Administration, drugs subcutaneous route

Intravenous administration of a drug produces the most rapid drug action. Next in order of time of action is the intramuscular route, followed by the subcutaneous route Giving a drug orally usually produces the slowest drug action. 

Advantages of the intramuscular and subcutaneous routes include an increased reliability and precision in the drug blood level Anally achieved and reasonably rapid absorption and onset of drug action. There are, however, serious disadvantages as well. Pain, tenderness, local tissue necrosis (primarily with highly alkaline injections), microbial contamination, and nerve damage may be associated with these forms of parenteral administration. 

Drugs are administrated by intravenous routes or ex-travascular routes including oral, sublingual, subcutaneous, intramuscular, rectal (by enema or suppository), and transdermal. Available dosage forms include suspensions, immediate-release capsules or tablets, sustained-release capsules or tablets, and enteric-coated capsules or tablets that resist dissolution in the acidic pfi of the stomach. 

Parenteral administration This route is applicable for drugs which are inactivated by gastrointestinal tract or absorption is poor when given orally or there is a urgency for fast response in small dose. Intramuscular, intravenous, or subcutaneous routes are commonly used. The intravenous injection (in aqueous solution) is introduced directly into the vein by which a rapid response is produced. The subcutaneous injection are given through the layer of skin, while intramuscular injection, introduced through the skin layer deep into the muscle. The nature of intramuscular injection may be in aqueous or oily solution/suspension form. The aqueous solution will be rapidly absorbed as compared to oily solution or suspension. So, the rate of absorption is dependent on the nature of the preparation. 

In most species, chloramphenicol is rapidly and almost completely absorbed from the gastrointestinal tract. This route of administration provides antibiotic levels in blood comparable witli or higher than die intramuscular or the subcutaneous routes. The only known exception is in ruminants in which the drug is destroyed by the rumen microflora. 

Some limitations are that the amount of drug that can be injected in this fashion is fairly small and that the injected drug must not irritate or inflame the subcutaneous tissues. The subcutaneous route can also be used when certain types of drug preparations are implanted surgically beneath the skin, so that the drug is slowly dispersed from the implanted preparation and then absorbed into the bloodstream for prolonged periods of time.62,86 A common example of this form of subcutaneous administration is the use of implanted hormonal contraceptive products (e.g., Norplant).9,53 The use of these implantable contraceptives is discussed in more detail in Chapter 30. 

Several types of CDD systems have been designed based on various mechanisms of drug release (Table I). These mechanisms are dependent on the required site of drug delivery, the physicochemical properties of the drug and also of the delivery vehicle (13), Modes of administration can be oral, sublingual, transdermal, rectal, intrauterine, ocular, or parenteral (intramuscular, peritoneal, and subcutaneous routes of injection). 

In this chapter we will provide information about the basic characteristics of liposomes staring from their building blocks, that is, phospholipids. After this, liposome structure, physicochemical properties, and stability, which are most important for their in vivo performance, will be discussed as well as methods used for liposome preparation, characterization, and stabilization. Following this first part which is more technological, we will move into the biological part and talk about the fate of conventional liposomes and sterically stabilized liposomes, as well as liposomal drugs, after in vivo administration by different routes [mainly intravenous (i.v.), intraperitoneal (i.p.), or subcutaneous (s.c.)] and also give some information about other possible routes for in vivo administration of liposomes. Finally, specific applications of liposomes in therapeutics will be presented, some in more detail, mainly for the therapy of different types of cancer. 

Successful treatment depends not only on the formulation characteristics but also on the route of administration. For example, the schistosomicidal drug tartar emetic incorporated in PEGylated liposomes was delivered either intraperitoneally or subcutaneously (27mgSb/kg) to mice infected with Schisostoma mansoni [189]. Indeed, 82 and 67% reduction levels of worm were obtained, respectively. However, the efficacy of the formulation given by either administrative route was not significantly different. The only difference was the slower liposome absorption by the subcutaneous route. 

The aim of many of the hydrogels that have been designed for controlled drug release is to have their administration through different routes, for example, oral, nasal, vaginal, subcutaneous, or transdermal. ... 

For the intramuscular and subcutaneous routes, the use of non-aqueous vehicles may be considered as a method of avoiding hydrolysis. For IV administration, the use of an oil-in-water emulsion is a possible, although little used, option. These approaches are discussed in the section Strategies for Formulating Poorly Soluble Drugs . 

Patients with anemia secondary to chronic kidney disease are ideal candidates for epoetin alfa therapy. The response in predialysis, peritoneal dialysis, and hemodialysis patients is dependent on the severity of renal failure, erythropoietin dose and route of administration, and iron availability. The subcutaneous route of administration is preferred to the intravenous route because absorption is slower and the amount of drug required is reduced by 20 to 40%. 

Absolute bioavailability of a drug is the systemic availability of the drug after extravascular administration of the drug and is measured by comparing the area under the drug concentration-time curve after extravascular administration to that after IV administration, provided the and Vd are independent of the route of administration. Extravascular administration of the drug comprises routes such as oral, rectal, subcutaneous, transdermal, nasal, etc. 

---