more effective.Recent studies have shown the effectiveness of smart nanoparticles that respond to biological cues, such as pH or redox conditions, thereby delivering drugs more precisely to tumor sites. For instance, pH-sensitive nanoparticles take advantage of the lower pH in tumor cells to release the drugs, which boost effectiveness while protecting healthy cells. Additionally, the use of biocompatible materials and switching the nanoparticle surfaces have improved their accuracy and release of delivery systems.
Advances in design have also made it possible to create multi-functional nanoparticles that are capable of handling tough challenges like multi-drug resistance in cancer. These systems can carry more than one type of drug, targeting specific molecules, which helps to deliver a stronger punch to tumor tissues. Altogether, these breakthroughs point to a potential for nanoparticle-based controlled-release therapies in the fields of cancer therapy and personalized medicine.