A route of administration is the path by which a drug, fluid, poison, or other substance is taken into the body. Routes of administration are generally classified by the location at which the substance is applied. Common examples include oral and intravenous administration. Routes can also be classified based on where the target of action is. Action may be topical (local), enteral (system-wide effect, but delivered through the gastrointestinal tract), or parenteral (systemic action, but delivered by routes other than the GI tract).

Routes of administration are usually classified by application location (or exposition). The route or course the active substance takes from application location to the location where it has its target effect is usually rather a matter of pharmacokinetics (concerning the processes of uptake, distribution, and elimination of drugs). Nevertheless, some routes, especially the transdermal or transmucosal routes are commonly referred to routes of administration. The location of the target effect of active substances is usually rather a matter of pharmacodynamics (concerning e.g. the physiological effects of drugs). Furthermore, there is also a classification of routes of administration that basically distinguishes whether the effect is local (in "topical" administration) or systemic (in "enteral" or "parenteral" administration).

Nanoparticles (NPs) occur naturally and have been in existence for thousands of years as products of combustion and cooking of food. Nanomaterials differ significantly from other materials due to the following two major principal factors: the increased surface area and quantum effects. These factors can enhance properties such as reactivity, strength, electrical characteristics, and in vivo behaviour. As the particle size decreases, a greater proportion of atoms are found at the surface compared to inside. An NP has a much greater surface area per unit mass compared with larger particles, leading to greater reactivity. In tandem with surface area effects, quantum effects can begin to dominate the properties of matter as size is reduced to the nanoscale. These can affect the optical, electrical, and magnetic behaviour of materials. Their in vivo behaviour can be from increased absorption to high toxicity of nanomaterials.

Size reduction is a fundamental unit operation having important applications in pharmacy. It helps in improving solubility and bioavailability, reducing toxicity, enhancing release and providing better formulation opportunities for drugs. In most of the cases, size reduction is limited to micron size range, for example, various pharmaceutical dosage forms like powder, emulsion, suspension etc. Drugs in the nanometer size range enhance performance in a variety of dosage forms. Major advantages of nanosizing include (i) increased surface area, (ii) enhanced solubility, (iii) increased rate of dissolution, (iv) increased oral bioavailability, (v) more rapid onset of therapeutic action, (vi) less amount of dose required, (vii) decreased fed/fasted variability, and (viii) decreased patient-to-patient variability.

Pharmaceutical nanotechnology has provided more fine-tuned diagnosis and focused treatment of disease at a molecular level. Pharmaceutical nanotechnology is most innovative and highly specialized field, which will revolutionize the pharmaceutical industry in near future. Pharmaceutical nanotechnology presents revolutionary opportunities to fight against many diseases. It helps in detecting the antigen associated with diseases such as cancer, diabetes mellitus, neurodegenerative diseases, as well as detecting the microorganisms and viruses associated with infections. It is expected that in next 10 years market will be flooded with nanotechnology devised medicine.

Smart drug delivery is a method of delivering medication to a patient in a manner that increases the concentration of the medication in some parts of the body relative to others. This means of delivery is largely founded on nanomedicine, which plans to employ nanoparticle-mediated drug delivery in order to combat the downfalls of conventional drug delivery. These nanoparticles would be loaded with drugs and targeted to specific parts of the body where there is solely diseased tissue, thereby avoiding interaction with healthy tissue. The goal of a targeted drug delivery system is to prolong, localize, target and have a protected drug interaction with the diseased tissue. The conventional drug delivery system is the absorption of the drug across a biological membrane, whereas the targeted release system releases the drug in a dosage form. The advantages to the targeted release system is the reduction in the frequency of the dosages taken by the patient, having a more uniform effect of the drug, reduction of drug side-effects, and reduced fluctuation in circulating drug levels. The disadvantage of the system is high cost, which makes productivity more difficult and the reduced ability to adjust the dosages.

A biomaterial is any substance that has been engineered to interact with biological systems for a medical purpose - either a therapeutic (treat, augment, repair or replace a tissue function of the body) or a diagnostic one. Biomaterials can be derived either from nature or synthesized in the laboratory using a variety of chemical approaches utilizing metallic components, polymers, ceramics or composite materials. They are often used and/or adapted for a medical application, and thus comprise whole or part of a living structure or biomedical device which performs, augments, or replaces a natural function. Such functions may be benign, like being used for a heart valve, or may be bioactive with a more interactive functionality such as hydroxy-apatite coated hip implants. Biomaterials are also used every day in dental applications, surgery, and drug delivery. For example, a construct with impregnated pharmaceutical products can be placed into the body, which permits the prolonged release of a drug over an extended period of time. A biomaterial may also be an autograft, allograft or xenograft used as a transplant material.

Vaccine is a material that induces an immunologically mediated resistance to a disease but not necessarily an infection. Vaccines are generally composed of killed or attenuated organisms or subunits of organisms or DNA encoding antigenic proteins of pathogens. Sub-unit vaccines though exceptionally selective and specific in reacting with antibodies often fail to show such reactions in circumstances such as shifts in epitopic identification center of antibody and are poorly immunogenic. Delivery of antigens from oil-based adjuvants such as Freunds adjuvant lead to a reduction in the number of doses of vaccine to be administered but due to toxicity concerns like inductions of granulomas at the injection site, such adjuvants are not widely used. FDA approved adjuvants for human uses are aluminium hydroxide and aluminium phosphate in the form of alum. Hence, search for safer and potent adjuvants resulted in the formulation of antigen into delivery systems that administer antigen in particulate form rather than solution form.

Other reasons driving the development of vaccines as controlled drug delivery systems are as follows:

• Immunization failure with conventional immunization regimen involving prime doses and booster doses, as patients neglect the latter. Vaccines delivery systems on the other hand:
• Allow for the incorporation of doses of antigens so that booster doses are no longer necessary as antigens are released slowly in a controlled manner.
• Control the spatial and temporal presentation of antigens to the immune system there by promoting their targeting straight to the immune cells.

Peptides and proteins have great potential as therapeutics. Peptides can be designed to target a broad range of molecules, giving them almost limitless possibilities in fields such as oncology, immunology, infectious disease and endocrinology. While the peptide and protein therapeutic market has developed significantly in the past decades, delivery has limited their use. Although oral delivery is preferred, most are currently delivered intravenously or subcutaneously due to degradation and limited absorption in the gastrointestinal tract. Therefore, absorption enhancers, enzyme inhibitors, carrier systems and stability enhancers are being studied to facilitate oral peptide delivery. Additionally, transdermal peptide delivery avoids the issues of the gastrointestinal tract, but also faces absorption limitations. Due to proteases, opsonization and agglutination, free peptides are not systemically stable without modifications.

Currently, the market for peptide and protein drugs is estimated to be greater than US$40 billion/year, or 10% of the pharmaceutical market. This market is growing much faster than that of small molecules, and will make up an even larger proportion of the market in the future. At present there are over 100 approved peptide-based therapeutics on the market, with the majority being smaller than 20 amino acids. Compared with the typical small-molecule drugs that currently make up the majority of the pharmaceutical market, peptides and proteins can be highly selective as they have multiple points of contact with their target. Increased selectivity may also result in decreased side effects and toxicity.