Parenteral route intradermal injection

A parenteral route is used to inject medication into the patient. There are four parenteral routes intradermal (ID), subcutaneous (SC), intramuscular (IM), and intravenous (IV). The healthcare provider determines the choice of route based on the medication, desired onset, and the patient s needs. 

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... 

Figure 9.17 Routes of parenteral medication, showing the tissues penetrated by intramuscular, intravenous, subcutaneous and intradermal injections the needles, with bevel up, penetrate the epidermis (cuticle) consisting of stratified epithelium with an outer horny layer, the corium (dermis or true skin) consisting of tough connective tissue, elastic fibres, lymphatic and blood vessels, and nerves, the subcutaneous tissue tela subcutanea) consisting of loose connective tissue containing blood and lymphatic vessels, nerves, and fat-forming cells, the fascia (a thin sheet of fibrous connective tissue), and the veins, arteries and muscle.

The intradermal parenteral route is an injection that is given slightly below the surface of the skin where the medication is not absorbed into the bloodstream. The area of the skin is hairless, lightly pigmented, and thinly keratinized, providing a clear view of the site. The intradermal parenteral route is used to determine if there is a reaction to the medication, which is signified by a blister (wheal) on the injection site. 

The choice of which of the parenteral routes to use is determined by the prescriber based on the nature of the medication, the desired onset of the therapeutic effect, and the patient s needs. For example, the test for TB is performed by injecting the purified protein derivative intradermally, which is under the skin. Insulin is injected subcutaneously, although regular insulin can also be administered intravenous. Medications administered intravenously have a faster onset of therapeutic effect than other parenteral routes. Vaccinations, some antibiotics, and other medications are injected intramuscularly. 

Parenteral drug administration means the giving of a drug by the subcutaneous (SC), intramuscular (IM), intravenous (IV), or intradermal route (Fig. 2-5). Other routes of parenteral administration that may be used by the primary care provider are intralesional (into a lesion), intra-arterial (into an artery), intracardiac (into the heart), and intra-articular (into a joint), hi some instances, intra-arterial dragp are administered by a nurse. However, administration is not by direct arterial injection but by means of a catheter that has been placed in an artery. 

The formulation of parenteral products involves careful consideration of the proposed route of administration and the volume of the injection. Injections are administered to the body by many routes into various layers of the skin, the subcutaneous and muscle tissue, into arteries or veins, into or around the spinal cord, or directly into various organs (e.g., the heart or the eye). The volume to be injected can range from microliters, typically diagnostic agents administered intradermally or insulin administered subcutaneously, to several liters administered intravenously as infusions. The route of administration and the volume to be injected affect the composition of the formulation. 

Most work on saponins as immunological adjuvants has been done following parenteral inoculation. Saponins are more toxic by parenteral (i.p. or i.v.) administration than by the oral route, presumably because of a more complete uptake by the former. Toxicity associated with Quil A has limited its development to veterinary vaccines. The maximum well tolerated i.p. dose in mice was estimated to be 25 ig. Significantly lower toxicity was observed by subcutaneous, intradermal, and intramuscular routes of administration. The toxicity of individual saponins varies considerably. For example, the major peak saponin QS-18 (2) was found to be toxic in mice at low doses (80% mortality within three days after i.d. injection of 125 p,g) whereas QS-7 was non toxic (100% survival with 0.5 mg, the highest dose tested). A simple analogy between hemolytic activity and toxicity is not possible since QS-21 (3), which was shown to have a slightly higher hemolytic activity than QS-18 (2), was proven to be less toxic [9]. 

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