Oral ingestion, gastrointestinal absorption

Anthocyanins are poorly absorbed from the gastrointestinal tract and the mechanisms involved remain unclear. These compounds are usually recovered in very small amounts in human serum after oral ingestion (less than 1% of the dose) or in the IN fraction after in vitro digestion (about 5%). ° Unlike other polyphenols, anthocyanins constitute an exception because intact glycosides are recovered in the body (without deglycosylation prior to absorption). - This may be explained by either the instability of the free aglycone form or by a specific mechanism of absorption for anthocyanins. 

After oral ingestion, ethanol pharmacokinetics must take into account (1) Absorption from the gastrointestinal tract. Since ethanol is absorbed most efficiently from the small intestines, the rate of gastric emptying is an important factor that governs the rate of rise of blood alcohol concentration (BAC), i.e., the slope of the ascending limb of the BAC-time curve, and the extent of first pass metabolism of ethanol by the liver and stomach. (2) Distribution of ethanol in the body. Ethanol distributes equally in total body water, which is related to the lean body mass of the person, and (3) the elimination of ethanol from the body, which occurs primarily by metabolism in the liver, first to acetaldehyde and then to acetate [7]. 

Elemental mercury in the form of mercury vapor is readily and rapidly absorbed into the bloodstream when inhaled and easily crosses the blood-brain barrier and the placenta. Oral ingestion of elemental mercury is far less hazardous than inhalation of mercury vapor due to its poor absorption in the gut. Acute, high level exposure to mercury vapor can result in respiratory, cardiovascular, neurological, and gastrointestinal effects, and even death. 

This presentation describes the effects of salvinorin A in humans, its deactivation by the gastrointestinal system and the essential role of the oral mucosa as an absorption site for salvinorin A from orally ingested leaves. 

As a rule, the highest concentrations of a poison are found at the site of administration. A large quantity of drug in the GI tract and liver indicates oral ingestion. The gastrointestinal (GI) tract may contain large amounts of unabsorbed toxicant. Cases that involve the oral administration of toxicants indicate analysis of GI contents. However, the presence of toxic material in the GI tract does not provide sufficient evidence that the agent is the cause of death. Absorption and transport of the toxicant to the site of action must be demonstrated. Blood and tissue analysis is necessary and would still be paramount. 

Epling and Jativa-M) containing the neoclerodane diterpene divinorin A or salvinorin A (Fig. 12.1). It was the first documented non-alkaloidal diterpene hallucinogen. It is inactivated by the gastrointestinal system if orally ingested, and the effect is produced after absorption through the oral mucous. 9... 

The majority of solid dosage forms are intended for oral ingestion. The drug released from the dosage form is available at the site of absorption or action within the gastrointestinal tract. 

Animal studies suggest that the acute oral toxicity of chlorhexidine is low, with little or no absorption from the gastrointestinal tract. However, although humans have consumed up to 2g of chlorhexidine daily for 1 week, without untoward symptoms, chlorhexidine is not generally used as an excipient in orally ingested formulations. 

Smoked cocaine is absorbed in seconds from the lungs, which results from volatilization of the alkaloid. Peak plasma concentrations occur within a few minutes. Absorption through mucous membranes is initially rapid, then slowed secondary to the vasoconstrictive effects of cocaine. Peak plasma concentrations occur within 1 h after oral ingestion and nasal application. After oral administration, bioavailability is decreased secondary to presystemic hydrolysis in the gastrointestinal tract. 

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