Parenteral routes, of drug administration

The IM and SC routes are by far the most frequently used extravascular parenteral routes of drug administration in farm animals. The less frequently used parenteral routes have limited application, in that they aim at directly placing high concentrations of antimicrobial agent close to the site of infection. These routes of administration include intra-articular or subconjuctival injection and intra-mammary or intra-uterine infusion. These local routes differ from the major parenteral routes in that absorption into the systemic circulation is not a prerequisite for delivery of drug to the site of action. The combined use of systemic and local delivery of drug to the site of infection represents the optimum approach to... 

Parenteral Routes of drug administration other than via the gastrointestinal tract. 

The route of administration is determined primarily by the properties of the drug (such as water or lipid solubility, ionization, etc.) and by the therapeutic objectives (for example, the desirability of a rapid onset of action or the need for long-term administration or restriction to a local site). There are two major routes of drug administration, enteral and parenteral. (Figure 1.2 illustrates the subcategories of these routes as well as other methods of drug administration.)... 

All routes of drug administration can affect ocular structures and functions. OADRs have been associated with topical ophthalmic administrations as well as local injections. Systemically, oral drug administration has been implicated most frequently in the development of OADRs. However, parenteral as well as inhaled or nasally applied drugs have also produced OADRs. Topical application to the skin, particularly if it is abraded or burned, may result in sufficient systemic absorption to lead to ocular side effects. Dermatologic use of antibiotics has resulted in ocular hypersensitivity reactions. 

In order to get to their site of action in the body, drugs have to be administered in some way. There are two major routes of drug administration enteral and parenteral. Enteral means to do with the gastrointestinal tract and includes oral and rectal administration. The parenteral route includes all other means of drug administration. There are many routes of parenteral administration, some of which are intended for a drug to have a systemic effect and others for a local effect. See Figure 2.1. 

Until recent times the routes of drug administration have remained essentially unchanged, consisting almost exclusively of either oral or parenteral administration. 

Besides the inhalative use, the development of a drug formulation for A9-THC has to address other bioavailabihty questions. A major problem is the hpophiUcity and poor solubiUty in water, hmiting oral uptake when given orally. Because of this, other parenteral routes of apphcation are imder investigation like puhnonal uptake by vaporization, subUngual or intranasal administration, and apphcation by injection of A9-THC incorporated in hpo-somes. 

The characteristics of the fluid to be injected will also influence the choice of parenteral routes. The drug must be compatible with other fluids (e.g., saline, dextrose, Ringer s lactate) with which it may be combined for administration to the patient, as well as with the components of the blood itself. 

When the first-pass effect of a drug going through the liver must be avoided, a parenteral route of administration is usually chosen, although a sublingual route or dermal patch will also avoid the first-pass effect. 

Many studies have been carried out regarding the absorption of peptides and proteins after pulmonary drug dehvery. The perspectives of a non-parenteral route of administration for larger proteins led to studies on the pulmonary absorption of proteins of different size. To date, over 30 different proteins have been evaluated with regard to absorption rate and... 

Some of the dosage formulations available for protein pharmaceuticals are listed in Table 5.7. An examination of Table 5.7 reveals that no protein drug up until this time has been formulated for oral administration. Most protein drugs are administered by means of injection (parenteral administration). Parenteral administration includes intravenous, intra-arterial, intracardiac, intraspinal or intrathecal, intramuscular, intrasynovial, intracuta-neous or intradermal, subcutaneous injections, and injection directly into a dermal lesion (e.g., a wart). The parenteral route of administration requires a much higher standard of purity and sterility than oral administration. It also may require trained... 

Protein-based drugs have been formulated mainly as stable liquids or in cases where liquid stability is limiting as lyophilized dosage forms to be reconstituted with a suitable diluent prior to injection. This is because their delivery has been limited primarily to the parenteral routes of intravenous (IV), subcutaneous (SC), or intramuscular (IM) administration. There are a few drugs that have been developed for pulmonary delivery, such as rhDNase (Pulmozyme ) and an inhalable formulation of insulin (e.g., Exubra ). However, even such drugs have been formulated as either liquid or lyophilized or spray-dried powders. This chapter will focus only on excipients that are applicable to liquid and lyophilized protein formulations. 

There are fewer reports on other parenteral routes of administration of emulsions such as intramuscular, subcutaneous, and intraperitoneal. V Mer-in-oil and w/o/w emulsions of bleomycin, mytomycin C, and 5-Luorouracil have been administered by these routes, apparently resulting in increased regional lymphatic uptake, hence the term lymphotropic emulsions (Davis et al., 1987). Gasco et al. (1990) developed a w/o emulsion of an LHRH analog measurements of testosterone levels after intramuscular administration to rats suggested that the formulation led to prolonged release of the drug. 

Intravascular Intravenous (IV) injection is the most common parenteral route. For drugs that are not absorbed orally, there is often no other choice. With IV administration, the drug avoids the Gl tract and, therefore, first-pass metabolism by the liver. This route permits a rapid effect and a maximal degree of control over the circulating levels of the drug. However, unlike drugs present in the Gl tract, those that are injected cannot be recalled by... 

The parenteral route of administration is effective only for drugs of low systemic toxicity that can be introduced into the eye at therapeutic concentrations. An important example of systemic dosing is the case of internal ocular infections, such as endophthalmitis, where a high concentration of antibiotic must be maintained. The systemic dose can also be augmented by topical drug applications to the eye. 

The U.S. Pharmacopoeia (USP) classifies injections into five different types. The dosage form selected for a particular drug product is dependent upon the characteristics of the drug molecule (e.g., stability in solution, solubility, and injectability), the desired therapeutic effect of the product (e.g., immediate vs. sustained release), and the desired route of administration. Solutions and some emulsions (e.g., miscible with blood) can be injected via most parenteral routes of administration. Suspensions and solutions that are not miscible with blood (e.g., injections employing oleaginous vehicles) can be administered via intramuscular or subcutaneous injection but should not be given intravenously. 

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