Parenteral delivery routes advantages

The success of vaccination depends primarily on the method of presenting the antigen to the host immune system. Antigens have usually been delivered by parenteral (such as intravenous, intramuscular, intraperito-neal, intradermal, and subcutaneous) administration, but recent studies have shown that other routes of delivery such as intranasal, oral, and transdermal delivery have also been effective. In some cases, vaccination through mucosal routes resulted in better responses in IgA production. Because non-parenteral vaccine delivery presents many obvious advantages, numerous attempts have been made on the development of non-parenteral delivery of vaccines. 

Parenteral Administration Parenteral dosage forms include a wide variety of delivery routes, including injections, implants, and liposomes. The advantages of parenteral delivery systems is that they avoid first-pass effects, oral metabolism, and the harsh chemical environment of the stomach s gastric juices. The disadvantage is that the delivery mechanism is invasive. 

Local delivery provides advantages compared to traditional drug injection and aerosol administrations perfect alternative to parenteral drug administration tolerance to delivery via systemic or local administration routes... 

Most peptides and proteins are currently formulated as parenteral formulations because of their poor oral bioavailability. Nevertheless, oral delivery of peptides and proteins would be the preferred route of administration if bioavailability issues could be overcome, as it offers the advantages of convenient, pain-free administration. Although various factors such as permeability, chemical and metabolic stability and gastrointestinal transit time can affect the rate and extent of absorption of orally administered peptides and proteins, molecular size is generally considered the ultimate obstacle [36]. 

The relatively non-invasive nature of transdermal drug delivery, and the fact that this route can simultaneously avoid problems associated with presystemic metabolism and mimic (at least, to some extent) parenteral input profiles, are significant advantages. There have been, therefore, diverse attempts to exploit the skin for peptide and protein delivery. As we have noted before, transdermal administration, with or without one or more enhancement technologies, will always be limited to potent drugs and this accounts, once more, for the effort devoted to peptide and protein (i.e., typically very active substances) administration via this route. 

Parenteral administration is the primary route of testing delivery for nucleic acid therapeutics irrespective of whether systemic or local effects are desired. However, to some extent, pulmonary and oral routes are also investigated as potential routes for local targeting to treat cystic fibrosis or colonic tissue (171-173). For nonparenteral delivery, the use of pharmaceutical excipients in the formulation is critical. In addition, the production costs of nucleic acid therapeutic-containing drug delivery systems should be minimized. Even for intravenously or subcutaneously injected nucleic acid-based therapeutics, the use of protective carriers is most likely necessary, and advantageous as compared to injection of the naked RNA or DNA. Carriers can be divided into viral or... 

The oral mucosal route offers a number of advantages over parenteral and other non-invasive routes for the systemic delivery of biologically active peptides and proteins as well as conventional dmgs [78]. However, most drugs absorbed via the... 

Multiple emulsions have been widely studied as means of delivering drugs via oral, topical, and parenteral routes. The applications include protein delivery (Cournarie et al., 2004), delivery of antibiotics to the vagina (Tedajo et al., 2005), sustained delivery (Vaziri and Warburton, 1994), and vaccine delivery (Bozkir and Hayta, 2004). The immunological response to a vaccine also depends on the route of administration. Most current vaccines are administered intramuscularly, which induces immunization as a systemic immunity. However, the live polio vaccine and the live typhoid vaccine are administered orally. Local immunization (oral, intranasal, or intravagina) may be preferred, since mucosal surfaces are the common entrance to many pathogens. Moreover local immunization induces both mucosal and systemic immunity. Ease of administration and avoidance of systemic side effects are additional advantages of local immunization (Walker, 1994 Shalaby, 1995). Nevertheless, successful local immunization has only been achieved with a limited number of oral vaccines. Also there are very few studies on multiple emulsions used in the immunization process, especially on parenteral and oral administration. 

The oral route has certain limitations for some drugs, such as drag degradation in the gastrointestinal tract, gastrointestinal tissue irritation, and/or gut wall and first-pass metabolism. In this context, the nasal route has received a great deal of attention because of the many advantages of nasal delivery over oral and parenteral administration. 

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