Enteral administration routes

The route of antibiotic administration might be crucial. Animal studies [193, 194] have shown that enteral administration (either by oral or rectal route) of antimicrobials reduces the rate of bacterial translocation and early mortality in rats or mice with experimentally induced pancreatitis. Indeed, in patients with ANP, selective bowel decontamination with oral and rectal antibiotics decreased the infection rate [195]. 

Drugs are administered to animals by parenteral or enteral administration, and topical application. Parenteral administration bypasses the alimentary tract and can be effected by a variety of routes including intravenous, intramuscular, subcutaneous, intraperitoneal, or intrapleural injections inhalation and percuta-neously. In intravenous injections, entry of dmgs into the system depends only upon the rate of injection and not on absorption into the bloodstream. As a result, water-soluble poorly absorbed drugs may be readily administered. 

Route of Administration There are three main routes of exposure for an environmental chemical to enter the body of an animal. These are the oral, dermal, or inhalation routes. The choice of administration route for a chemical depends on the physical and chemical characteristics of the test chemical and the form typifying exposure in humans. In general, the frequency of exposure may vary according to the administration route chosen and should be adjusted according to the toxicokinetic profile of the test chemical, if available. 

The deltoid muscle can be used for i.m. injections in older children, but it is not an option for young infants and children because of their limited muscle mass. Although there are few complications associated with this administration route, nerve injury can occur. The technique is shown in Fig. The area for deltoid administration should be fully visible so that the anatomical landmarks can be visualized. Then the needle for deltoid injection should enter the muscle halfway between the acromium process and the deltoid tuberosity to avoid hitting the underlying nerves. The drug volume that can be administered by this route to older children and adults is 0.1-2ml.The recommended needle length for older children is 1 in. (2.5 cm). 

Parenteral is defined as situated or occurring outside the intestine, and especially introduced otherwise than by way of the intestines —pertaining to essentially any administration route other than enteral. This field is obviously too broad for an adequate focus in one book, let alone one chapter. Many have nonetheless used the term synonymously with injectable drug delivery. We restrict ourselves to this latter usage. This would thus include intravenous, intramuscular, subcutaneous, intrathecal, and subdural injection. In this chapter we discuss the theoretical and practical aspects of solubilizing small molecules for injectable formulation development and will examine the role of surfactants and other excipients in more recent parenteral delivery systems such as liposomes, solid-drug nanoparticles and particulate carriers. 

There are two main ways by which substances may be administered to humans the enteral and the parenteral routes. For enteral administration the substance is placed directly into the gastrointestinal tract by permitting a tablet to dissolve when it is placed under the tongue (sub-lingual administration), or by swallowing a tablet, capsule or a solution (oral) or by rectal administration as a suppository. In parenteral administration the substance in solution may be injected subcutaneously, intramuscularly or intravascularly, inhaled as an aerosol, applied topically to the skin as a cream or ointment, or, rarely, in the form of a pessary. 

The most widely used parenteral administration avenues are intravenous (iv), intramuscular (im), and subcutaneous (sc). In addition, there are several minor applications (e.g. intraarterial). Application of a protein drug by the different main parenteral administration routes may have profound effects on the pharmacological performances. When the drug is administered iv, it is immediately available for action in the circulation, while drugs administered im or sc need more time to reach the blood (depot effect), and consequently the pharmacokinetic (PK) profiles could be different. Besides the PK, the route of administration may have influence on the primary distribution of the drug. For example, when administered sc, smaller and hydrophiUic proteins tend to enter the venous system, while larger and/or more hydrophobic proteins tend to... 

In nursing homes psychoactive medicines are commonly administered as drops. If there is no oral liquid form available, the pharmacist may receive a doctor s prescription for the adaptation of an oral solid into an oral liquid. Tablets may be pulverised or capsules can be emptied and administered with semisolid food. However, there may be other solutions such as improving swallowing technique or a different administration route. Even for patients with an enteral feeding tube there may be alternatives or at least points of attention. 

Area under the Curve (AUC) refers to the area under the curve in a plasma concentration-time curve. It is directly proportional to the amount of drug which has appeared in the blood ( central compartment ), irrespective of the route of administration and the rate at which the drug enters. The bioavailability of an orally administered drug can be determined by comparing the AUCs following oral and intravenous administration. 

O Parenteral nutrition (PN), also called total parenteral nutrition (TPN), is the intravenous administration of fluids, macronutrients, electrolytes, vitamins, and trace elements for the purpose of weight maintenance or gain, to preserve or replete lean body mass and visceral proteins, and to support anabolism and nitrogen balance when the oral/enteral route is not feasible or adequate. 

Maintaining adequate nutritional status, especially during periods of illness and metabolic stress, is an important part of patient care. Malnutrition in hospitalized patients is associated with significant complications, including increased infection risk, poor wound healing, prolonged hospital stay, and increased mortality, especially in surgical and critically ill patients.1 Specialized nutrition support refers to the administration of nutrients via the oral, enteral, or parenteral route for therapeutic purposes.1 Parenteral nutrition (PN), also... 

It might be expected that EN via tubes would have been used widely before the development of parenteral nutrition (PN) however, this was not actually the case. EN via tubes inserted down the mouth or nose into the stomach and also via rectal tubes was used occasionally in the decades before the development of PN in the 1960s.1 However, modern techniques for enteral access, both the placement of the tubes themselves and the materials for making pliable, comfortable tubes, had not yet been developed. Before the PN era, the formulas delivered by the tube route often were blenderized foods. The National Aeronautics and Space Administration effort in the United States in the 1960s led to the development of low-residue (monomeric) diets for astronauts. These diets were adapted for use in sick patients requiring EN. Nonvolitional feedings in patients who cannot meet nutritional requirements by oral intake thus include EN and PN these techniques are collectively known as specialized nutrition support (SNS). 

For all commonly used routes of administration except intravenous, the drug must dissolve in body fluids and diffuse through one or more membranes to enter the plasma. Thus, all routes except intravenous are classed as extravascular routes, and absorption is defined as appearance of the drug in plasma. 

When 20 mg/kg of methimazole was administered i.p. or orally to rats, urinary methimazole glucuronides accounted for 36-48% of the dose in 24 hours. The only other urinary metabolite accounted for 10-20% and was not characterized. An additional 14-20% of methimazole was excreted unchanged in 24 hour urine. The bile contained methimazole glucuronide and two unidentified metabolites. One of which was the same as the unidentified urinary metabolites. Plasma proteins bound 5% of methimazole which had no affinity for any specific tissue. Methimazole had a much greater CHCI3/H2O partition coefficient and 1 0 solubility than did propylthiouracil. Between 77 and 95% of the methimazole was excreted in the urine and approximately 10% in the bile. Since fecal excretion was neglegible an enter-ohepatic circulation was present. The half life of urinary excretion was 5-7 hours regardless of the route of administration (15). 

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