Gastrointestinal tract stomach mucosa

Absorption. Absorption of cyanide across the gastrointestinal mucosa depends on the pH of the gut and the pKa and lipid solubility of the particular cyanide compound. Hydrogen cyanide is a weak acid with a pKa of 9.2 at 25 °C. The acidic environment in the stomach favors the non-ionized form of hydrogen cyanide and facilitates absorption. Information regarding the rapid lethal effects following oral intake of cyanide in humans (Gosselin et al. 1976) indicates that cyanide is rapidly absorbed from the gastrointestinal tract. 

After a 24 h starvation period groups of 8-10 rats weighing 150-200 g are used. The candidate compound is administered orally in 0.1 % Tween 80 solution. Six hours later, the rats are sacrificed in CO2 anesthesia and their stomachs and intestines are removed. The stomach and gastrointestinal tract are removed. The mucosa is examined with a stereomicroscope and examined and assessed in relation to an ulceration index. The number of ulcers is noted and the severity recorded with the following scores ... 

Absorption. The rate of absorption from the gastrointestinal tract after oral dosage determines the speed of the onset of action of a benzodiazepine. For a quick onset of action, the benzodiazepine must dissolve completely in the stomach and cross the stomach mucosa into the systemic circulation. The different dissolution and absorption kinetics of benzodiazepines will affect their onset of action. Once the benzodiazepine is in the systemic circulation, it must also cross the blood-brain barrier to enter the CNS. Therefore, the lipophilidty of the benzodiazepine is important in determining the entry into the CNS and the onset of clinical action. Most benzodiazepines are highly lipophilic with the 3-hydroxy-substi-tuted benzodiazepines (lormetazepam, loraz-epam, temazepam, and doxefazepam) triazolam is the least lipophilic. 

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