Fasting state

The decreased insulin/glucagon ratio activates degradation of glycogen, protein, and triacylglycerols. 

In its critical role as the central organ for synthesis and distribution of fuel molecules, the liver is mainly focused on export of glucose to peripheral tissues during a short-term fast. 

The decreased insulin/glucagon ratio leads to inhibition of glycogen synthesis and increased glycogenolysis to supply some of the body s glucose needs on an immediate basis. 

The combination of these effects leads to increased intracellular glucose concentration, much of which is exported from the liver via reversal of transport mediated by GLUT2. 

During the fasting state, the energy needs of the liver are provided by fatty acid catabolism ( 3-oxidation), which spares further glucose for export to peripheral tissues. 

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The osmotic diuretics urea and mannitol are administered intravenously (IV), whereas glycerin and isosorbide are administered orally Administration by the IV route may result in a rapid fluid and electrolyte imbalance, especially when these drugs are administered before surgery with the patient in a fasting state ... 

FaSSIF fasted-state simulated artificial intestinal fluid... 

Over the course of these experiments, if gastric retention in the fasted state was observed for 24 h, the animal was given a standard pelletized meal once-a-day. The purpose for this was to observe the effects of food on hydrogel retention and also to determine if the presence of the gel had any effect on inhibiting the transit of food. 

The BCS scheme can be made more useful by incorporating a further improved basis of physicochemical profiling. For example, the role of pH in permeability measurements could be better defined. The use of simulated intestinal fluids for solubility measurements could be better promoted. The effects of fed/fasted states on absorption could be better address, in methods that have optimum clinical relevance. 

Surfactants added to dissolution media of insoluble drugs may produce dissolution results which are more indicative of the in vivo fed state than of the fasted state. 

Adult subjects who ingested soil (particle size less than 250 im) from the Bunker Hill NPL site absorbed 26% of the resulting 250 pg/70 kg body weight lead dose when the soil was ingested in the fasted state and 2.5% when the same soil lead dose was ingested with a meal (Maddaloni et al. 1998). There are no reported measurements of the absorption of soil-bome lead in infants or children. Additional evidence for a lower absorption of soil-bome lead compared to dissolved lead is provided from studies in laboratory animal models. In immature swine that received oral doses of soil from one of four NPL sites (75 or 225 ig Pb/kg body weight), bioavailability of soil-bome lead ranged from 50% to 82% of that of a similar... 

The important stages in delivering a drug to its desired target after an oral dose can be summarized as shown in Fig. 6.2. Initially the formulation has to be swallowed and survive the transition to the site of absorption - the gastrointestinal tract (GIT). The time required for this to happen will depend on the stomach emptying time, which in turn will be a function of the fed/fasted state of the subject or animal that is being studied (see for example Ref. [7]). This kind of information can only be obtained from in vivo studies. 

Fig-1. The density of bacteria along the gastrointestinal tract of man is shown schematically based on data from references 1-5 in the text. Density is given by logio CFU/ml of luminal contents in the fasting state. TBC = Total bacterial count. 

There are also segmental variations of intragastric acidity. Because the antrum is usually empty in the fasting state, local pH is substantially influenced by duodenogas-... 

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